UNIVERSITY OF CALIFORNIA 
 
 COLLEGE OF AGRICULTURE 
 
 AGRICULTURAL EXPERIMENT STATION 
 
 BERKELEY, CALIFORNIA 
 
 POULTRY FEEDING: PRINCIPLES 
 AND PRACTICE 
 
 WALTHER F. HOLST and WILSON E. NEWLON 
 
 BULLETIN 417 
 
 February, 1927 
 
 UNIVERSITY OF CALIFORNIA PRINTING OFFICE 
 
 BERKELEY, CALIFORNIA 
 
 1927 
 
Digitized by the Internet Archive 
 
 in 2012 with funding from 
 
 University of California, Davis Libraries 
 
 http://www.archive.org/details/poultryfeedin4171927hols 
 
POULTRY FEEDING: PRINCIPLES AND PRACTICE 
 
 WALTHEE F. HOLSTi and WILSON E. NEWLON2 
 
 PRINCIPLES OF POULTRY FEEDING 
 
 The production of eggs and market poultry is a process of trans- 
 forming comparatively cheap feeds into high-priced products for 
 human consumption. The fowl's body is the agent which effects this 
 transformation. Under the highly specialized conditions of com- 
 mercial egg production in California, the poultryman cannot expect 
 the greatest efficiency from his birds without a working knowledge of 
 the principles of animal nutrition. Poultry feeding should be based 
 on the food requirements of the birds, the nutritive value of the 
 different feeds and a knowledge of how to use these with particular 
 objects in view. 
 
 NECESSITY FOR FOOD 
 
 Although plants can nourish themselves from such simple sources 
 as soil and air, domestic birds, like all other animals, require ready- 
 made nutrients. They utilize these for two main purposes : 
 
 1. As building material for the construction of new tissues and 
 
 their products. 
 
 2. As a source of heat and energy. 
 
 At all times newly formed tissue is needed for replacement of the 
 tissue destroyed by the general wear and tear of the body. Cells (i.e., 
 the small units of which the tissues of the body are composed), are 
 constantly being worn out, broken down and sloughed off. These 
 cells have to be replaced by material from the outside. During cer- 
 tain periods new tissue is needed also for growth and reproduction; 
 that is, for the formation of new body material and reproductive cells. 
 The body also needs energy for the production of heat, which is 
 necessary to maintain the body temperature and for all the body 
 activities, including locomotion, blood circulation, respiration, diges- 
 tion, absorption and excretion. These activities are the distinguishing 
 characteristics of what is called animal life, and all consume energy. 
 
 1 Assistant Poultry Husbandman, Agricultural Experiment Station. 
 
 2 Poultry Specialist, Agricultural Extension Service. 
 
4 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION 
 
 For these purposes birds need a constant supply of food. If this 
 supply should fail for any length of time the birds would begin to 
 lose weight, living on and consuming their own body material until 
 death occured. This usually happens within about 34 days, during 
 which time there is a loss of body weight of from 20 to 50 per cent. If, 
 on the other hand, the supply exceeds the demand ; that is, more food 
 is provided than is required for these activities, the body has the power 
 to store the excess digested food as body fat. Body fat is nature's 
 provision of a reserve, in case the food supply should fail partly or 
 completely for a short period. 
 
 Food is composed of several distinctly different groups of sub- 
 stances, which are called nutrients. Of these the following six groups 
 are recognized : proteins, carbohydrates, fats, vitamins, minerals, and 
 water. 
 
 DIGESTION OF FOOD 
 
 Most of the nutrients cannot be used by the birds in the form in 
 which they are supplied in the food. They must undergo digestion, 
 which means breaking them down into their very simplest and most 
 soluble forms, so that they can pass through the intestinal wall, be 
 absorbed by the blood, and distributed through the body. Digestion 
 is made possible by the agency of various chemical substances, called 
 enzymes or ferments. These are supplied in the digestive juices, and 
 partly, also, in ordinary feeds. Digestion in birds is very rapid. 
 Complete digestion of grains requires from ten to fifteen hours while 
 digestion of mash requires from two and a half to four hours only. 
 
 NUTRIENTS 
 
 Proteins. — Protein is the name of a group of very complex organic 
 substances, which always contain carbon, hydrogen, oxygen, and 
 nitrogen. Proteins usually also contain sulphur and frequently phos- 
 phorous. These substances are widely distributed, both in plants, 
 which, as indicated, build them up from simple sources in the soil 
 and air, and in animal tissues, which must derive them directly or 
 indirectly from plant tissues. The thousands of different known 
 forms of protein vary widely in character but have two characteristics 
 in common; they all contain nitrogen in a definite proportion (16 
 per cent) and all are composed of certain simpler building-stones, the 
 amino acids. 
 
 A bird's body contains as much protein as all other groups of 
 nutrients together, if water is excepted. Twenty per cent of the live 
 
BUL. 417] POULTRY FEEDING: PRINCIPLES AND PRACTICE 5 
 
 weight and practically 50 per cent of the dry weight is protein. It is 
 therefore easy to understand the importance of this group of nutrients 
 in feeding. 
 
 Of the amino acids which form the proteins, about twenty are 
 known. Certain of the amino acids are more important from the 
 standpoint of feeding practice than others. This is because some of 
 them, such as tryptophane, lysine, and cystine cannot be built up by 
 fowls from other amino acids, while certain others, such as glycocol, 
 can be formed in the bird 's body from the excess of other amino acids 
 present. 
 
 
 
 
 
 
 
 
 y 
 
 / 
 
 
 
 
 
 
 
 
 
 
 
 
 
 f 
 
 s 
 
 
 
 
 
 
 
 
 
 
 
 
 
 /' 
 
 
 
 
 
 
 
 
 
 
 
 
 
 .~y 
 
 <f 
 
 
 
 
 
 
 
 
 
 ■/ 
 
 s 
 
 
 
 i 
 1 
 
 f 
 
 
 
 
 
 
 
 
 ** 
 
 
 s 
 
 
 
 ^ 
 
 1 
 1 
 
 
 
 
 
 Zei 
 
 ■» *■ T 
 
 "ypi-op 
 
 hone 
 
 X 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 ^ 
 
 
 
 
 
 
 +ZOdoys-* 
 
 
 
 
 
 
 Fig. 1. — Comparison of growth on complete and incomplete proteins 
 (after Mendel). 
 
 Figure 1 illustrates the changes in body weight of rats fed on poor 
 proteins ; that is, proteins lacking in one or more of the essential 
 amino acids. In the case which supplied the data Indian corn was 
 the only source of protein. The protein part of corn, which is called 
 zein, is known to be lacking in the two amino acids, tryptophane and 
 lysine. Not until those two were added did growth take place. The 
 addition of tryptophane only was sufficient to maintain body weight, 
 but growth did not begin until lysine was added also. Exactly similar 
 results would be expected if chicks were used. Other grain proteins 
 have similar deficiencies. 
 
 To be complete and give the best results as a food, a protein must 
 contain all of these essential amino acids. Naturally the necessary 
 amino acids may be provided by a combination of properly chosen 
 incomplete proteins. Proteins in the form in which they are present 
 
b UNIVERSITY OF CALIFORNIA EXPERIMENT STATION 
 
 in the feed are of no value to the birds ; as indicated in figure 2, they 
 have to be broken down by digestion into the amino acids, which are 
 soluble and therefore can be absorbed by the blood. The blood carries 
 the amino acids to different parts of the body, where, according to the 
 bird's needs, they are put together again into new proteins, the body 
 proteins. 
 
 CRUPE FOOD PROTEINS 
 
 Undigested 
 Food 
 
 Digestive Tract 
 
 Amino Acids 
 
 Body 
 
 i 
 
 Body Protein 
 
 Excess Amino Acids 
 
 Uric Acid, Urea 
 Ammonia, etc. 
 
 Nitrogen Part Carbohyt rate Part Fat Par + 
 
 Liver 6iycogen Body Fat 
 
 I 
 
 1 
 
 Muscle 6 iy coy en 
 
 k-. 
 
 1 
 
 Fgg Protein + Fot 
 
 Burned (Oxidized) ] 
 I for tfeat r Energy \ 
 ~lr 
 
 «j 
 
 *■ no 
 
 Fig. 2. — Scheme illustrating the use of proteins in the body. 
 
 If protein is provided in excess of requirements, the amino acids 
 are formed and absorbed by the blood as usual. In the liver, however, 
 they are deprived of their nitrogen, thus being transformed into one 
 or both of two other classes of nutrients, carbohydrates and fats. The 
 fate of the tissue protein after it is worn out is similar. It is broken 
 down into amino acids, which are then deprived of their nitrogen, the 
 remaining part being used in the animal organism. The nitrogen thus 
 separated from the amino acids does not appear in the free form, but 
 is normally split off as ammonia, which is transformed inside the 
 bird 's liver into uric acid and urea, substances which are then expelled 
 as parts of the urine through the kidneys. A diet too high in protein, 
 therefore, puts an unnecessary and dangerous burden on these organs. 
 
BUL. 417] POULTRY FEEDING : PRINCIPLES AND PRACTICE 7 
 
 As indicated above, excess of protein in a feed is not wholly wasted. 
 The nitrogenous part is wasted, but the rest becomes carbohydrates 
 and fats. While protein can thus replace carbohydrates or fats to a 
 certain degree, the reverse is not possible, because these latter nutrients 
 do not contain nitrogen and are not capable of taking it up. A lack 
 of protein in a ration may lead to cannibalism, which in that case is 
 merely an expression of the craving for protein. 
 
 Carbohydrates. — These organic compounds contain only three 
 chemical elements : carbon, hydrogen, and oxygen. The last two ele- 
 ments nearly always appear in the same proportions as they exist 
 
 Food Carbohydrates 
 
 Digest i\ 
 
 e Tract 
 
 Simple 5ugars 
 
 Body 
 
 L 
 
 1 
 
 Undigested 
 Food 
 
 Liver Glycogen 
 
 I 
 
 1 
 
 Body Fat 
 
 Muscle 6lc/cogen 
 
 x 1 , 
 
 I Burned (Oxidized) j 
 \ibr Heat t Energy 
 
 Egg Fat 
 
 CQsHJ) 
 
 Fig. 3. — Scheme illustrating the use of carbohydrates in the body. 
 
 in water, in fact, the name carbohydrate means carbon-water. The 
 carbohydrate group includes the starches, sugars, and celluloses. The 
 celluloses, however, are generally classed separately under various 
 headings as "fiber," "crude fiber," etc., in tables giving the composi- 
 tion of feeds. The crude fiber is wholly indigestible for poultry. 
 
 In the course of digestion the carbohydrates as shown in figure 3, 
 are broken down into the simplest kind of sugars, the so-called mono- 
 saccharids, in which form they are absorbed. The monosaccharids 
 readily combine with oxygen (which is absorbed from the lungs by the 
 haemoglobin of the blood) ; they are thus oxidized (or burned) to 
 carbon dioxide and water with the production of heat. Upon this 
 heat liberation, as already mentioned, the different life processes of 
 birds, as of other animals, are absolutely dependent. 
 
8 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION 
 
 The scarcity of carbohydrates in the animal body and their pre- 
 ponderance in the feeds indicate that they are stored only temporarily 
 as carbohydrates and are either nsed comparatively soon, serving as 
 fuel for the animal organism, or for the most part stored in some 
 other form (fat, see below). They are found stored in certain tissues, 
 however. This is because the body requirements for fuel vary widely, 
 being high during vigorous exercise and low during rest and sleep. 
 The liver acts as a regulator of this fuel supply. As the blood, with 
 the dissolved sugars, passes from the intestines on its way to the heart, 
 it circulates through the liver, where excess sugars are deposited, to 
 be stored in the form of animal starch or glycogen. This carbohydrate 
 is also stored in the muscles. 
 
 After feeding and during rest this starch may compose as much 
 as 15 per cent of the weight of the liver. At other times, as during 
 starvation or after vigorous exercise, it may be found to compose as 
 little as 2 per cent of this organ. The muscles normally contain about 
 0.6 per cent of glycogen, the total amount in all the muscles of the 
 body being approximately equal to that in the liver. When any muscle 
 or organ of the body is used, a supply of energy in the form of 
 glycogen is present within the particular muscle or organ of which 
 work is required. The glycogen is broken down and oxidized, setting 
 free the necessary energy. The muscles then immediately begin to 
 draw on the main reserve of glycogen in the liver for the replenishing 
 of their supply. The liver in turn receives its replacements from 
 the food. 
 
 Consequently the liver is not only a storage place for but also the 
 regulator of the carbohydrate supply. It stores the excess sugar after 
 meals and later gives it up to the blood which distributes it to the 
 different body parts according to demand. 
 
 p a ts. — These are compounds of an alcohol (usually glycerin) and 
 the fatty acids (commonly, stearic, palmitic and oleic acid). Like 
 carbohydrates they contain only the three elements, carbon, hydrogen, 
 and oxygen. They differ from carbohydrates in that oxygen is con- 
 tained in much smaller proportions. (Starch and sugars contain 
 between 49.4 and 53.3 per cent; fats on the other hand contain about 
 11.0 per cent oxygen.) 
 
 In the body, fats from the food are broken down (digested) to 
 free fatty acids and glycerin, as illustrated by figure 4, which pass 
 through the intestinal wall, immediately to be recombined into fats. 
 These are taken up by and pass along with the blood in a suspended 
 form. The fats are used for energy purposes, probably being first 
 
BUL. 417] POULTRY FEEDING : PRINCIPLES AND PRACTICE 9 
 
 transformed into sugars, which then combine with more oxygen, pro- 
 ducing heat, carbon dioxide, and water. If not needed immediately as 
 a source of energy they are deposited within the cells and in the 
 so-called adipose or fatty tissue. This is found below the skin, in the 
 folds of the abdominal cavity, and as protective layers around certain 
 vital organs like the kidneys. 
 
 Body fats are also derived from another source. Since the storage 
 places for carbohydrates, the liver and muscles, soon become loaded to 
 their limit, a transformation process sets in, changing carbohydrates 
 into fats. Carbohydrates in excess, therefore, produce body fats, and 
 
 Food Fat 
 
 Digestive Tract 
 \6lycerin + Fatty Acids 
 
 Body 
 
 I 
 
 Undigested 
 Food 
 
 Fat in Bfood 
 
 I 
 
 Body Fat 
 
 JL 
 
 I 
 
 J Burned (Oxidized) \ \Fgg Fat 
 i For Heat •+ Fnergy^ 
 
 Fig. 4. — Scheme illustrating the use of fats in the body. 
 
 fats under certain conditions are transformed back to carbohydrates. 
 Approximately two and one-fourth parts of carbol^drates yield one 
 part of fat, or one part of fat corresponds to two and one-fourth parts 
 of carbohydrates. 
 
 This difference is due to the fact mentioned above, namely, that 
 fats contain less oxygen than do carbohydrates. The presence of 
 oxygen in a compound always indicates that some oxidation (burning) 
 has already taken place. The more oxygen present in a compound, 
 therefore, the less energy will be liberated on complete oxidation 
 (burning to carbon dioxide and water). Or stating the reverse, the 
 less oxygen there is present, the more energy will be liberated. 
 
 Animals do not create any energy. Therefore they use two and 
 one-fourth parts of carbohydrates to produce one part of fat, losing 
 
10 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION 
 
 oxygen in the process. Fats on the other hand form carbohydrates, 
 taking np oxygen and thereby increasing their weight and giving off 
 heat. 
 
 It is a matter of common knowledge that in the fattening of poultry 
 and other domestic animals, not fats but carbohydrates, are fed in 
 excess. This is because carbohydrates even in large quantities are very 
 easily digested, absorbed, and transformed into fat with practically no 
 loss of energy. Fats, on the other hand, are digested only with diffi- 
 culty, and are absorbed slowly. Such are the difficulties that large 
 proportions of fat in the food may retard and upset the normal meta- 
 bolism of the other nutrients. Consequently large amounts of fat are 
 always avoided in animal feeding. The amount that birds can handle 
 and make proper use of increases with the exercise they have and the 
 coldness of the weather to which they are exposed. 
 
 Vitamins. — There are five known members of this group of 
 nutrients, called by the first letters of the alphabet, A, B, C, D, and E. 
 Recent investigations indicate that doubtless there are still others, 
 but not enough is known of them to warrant discussion. The physio- 
 logical importance of the vitamins in life and their main sources are 
 well known, but their chemical composition is still a mystery. 
 Vitamins are characterized by the lack of proportion between their 
 great importance in nutrition and the extremely small quantities in 
 which they are normally required. The quantities in which they are 
 present in food are far too small to contribute to the body any energy 
 worth mentioning. It is so far unknown whether the vitamins are 
 actual building stones (structural components) of the body, or whether 
 they are simple catalysts (accelerators) which speed up certain essen- 
 tial body processes. It has been found, however, that if certain very 
 small, indeed minute, parts are removed from an adequate ration, this 
 ration fails to support life. If they are removed for any length of 
 time, the result is inevitably disease (so-called deficiency disease) and 
 eventually death. On the other hand this failure may be prevented or 
 health may be restored if these small parts, which were withdrawn 
 from the adequate ration, are again added to it. Unlike the other 
 classes of nutrients which are very stable chemical compounds, the 
 vitamins are all more or less unstable, which makes their study much 
 more difficult. Because of this instability, care must always be taken 
 to ensure an adequate supply of vitamins in poultry rations. When 
 the individual needs have been covered, an excess can in certain cases 
 be stored (see p. 11) in the animal tissues. A supply of any of the 
 vitamins discussed beyond that which is needed and that which can 
 
BUL. 417] POULTRY FEEDING: PRINCIPLES AND PRACTICE 
 
 11 
 
 be stored by the body, is either destroyed or excreted. In no case has 
 any benefit to the bird from such an excess been demonstrated. 
 
 Vitamin A (or fat-soluble A) is also called the growth vitamin, 
 because one of its main effects seems to be that of promoting growth in 
 young stock. Animals fed on an otherwise perfect ration, but lacking 
 this vitamin stop growing. Examples of this effect are shown in the 
 growth records in figure 5. Another condition also results, namely an 
 eye disease called zerophthalmia, meaning dryness of the eye. Not 
 only the secretory glands of the eye, but also those of the mouth, nose, 
 and throat dry up. As the secretions of these glands are germicides 
 to some extent, infections in these locations are frequent when the 
 
 Fig. 5. — Growth with and without Vitamin A (after Hopkins). 
 
 ration is deficient in vitamin A. This condition, sometimes called 
 nutritional roup, always is caused by a vitamin A deficiency and can 
 always be prevented or cured by the feeding of substances known to. 
 be good sources of this vitamin, as shown by Beach 3 (1924) and Davis 
 and Beach (1925). 
 
 Vitamin A is synthesized (built up) by plants and is found in 
 green food and also to a less extent in the embryos of many seeds, as 
 millet, linseed, and yellow corn. It is also found in tomatoes and 
 yellow carrots. The vitamin is not present in white corn, white leaves 
 of plants, or in most root crops. Other good sources are certain 
 animal fats, such as butterfat, egg-yolk fat, and, best of all, a good 
 grade of cod-liver oil. 
 
 Although vitamin A is synthesized in plants it cannot be syn- 
 thesized by animals, but appears in animal fats because of the ability 
 of the animals to store it. The significance of this storing ability is 
 
 3 Full citations of these and similar references given in this publication will be 
 found in the bibliography, page 47. 
 
12 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION 
 
 great ; it enables the hen to provide her chicks with a high concentra- 
 tion of this vitamin in the egg yolk. Young mammals get their supply 
 in a similar way through the milk. But because the vitamin cannot 
 be synthesized, in animal tissues, the amount present will always 
 depend upon the amount provided in the food. 
 
 When vitamin A is exposed to the air, particularly at temperatures 
 above room temperature, it is very unstable, being rapidly oxidized. 
 If cod-liver oil is not kept in closed containers, the vitamin A in it 
 is soon destroyed. On the other hand, this vitamin is well preserved 
 in plants, like alfalfa, when the curing conditions are favorable ; that 
 is, when the drying is accomplished rapidly, but without exposure to 
 excessively high temperatures. 
 
 Vitamin B (also called water-soluble B or the anti-neuritic factor) 
 is without question the most widely distributed of all vitamins. It 
 appears in the germ and bran of all grains, and also in fresh vegetables 
 and green feed, milk, and egg yolk. Yeast is a particularly good 
 source. 
 
 A dietary deficiency with regard to this vitamin causes a nervous 
 disorder in poultry, called avian polyneuritis, which is physiologically 
 equivalent to human beri-beri. Both diseases, the avian as well as the 
 human, develop paralysis of the limbs, at times edema, and finally heart 
 failure. The earliest result of a deficiency, however, is an immediate 
 and marked decrease in the food consumption of the animal, so that 
 any disturbance with regard to the vitamin B supply may be sufficient 
 to throw an animal out of condition. The fact that vitamin B is 
 present in practically all common poultry feeds is probably due to the 
 greater stability of this substance. Exposure to air and even quite 
 long heating do not destroy it. 
 
 Vitamin C (also called water-soluble C or the antiscorbutic 
 vitamin) is of little importance in poultry feeding, as fowls seem to be 
 able to build up sufficient amounts of this substance in the liver, 
 kidneys, and other organs. It prevents a disease known as scurvy, to 
 which domestic birds do not seem to be susceptible. 
 
 Vitamin D is known as the antirachitic factor. It is perhaps the 
 most peculiar of these newly discovered substances, since its place 
 may be taken by a purely physical agent — certain light rays. It is con- 
 tained in a few animal fats where it often, though not always, occurs 
 associated with vitamin A. The outstanding source of both of these is 
 cod-liver oil. Vitamin D may also under certain conditions be con- 
 tained in cured hay. It is not found in the fresh green plant, but 
 seems to be formed during the curing process if there is long exposure 
 to the sunlight, a condition under which vitamin A is destroyed. 
 
BUL. 417] POULTRY FEEDING : PRINCIPLES AND PRACTICE 13 
 
 The best known abnormality caused by a lack of this vitamin is a 
 bone disease called rickets. The most prominent characteristic of this 
 disease is a disturbance of the utilization and retention of lime salts 
 in the body. Lime salts, of which calcium phosphate is one of the 
 most important, are either not deposited, or are deposited to an insuffi- 
 cient degree in the growing bone, the result being many forms and 
 degrees of deformities. Provided with an abundance of calcium in the 
 diet, the bird cannot make use of it unless the antirachitic factor 
 (vitamin D or certain light rays) is also provided. Lack of this factor 
 inevitably results in poor bone formation. A mineral deficiency 
 obviously will have the very same result. Unless minerals are present, 
 no minerals can be deposited, but even a large excess of lime salts is 
 of no use to the bird without the cooperation of the vitamin D or the 
 light rays mentioned above. 
 
 These rays are usually referred to as the ultra-violet rays or ultra- 
 violet light. They are rays of comparatively short wave length found 
 in sunlight and may be produced artificially by means of the so-called 
 ultra-violet lamp. These rays prevent or cure rickets just as effectively 
 as does vitamin D. 
 
 The disease generally affects the growing stock, in which it is called 
 leg weakness. Adult birds may also suffer from the same disease. 
 The effort of laying birds to produce normal eggs is so intense that 
 they actually deprive their own bones of calcium, and may develop 
 severe cases of rickets unless the factor which controls the utilization 
 of lime, is also provided in sufficient amount. The crooked breast 
 bones observed in good layers are often a result of this condition. 
 
 The antirachitic vitamin, although not as unstable as vitamin A, 
 is also affected by prolonged oxidation and high temperature. 
 
 Vitamin E is closely connected with the functions of the reproduc- 
 tive organs of animals. The only experimental work done so far with 
 this vitamin has been with rats, but presumably similar results would 
 be obtained with birds. This vitamin seems more essential to the 
 males, where a continued deficiency may produce permanent sterility. 
 
 Vitamin E is contained in many plants and in the embryos of seeds. 
 
 Minerals. — In addition to the foregoing groups of substances, 
 which are all organic, the bird 's body also contains inorganic material. 
 Included in this are the minerals, which are to be found not only in the 
 skeleton but, in smaller proportions, in all organs, tissues, and fluids 
 of the bird's body. It is evident that growing birds need a constant 
 supply of minerals so that they may be enabled to form new bone and 
 other mineral-containing tissue. Just as evident is the necessity of 
 providing laying birds with the essential minerals for egg-shell forma- 
 
14 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION 
 
 tion. Experience has, moreover, proved the necessity of supplying all 
 kinds of adult birds with minerals, because their tissues are subject to 
 general wear and tear, and must be renewed. 
 
 The parts played in metabolism by the various minerals are little 
 known. Calcium, magnesium, and phosphorus are needed for bone 
 formation, calcium also for shell formation. Calcium in addition is 
 an important constituent of the blood, giving to this fluid its ability 
 to coagulate (clot). Calcium is also a constituent of the white of egg 
 and of the phosphates of egg yolk. Sodium chloride is also needed by 
 all plant eating animals for the elimination of the excess potassium 
 contained in the feed. Chlorides of sodium and potassium are needed 
 as constituents of the body fluids and tissues. Iodine is required in 
 small quantities, and is found in the thyroid gland. Sulphur and 
 silicon are constituents of the feathers. Iron appears in eggs and also 
 is an important constituent of the haemoglobin which gives to the 
 blood its power to carry oxygen. Besides these, copper, zinc, and 
 arsenic are found in small quantities. The requirements are small 
 because the body waste is inconsiderable. 
 
 Besides acting as building material for the body, the minerals aid 
 in the digestion, absorption, distribution, and excretion processes. 
 It is an interesting fact that birds can stand starvation with regard 
 to the organic nutrients, which are commonly considered to be the 
 most important, longer than they can stand mineral starvation. As 
 each particular mineral has one or more specific functions in the 
 organism, a deficiency results in disease. Toe picking is, in some cases 
 at least, such a disease and is paralleled by the condition of horn eating 
 occurring in cattle in South Africa. Rickets, caused by lack of lime, 
 has already been dealt with under vitamin D, the factor controlling the 
 deposition of that mineral. Lack of iron causes anemia. Too little 
 iodine also causes ill effects in poultry, as in mammals, where it results 
 in certain types of goiter. 
 
 Although the organic nutrients, when fed in excess, are stored, 
 such is not the case with minerals. Whatever is not needed by the 
 body is immediately disposed of through excretion. It is evident, 
 therefore, that their supply in the food must be continuous. 
 
 Water. — Water as a nutrient is of the utmost importance to the 
 body. Besides being an important structural component, water is a 
 necessary agent in practically all body processes which are chemical 
 reactions between dissolved substances with water as the solvent. 
 
 The fowl's body is continuously losing moisture through the 
 expired air and the excretions. Laying birds lose additional moisture 
 through the eggs. Therefore water must be provided continuously. 
 
BUL. 417] POULTRY FEEDING : PRINCIPLES AND PRACTICE 
 
 15 
 
 The water formed in the body by oxidation of organic nutrients does 
 not cover more than a small fraction of the actual needs. With 
 increasing environmental temperature the needs for water are cor- 
 respondingly increased, because of increased loss of water through the 
 lungs. This increased evaporation of water through the lungs 
 apparently is the bird's only means of temperature regulation. Most 
 of the common mammals possess a further mechanism for heat regula- 
 tion in the sweat glands, which is probably the explanation of the 
 commonly observed fact that they are better able to withstand high 
 temperatures than birds. 
 
 FEEDS AS COMBINATIONS OF NUTRIENTS 
 
 During the previous discussion the nutrients have been considered 
 as pure and well defined substances, which can be accurately identified 
 by chemical or biological examination. This was to explain clearly 
 their individual characteristics and behavior. 
 
 In practical feeding, however, it is not the separate nutrients which 
 are dealt with, but feedstuffs which are mixtures of them. Neither 
 are the nutrients present in pure form, but as so-called crude proteins, 
 crude fats, etc. The fact that the nutrients are present in a mixture 
 does not affect the underlying principles of nutrition, which govern 
 each one of them separately. Of much more concern is the form in 
 w r hich they are present. This is of primary importance with proteins, 
 carbohydrates, and fats. 
 
 TABLE 1 
 The Per Cent Composition of Feedstuffs Used in Digestibility Trials with 
 
 Poultry 
 
 Feedstuff 
 
 Barley 
 
 Corn 
 
 Fish meal 
 
 Meat scrap 
 
 Potatoes 
 
 Rice, unpolished 
 
 Rice bran 
 
 Rye 
 
 Soybean meal 
 
 Wheat 
 
 Wheat bran 
 
 Yeast 
 
 Moisture 
 
 Minerals 
 
 Organic 
 substance 
 
 Crude 
 protein 
 
 Nitrogen- 
 free 
 extract 
 
 Crude 
 
 fat 
 
 12.33 
 
 2.88 
 
 84.79 
 
 13.93 
 
 64.16 
 
 1.80 
 
 13.00 
 
 1.30 
 
 85.70 
 
 9.90 
 
 69.20 
 
 4.40 
 
 9.89 
 
 12.30 
 
 77.81 
 
 61.93 
 
 2.57 
 
 13.31 
 
 9.32 
 
 17. 15 
 
 73.53 
 
 50.24 
 
 2.21 
 
 16.15 
 
 74.69 
 
 1.39 
 
 23.92 
 
 1.84 
 
 21.23 
 
 0.10 
 
 11.65 
 
 1.72 
 
 86.63 
 
 10.45 
 
 73.52 
 
 1.93 
 
 11.05 
 
 11.43 
 
 77.52 
 
 14.13 
 
 35.96 
 
 19.31 
 
 15.32 
 
 1.98 
 
 82.70 
 
 9.83 
 
 69.02 
 
 1.65 
 
 10.79 
 
 6.21 
 
 83.00 
 
 42.68 
 
 28.76 
 
 7.23 
 
 13.42 
 
 1.92 
 
 84.66 
 
 14.03 
 
 66.47 
 
 1.93 
 
 12.40 
 
 5.41 
 
 82.19 
 
 14.87 
 
 54.25 
 
 4.06 
 
 8.73 
 
 6.66 
 
 84.61 
 
 55.44 
 
 26.44 
 
 2.73 
 
 Crude 
 fiber 
 
 4.90 
 2.20 
 
 4.93 
 0.75 
 0.73 
 8.12 
 2.20 
 4.33 
 2.23 
 9.01 
 0.50 
 
16 
 
 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION 
 
 TABLE 2 
 
 Digestibility Coefficients for the Different Nutrients of Common 
 Feed-stuffs for Poultry* 
 
 Feedstuff 
 
 Barley 
 
 Corn 
 
 Fish meal 
 
 Meat scrap 
 
 Potatoes 
 
 Rice, unpolished. 
 
 Rice bran 
 
 Rye 
 
 Soybean meal 
 
 Wheat 
 
 Wheat bran 
 
 Yeast 
 
 Organic 
 substance 
 
 75.4 
 86.2 
 88.9 
 76.6 
 78.3 
 78.0 
 59.7 
 79.2 
 76.6 
 84.3 
 55.3 
 75.5 
 
 Crudo 
 protein 
 
 75.1 
 
 58. Of 
 
 90.6 
 
 73.6 
 
 46.9 
 
 76.9 
 
 66.9 
 
 63.0 
 
 83.4 
 
 78.9 
 
 64.3 
 
 76.2 
 
 Nitrogen-free 
 
 extract 
 
 (carbohydrates) 
 
 Fat 
 
 82.2 
 
 48.0 
 
 93.0 
 
 8.53 
 
 
 98.2 
 
 
 82.1 
 
 84.5 
 
 
 88.1 
 
 64.1 
 
 58.2 
 
 87.7 
 
 85.6 
 
 28.5 
 
 75.3 
 
 84.1 
 
 89.3 
 
 39.8 
 
 61.2 
 
 55.6 
 
 82.8 
 
 57.1 
 
 Crude 
 fiber 
 
 * Figures in this, the preceding and the followiug table mainly from Katayama (1924) supplemented 
 from Voltz (1909 and 1923). 
 
 t This figure was obtained by a different method which possibly gives a somewhat low value. 
 
 TABLE 3 
 
 Pounds of Nutrients Digestible to Poultry in 100 Pounds of Feed (Based 
 on Composition of Feeds as Given in Table 1) 
 
 Feedstuff 
 
 Barley 
 
 Corn 
 
 Fish meal 
 
 Meat scrap 
 
 Potatoes 
 
 Rice, unpolished 
 
 Rice bran 
 
 Rye 
 
 Soybean meal 
 
 Wheat 
 
 Wheat bran 
 
 Yeast 
 
 Organic 
 substance 
 
 63.93 
 73.87 
 69.17 
 53.03 
 18.73 
 74.05 
 46.28 
 65.50 
 63.58 
 71.37 
 45.45 
 63.88 
 
 Protein 
 
 10.46 
 
 5.74 
 
 56.11 
 
 36.98 
 
 0.86 
 
 8.04 
 
 9.45 
 
 6.19 
 
 35.61 
 
 11.07 
 
 9.56 
 
 42.25 
 
 Nitrogen-free 
 
 extract 
 
 (carbohydrates) 
 
 52.74 
 
 64.38 
 
 None 
 
 (2.21) 
 
 17.94 
 
 64.77 
 
 20.93 
 
 59.08 
 
 21.65 
 
 59.36 
 
 33.20 
 
 21.89 
 
 Fat 
 
 0.86 
 
 3.75 
 13.07 
 13.24 
 
 1.24 
 16.93 
 0.47 
 6.08 
 0.77 
 2.26 
 1.56 
 
 The proportions in which these nutrients are present can be accurately 
 determined by analysis. Tables of the composition of feedstuffs give 
 the average proportion of these classes of nutrients in the common 
 feeds. 
 
BUL. 417] POULTRY FEEDING : PRINCIPLES AND PRACTICE 
 
 17 
 
 Digestibility. — Although analyses of composition are of great 
 importance, of still greater importance to the practical feeder is the 
 digestibility of the feed. Such information can be obtained only by 
 actual feeding tests under carefully controlled laboratory conditions. 
 
 In these tests definite amounts of an analyzed food are given to 
 an animal and the corresponding excretions are analyzed. The 
 nutrients fed and not excreted in the feces are accepted as the actually 
 digested food. In this way, therefore, the digestible matter is deter- 
 mined, which again makes possible the computation of the digestibility 
 coefficients. These give the number of parts digested, that is, the parts 
 available to the body, of each 100 parts of the particular nutrient fed. 
 
 Example: Katayama (1924) found as the average of three experi- 
 ments with wheat bran fed to poultry, the following digestibility 
 coefficients : 
 
 Organic 
 substance 
 
 Protein 
 
 Carbohydrates 
 
 Fat 
 
 Crude fiber 
 
 55.3 
 
 64.3 
 
 61.2 
 
 55.6 
 
 - 
 
 These figures simply mean that of each 100 parts of organic substance 
 (gross weight of every feed less moisture and mineral content) in 
 wheat bran fed to poultry, 44.7 parts by weight were regained from 
 the feces i.e., wasted). Consequently only the remaining 55.3 parts 
 were retained by the body, that is to say, digested. Therefore the 
 digestibility coefficient of the organic substance of wheat bran for 
 poultry is 55.3. It is low because of the large amount of crude fiber 
 and pentosans it contains. The corresponding figure for the protein 
 part of bran was 64.3 ; carbohydrates 61.2 ; and fats 55.6. 
 
 For the sake of convenience in compounding rations, tables are 
 general^ given for the pounds of digestible nutrients in 100 pounds 
 of feed. These figures are computed from the composition and diges- 
 tibility coefficients. The composition of the wheat bran used in the 
 experiments was as follows : 
 
 
 Pounds in 100 pounds of wheat bran 
 
 Component 
 
 Total 
 
 Digestible 
 
 Moisture 
 
 12.40 
 
 5.41 
 
 82.19 
 
 14.87 
 
 54.25 
 
 4.06 
 
 9.01 
 
 
 Mineral (also called ash) 
 
 
 Organic substance 
 
 45.44 
 
 Proteins 
 
 9 56 
 
 Carbohydrates 
 
 Fats 
 
 33.20 
 2 26 
 
 Crude fiber 
 
 00 
 
 
 
 Total 
 
 100.00 
 
 45.44 
 
 
 
18 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION 
 
 That is, 100 pounds of bran contained. 82.19 pounds of organic sub- 
 stance ; and this organic substance was made up of 14.87 pounds of 
 protein, 54.25 pounds of carbohydrates, 4.06 pounds of fat and 9.01 
 pounds of crude fiber. The digestible organic nutrients in 100 pounds 
 
 55 3 
 of bran, therefore, were 82.19 X * =45.44 pounds. Correspond- 
 
 64 3 
 ing figures for protein are given by 14.87 X -77^: ; for carbohydrates, 
 
 61 2 55 6 
 
 54.25 X -j^ ; and for fat, 4.06 X -tttx ; crude fiber, 0. As a result the 
 
 following are obtained : 
 
 Pounds of Digestible Nutrients in 100 Pounds of Wheat Bran 
 
 Organic 
 substance 
 
 Protein 
 
 Carbohydrates 
 
 Fats 
 
 Proteins+ 
 carbohydrates 
 
 +fats 
 
 45.44 
 
 9.56 
 
 33.20 
 
 2.26 
 
 45.02 
 
 The sum of digestible proteins, carbohydrates, and fat should always 
 be equal to the digestible organic substance. Because of unavoidable 
 experimental errors, there are always slight discrepancies. In this 
 case the discrepancy, as will be noted, amounted to 0.42 pounds. 
 
 Since different kinds of animals have marked differences in their 
 digestive systems, the digestibility will vary for different species and 
 has to be specially determined for each species (i.e., for cattle, horses, 
 hogs, chickens, etc.). Because of the experimental difficulties, caused 
 by the combined excretions of feces and urine, work with chickens 
 has been carried out only on a very limited scale. Outside of the few 
 coefficients given in table 2, figures have to be accepted with the 
 greatest caution. Digestibility coefficients obtained in experiments 
 with other kinds of animals, even with other species of poultry, posi- 
 tively cannot be applied to chickens ; they are very misleading. No 
 complete fundamental standards being available, feeding of poultry 
 has to be based more or less on practical experience, and knowledge 
 of the composition of the feeds. 
 
 Nutritive Ratio. — Even when the digestibility coefficients are 
 known it is not possible to arrange feeding standards, without taking 
 into consideration the balance between the different organic nutrients 
 (excepting the vitamins). This is called the nutritive ratio and gives 
 the ratio between digestible proteins on the one hand and digestible 
 carbohydrates and fats on the other. To put it in other words, the 
 nutritive ratio gives, for a particular feed or combination of feeds, 
 the proportions of available body building material, the proteins, as 
 opposed to the available energy and heat sources, carbohydrates and 
 fats. 
 
BUL. 417] POULTRY FEEDING : PRINCIPLES AND PRACTICE 
 
 19 
 
 In the given case of wheat bran the nutritive ratio for poultry 
 expresses the ratio of the digestible proteins (9.56) to the sum of the 
 digestible carbohydrates (33.20) plus 2^4 times the digestible fats 
 (2.26) in 100 pounds of bran, that is 9.56 to (33.20 + 5.08), which on 
 reduction to simplest terms gives one part of protein to four parts of 
 the rest of the ration (usually written 1:4.0). 
 
 In the case of combinations of feeds the actual digestible amounts 
 of the different nutrients are found by addition. Example : 
 
 
 Pounds of digestible nutrients* 
 
 Composition of mash 
 
 Proteins 
 
 Carbohydrates 
 
 Fats 
 
 26.67 pounds ground wheat 
 
 2.95 
 
 2.79 
 1.53 
 
 7.4 
 
 15.83 
 
 14.07 
 
 17.17 
 
 0.44 
 
 0.21 
 
 26.67 pounds ground barley 
 
 0.23 
 
 26.67 pounds yellow corn 
 
 20.00 pounds meat scrap 
 
 1.00 
 2.60 
 
 Total 
 
 14.67 
 
 47.51 
 
 4.04 
 
 14. 67 : 47. 51 + (2^X4. 04) = 14. 67 : 56. 60 = 1 : 3. 86. 
 
 * Digestible nutrients in 100 pounds of each feed taken from table 3 and reduced to corresponding 
 figure for amount of each feed in 100 pounds of mash. 
 
 Proteins cannot be compared with substances as different as carbo- 
 hydrates and fats, without being translated into the same terms. The 
 characteristic common to all three groups of nutrients is, that under 
 certain conditions they burn and yield heat. The unit of heat is the 
 Calorie ; 4 the nutritive ratio therefore expresses the number of Calories 
 (that is, the amount of heat) derived from proteins as compared with 
 the Calories derived from carbohydrates and fats. Proteins and carbo- 
 hydrates give practically the same heat on complete oxidation in the 
 body (about 1860 calories to a pound) ; fats, however, give, as already 
 explained, two and one-fourth times as much heat (about 4200 to a 
 pound) . The nutritive ratio of a food, therefore, is properly expressed 
 as proteins to carbohydrates + 2% times fats. The nutritive ratio is 
 also frequently computed from "the total digestible nutrients" 5 and 
 is thus expressed as proteins to total digestible nutrients minus pro- 
 teins. These two ways of computing should give the same result for 
 a given ration. 
 
 * A Calorie (with the capital C) is the energy which (in terms of heat) is 
 required to raise the temperature of 1 kilo of water 1° Centigrade or 1 pound of 
 water 4° Fahrenheit and equals 1000 calories (small c). 
 
 5 ' ' Total digestible nutrients ' ' is used by some authorities to mean the diges- 
 tible organic substance in 100 pounds of feed, when allowance is made for the 
 higher energy content of fat. It is equal to protein + carbohydrates + 2^ fat. 
 In the given case of wheat bran "the total digestible nutrients' ' are therefore 
 47.85 pounds as compared with 45.44 pounds of digestible organic substances. 
 
20 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION 
 
 The proper nutritive ratio has to be determined experimentally. 
 It will vary with the different purposes for which the feeding is done, 
 as, for example, growth, fattening, or egg production. The processes 
 of growth and egg production naturally require more of the tissue- 
 forming material, proteins, than the process of fattening. Not know- 
 ing the digestibility of the different feeds, it is, of course, not possible 
 to determine nutritive ratios with any degree of exactness. It has 
 been assumed, however, that growth and egg production require ratios 
 between 1 A and 1 :6, which may be called narrow ratios. Fattening, 
 on the other hand, requires more of the heat and fat-forming nutrients, 
 the optimum ratios ranging between 1 :6 and 1 :8, and these are called 
 wide ratios. 
 
 The fact that the digestible part, of the food has to be specially 
 determined, indicates that not all of a food is digestible. A part, 
 varying greatly with the different kinds of food, is not digested and is 
 passed out with the droppings. A large part of the undigested food 
 in poultry is always the crude fiber, which as cellulose makes up as 
 much as 30 per cent of the walls of the cells of which the grains are 
 composed. Neither are certain carbohydrates, the pentosans, digested 
 to any considerable degree. These are present in appreciable per- 
 centages in the common grains, comprising about 7 per cent of corn, 
 6.5 per cent of wheat and as much as 25 per cent of wheat bran. 
 
 It has been demonstrated that birds cannot exist on pure digestible 
 nutrients alone, but that addition of bulk in the form of crude fiber 
 is needed to maintain them in good condition. The explanation of 
 this phenomenon is not known, but it is assumed that the rough fiber 
 acts as an irritant stimulating the secretion of digestive juices and the 
 peristaltic movement of the intestines. There is no evidence in sup- 
 port of the prevalent opinion that the presence of bulk is of any assist- 
 ance in "opening up" the rest of the food to digestion. All poultry 
 rations furnish more or less bulk, a large part of it in the form of 
 crude fiber. The amount of bulk giving the best results has not yet 
 been definitely determined. It appears as if there is rather a large 
 margin of safety within which variations do not seem to make much 
 difference. Thus certain rations with as little as 2 per cent and others 
 with as much as 10 per cent crude fiber have given good results. Most 
 common rations, with 6 per cent crude fiber, have more than 6 per cent 
 of bulk because of other indigestible matter. The bulk may be as 
 high as 30 per cent, which is certainly more than is desirable. 
 
 Not all of the digested and absorbed food, however, is available to 
 the body as energy. In particular, the proteins are not broken down 
 completely ; parts which are still able to combine with oxygen, yielding 
 
Bul. 417 
 
 POULTRY FEEDING : PRINCIPLES AND PRACTICE 
 
 21 
 
 heat, are always excreted through the kidneys as uric acid and urea. 
 Thus energy is lost as far as the bird's body is concerned. 
 
 The digestion of food requires energy, which must also be sub- 
 tracted from the food energy, in order that the amount actually avail- 
 able to the bird for other purposes may be known. The digestive work, 
 of course, varies with the different foods, the digestion of animal 
 products naturally being easier than the digestion of fibrous vegetable 
 products. Therefore the available or net energy of feeds is denned as 
 the food energy less the sum of remaining energy in the excretions and 
 the energjr required for digestive work. 
 
 By measuring the loss of heat and the respiratory gases from the 
 bird's body under the different conditions of starvation, maintenance, 
 and production, the energy requirements (or actual food needs) of 
 the bird have been determined. The requirements are directly cor- 
 related with the surface area of the body. Feed requirements there- 
 fore vary with the size of the bird, since the smaller body always has 
 a greater surface in proportion to body weight. In spite of frequently 
 made statements to the contrary, the actual energy requirements of 
 poultry (not laying) do not exceed those of other farm animals or 
 humans on the basis of body surface. On the basis of a given unit of 
 weight the requirements of an animal increase with decreasing size, 
 as will be seen from table 4. 
 
 TABLE 4 
 
 Comparative Energy Requirements for Man and Some Farm Animals 
 
 (Data from Ellenberger imd Scheunert, 1925, and Gerhartz, 1914) 
 
 Kind of animal 
 
 Horse 
 
 Hog 
 
 Human 
 
 Dog 
 
 Goose, young 
 
 Domestic fowl, non-laying. 
 
 Body weight 
 in pounds 
 
 970 
 
 282 
 
 141 
 
 33 
 
 7. 
 
 4.4 
 
 Energy requirements per 24 
 hours in calories 
 
 Per pound 
 body weight 
 
 5.1 
 8.7 
 14.6 
 23.4 
 30.3 
 38.7 
 
 Per square 
 
 meter surface 
 
 area 
 
 948 
 1078 
 1042 
 1039 
 
 967 
 1020 
 
 Energy requirements during molt and broodiness are practically the 
 same as under ordinary non-laying conditions. 
 
 The laying process, involving the formation of eggs, however, 
 requires approximately 80 per cent more energy than simple main- 
 tenance, which is four times as much energy as is required for the 
 
22 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION 
 
 formation of an equivalent amount of body fat in hogs. Egg pro- 
 duction as an industry, therefore, is badly handicapped as compared 
 with the fattening of cattle or hogs, and it is evident that great care 
 should be taken to supply both the most efficient and cheapest feed to 
 poultry. 
 
 Comparison of Quality of Nutrients in Different Feeds. — Not 
 expressed in the digestibility coefficient and the nutritive ratio, but 
 just as important if not more so, is the quality of the food protein. 
 There is no fundamental difference between animal and vegetable pro- 
 teins, provided these latter contain the essential amino acids. There 
 is, however, a difference between the efficiency of the two, because the 
 vegetable cell membrane, being composed largely of non-digestible 
 cellulose (crude fiber), hinders digestion of the included proteins, so 
 that more energy is required for their digestion. Even considering 
 this, there is frequently sufficient difference in price to justify a more 
 extensive use of the vegetable protein concentrates. 
 
 Another point to consider is that, as indicated before, many of 
 the grain proteins are lacking in one or more of the essential amino 
 acids. This deficiency is not the same in all of them, so that perfectly 
 well balanced proteins might be obtained by making the proper selec- 
 tion of grains alone. This is more practically accomplished, however, 
 by introducing suitable protein concentrates, such as fish scrap, meat 
 scrap, soybean meal, peanut meal, etc., as supplements to the grains. 
 
 Although the question of quality is thus of great importance in 
 the case of proteins, with carbohydrates all digestible carbohydrates 
 are equivalent. The digestible carbohydrates consist largely of starch. 
 Organic acids like lactic acid and tartartic acid and also alcohols in 
 the feed are generally counted as carbohydrates, since they have prac- 
 tically the same energy content as sugars and are used by the body like 
 the other members of the group. Sometimes, however, this whole 
 group is called "nitrogen-free extract." This is because "carbo- 
 hydrates" in the strict sense of the term, do not include these acids 
 and alcohols. 
 
 The fats of animal feeds are more easily digested by birds than 
 those of vegetable feeds. This difference is not caused by any differ- 
 ence in composition but is due to the fact that vegetable fats generally 
 are less accessible to the digestive juices because contained in cells with 
 cellulose walls. 
 
 Vitamins practically always originate from plants, but whether 
 they are supplied from vegetable or animal products is immaterial, as 
 far as known. Nothing is known about their digestibility, their 
 chemical composition not having been ascertained as yet. Their defini- 
 
BUL. 417] POULTRY FEEDING : PRINCIPLES AND PRACTICE 23 
 
 tion really is based on the utilized part of them, since their presence 
 and potency are judged wholly by their physiological effects. Of the 
 vitamins, vitamin C does not have to be provided in the feed and the 
 vitamins B and E are widely distributed in the ordinary poultry feeds, 
 so that no special attention has to be paid to them to ensure an ade- 
 quate supply. With regard to the two remaining vitamins, care has 
 to be taken that the bird's needs are met. Excessive feeding of the 
 vitamins discussed in this bulletin, however, has never been demon- 
 strated to do any good. 
 
 There is no way of testing the digestibility of minerals. In order 
 to determine definitely whether they are supplied in sufficient amounts, 
 it is necessary to determine what is called the mineral balance. If 
 more of a mineral is taken in with the food than is passed out in the 
 combined excretions and eggs, the bird is said to be in a positive 
 balance; the reverse illustrates a negative balance. The effort is 
 always made to feed at least enough minerals to get the intake as high 
 as the outgo. In growing birds the intake must be higher than the 
 outgo to allow for bone and tissue formation. 
 
 With the exception of calcium, phosphorus, sodium, and possibly 
 chlorine, the minerals are found in sufficient amounts in ordinary 
 feeds. The quantities present are always small, but the needs are 
 slight, so that special attention generally need be given only to the 
 supply of the four elements just mentioned. 
 
 Although these four elements can be supplied in inorganic form, 
 such as limestone, phosphates, and common salt, or tied up with 
 organic matter, one element, sulphur, behaves differently. It has to 
 be supplied in a particular form. This element cannot be used in the 
 pure form by birds, but must be provided in certain proteins in which 
 it appears as a constituent of the amino acid called cystine. 
 
 POULTRY FEEDING PRACTICE 
 
 GENERAL COMPOSITION OF A POULTRY RATION 
 
 The common fowl is by nature a grain and insect eater, wherefore 
 poultry feeding properly is based on grains as the main supply of 
 nourishment. Such grains should be used in composing a poultry 
 ration as are available at a reasonable cost, because the main nutrient 
 group contained, namely, the carbohydrates, is the same, whether 
 obtained from one grain or another. Consequently there is no "best" 
 grain for poultry. 
 
24 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION 
 
 Grain prices always fluctuate, and they fluctuate unevenly for the 
 different kinds of grain. Grain prices also depend upon locality, the 
 locally grown grains usually being cheaper than those imported from 
 other districts. Since one grain is practically as good as any other, 
 poultry rations often vary, and always should vary according to local 
 prices and market conditions. This explains the fact that poultry- 
 men in wheat districts use wheat as the base of their poultry feeds, 
 while those in the corn districts use corn. Since in California barley 
 ordinarily is the cheapest grain, barley should here have a conspicuous 
 place in any feed formula. 
 
 Although grains are the base of the feed, they are not under 
 ordinary conditions a complete feed for poultry kept for commercial 
 purposes. The proteins of common grains are inadequate as to kinds 
 and amounts. The grains are further deficient in certain minerals, 
 certain vitamins, and in water. It is therefore altogether essential that 
 the grain ration for birds be supplemented with water, vitamins, pro- 
 teins, and minerals. Because the protein concentrates are usually 
 available in the form of meals or scraps, which cannot easily be fed 
 in a mixture with the whole grains, it is customary to divide the 
 poultry ration into two parts by supplying the supplements in the 
 form of a mash. 
 
 For the sake of convenience it is common practice to compose the 
 mash in such a way as to make the proportions of the different 
 nutrients about right when grains and mash are fed in equal amounts. 
 In such case it is always necessary to add to the concentrates a certain 
 amount of ground grains and possibly grain by-products in order to 
 maintain the proper nutritive ratio. 
 
 It is convenient also to include suitable mineral concentrates in the 
 mash. This is in order to ensure at all times consumption of the right 
 kinds and amounts of minerals for growth and egg production. Water 
 and certain vitamin supplements are commonly fed separately. 
 
 GRAINS 
 
 The exact combination of grains is of slight importance. The 
 separate kinds, and also the proportions of each kind, to be used at a 
 time will depend largely upon price conditions. 
 
 A variety of grains is always preferable, because it increases the 
 palatability and therefore also increases food consumption. A variety 
 is, on the other hand, by no means necessary. Birds have repeatedly 
 been raised and kept in good production by using one grain only 
 when it was properly supplemented. 
 
BUL. 417] POULTRY FEEDING : PRINCIPLES AND PRACTICE 25 
 
 Barley. — Barley is an excellent feed for poultry, particularly when 
 the price is considered. The only limitation to the feeding of barley 
 may be the comparatively low palatability. Birds raised on other 
 grains do not take to barley readily, but if they have been trained to 
 eat it early enough they like it and eat about as much of it as they 
 would of any other grain. Whole barley can be fed to birds as early 
 as six weeks of age. In large sections of Europe, barley is fed as the 
 only grain, and the results are very satisfactory. In order to train 
 adult birds to eat this grain or in order to make them eat more of it, 
 it is a common practice to soak or "process" it (letting it germinate 
 and develop root sprouts). Hulled barley has no advantage over the 
 whole grain and may moreover be less palatable. The higher price 
 therefore is not justified, particularly as a poor grade grain is often 
 used in the manufacture. The digestible nutrient content of barley 
 is about 64 pounds to 100 pounds of grain; it should weigh at least 
 42 pounds to the bushel. 
 
 Corn. — Yellow corn is a most valuable grain for poultry, being 
 highly palatable, highly digestible, and generally also reasonable in 
 cost. Figures of different observers do not exactly agree, but it is 
 known that 100 pounds of corn contain at least 73 pounds of digestible 
 nutrients. 
 
 In Roumania, a corn producing country of Europe, it is a common 
 experience that stored corn is to be preferred to new corn in feeding. 
 In trials with poultry, Nitzescu (1918) found that corn a year old 
 was better utilized and contained over three pounds more of digestible 
 nutrients to a hundred than new corn. 
 
 Yellow corn differs from white corn and most other grains in that 
 it contains vitamin A. The amounts, however, are rather small, 2% 
 ounces of yellow corn per adult bird a day being needed in order to 
 prevent nutritional disease (see p. 11). 
 
 Yellow corn also contains the pigment (xanthophyll) which gives 
 yellow color to the skin and shanks of the bird and to the egg yolk. 
 There is not enough of this pigment, however, to make it an unde- 
 sirable poultry feed, even when fed in large amounts. 
 
 As a matter of fact, yellow corn is such a desirable grain that it 
 perhaps always should be a part of the poultry ration. There is no 
 advantage in feeding the grain in cracked form to adult birds ; on the 
 contrary, certain valuable parts of the corn are usually lost in the 
 cracking process. 
 
 White corn is presumably just as digestible, but possibly not quite 
 as palatable for poultry as the yellow variety. It does not contain 
 vitamin A. 
 
26 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION 
 
 Oats. — Heavy oats are another desirable poultry grain. Light oats 
 (i.e., weighing less than 36 pounds to the bushel), since they contain 
 much more undigestible fiber, are of low value. Hulled oats have no 
 advantage over whole oats as feed for adult birds, but do have an 
 advantage of lower price over steel cut oats as feed for young stock. 
 The digestibility of oats has not been fully determined. It is probably 
 slightly lower than that of barley because of the pentosan content, the 
 crude fiber content being practically the same. 
 
 Wheat. — Wheat is also eaten very readily by birds, in fact so 
 eagerly that it has for a long time been looked upon as essential in 
 poultry feeding. As was shown during the late war, it is not at all 
 indispensable, and the high price, as compared with other grains, 
 should doubtless make it much less popular than it is at the present 
 time. Wheat contains about 72 pounds of digestible nutrients to the 
 hundred. 
 
 Other Grains. — Feterita, kafir, millet, milo, rice, and other grains 
 can likewise be fed successfully to poultry, kafir perhaps being the 
 most palatable. Rice is now being produced in California in steadily 
 increasing amounts. While the superior grades are far too expensive 
 for use in poultry feeding, offals, such as cracked rice, and by- 
 products, such as bran and rice polish, can be obtained at very reason- 
 able prices and represent very desirable poultry feeds, provided the 
 products are of standard good quality. 
 
 Summary of the Feeding Value of Grains. — Grains primarily sup- 
 ply carbohydrates, but at the same time also provide some of all other 
 nutrients. Apart from the slight vitamin A content of yellow corn, 
 there is, as pointed out, little qualitative difference between the differ- 
 ent grains with regard to vitamins. Therefore their total digestible 
 nutrients give a fair expression of their relative feeding value. Com- 
 paring the digestible nutrients (see table 3) and not considering the 
 value of variety, it is seen that corn is slightly higher in feeding value 
 than wheat and that they are both worth about 15 per cent more than 
 barley or oats. 
 
 In feeding grain, as well as any other feed, these comparative 
 figures should always be borne in mind and serve as a fundamental 
 basis in composing the ration. 
 
 SUPPLEMENTS 
 
 Protein Supplements. — Blood, neither fresh nor dried, should ever 
 be fed to poultry as it is not palatable and not well digested. Further- 
 more, the price in most cases will be prohibitive. 
 
BUL. 417] POULTRY FEEDING: PRINCIPLES AND PRACTICE 27 
 
 Fish scrap or meal is the dried product derived from the whole 
 fish, such as dog-fish or herring, and from the waste from canneries. 
 Pish proteins are not very different from or superior to proteins of 
 other animal products, but the fish products generally are manufac- 
 tured at lower temperatures than the corresponding meat products. 
 They are, as a consequence, more palatable and better digested than 
 meat scraps or tankage. An average fish scrap which contains about 
 60 per cent protein, will have about 70 pounds of digestible nutrients 
 to the hundred. It is usually worth about 30 per cent more than a 
 meat scrap of the same protein content as shown by analysis. Unless 
 the fat content is far above the average, which should be between 4 
 and 6 per cent, fish scrap, even when fed in large amounts, does not 
 under any circumstances give taste or odor to the eggs produced by 
 flocks to which it is fed. 
 
 In addition, fish scrap contains lecithin, an organic substance 
 which is supposed to be very important, and certain desirable minerals, 
 like iodine. 
 
 Meat scrap and tankage are very similar packing house products. 
 They represent the dehydrated residue from fresh meat scraps, bones, 
 etc., from which most of the fat has been removed by boiling, and the 
 residue from the manufacture of boullion cubes. The protein content 
 generally is around 50 per cent, but varies according to the amount 
 of bone contained. The two products are also derived from diseased 
 animals. 
 
 Meat scrap and tankage of high quality are excellent feeds, but 
 very often in the form in which they are obtained on the market, they 
 have been overcooked to a degree that has injuriously affected their 
 palatability and their digestibility. The same commercial brands often 
 vary widely in quality from time to time, so that it may be difficult 
 to obtain a uniform product over a long period of time. A good 
 tankage or meat scrap with about 50 per cent protein will contain 
 about 53 pounds of digestible nutrients to the hundred. 
 
 Fresh meat, such as horse meat, is an excellent feed if acquired 
 and fed under sanitary conditions, which unfortunately is not usually 
 the case. Therefore this product means a constant menace to the health 
 of the flock. Because of the high moisture content, however, the price 
 which is usually asked is too high. Assuming about the same digesti- 
 bility for fresh meat as for a good tankage (meat scrap), the former 
 would be worth not more than 40 per cent of the value of the dried 
 product, not counting the additional labor involved in feeding the 
 fresh meat and the difficulties in distributing it evenly among the 
 birds. 
 
28 UNIVERSITY OP CALIFORNIA EXPERIMENT STATION 
 
 Milk in any form is an excellent feed. Very satisfactory produc- 
 tion has been obtained when milk has been fed as the only supplement 
 to grains besides green feed. (In that case water was not given at 
 all.) Considering, however, that skim milk (and whole milk is too 
 expensive to deserve consideration), is simply a source of the ordinary 
 nutrients and contains no great amount of any costly constituents, 
 such as vitamins, it is clear that milk has to be compared with other 
 feeds on the basis of digestible nutrients and price. Such a com- 
 parison brings out the fact that milk and milk products generally are 
 too expensive to justify an extensive use for laying birds, except in 
 case of a cheap local supply. Because birds are extremely fond of it, 
 however, a temporary feeding of milk, with its high protein content, 
 in addition to the ordinary ration, is a good stimulant for egg pro- 
 duction for pullets starting to lay and for hens when production 
 decreases in the fall, providing they are not losing in weight. 
 
 There is but little difference in feeding value between fresh, semi- 
 solid, and dried milk products. The modern process of manufacture 
 does not seem to change the quality of the nutrients, so that the value 
 in each case depends on the amount of solids contained. Roughly 
 speaking, 1 pound of dry milk is equivalent to 3% pounds of semi- 
 solid, or 10 pounds of fresh skim milk. Neither is there any difference 
 in value between sweet and sour milk. In order to avoid digestive 
 troubles, the milk should preferably be fed either sweet all the time, 
 or sour all the time. It is generally easier to feed the sour milk. The 
 acidity is, contrary to general belief, of no particular feeding value 
 to the bird under normal conditions. Where, as in the case of milk 
 feeding for the prevention or cure of coccidiosis, the lactic acid itself 
 seems to be beneficial, the acid should preferably be formed from the 
 milk by fermentation in the intestines. The nutrients of milk are 
 almost completely digested. 
 
 The oil meals, also called oil cake meals, are protein-rich residues 
 from coconuts, linseeds, peanuts, soybeans, etc., which have had their 
 oil extracted. The fat is removed by high pressure in the "old" or 
 ' ' English ' ' process ; or by extraction with a solvent, the ' ' new ' ' pro- 
 cess. The "old" process residue has a high fat content and may 
 therefore be valuable as feeds for other classes of stock, but only 
 "new" process products should be used for feeding poultry, as a 
 high fat content cannot be made use of by birds and it may retard 
 the digestion of the other nutrients. Also the "old process" (0. P.) 
 products do not keep as well as the "new process" (N. P.) products, 
 because with a high fat content they easily become rancid. 
 
BUL. 417] POULTRY FEEDING : PRINCIPLES AND PRACTICE 29 
 
 Coconut oil meal is a fair feed for poultry. It is not as palatable 
 as the other products of this same class and is known to have caused 
 digestive troubles in- poultry as well as in other farm animals, horses 
 for example. 
 
 Linseed meal is a good feed, being high in suitable proteins. 
 Because of its laxative effect it should never be added to a mash in a 
 higher proportion than 5 per cent. Linseed meal is too high in price 
 compared with its feeding value to justify its use as a poultry feed. 
 
 Peanut meal is one of the best of these protein-rich supplements. 
 Its use in this country is of comparatively recent date, but it has been 
 successfully used in the Orient and in Europe over a long period 
 of years. 
 
 Soybean meal is another very valuable concentrate. Like peanut 
 meal, it has only of recent years been of any importance in this 
 country. Now considerable quantities are imported and steadily 
 increasing amounts are also being manufactured in the United States. 
 Philips (1925) has clearly demonstrated the high value of soybean 
 meal in poultry feeding and it is doubtless gaining in popularity all 
 the time. It contains about 63 pounds of digestible nutrients to the 
 hundred. 
 
 The wheat by-products are at the present time enjoying an alto- 
 gether undeserved popularity as feed for poultry. They are all low 
 in proteins, and the protein contained, being nothing but a deficient 
 grain protein itself, is of course poorly suited as a supplement to a 
 grain ration. In addition, the wheat by-products are rich in a par- 
 ticular kind of carbohydrates? the pentosans, which are practically 
 not digested by poultry. As a consequence the wheat by-products are 
 low in total digestible nutrients, wheat bran, for instance, containing 
 only about 45 pounds to the hundred. The present prices, therefore, 
 should exclude these products from poultry feeds, and it is a question 
 whether such bulky feeds should not always, at any price, be 
 fed with caution. 
 
 There is a popular idea that wheat bran is essential for poultry. 
 This is not the case, for it contains nothing important that is not pro- 
 vided by the whole grains. The slightly laxative effect, if it should 
 ever be desired, can just as well be obtained from more efficient feeds, 
 like linseed meal. 
 
 Animal versus vegetable protein supplements. — The question as to 
 whether to use animal or suitable vegetable protein concentrates in 
 feeding for growth and egg production should largely be decided by 
 prices per unit of protein in the different products. A good prac- 
 tical rule is to introduce vegetable protein supplements into a poultry 
 
30 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION 
 
 ration, when the price per unit of digestible protein in the vegetable 
 concentrates is at least 10 per cent less than for corresponding animal 
 protein. One should never be afraid of using the- vegetable products, 
 as there is no fundamental difference between the two classes. 
 Dougherty (1916) obtained as good an egg production with a mash 
 containing 7.5 per cent meat scrap as with much higher concentrations 
 of animal protein, provided proper vegetable protein concentrates 
 were added to make up for the difference. Moreover, Wheeler (1899) 
 demonstrated that satisfactory growth and egg production in the 
 domestic fowl could be obtained on vegetable protein exclusively. 
 These results have been verified by Kennard and co-workers (1922) 
 and Philips (1925). 
 
 While thus the protein may be supplied from vegetable sources 
 only, there is one reason for always including a small quantity, say 
 4 or 5 per cent, of milk products, fish or meat scraps. These sub- 
 stances have the peculiar effect, on entering the glandular stomach, 
 of causing a particularly strong flow of digestive juices, which must 
 be assumed to cause a more rapid and complete digestion of the rest 
 of the food. 
 
 If suitable vegetable protein concentrates are used, it is of little 
 concern whether one product only is used or several concentrates in 
 combination, variety here seeming to have small value. 
 
 Mineral Supplements. — Care should always be taken to ensure 
 sufficient consumption of minerals. The best practice is, therefore, to 
 include most of the necessary mineral supplements in the mash. 
 Growing and laying mashes should contain between 8 and 10 per cent 
 of minerals, a part of which should always consist of calcium car- 
 bonate, such as ground limestone. This will aid in the neutralization 
 of organic and inorganic acids produced in the body. 
 
 A certain part of the minerals needed by the birds is naturally 
 contained in the grain and protein concentrates in the ration. These 
 products do not, however, provide sufficient sodium, calcium, phos- 
 phorus, chlorine, and iron, particularly for growing and laying birds. 
 The deficient minerals can be easily and cheaply obtained ; sodium and 
 chlorine from common salt; calcium from limestone, oyster shell, 
 ground marble, hydrated lime, etc. ; phosphorus and calcium from 
 fresh bones or bone meal, steamed bone meal, acid phosphate, etc. 
 The iron requirements are usually taken care of by the iron in the 
 vitamin supplements. A possible iodine deficiency is overcome by 
 using fish scrap as a source of protein or by using oyster shell for 
 supplying calcium carbonate. 
 
BUL. 417] POULTRY FEEDING: PRINCIPLES AND PRACTICE 31 
 
 As Henry and Morrison (1923) point out, there is never any reason 
 for paying high prices for proprietary mineral supplements, since an 
 adequate supply can always be provided very cheaply. Moreover, 
 with the exception of green bone (see below) there is no basis for 
 preference between the different sources mentioned for the particular 
 minerals. Therefore it will not be necessary to discuss them all indi- 
 vidually, but only to point out the following considerations. 
 
 Finely ground common salt should be added to the mash in the 
 proportion of from one-half to one per cent. Salt stimulates the 
 appetite, aids digestion, and is also required for other body processes. 
 According to an old superstition, salt is poisonous to birds. Salt, 
 however, is not poisonous, but when fed in concentrated form it may 
 be injurious to birds not having an adequate supply of water. Under 
 similar conditions salt may even be harmful to humans. 
 
 Fresh green bone is a good source of calcium and phosphorus. It 
 is very readily eaten but it contains too much fat to be fed in large 
 amounts and the protein contained, being deficient in essential amino 
 acids, has a low value. As usually fed it is difficult to get an even 
 distribution among the members of a flock and in addition it is 
 extremely difficult to handle and feed in large quantities under sani- 
 tary conditions. It should not be considered as a feed for flocks in 
 most sections of California. 
 
 Calcium and phosphorus should however, always be included in 
 the mash, some of the calcium always in the form of calcium 
 carbonate (as in limestone or oyster shell) to give the desired alkaline 
 reaction. If animal protein concentrates with 30 per cent mineral 
 content are used, they supply calcium and phosphorus in such an 
 amount that it is only necessary to add about 2 per cent limestone 
 to the mash. If the mineral content of the fish or meat scrap is less 
 than 30 per cent, sufficient bone meal should be added to bring it up 
 to 30 per cent. When vegetable protein concentrates are used, it is 
 always necessary to add both limestone and bone meal, about one 
 pound of mineral mixture for every five pounds of vegetable con- 
 centrates, in the proportions of 40 per cent ground limestone and 
 60 per cent steamed bone meal. 
 
 Other minerals like sulphur, sulphur compounds, Epsom salts, 
 etc., are frequently advertised as highly essential for birds. They 
 have never been demonstrated to have any good effect. If birds are 
 sick or out of condition, they need specific remedies ; general tonics 
 are of no value. 
 
 Charcoal should also be mentioned in this connection. It is most 
 generally recommended and used as a supplement to poultry rations. 
 
32 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION 
 
 Much investigational work has been carried out in order to demon- 
 strate the benefit of charcoal feeding but with no success. It is cer- 
 tain that the absorbing power of charcoal has been much over- 
 emphasized. Even if present, the absorbing power would be of ques- 
 tionable value. Charcoal feeding for poultry should be given up as an 
 unnecessary expense just as it has been abandoned in human dietetics, 
 where it was formerly recommended. 
 
 Grit should be given to poultry at all times, in order to enable 
 the birds to grind the feed in an efficient way. Hard grit, such as 
 granite grit, will serve such a purpose better than soft grit like lime- 
 stone grit, but the latter can be used satisfactorily. Hard grit is 
 absolutely insoluble and consequently does not supply any kind of 
 nourishment, so that it does not take the place of mineral supplements. 
 
 Vitamin Supplements. — In order to make the poultry ration com- 
 plete, certain vitamin supplements have to be added. The vitamins to 
 which particular attention has to be paid, for the reasons explained 
 above* are A and D. Vitamin A is commonly supplied by fresh greens 
 such as alfalfa, clover, kale, chard, lettuce, sudan grass, green barley, 
 green oats, young corn, etc. It may be supplied equally well by dried 
 greens, yellow, carrots, or cod-liver oil. 
 
 Provided an abundance of direct sunlight is available no further 
 provision of vitamin D in the diet has to be made. When it is neces- 
 sary to add vitamin D to the ration, the most practical way at the 
 present time is to use cod-liver oil. 
 
 A regular, plentiful supply of fresh greens is the common method 
 of supplying vitamin A to poultry. Fresh greens also supply suc- 
 culence, which, however, has not been demonstrated to have any 
 value. When depending upon fresh greens as a source of vitamin A, 
 the poultryman has to plan ahead for a regular every-day supply of 
 from 5 to 6 pounds of green feed for every 100 birds. Much more 
 should not be fed as the feed value of green feed is too low to justify 
 the expense. An excess of green feed also makes the egg yolks dark, 
 since it is the main source of the pigment xanthophyll. Tests of 
 different fresh greens as a source of vitamin A have shown very little 
 difference in the value of the different greens. Therefore the green 
 feed which can be procured most economically at any particular time 
 or place should be used. 
 
 Alfalfa can generally be depended upon during a large part of the 
 year. It should preferably be cut when young and tender because the 
 woody stems of the mature plant make it less digestible and palatable. 
 They are also low in vitamin A content. 
 
BUL. 417] POULTRY FEEDING : PRINCIPLES AND PRACTICE 33 
 
 In many sections of California kale is depended upon for the 
 green feed. Some poultrymen use the whole plant, running it through 
 a feed chopper. A better practice probably is to feed the leaves only, 
 as they are the most valuable part, and as the plant under those con- 
 ditions will give continued growth and production. 
 
 Green barley, in most sections of California, is one of the best 
 sources of fresh greens during the winter months when many other 
 greens are not available. Even in the coldest weather green barley 
 can be obtained by sprouting. Of the tw r o common methods, one is 
 that of ground sprouting out of doors. The grain is spread in thin 
 layers on the ground, or on wooden floors constructed for the purpose, 
 and covered with an inch of moist dirt or horse manure (not poultry 
 manure). If the seed is protected in this way green barley has been 
 obtained at air temperatures which for a short time were as low as 
 23° F. Barley can also be successfully sprouted indoors, in grain 
 sprouters constructed for the purpose, or on the floor of basements, 
 for instance. In order to obtain well sprouted grain it is necessary 
 to provide for moisture, heat, ventilation, and light. Only the green 
 sprouts have any value as vitamin supplements. Processed grains, 
 or the colorless sprouts produced in the dark have no such value. 
 
 In order to supply sufficient vitamin A from sprouted barley it is 
 necessary that 30 per cent of the daily grain allowance? that is, about 
 3 pounds to 100 birds, should be sprouted. It must be considered, 
 however, that the sprouting process decreases the feeding value of the 
 grains, so that this way of producing green feeds is far too expensive 
 for any great length of time. Moreover there is a danger in using 
 sprouted barley, because the grains that do not sprout during the 
 process, deteriorate and may develop injurious moulds which cannot 
 be easily detected. 
 
 Green oats can be used in the same way as green barley, but in 
 California are generally more expensive with no compensating 
 advantage. 
 
 There are certain advantages in using dried greens rather than 
 fresh greens as a source of vitamin A for poultry. If cured under 
 proper conditions, the vitamin A content is not much lowered. Greens 
 to be used dried can be produced more cheaply since they are grown 
 under more specialized conditions than when raised by each individual 
 poultryman. Dried greens can be included in the mash and therefore 
 more evenly distributed among the birds. 
 
 The proper curing conditions are rapid drying without long 
 exposure to the sun and this quick curing will yield a product of a 
 
34 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION 
 
 deep green color. The color therefore can be taken as the best prac- 
 tical indication of the quality. Bleached out products, that is, those 
 which have lost their green color, have no value as a source of 
 vitamin A. 
 
 At present alfalfa meal is the best kind of dried greens and has 
 been used in many sections with as much success as fresh greens. The 
 meal made from leaves and blossoms only is to be preferred to the 
 ordinary alfalfa meal because the woody stems have little value. The 
 vitamin A requirements will be met by an addition to the mash of 
 10 per cent ordinary good alfalfa meal or 5 per cent of the meal made 
 from alfalfa leaves and blossoms. Caution should be used in purchas- 
 ing leaf and blossom meal because some mills dispose of their sweepings 
 under the name at a low price. 
 
 It should be pointed out that birds do not like dried alfalfa until 
 they get used to it. If they are switched over too suddenly to a mash 
 containing alfalfa, they may go off feed, but when the change is made 
 gradually, dried alfalfa never causes any trouble, and moreover has an 
 advantage in that it contains proteins which are well suited as supple- 
 ments to the grain proteins. 
 
 If alfalfa meal is not available, practically the same results can be 
 obtained by feeding alfalfa hay in hoppers. In feeding by this 
 method, however, the advantage of even distribution is lost. 
 
 Except that in most places clover is more expensive to grow than 
 alfalfa, all the statements made concerning dried alfalfa apply to 
 dried clover. 
 
 Still another source of vitamin A has been found to be yellow 
 carrots. Yellow carrots in contrast to all other root crops have 
 proved to be fully equivalent to fresh greens for this purpose. They 
 have not been popular as a poultry feed because there is a common 
 belief that birds do not relish them. Like any new feed, birds have to 
 become used to them, but they do so quickly. Yellow carrots can fre- 
 quently be produced more cheaply than fresh greens and they also 
 have an advantage in that they can be stored for a time. It is an 
 interesting fact that the yellow pigment of carrots is carotin, which 
 does not color egg yolks. 
 
 The last vitamin A supplement to be considered is cod-liver oil. 
 One-half of one per cent, or one-half pint of tested cod-liver oil added 
 to every 100 pounds of mash or of grains will take care of the vitamin 
 A requirements of poultry. Cod-liver oil lacks important minerals like 
 iron, and can therefore be recommended only as a temporary vitamin 
 A supplement, and then only if a high-grade oil is used. It should be 
 
BUL. 417] POULTRY FEEDING : PRINCIPLES AND PRACTICE 35 
 
 recalled in this connection that vitamin A in cod-liver oil- is easily 
 destroyed. It is therefore essential, to be snre of good results, to use 
 an oil which has been tested and found rich in vitamin A. Ordinary 
 untested commercial cod-liver oils vary widely and are undependable 
 as a source of vitamin A. Recommendation of 1 per cent cod-liver 
 oil is commonly made to allow for variation of the vitamin A content 
 when untested oils are used. This doubling of the amount hoVever is 
 no guarantee that sufficient vitamin A will be present, so it is better 
 to use the tested oil in spite of the higher price. Even tested oil 
 should never be mixed into feeds and stored, as it then rapidly loses 
 its effectiveness. The cod-liver oil mash must be mixed fresh every day. 
 
 Cod-liver oil, besides supplying vitamin A, also supplies vitamin D, 
 which will be needed by young stock spending a considerable part of 
 the time indoors in the early part of the year because of the cool 
 weather or rain, and in the summer because of the heat. It is therefore 
 always advisable (at least in most sections of California) to feed cod- 
 liver oil as a source of vitamin D to young chicks during the first 6 to 
 10 weeks of their life. Older birds need cod-liver oil for the same 
 purpose during long continued cloudy or foggy weather. Laying birds 
 may also need this additional supply of vitamin D during seasons of 
 very heavy production and late in the season, when the evidence of 
 poor calcium utilization can often be observed in the poor shell texture 
 of the eggs produced. Cod-liver oil should also be fed to breeding 
 birds at all times, not because it is always needed, but as a precaution, 
 because it may be needed at any time. 
 
 One-half per cent or one-half pint of cod-liver oil added to 100 
 pounds of the mash or of the grains, supplies sufficient vitamin D for 
 the birds. As this vitamin is far more stable than vitamin A, an ordin- 
 ary commercial cod-liver oil generally is good enough for this purpose. 
 As mentioned previously particular light rays present in direct sun- 
 light (not passed through ordinary glass), or in light from special 
 lamps take the place of vitamin D. It is not practical on commercial 
 poultry farms to provide these ultra-violet rays artificially from 
 mercury quartz lamps ; neither has it as yet proved practical to 
 irradiate feeds. 
 
 Water. — It is essential that birds should at all times have access to 
 clean, fresh water, except when milk is given as the only protein sup- 
 plement, in which case no water should be given. The best way to 
 ensure a continual supply of fresh water is to have running or drip- 
 ping water in a trough or fountain which should be so constructed that 
 the overflowing water does not wet the surrounding litter or ground. 
 
36 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION 
 
 In hot weather it may be necessary to supply additional drinking 
 space because facilities which are sufficient for ordinary times of the 
 year may not take care of the greatly increased water consumption. 
 Neglecting this precaution will inevitably check production. 
 
 LAYING RATIONS 
 
 A laying ration that has given good results in the hands of many 
 poultrymen was recommended by Dougherty (1922), and contains 
 the following : 
 
 Grains Mash 
 
 50 pounds yellow corn 50 pounds wheat "1 
 
 50 pounds barley 25 pounds yellow corn or milo I Ground 
 
 25 pounds barley or oats J to S etner 
 
 Milk kept before the birds all 
 the time and used to moisten 
 mashes 
 
 Vitamin A supplement and minerals in any of the forms mentioned 
 have to be provided separately. 
 
 Another widely used ration is one recommended by Payne (1926). 
 It is formulated on the same principle, namely, the use of whole and 
 ground grains supplemented by protein and minerals. This ration is 
 no better but at present price levels is somewhat cheaper. With slight 
 modification it is as follows : 
 
 Grains Mash 
 
 100 pounds corn or milo 80 pounds corn or milo 1 
 
 100 pounds wheat or kafir 80 pounds wheat or kafir t 
 
 100 pounds barley or oats 80 pounds barley or oatsj °^ e ner 
 
 60 pounds fish or meat scrap (50 per 
 
 cent protein) 
 2 pounds ground limestone or oyster 
 
 shell 
 iy 2 pounds finely ground salt 
 
 Vitamin A supplement and lime in any of the forms mentioned 
 have to be provided separately. 
 
 (If fish or meat scrap contains less than 30 per cent minerals the 
 deficiency has to be made up by the addition of bone meal.) The grain 
 mixture of this ration has the nutritive ratio of 1 :6.92, the mash that 
 of 1 :3.86. Grains and mash combined give the nutritive ratio of 
 1 :5.39. This ration, therefore, contains far less protein than most 
 other poultry rations recommended at the present time; that is, the 
 nutritive ratio is wider than is usually the case. The fact that this 
 ration gives as satisfactory production as any other, is an illustration 
 
BUL. 417] POULTRY FEEDING: PRINCIPLES AND PRACTICE 37 
 
 of the fact that proteins when of the proper kinds, are required in 
 much smaller proportions than is popularly supposed. 
 
 Laying Rations with Vegetable Protein. — If market conditions 
 make such changes desirable, vegetable protein concentrates can suc- 
 cessfully be substituted for concentrates of animal origin. This sub- 
 stitution is easily undertaken by replacing each 3 pounds of animal 
 concentrates with 5 pounds of soybean meal (or peanut meal) and 
 1 pound of mineral mixture. Considering the previous recommenda- 
 tion, that the mash should always contain about 5 per cent of fish or 
 meat scrap, the ration, making use of the maximum amount of 
 vegetable protein concentrates will be : 
 
 Grains Mash 
 
 116 pounds corn or milo 80 pounds corn or milo "] 
 
 116 pounds wheat or kafir 80 pounds wheat or kafir I Groimd 
 
 116 pounds barley or oats 80 pounds barley or oats] °^ e lcr 
 
 15 pounds fish or meat scrap (50 per 
 cent protein) 
 
 75 pounds soybean meal (or peanut 
 
 meal) 
 17 pounds mineral mixture 
 1% pounds finely ground salt 
 
 Vitamin A supplement and lime in any of the forms mentioned 
 have to be provided separately (mineral mixture, see page 31). 
 
 Laying ration without fresh green feed: 
 
 Grains Mash 
 
 105 pounds corn or milo 80 pounds corn or milo "1 
 
 105 pounds wheat or kafir 80 pounds wheat or kafir I Tl oun' 
 
 105 pounds barley or oats 80 pounds barley or oats I °^ e 
 
 60 pounds fish or meat scrap 
 2 pounds limestone 
 iy 2 pounds salt 
 
 16 pounds alfalfa leaves and blossoms 
 
 Lime in any of the forms mentioned has to be provided separately. 
 This mash should be fed dry, as any other mash ; there is no need 
 of moistening the alfalfa meal. 
 
 CHICK RATIONS 
 
 There is no fundamental difference between a laying ration and a 
 growing ration for poultry. As Wheeler (1909) pointed out, the 
 protein requirements of rapidly growing chicks (that is, up to the age 
 of 14 to 16 weeks) are as high or higher than the protein requirements 
 of laying hens. Since no investigational work has ever been done that 
 upsets Wheeler's conclusions, which moreover are in close agreement 
 
38 
 
 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION 
 
 with the general principles of nutrition, it is a surprising fact that 
 most chick mashes on the market at the present time contain less pro- 
 tein than do laying mashes. 6 Some poultrymen go so far as to start 
 chicks on grain alone, a practice which is unsound because of the 
 deficient protein and mineral content. 
 
 There is no apparent reason why the laying rations previously 
 recommended should not also be excellent chick rations, when cod-liver 
 oil, as recommended above for young stock, is added and the whole 
 grains are reduced to suitable size. It should be mentioned, however, 
 that this station has as yet been unable to test these rations on young 
 
 e Theoretical considerations strongly suggest the advisability of feeding 
 more protein to baby chicks than to laying birds. Bunge (1905) has pointed 
 out the close relationship between the rate of growth of different animals and 
 the protein content of the mother's milk. This relationship is apparent from 
 the following figures, obtained from Bunge, and Ellenberger and Scheunert: 
 
 Animal 
 
 Days required for 
 
 doubling initial 
 
 weight 
 
 Per cent protein 
 in mother's milk 
 
 Nutritive ratio of 
 mother's milk 
 
 Man 
 
 180 
 
 1.6 
 
 1 :8.6 
 
 Horse 
 
 60 
 
 2.0 
 
 1 :4.2 
 
 Cow 
 
 47 
 
 3.5 
 
 1 :3.8 
 
 Goat 
 
 22 
 
 3.7 
 
 1 :3.6 
 
 Sheep 
 
 Hog 
 
 Dog 
 
 Rabbit 
 
 15 
 
 14 
 
 9 
 
 6 
 
 4.9 
 
 6.1 
 
 9.7 
 
 15.5 
 
 1 :3.4 
 1 :3.0 
 1 :2.5 
 1 : 1.5 
 
 It is quite evident that the rate of growth during early life is directly pro- 
 portional to the per cent of protein in the natural food, and consequently to 
 narrowness of the nutritive ratio. 
 
 By determining the protein retention at different ages Bunge was also able 
 to demonstrate that the protein requirements decreased as the rate of growth 
 progressively slowed down. At the same time carbohydrate requirements 
 increased in direct proportion to the increasing size of the animal. 
 
 Absorbed egg yolk, which furnishes chicks with their first nutriment after 
 hatching, has a protein content of about 44 per cent and a nutritive ratio of 
 1:2.5. Mitchell, Card and Hamilton (1926) have recently shown that Plymouth 
 Bock chicks double their initial weight in 14 to 15 days, which is about the 
 time required by a pig. 
 
 When one considers the fact that the pig at birth is many times larger 
 than the chick at hatching, and so requires a larger proportion of energy 
 nutrients (carbohydrate or fat) than chicks, the implication is very strong 
 that a chick ration should be much narrower than popularly supposed, narrower 
 to begin with in fact, than at any other time of life. It is also implied that the 
 ration should be gradually widened as chicks grow and the rate of growth 
 progressively slows down. 
 
 This may be accomplished by feeding mash only for the first ten days and 
 then introducing small and progressively increasing proportions of grain. 
 Since the mash recommended in this bulletin has a nutritive ratio of approxi- 
 mately 1 to 3.9, such a practice would appear fairly conservative. 
 
 This matter is being put to a comparative test at University Farm. As a 
 matter of fact while this bulletin was being written it came to the writers' 
 attention that the practice suggested above had been used with gratifying 
 success for at least three years in San Diego County. 
 
BUL. 417] POULTRY FEEDING : PRINCIPLES AND PRACTICE 
 
 39 
 
 stock. Caution therefore is urged not to use them on large numbers 
 of chicks, before results from smaller tests have been obtained. 
 
 For the use of poultrymen who prefer to use standard rations, the 
 following- are samples, many more of which could be given : a 
 (Dougherty 1922), b (Payne 1926), c (Vandervort 1925) and d 
 (Heuser 1920, and Rice and Botsford 1925). 
 
 Grains 
 33% pounds cracked wheat 
 33% pounds cracked yellow corn 
 33% pounds steel cut oats 
 
 Mas /* 
 25 pounds bran 
 25 pounds shorts 
 20 pounds yellow corn meal 
 10 pounds soybean meal 
 15 pounds meat scrap (or fish scrap) 
 5 pounds bone meal 
 
 Grains 
 50 pounds finely cracked corn 
 30 pounds finely cracked oats 
 20 pounds pine-head or steel 
 cut oats 
 
 Mash 
 
 33% pounds bran 
 
 16% pounds flour middlings or stand- 
 ard wheat middlings 
 
 16% pounds ground rolled oats or 
 sifted ground oats 
 
 16% pounds finely ground yellow corn 
 
 16% pounds finely ground meat scrap 
 
 Salt, 1 per cent of mash 
 
 Grains 
 60 pounds cracked corn 
 20 pounds cracked kafir or pin- 
 head oats 
 20 pounds cracked wheat 
 
 Mash 
 30 pounds bran 
 30 pounds shorts 
 25 pounds corn meal 
 10 pounds meat scrap 
 
 5 pounds mineral mixture 
 
 1 pound salt 
 
 Grains 
 50 pounds cracked corn 
 30 pounds cracked wheat 
 20 pounds pin-head or steel cut oats 
 
 Mash 
 20 pounds wheat bran 
 20 pounds middlings 
 25 pounds yellow corn meal 
 10 pounds oats 
 10 pounds meat scrap 
 
 5 pounds bone meal 
 10 pounds dried milk 
 % pound finely ground salt 
 
 1 per cent cod-liver oil 
 
40 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION 
 
 FEEDING METHODS 
 
 Feeding of Chicks. — Baby chicks should not be fed before they are 
 from 36 to 48 hours old, neither should the feeding be started very 
 much later. They may be given lukewarm water before this time, a 
 practice which is particularly advisable in hot weather. It is also good 
 practice to keep the chicks on a bare wooden floor, or on floor covered 
 with burlap, until after they are fed for the first time. 
 
 There are several methods used in starting to feed chicks. While 
 certain poultrymen start their chicks off on grain only, for the first 
 7 to 10 days the growing practice is that chicks be fed grain as well 
 as mash and vitamin supplements from the start. The amounts of 
 mash and grain should be at least equal and it is a question, as noted 
 above, whether we may not go even further in emphasizing the mash 
 (see footnote, page 38). A good practice has been developed in south- 
 ern California. The chick grains are mixed with the mash to form a 
 combination feed and kept before the birds all the time for the first 
 ten days. After this time grains and mash are fed separately. This 
 method of feeding also enables the smaller and more timid chicks to 
 get a good start by getting their supply of a proper ration. 
 
 If the vitamin supplements are given in the form of fresh greens, 
 it is customary to feed as much as the chicks will eat at least once a 
 day. The birds should under any circumstance consume 1 part of 
 tender greens by weight for every 4 parts of the other feed. If dried 
 greens are supplied, 5 per cent alfalfa leaf and blossom meal or 
 10 per cent of good alfalfa meal should be added to the mash. 
 
 It has generally been considered essential to feed only small 
 quantities at a time and to feed frequently. Recommendations have 
 been made in the past to feed only as much at a time as would be 
 cleaned up within ten or twenty minutes, so as to always keep the 
 birds hungry. This method, when properly used, gives excellent 
 results, but it has now been clearly demonstrated that it is just as well, 
 and perhaps even better for the inexperienced poultryman, to have 
 the dry mash in front of the chicks all the time and to feed the grains 
 in small quantities three or four times a day. The chicks, as well as 
 birds of all other ages, prefer the grains and will eat only as much 
 mash as is necessary to satisfy their worst hunger. It is therefore 
 always possible to regulate the feed consumption by regulating the 
 amount of grain fed. 
 
BUL. 417] POULTRY FEEDING : PRINCIPLES AND PRACTICE 41 
 
 As to the amounts of feed to be given to chicks at different ages, 
 no definite figures can be given. The food requirements vary with 
 different lots of birds, with the weather and with management. Closely 
 confined chicks, for instance, will not eat as much as chicks given 
 unlimited liberty. Therefore successful feeding of chicks depends on 
 good personal judgment. If this judgment is deficient or altogether 
 absent, no rules can be formulated that would cover even a minority 
 of the different conditions and possibilities. On the average, mash 
 and grains during the first ten to twelve weeks should be fed in equal 
 proportions, but it may be necessary to deviate from this rule, at one 
 time in one direction, at another in the opposite. The aim is to keep 
 the chicks as healthy and lively as possible. With good chicks and 
 good weather this is comparatively easy, but during bad weather and 
 with poor chicks it may be more difficult to keep the birds as active as 
 is desirable. One method of doing this, which should be used for only 
 a few days at a time, is to feed mash sparingly and to let the chicks 
 work for the scratch grain most of the time. Under such conditions 
 it is, of course, a necessity to restore the nutritive balance by feeding 
 more mash than grains as soon as possible. 
 
 With only a small number of chicks it is comparatively easy to 
 determine fairly accurately the amount of mash consumed every day 
 by weighing back, and then feed grain accordingly. With larger 
 numbers of birds this is hardly practical, and less accurate estimates 
 will usually have to suffice. 
 
 While the grain portion during the first two or three weeks has to 
 be divided up and fed from three to four times a day, the grain feed- 
 ing later on can be limited to mornings and evenings only. The equal 
 proportions of grain and mash should be maintained up to the twelfth 
 week, the grain feeding thereafter should be gradually increased and 
 the mash feeding correspondingly decreased, since from this time until 
 laying the protein requirements go down because of the slowing down 
 of rate of growth. At from fourteen to sixteen weeks the chicks should 
 have approximately two-thirds grain and one-third mash, with the 
 mineral mixture given on page 31 hopper-fed and a vitamin A supple- 
 ment provided. At sixteen weeks of age, if raised properly, Leghorn 
 pullets should weigh 2y 2 pounds or more. After sixteen weeks of 
 age, according to the development of the birds, it may be necessary to 
 feed even more grain, possibly as much as 85 per cent grain with only 
 15 per cent mash, which is easily accomplished by feeding mash only 
 two half -days a week. 
 
 It must be pointed out, however, that the success of developing 
 pullets will depend entirely upon uniformity of the flock. The birds 
 
42 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION 
 
 have to be selected for size and development and fed in separate 
 groups. Otherwise more harm than good may be done in trying to 
 regulate the growth. 
 
 This is a good time to break the birds in on barley and others of 
 the less palatable grains, if this has not been done before. It is then 
 practical to hopper-feed these grains and to feed the more attractive 
 grains in the morning and at night. 
 
 Provided the birds are well developed, it should be realized that 
 grain feeding during this time can hardly be overdone. The birds 
 will be held back from premature laying and be given a chance to 
 mature physically, a condition which is altogether essential if the best 
 results are to be obtained later on. This method of management also 
 tends to do away with an excess of too small eggs during the pullet 
 year. The pullets will, of course, get more or less fat in this way, but 
 pullets bred for production can hardly get too fat. It is the fat that 
 enables them later on to stand the strain of egg production over a long 
 period, and that carries them over the beginning of production until 
 their digestive tract has adapted itself to the increased demands on its 
 activity. 
 
 The common practice of feeding more bran during this time is 
 not good. The bran certainly will retard sexual maturity, but it will 
 tend to stunt the birds physically also, at a time when their growth 
 should be promoted. 
 
 The feed consumption of pullets from the start up to maturity is 
 approximately 28 pounds of grain and mash, more than two-thirds of 
 the amount being grain. During all this time, care should be taken 
 to ensure a sufficient supply of vitamin A supplement, preferably in 
 the form of alfalfa or clover, hopper feeding the mineral mixture (see 
 page 31) to which 5 per cent salt has been added. 
 
 Feeding Laying Birds. — When pullets (Leghorns) have reached 
 the age of five and a half or six months they should weigh 3% pounds. 
 They should again be selected for maturity and those that are under- 
 sized should be developed further or, preferably, be marketed. As 
 far as the others are concerned, production may be allowed to begin. 
 Production at this time is brought on simply by changing the ration 
 back to half grain and half mash. Temporarily mash may be fed even 
 in slight excess of the grains. Laying will normally start within ten 
 to fourteen days of the change. 
 
 From that time until the end of the first laying year the feeding 
 must be regulated according to the production. The feed consumption, 
 of course, will depend upon the digestibility of the ration and will also 
 vary with the production. On an average, however, a Leghorn hen 
 
BUL. 417] POULTRY FEEDING: PRINCIPLES AND PRACTICE 43 
 
 will eat in a year from 70 to 75 pounds of grain and mash together, 
 which means that approximately 10 pounds of grains and 10 pounds of 
 mash should be fed each day to a hundred birds. 
 
 By feeding the grain and mash in equal proportions, production 
 Will reach a certain point. If the same feeding is continued, the birds 
 may not be able to stand the strain and will soon start losing weight 
 and finally go out of production. They may even go into a molt. On 
 the other hand on this same ration other flocks may never come up to 
 a satisfactory production and may even put on fat. 
 
 Here the art of feeding comes in. It will be found that if birds 
 lay too well for their physical capacity, they will inevitably lose body 
 weight. The maximum point of production for a given flock has to 
 be recognized by the poultryman either by means of an intimate knowl- 
 edge of them or by weighing a few birds from time to time, the feeding 
 being regulated accordingly. If birds are losing weight because of 
 too heavy production, more grain should be fed. The protein propor- 
 tion is thereby decreased ; production will go down, and the increased 
 carbohydrates and fats will cause the birds to take on weight and 
 gain in power of resistance. 
 
 If, on the other hand, production is unsatisfactorily low and the 
 birds seem to get heavy and lazy, a cut in their grain allowance will 
 increase the consumption of mash, thereby increasing the propor- 
 tion of protein consumed, and stimulating activity, appetite, and 
 production. 
 
 Thus it appears in this connection, there are two frequent causes 
 for a decrease in egg production. First, a breakdown due to too much 
 protein resulting in too heavy production; second, too wide a ration 
 resulting in the birds getting too fat. Molting of pullets in the fall 
 and spring is frequently a natural reaction against forced production. 
 
 Figure 6 illustrates records of feed consumption and egg produc- 
 tion in a flock of birds in California. The decrease of production 
 from the first of October to the first of December was probably due 
 to wrong feeding methods. Pullets starting to lay should have been 
 brought into a condition in which they would stand at least as much 
 mash as grain during the first month or so, with a resulting produc- 
 tion of at least 40 or 45 per cent. Since these birds showed a decrease 
 in production and were getting more grain than mash, they were 
 probably getting fat, and should have been forced to eat more mash. 
 After the first of December the production went up — as would be 
 expected — and reached its maximum about the first of April. That 
 this maximum was beyond the physical capacity of the birds is clearly 
 shown by the marked decrease of production and mash consumption 
 
44 
 
 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION 
 
 and the increasing grain consumption. If, therefore, the birds had 
 started on more mash, but had been given more grains during the time 
 from January to July, a more even production on a higher plane 
 would normally have resulted. The birds would then also have been 
 in such good physical condition that from July on they would have 
 been able to stand a temporary forcing by means of increased mash 
 feeding, the result of which would have been an extended laying 
 period. 
 
 Lbs. 
 7 
 
 
 
 
 
 
 
 
 
 
 
 
 ngrLe 
 
 
 
 
 
 > 
 
 * 
 
 ». 
 
 •**. 
 
 
 
 
 
 
 
 
 / 
 
 ,<<- 
 
 Prodcn 
 
 rrion 
 
 
 
 \ 
 
 
 60 
 
 
 
 1 
 
 / 
 
 / 
 
 
 Mash, 
 
 t 
 
 
 
 
 
 \ 
 
 
 \ 
 
 
 A 
 
 :>. 
 
 / 
 
 
 
 
 ^~***>* 
 
 \ 
 
 \\ 
 
 
 
 
 / 
 
 
 K 
 
 Grain 
 
 
 
 
 
 A 
 
 30 
 
 
 
 ZO 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 O 
 
 Jan. 
 
 Apr. Mau June July Aug. 5ep+. 
 
 Fig. 6. — Records of feed consumption and egg production in a flock of birds 
 
 in California. 
 
 All-mash or Combination Feeding. — During recent years the new 
 practice of feeding all the grain finely ground and mixed together 
 with the mash is being advocated. This method of feeding is still in 
 an experimental stage, so that the final word cannot be said about it. 
 There are, however, definite objections to such a practice. The nutri- 
 tive requirements of the same flock are not the same at different times, 
 much less the requirements of the different individual birds. Feeding 
 mash only leaves no opportunity for variations without changing the 
 proportions in the mixture, making frequent changes for the flock 
 impractical and variations by the individuals impossible. The feeding 
 of grains and mash separately enables the individual bird to influence 
 its own ration by eating more of one or the other, thereby more or less 
 meeting its individual needs. An instinctive ability of the bird to do 
 this has been demonstrated by Pearl and Fairchild (1921) with flocks 
 fed all feeds on the cafeteria style. 
 
BUL. 417] POULTRY FEEDING: PRINCIPLES AND PRACTICE 45 
 
 It is quite true that an ' ' all-mash ' ' method of feeding decreases the 
 labor to some extent. This advantage, however, may be more than 
 offset by the diminished personal attention that will be given to the 
 birds. Regular feeding hours every day are an inducement to the 
 poultryman to give his birds some of the care that can only be the 
 result of personal contact. Such personal contact and attention, or 
 lack of them, often determine the success or failure of the poultry 
 venture. 
 
 Feeding of Breeding Birds. — The production of hatching eggs, as 
 far as feeding methods are concerned, is ordinarily attained by the 
 same methods as that of commercial eggs. Frequently birds from 
 which the eggs are collected for hatching purposes are fed less protein 
 in order to keep production down to some extent. The benefit of this 
 practice is doubtful, although it may be advisable to reduce production 
 previous to the hatching season. 
 
 Certain poultrymen claim to obtain better hatching eggs when 
 milk, either fresh or dried, is included in the feed. A liberal supply of 
 vitamin A and vitamin D supplements in any of the forms recom- 
 mended should always be provided. 
 
 Feeding of Molting Birds. — Ordinarily not all birds in a flock are 
 molting at the same time. Special consideration to the feeding of 
 molting birds therefore is effective only if the molters are separated 
 from the other birds. In that case the molters, if they have the proper 
 weight, do not need as much feed as laying birds, but they should be 
 fed well. They should preferably be kept in a quiet place since they 
 are very easily disturbed because of the increased sensitivity of the 
 skin. It may be a good practice to aid the feather growth by including 
 in the mash substances rich in sulphur, such as hydrolyzed hoof and 
 hair meal, or hydrolyzed feathers. 
 
 Feeding Birds for Fattening. — In common usage the term is used in 
 referring both to the fattening of mature birds for market and to the 
 forced growth of young stock for market. In one case the formation 
 of fat is required and in the other the formation of muscle, but the 
 rations which are commonly used are practically identical. They are 
 composed of ground grains moistened with milk into a sloppy soup. 
 This brings about the desired effect by virtue of the fact that birds 
 will eat more of a wet mixture than of dry food and will digest it more 
 quickly. If milk is not available, meat scrap is used instead and the 
 mixture is moistened with water. 
 
 This is a branch of the poultry industry which can for several 
 reasons be better undertaken by people who specialize in this par- 
 
46 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION 
 
 ticular field. It needs particular skill and experience, and can also 
 be more efficiently undertaken on a large commercial scale near the 
 market than in small lots on individual ranches at a distance from the 
 market. If special conditions make it advisable for the individual to 
 fatten his birds before marketing them, the nutritive ratio should be 
 adapted to the kind of grain required. In the case of broilers the 
 nutritive ratio should be about 1 to 4, and any combination of the 
 ordinary feeds which will give this ratio may be used. For fatten- 
 ing mature birds, however, the feed should be so chosen as to give a 
 wider nutritive ratio. 
 
 Commercial Poultry Feeds. — For many years commercial feed 
 mixtures have had a large place in the poultry industry of California. 
 This fact seems to indicate that they are serving a very useful purpose. 
 Whether in a given case it is better for the poultryman to mix his 
 own, or purchase ready mixed feeds is largely an economic question. 
 
 The feed dealer has the advantage of buying feedstuffs and mixing 
 feeds in large quantities. Not infrequently he can lay his products 
 down in the poultryman 's feed house as cheap or cheaper than the 
 latter can by doing his own mixing. This leaves the poultryman free 
 to devote his whole time to the management of his flock. 
 
 The decision as to whether commercially mixed or home-mixed 
 feeds are to be employed in a given instance is a matter of business 
 judgment and common sense, provided always that the principles out- 
 lined above have been followed reasonably closely. 
 
 It has been pointed out and indeed emphasized that there is no one 
 best ration. Any ration which provides the proper kinds and propor- 
 tions of nutrients as economically as possible is a good ration. There 
 is no reason to believe that anyone can do more than this. There does 
 not appear to be much foundation for large claims concerning secret 
 formulae or particular substances. 
 
BUL. 417] POULTRY FEEDING : PRINCIPLES AND PRACTICE 47 
 
 BIBLIOGRAPHY 
 
 Beach, J. R. 
 
 1924. Studies on a nutritional disease of poultry caused by vitamin A 
 
 deficiency. California Agr. Exp. Sta. Bui. 378: 2-22. 
 
 Bunge, G. V. 
 
 1905. Lehrbuch der Physiologie des Menschen, Vol. II, 2nd edition, 
 pp. 141-163. F. C. W. Vogel, Leipzig. 
 
 Davis, D. E., and J. R. Beach 
 
 1925. A study of the relative values of certain succulent feeds and alfalfa 
 
 meal as sources of vitamin A for poultry. California Agr. Exp. 
 Sta. Bui. 384: 3-14. 
 
 Dougherty, J. E. 
 
 1916. Source of protein for fowls. Ann. Rept. California Agr. Exp. Sta., 
 p. 58. 
 
 1922. Poultry feeding. California Agr. Exp. Sta. Cir. 242: 1-22. 
 
 Ellenberger, W., and A. Scheunert 
 
 1925. Lehrbuch der vergleichenden Physiologie der Haussaugetiere, 3rd 
 edition, p. 317. P. Parey, Berlin. 
 Gerhartz, H. 
 
 1914. Untersuchungen iiber die Energieumsetzungen des Haushuhns. Land- 
 wirtschaftliche Jahresblicher 46: 797-814. 
 
 Henry, W. A., and F. B. Morrison 
 
 1923. Feeds and feeding. 18th edition, p. 194. The Henry Morrison 
 
 Company, Madison, Wis. 
 
 Heuser, G. F. 
 
 1920. Feeding for egg production. New York Agr. Exp. Sta. Bui. 157: 3-34. 
 
 Hopkins, G. F., et al. 
 
 1924. Report on the present state of knowledge of accessory food factors 
 
 (vitamins). Medical Research Council. London. Second ed. 
 enlarged, p. 171. 
 
 Katayama, T. 
 
 1924. tiber die Verdaulichkeit der Futtermittel bei Hiihnern. Imp. Agr. 
 Exp. Sta. (Japan), Bui. 3: 1-78. 
 
 Kennard, D. C, R. C. Holder, and P. S. White 
 
 1922. Mineral supplements to rations for chickens: Corn meal and soybean 
 
 meal. Poultry Sci. 1: 65-74. 
 
 Mendel, L. B. 
 
 1923. Nutrition: The chemistry of life. p. 118. Yale University Press, 
 
 New Haven. 
 
 Mitchell, H. H., L. E. Card, and T. S. Hamilton 
 
 1926. The growth of White Plymouth Rock chickens. University of Illinois, 
 Agr. Exp. Sta. Bui. 278: 70-132. 
 
48 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION 
 
 NlTZESCU, J. J. 
 
 1918. Der Naherwert des neuen und alten Maises. Archiv. f. d. g. Physiol. 
 172: 275-317. 
 Payne, L. F. 
 
 1926. Poultry management on the farm. Kansas Agr. Exp. Sta. Cir. 122: 
 1-50. 
 
 Pearl, E., and T. E. Fairchild 
 
 1921. Influence of free choice of food material on winter egg production 
 and body weight. Amer. Jour. Hygiene 1: 253-277. 
 
 Philips, A. G., and S. M. Hauge 
 
 1925. Soybean oil meal in rations for laying pullets. Purdue Agr. Exp. 
 Sta. Bui. 293: 3-20. 
 
 Rice, J. E., and H. E. Botsford 
 
 1925. Practical poultry management. 1st edition, p. 368. John Wiley & 
 Son, New York. 
 
 Vandervoort, J. 
 
 1925. Raising chicks for profit. Illinois Agr. Exp. Sta. Cir. 294: 3-15. 
 
 VOLTZ, W., AND G. YAKUWA 
 
 1909. Studien iiber Stoffwechsel des Haushuhnes. Landwirtschaftliche 
 Jahresbucher 38: 555-592. 
 
 Voltz, W., and W. Dietrich 
 
 1923. Untersuchungen iiber den Nahrstoff und Energiebedarf fur die Eier- 
 produktion des Haushuhnes. Landwirtschaftliche Jahresbucher 
 58: 355-377. 
 
 Wheeler, W. P. 
 
 1899. Animal food for poultry. New York Agr. Exp. Sta. Bui. 171: 
 
 461-506. 
 1909. In Jordan, W. H. The feeding of farm animals. 6th edition. 
 
 p. 379-399. The Macmillan Co., New York.