UNIVERSITY OF CALIFORNIA COLLEGE OF AGRICULTURE AGRICULTURAL EXPERIMENT STATION BERKELEY, CALIFORNIA CIRCULAR 300 December, 1925 COCCIDIOSIS OF CHICKENS J. K. BEACH and D. E. DAVIS* Coccidiosis is one of the most destructive diseases of young chickens. It is so widespread that, in poultry districts, practically all established poultry farms are infected and new farms quickly become so. The heaviest losses occur in chicks from four to eight weeks old. In infected flocks from 25 to 50 per cent and sometimes nearly all of the chicks die in two or three weeks. The large number of unthrifty or "cull" chicks among the survivors in infected flocks that have not been given effective treatment sometimes causes a greater loss to the poultryman than the mortality. Older birds become affected with a slowly fatal (chronic) type of the disease, which may be general in the flock or, as frequently happens, affect only a few birds. The disease frequently occurs in young turkeys as well as in chickens. CAUSED BY A PARASITE Coccidiosis is caused by the presence in the intestines of chicks of a microscopic, protozoan parasite called Eimeria avium. The parasite develops and multiplies in the cells of the walls of the intestines. The disease results from the injury to the cells during this period of development. In young chicks, the ceca (blind pouches) are the parts affected, while in older birds with the chronic type of the disease, the small intestines, rather than the ceca, are involved. Severe outbreaks of coccidiosis so frequently occur in flocks which have not received suitable food or care or which are not properly housed, that some poultrymen believe it to be due to such conditions. These conditions do not cause coccidiosis, but render them more sus- ceptible by lowering their natural resistance. Therefore, such things as over-feeding, sudden changes in the ration, poorly ventilated houses, raising too many chicks in a house, failure to keep the houses warm and dry day and night and especially during cold, rainy weather, and failure to keep the houses clean favor the occurrence of serious outbreaks. * Division of Veterinary Science. UNIVERSITY OF CALIFORNIA EXPERIMENT STATION CIRC. 300] COCCIDIOSIS OF CHICKENS LIFE CYCLE OF THE PARASITE In the completion of its life cycle, the parasite - passes through many forms or stages of development. A knowledge of certain of these stages is of practical importance in the application of effective preventive and control measures. The first stage, or egg stage, of the parasite is known as an oocyst (fig. 1, A). Large numbers of oocysts are present in the drop- pings of affected chicks. Oocysts in freshly expelled droppings are not harmful when taken into the intestines of chicks. Under the conditions of moisture and temperature such as are found in brooder houses, how- ever, in two or three days they undergo a change known as sporulation. (% 1, B.) In the brooder yards, conditions are less favorable for sporulation and a longer time is required for it to take place. It is the sporulated oocyst which causes coccidiosis when ingested by susceptible chicks. This form is very resistant and may remain alive in the soil of poultry yards for a year or longer. When the sporulated oocysts are taken into the intestine, very minute, motile forms, known as sporozoites, (fig. 1, C), are released. These penetrate the cells of the mucous membrane lining of the ceca or small intestines. There they develop and multiply by what is known as the asexual cycle. The final stage of this developmental is called a merozoite (fig. 1, C). The merozoites migrate to other cells and either pass through an asexual cycle, like the sporozoites, or through what is known as the sexual cycle, the final stage of which is the oocyst (egg stage). The oocysts do not develop further in the intestines of the birds, but pass out with the droppings and undergo sporulation as previously described. The development and multiplication of the parasite in the walls of the ceca and intes- tines cause extensive destruction of the mucous membrane lining. Often also the walls of small blood vessels are destroyed. This results in hemorrhage into the ceca and the appearance of blood in the droppings. CONTAMINATED SOIL COMMON SOURCE OF INFECTION Chickens become infected with coccidiosis by the ingestion of food or drinking water contaminated with sporulated oocysts. The soil of yards in which infected chickens have been kept is the most common source of the infection. Brooder houses, feeding and watering vessels, hovers and other accessories previously used for infected birds and which have not been property cleaned may be a source of the infection. 4 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION Attendants may carry infection into brooder houses from contami- nated yards. Chicks may become infected when allowed to run in orchards or gardens that have been fertilized with chicken manure. The infection may be introduced on to new premises by such means as healthy adult fowls which harbor the germs, wild birds, dust -laden wind, visitors, etc. It is improbable that infected hens ever transmit the disease through the egg to their offspring. Fig. 2. Cliick with coccidiosis. DROOPINESS FIRST SYMPTOM IN CHICKS Usually the first indication of the presence of coccidiosis in a flock of chicks is droopiness of a few. The affected birds remain close to the hover, do not eat, and stand with wings drooping, head drawn in, and eyes closed for long periods of time unless disturbed. This attitude is quite characteristic of the disease (fig. 2). Droopy birds may be seen for two or three days before any deaths occur. BLOODY DIARRHEA NOT ALWAYS PRESENT The droppings of affected chicks frequently contain blood. The amount varies from that sufficient only to slightly tinge the droppings to enough to give them the appearance of consisting entirely of blood. The bloody droppings usually are seen in the early stages of the out- break. Occasionally they are the first indication of disease observed. Although the presence of blood in the droppings is a frequently occurring and quite characteristic symptom, it must be borne in ClRC. 300] COCCIDIOSIS OF CHICKENS 5 mind that, in many outbreaks of coccidiosis, this does not occur. Therefore, " bloody diarrhea," the name for the disease commonly used by poultrymen, does not always apply. The use of this name should be discouraged, since it may give poultrymen the impression that coccidiosis is not present in their flocks unless blood is seen in the droppings. Fig. 3. Seven-months old pullet with chronic coccidiosis. MORTALITY GREATEST AT START OF OUTBREAK The heaviest mortality usually occurs during the first week or ten days after the first droopiness appears. After this, deaths become less frequent but may continue for from three to four weeks. When effective measures of control are not adopted, a large percentage of the survivors fail to develop normally. Such birds may never become profitable and the loss to the poultrymen from this source may be as great as that resulting from mortality. OLDER BIRDS HAVE CHRONIC TYPE OF THE DISEASE The chronic type of the disease is seen in older birds, usually pullets between the ages of four and eight months. It develops slowly and may affect only a few fowls in a flock. The prominent symptoms are loss of appetite, roughened, dirty plumage, gradual loss of flesh, paleness of the comb and wattles, leg weakness or "par- alysis" of the legs, or sluggish, weak movements when walking. In extreme cases of leg weakness, the fowl may lie on its side with both legs extended backward (fig. 3), or it may lie on its breast with one 6 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION leg extended forward and the other backward (fig. 4). Some pullets that are unable to stand appear quite normal in a sitting posture. Death from chronic infection occurs only after several days or even weeks of sickness. Chronic coccidiosis may be easily confused with the symptoms resulting from external parasites, intestinal worms or nutritional disturbances. Fig. 4. Four-months old pullet with chronic coccidiosis. DISEASE AFFECTS CECA OF CHICKS The changes in the organs observed upon examination of dead birds vary with the duration of the disease or the severity of the infection. In chicks, the changes are usually confined to the ceca. The walls of these organs are, as a rule, thickened. The ceca may be normal in size or markedly distended. They often contain suffi- cient blood to give them a reddish appearance. In some birds, small, whitish areas may be present in the walls of the ceca. Such areas are sometimes distributed throughout the small intestine. The ceca of chicks which linger for a week or more before death often contain an accumulation of grayish or yellowish -white, cheesy material (fig. 5). This may consist of a solid mass which appears to have been deposited in layers or it may consist of a grayish-white plug with a hollow center. Frequently chicks which have died of coccidiosis exhibit no definite marked change in the appearance of the ceca or of the cecal contents. In such cases, the disease can be recognized only by the finding of oocysts on microscopic examination of the contents of the ceca. Occasionally the liver is involved. The liver lesions, when present, consist of small, white or yellowish specks on the surface. CIRC. 300] COCCIDIOSIS OF CHICKENS CHRONIC TYPE AFFECTS SMALL INTESTINES In pullets with the chronic type of the disease, the lesions are con- fined to the small intestines. The intestinal walls become thickened and the lining has a spongy appearance. In severe cases, red blotches or hemorrhagic areas may be present. Occasionally there is a slough- ing of patches of the lining. The ceca rarely show any change. Fig. 5. Ceca of chick with coccidiosis. DISEASE IN CHICKS NOT ALWAYS EASY TO RECOGNIZE Coccidiosis is easy to recognize when affected chicks void bloody droppings or when bloody or cheesy material is found in the ceca of dead chicks. When these indications of the disease are absent, it is necessary to find the parasite in the ceca in order to definitely deter- mine the presence of coccidiosis. This requires a microscopic exami- nation. However, the disease is so prevalent that whenever droopiness or death of a few chicks occurs in a previously healthy flock, the presence of coccidiosis should be at once suspected and proper control measures adopted without waiting for a microscopic examination to be made. Chicks may then be submitted for examination to a veteri- y UNIVERSITY OF CALIFORNIA EXPERIMENT STATION narian or a laboratory. The chicks will not be injured by the control measures and, if coccidiosis is found, they will be benefited by receiving treatment so promptly. CHRONIC TYPE RESEMBLES OTHER DISEASES Chronic coccidiosis can be differentiated from the effects on chickens of certain species of intestinal worms or from some nutritional dis- turbances only by microscopic examination of intestinal contents or of scrapings from the lining of the intestines of affected fowls. Frequently both coccidial parasites and one or more species of intes- tinal worms may be present in the same fowl. Therefore, before an intelligent decision can be made as to the treatment of fowls suspected of having chronic coccidiosis, it must be determined: first, whether coccidial parasites are present ; second, whether other intestinal para- sites are present; and third, whether there is any relation between nutrition and the condition of the fowls. CONTROLLED BY DIET AND SANITATION The results of experiments 1 conducted at this station indicate that feeding sufficient buttermilk or skim-milk is of considerable value in controlling outbreaks of coccidiosis. The benefit derived from the milk appears to be due to two factors : first, its property of producing acidity in the ceca, and, second, its ability to stimulate rapid growth. The production of acidity is due to the milk sugar. Acidity can be produced equally well by feeding milk sugar alone, sweet milk, sour milk, or dry skim-milk. Therefore, acidity in sour milk, butter milk, or other milk products is not a necessary factor in producing acidity in the intestinal tract of chickens. The same is true of the milk- souring bacteria. Even the feeding of cultures of lactic acid-producing bacteria adds nothing to the effectiveness of milk. The acidity pro- duced in the ceca by the milk sugar appears to be harmful to some of the forms of the coccidial parasites present in those organs. In 1 Beach, J. E., and Corl, J. C. Studies in the control of avian coccidiosis. Poultry Science 4: 83-93, 1925. Beach, J. E. The effect of feeding lactose, cultures of B. acidophillus, whole milk or dry skim-milk on the hydrogen ion concentration of the cecal contents of chickens. Hilgardia 1: 145-166, 1925. Beach, J. E., and Davis, D. E., The influence of feeding lactose or dry skim-milk on artificial infection of chickens with sporulated oocysts of Eimeria avium. Hilgardia 1: 167-181, 1925. CntC. 300] COCCIDIOSIS OF CHICKENS 9 order to continuously maintain acidity in the ceca, a more or less continuous flow of milk sugar through the intestinal tract is necessary. This has been accomplished by feeding mash containing 20 per cent milk sugar or 40 per cent dry skim-milk. The ability of milk to stimulate rapid growth of chicks gives to them increased resistance against diseases in general and, therefore, against coccidiosis. Milk sugar alone is not so suitable for use in controlling coccidiosis as dry skim-milk or milk in liquid state, such as buttermilk, because it is not relished by the chicks and is less nutritious. Sanitation in the houses and yards and the care of the chicks are as important in the control of the disease as the use of milk in the ration. If these factors are neglected little benefit from milk feeding can be expected. Recommendations concerning the use of milk in the ration and san- itary measures to control coccidiosis follow: DRY SKIM-MILK IN MASH If dry skim-milk is used it should constitute 40 per cent of the mash. Since dry skim-milk is more expensive than the poultry feeds commonly used, this amount may seem unnecessarily large ; however, if less is used, satisfactory results cannot be expected. The dry skim- milk is relatively rich in protein, and, therefore, it should not simply be added to a chick mash mixture containing meat scrap or other protein concentrate ; instead, a special mixture should be prepared. One that has been found satisfactory, both in experimental flocks and in the few cases where it has been used on poultry farms, consists of the following ingredients : Dry skim-milk 40 pounds Wheat bran 10 pounds Yellow cornmeal 30 pounds Ground barley 20 pounds Start feeding the mash as soon as the presence of the disease is determined. Keep the mash constantly before the chicks in hoppers or troughs constructed so as to prevent waste. 2 Provide sufficient hoppers so that all chicks can eat freely. Fail- ure to do this will result in the weaker chicks being crowded out and 2 Dougherty, J. E., and Gossman, S. S. Inexpensive Labor Saving Poultry Appliances. Calif. Agr. Exp. Sta. Cir. 268: 1-32, 1923. 10 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION not getting sufficient mash. Determine the weight of the mash con- sumed each day. 3 Feed grain once or twice daily but restrict the amount to from one-third to one-half the weight of mash consumed. If more grain is fed, mash consumption will be reduced and less satisfactory results will be obtained. Continue this system of mash and grain feeding as long as there is any indication of the disease. This usually requires from one to two weeks. If desired, the ration can then be very gradually changed to the one in use before coccidiosis started. Do not start the change in the ration too soon nor make it too abruptly. Feed greens as usual. If the supply of greens is insufficient, add one quart of cod liver oil to each one hundred pounds of mash. This is also advisable when weather conditions or weakness of chicks pre- vents them from running outside. Do not neglect sanitation. See p. 12. In our experimental work, as previously stated, it was found that this method of feeding was suitable for use for the short periods the experiments were in progress. A few poultrymen have followed this feeding program from the time the chicks were placed in the brooder house until they were two months of age. They report that the chicks made rapid growth and matured early, and that the percentage of culls and the mortality were unusually low. The brooder yards used were contaminated with the coccidiosis germs (oocysts) and a few deposits of bloody droppings were observed at times during the brood- ing period, showing that some had become infected. However, there were no other indications of coccidiosis, such as droopiness, and none died from this disease. Although the continuous use of this feeding method may be highly effective in preventing coccidiosis, the high percentage of milk protein in the ration may result in such unnaturally rapid growth that the chicks will suffer a setback when the ration is changed to the usual grain mixture. Until further information on this point is available, we cannot recommend that mash containing 40 per cent dry skim- milk be fed longer than three or four weeks. 3 The weight of mash consumed can be determined by weighing the amount of mash supplied in the morning and weighing back the unconsumed portion on the following morning. The difference in the weights represents the amount consumed during the twenty-four hour period. This weight is used to deter- mine the amount of grain to feed. ClRC. 300] COCCIDIOSIS OF CHICKENS 11 BUTTERMILK AS A DRINK When liquid milk, such as buttermilk or skim-milk, is to be used, first locate an adequate supply of good quality. Keep the milk constantly before the chicks in fountains or troughs. If troughs are used, provide covers that will prevent the chicks from walking in them or roosting over them. Provide sufficient containers so that all the chicks can drink freely and the weaker chicks will not be crowded away. Allow the chicks no water. Feed no mash. Feed grain twice daily, very sparingly in the morning and a larger amount at night. Feed greens as usual. Add one quart of cod liver oil to each one hundred pounds of mash if the supply of greens is insufficient or the chicks cannot go out of doors. After all evidence of the disease has disappeared, the feeding of mash may be very gradually resumed, water again given, and the amount of milk reduced. Do not start this change in feeding too soon nor complete it too rapidly. Do not neglect sanitation. See p. 12. A condensed milk product, such as semi-solid buttermilk, may be used after dilution in the same manner as buttermilk. Use one part to two or three parts of water. Greater dilutions are less bene- ficial. Many poultrymen report satisfactory results from the use of undiluted semi-solid buttermilk. If it is fed in this way, water must be supplied. MILK FEEDING CAUSES WATERY DROPPINGS When chicks are fed liberally with milk, either dry or liquid, the droppings become watery and are voided frequently. This, in itself, is not harmful. The watery consistency of the droppings, however, causes the litter and floor to become wet in a short time. This makes it necessary to clean out the houses and renew the litter daily in order to keep the floor dry. When this is not done, the floor becomes wet. A condition is thus created that is extremely favorable for the devel- opment of oocysts from the harmless to the harmful stage and one very unfavorable for the continued good health of chicks. This is the only way the discharge of watery droppings, resulting from milk feeding, may prove harmful. 12 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION ADVANTAGES OF DRY SKIM-MILK As previously indicated, the form of milk used in the control of coccidiosis is not of great importance as long as a sufficient quantity is consumed by the chicks. Dry skim-milk, however, possesses advan- tages which make it somewhat more desirable for general use. Some of these are as follows: It is the most condensed form of milk. Therefore, it is easier to transport and a sufficient quantity may be more easily consumed. A good grade of dry skim-milk contains about 2.5 per cent of water, semi-solid buttermilk from 60 to 70 per cent of water, and buttermilk about 91 per cent of water. It is easier to feed than a liquid milk. It is relished by chicks. Buttermilk is sometimes unpalatable. It keeps well if stored in tight containers. Therefore, a quantity sufficient to last for several weeks may be obtained at one time and daily trips to a creamery avoide'd. This quality also makes milk available in localities distant from dairying districts. It promotes rapid development of chicks. It provides a practical means of feeding chicks during the period of greatest danger from coccidiosis (from four to eight weeks of age), so that they are less liable to become fatally infected when they are run on contaminated soil. SANITATION AND CARE ESSENTIAL TO CONTROL The sanitary measures recommended are designed to prevent the spread of the germs from the diseased chicks to those that are either not infected or, if infected, have not acquired a sufficient number of the germs to become visibly sick. The points regarding care are intended to provide conditions favorable to maintaining good health so that the natural resistance of the chicks to disease will not be lowered. When coccidiosis appears: Thoroughly clean the brooder houses or move the chicks to other brooders that have been cleaned and disinfected. Cover the floor with litter. Clean the houses and put in fresh litter daily. By this procedure a large percentage of the oocysts that are present in the fresh droppings of infected chicks are removed from the houses before sporulation has taken place and they have become capable of producing disease in healthy chicks (see fig. 1, A and B). The daily cleaning is also necessary to keep the floor dry. This is of great importance ClRC 300] COCCIDIOSIS OF CHICKENS 13 because dryness inhibits sporulation of the oocysts and is essential for the health of the chicks. Divide the chicks into as many flocks as the number of brooders available will permit. When the flocks are small, it is easier to keep the houses clean and dry and, therefore, outbreaks of coccidiosis can be more quickly brought under control. Be sure that the brooder houses are kept warm enough and are well ventilated. Warmth and fresh air are essential for the health of the chicks and also assist in keeping the houses dry. Separate the visibly sick chicks from those apparently healthy as soon as the disease appears. Kill the worst cases. Burn the dead. Watch the healthy chicks carefully so that those that later become sick can be promptly detected and removed. By this means, the exposure of the healthy chicks to the coccidiosis germs will be lessened, and the sick will be afforded a better opportunity to partake of food and their chances for recovery increased. Clean and plough or spade the yards. Contamination of the soil with coccidiosis germs is greatest in that part of the yards adjacent to the houses where the cjiicks spend most of their time when outside. The surface of this part of the yard should be scraped or swept and the sweepings removed. The entire yard should be ploughed as deeply as possible. Corners and other places that cannot be reached by the plough should be spaded. MEDICINES ARE OF LITTLE VALUE Carefully controlled experimental trials have been made at this station to determine the value of the drugs that have been most frequently used by poultrymen in their efforts to combat coccidiosis. The drugs that were tried are hydrochloric acid, catechu, a mixture of bichloride of mercury and sulphocarbolates (coccidiosis powder), potassium dichromate, powdered ipecac, and bismuth subnitrate. None of these were found to be effective. SOME CAUSES OF FAILURE TO CONTROL THE DISEASE The successf ill control of outbreaks of coccidiosis by the previously described methods depends upon careful attention to all the details. Below are listed some of the mistakes or omissions that, if made, might result in failure : 1. Feeding too much grain with either dry or liquid milk. 2. Continuing to feed mash with liquid milk. 3. Continuing to give water with liquid milk. 14 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION 4. Diluting condensed milk (semi-solid) too much. 5. Discontinuing the milk feeding too soon. 6. Feeding unpalatable (bitter) buttermilk or semi-solid buttermilk. The chicks fail to consume enough. 7. Feeding buttermilk containing too much water (churn washings). 8. Having too few mash hoppers or milk containers. The weaker chicks are crowded out. 9. Keeping too many chicks in a house. The chicks suffer from crowding. 10. Delaying the start of treatment until a large part of the flock is affected. 11. Failing to recognize the presence of other intestinal parasites, such as intestinal round worms. 12. Neglecting to clean houses (most commmon omission). SANITATION PREVENTS DISEASE Infection with coccidiosis can be prevented by raising chicks in houses and on soil that are free from contamination with the causative organism. Houses can be made safe by thorough cleaning and disin- fection of the floors, sidewalls, hovers, mash hoppers, drinking foun- tains, and all other appliances before the chicks are placed in them. A house cannot be regarded as thoroughly cleaned until all of the droppings that have become dried onto the floor, hover, etc., are scraped or scrubbed loose. Cleaning is facilitated by the use of a hot lye solution (one pound lye to forty gallons of water). Oocysts are destroyed by sufficient exposure to a 5 per cent solution of compound solution of cresol. It is, therefore, a suitable disinfectant for use in brooder houses. The house should be kept clean and dry throughout the brooding period. Soil that has not previously been used for chickens and that has not been fertilized with poultry manure may be regarded as safe. Soil that has become contaminated can be made comparatively safe by excluding poultry from it for at least a year, during which time it is cultivated so as to dry the top layer as much as possible. Since the germ is quite susceptible to dryness, the greater the degree and depth of the dryness of the soil that is obtained, the more effective the treatment. Merely plowing and cropping for a season will not suffice. There is no practical method of chemical treatment of soil to assist in eradicating contamination. Soil that is used for chicks each year is almost certain to be continuously contaminated. This is true even though but a single lot of chicks is reared on it each year and all poultry are excluded from it during the remainder of the time. This practice, however, is much less dangerous than raising two or more lots of chicks in the same yards during the year. It is the common experience of poultry men who follow the latter practice ClRC 300] COCCIDIOSIS OF CHICKENS 15 to suffer increasingly greater losses from coccidiosis in each successive lot of chicks brooded during any one year. Providing sufficient brooder yards so that each one need be used only every other year would undoubtedly accomplish much toward eliminating losses from coccidiosis. An alternate method that may be used on poultry farms on which the area available for brooder yards is too limited to permit more than one yard for each brooder house is to reduce the size of the yards so that they may be floored with concrete at a reasonable cost. This plan was successfully used during the 1925 brooding season by the Division of Poultry Husbandry at the University Farm, Davis, Cali- fornia. The soil of orchard or garden land that has been fertilized with poultry manure is liable to contain oocysts and, therefore, is not suit- able for chicks. Moist soil around outside watering places is a very favorable place for the parasites to sporulate and may readily become a serious source of infection in yards that are otherwise clean. To avoid this, remove the dirt to a depth of about two feet from the area around the watering vessels that becomes moistened by overflow or by the water that drops or is thrown off the beaks of the birds when they drink. Replace the dirt with coarse gravel ; cover this with a slat platform, and place the watering vessels in the center of the platform. This arrangement is also of value in the prevention of infection by other forms of intestinal parasites. INFECTION MAY BE CARRIED TO NEW PREMISES Poultrymen on new premises should avoid as much as possible contamination of the soil of brooder yards by mature stock that may harbor the infection, or by wild birds, dust-laden wind, streams, visitors, dogs, cats or other animals that may serve as mechanical carriers of the germs. There is no other apparent explanation of the source of the infection responsible for some outbreaks that occur in the first brood of chicks raised on new premises, Usually, however, infection introduced by these means does not result in immediate serious losses. 25m-12,'25