UNIVERSITY OF CALIFORNIA 
 
 COLLEGE OF AGRICULTURE 
 
 AGRICULTURAL EXPERIMENT STATION 
 
 BERKELEY, CALIFORNIA 
 
 THE DIGESTIBILITY OF 
 
 CERTAIN FRUIT BY-PRODUCTS AS 
 
 DETERMINED FOR RUMINANTS 
 
 PART II. DRIED PINEAPPLE PULP, DRIED LEMON 
 PULP, AND DRIED OLIVE PULP 
 
 S. W. MEAD AND H. R. GUILBERT 
 
 BULLETIN 439 
 
 November, 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/digestibilityofc439mead 
 
THE DIGESTIBILITY OF CERTAIN FRUIT BY-PRODUCTS 
 AS DETERMINED FOR RUMINANTS 
 
 PART II. DRIED PINEAPPLE PULP, DRIED LEMON PULP 
 AND DRIED OLIVE PULP 
 
 S. W. MEADi and H. R. GUILBERT2 
 
 INTRODUCTION 
 
 Requests have come to the University for information concerning 
 the digestibility of certain fruit by-products. During the fall of 1925 
 experiments were conducted on dried orange pulp and raisin pulp. 
 The results of these experiments were reported in Bulletin 409 under 
 the title, "The Digestibility of Certain Fruit By-Products as Deter- 
 mined for Ruminants. Part I. Dried Orange Pulp and Raisin 
 Pulp." 3 For purposes of comparison the digestible composition of 
 these feeds is also given in table 11 of the present publication. In 
 continuation of the study, Part II is a report of experiments con- 
 ducted to determine the digestible composition of dried pineapple 
 pulp, dried lemon pulp and dried olive pulp. 
 
 The methods used in conducting these experiments were fully 
 described in Part I. Wether sheep were used since they are easily 
 handled and better adapted to this type of investigation than other 
 ruminants. There is little difference in the coefficients of digestibility 
 of the great majority of feeds as determined with sheep and with 
 cattle. 4 
 
 The length of the preliminary feeding period was 10 days and the 
 period during which feces were collected, and analyzed, was 15 days. 
 
 1 Assistant Animal Husbandman in the Experiment Station. 
 
 2 Junior Animal Husbandman in the Experiment Station. 
 
 3 Mead, S. W., and H. R. Guilbert. The digestibility of certain fruit by- 
 products as determined for ruminants. Part I, Dried orange pulp and raisin 
 pulp. California Agr. Exp. Sta. Bui. 409:1-12. 1926. 
 
 * Armsby, Henry Prentiss. The nutrition of farm animals, p. 603-605. The 
 Macmillan Company, New York. 1917. 
 
4 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION 
 
 The feeds investigated were all fed in combination with alfalfa 
 hay. A quanta sufficient for all the trials was set aside for these 
 experiments and a digestion trial was conducted on a representative 
 lot of this hay. 
 
 The chemical determinations were made by H. W. Allinger of the 
 Division of Chemistry. 
 
 In working out the method used in these and previous trials for 
 the preservation of feces, nitrogen determinations were made on 
 samples of feces at the time of collection and after 15 days preserva- 
 tion. As there were no appreciable differences in these determinations 
 it was assumed that there would be no losses in the other nutrients. 
 Later, it occurred to the writers that there was a possibility of a loss 
 in some of the other constituents and especialty in ether extract and 
 it was therefore deemed advisable to make a complete analysis of a 
 fresh sample of feces and another analysis of the same sample after 
 having been preserved 15 days. The sample was placed in a quart 
 glass jar which had previously been rinsed with a 10 per cent alcoholic 
 solution of thymol. To this was added 5 grams of powdered thymol 
 and the whole thoroughly mixed. A portion of this sample was imme- 
 diately analyzed and the remainder carefully sealed in the jar and 
 placed in a refrigerator, the temperature of which was maintained at 
 between 30-40 degrees Fahrenheit. Since the collection period in the 
 digestion trials lasted 15 days, the longest possible period of storage 
 would be only 14 days, as the samples are analyzed immediately after 
 the termination of the collection period. Hence the check sample 
 was again analyzed at the end of 14 days. That there was no signifi- 
 cant change in the composition of the feces is shown in table 1. The 
 results of the two analyses are almost identical. The slight difference 
 might easily be expected of two separate samples of feces taken from 
 the same source at the same time. 
 
 TABLE 1 
 Preservation of Feces 
 
 Feces 
 
 Moisture 
 
 Crude 
 protein 
 
 Nitrogen-free 
 extract 
 
 Ether 
 extract 
 
 Crude 
 fiber 
 
 Total 
 ash 
 
 Fresh 
 
 61.44 
 61.70 
 
 5.00 
 4.99 
 
 17.36 
 17.26 
 
 1.52 
 1.43 
 
 11.66 
 11.60 
 
 3.02 
 
 Preserved 14 days 
 
 3.02 
 
BUL. 439] DIGESTIBILITY OF CERTAIN FRUIT BY-PRODUCTS 
 
 RESULTS OF THE DIGESTION TRIAL WITH DRIED PINEAPPLE PULP 
 
 Pineapple pulp, a by-product of the canneries, consists of the outer 
 skin, trimmings, core and ends of the pineapple, from which the juice 
 has been extracted. At the present time the production in the 
 Hawaiian Islands amounts to 5000 tons of dried pulp annually, about 
 one-half of which is exported to California, for the feeding of dairy 
 cows in the Los Angeles district. As several pineapple canneries are 
 not yet drying pulp the amount available may be increased somewhat 
 but the supply will probably never be large. Pineapple pulp has been 
 used for sometime with satisfactory results as a feed for dairy cattle 
 and swine at the University of Hawaii, 5 where comparative feeding 
 trials are now r being conducted with it. However, no data have been 
 available concerning its digestibility. 
 
 The nutritive value of any feed is dependent largely upon its 
 digestible composition. Data reported in table 11 show that the dried 
 pineapple pulp used in this trial contained 59.9 per cent total digestible 
 nutrients as compared to 71.6 per cent in dried beet pulp, a feed of 
 somewhat similar physical characteristics. It is interesting to note 
 that a sample of the particular pulp used in this trial was analyzed 
 five months previously and found to contain 11.36 per cent moisture. 
 At the time of the trial the moisture content was 16.40 per cent. A 
 variation as great or even greater than this would be expected of any 
 similar feed under varying climatic conditions such as are common to 
 California. The average dry matter content for dried beet pulp as 
 given in table 11 is 91.8. Calculating dried pineapple pulp on the 
 same dry matter basis 100 pounds should contain approximately 66 
 pounds of digestible nutrients. The digestible protein content of pine- 
 apple pulp is, however, extremely low, because of the small amount of 
 total crude protein and its low coefficient of digestibility. The small 
 amount of ether extract present in the feed may explain the negative 
 coefficient of digestibility of that nutrient. 
 
 In many parts of California dairy cattle are fed largely on alfalfa. 
 Under such conditions dried pineapple pulp and other feeds of a 
 carbonaceous nature, when they can be purchased at a reasonable 
 price, may be used with advantage in balancing the ration. 
 
 s Henke, L. A. Ninth annual report of the agricultural department of the 
 University of Hawaii for the fiscal year July 1, 1925, to June 30, 1926. Univ. 
 Hawaii Quart. Bui. 6:14-16. 1926. 
 
 (i Fraps, G. S. Energy-production coefficients of American feeding stuffs. 
 Texas Agr. Exp. Sta. Bui. 329:6-13. 1925. 
 
UNIVERSITY OF CALIFORNIA EXPERIMENT STATION 
 
 TABLE 2 
 Total Feed Consumed and Total Feces Collected 
 
 Sheep number 
 
 Alfalfa hay 
 
 Pineapple pulp 
 
 Feces 
 
 
 Grams 
 
 Grams 
 
 Grams 
 
 137 
 
 4500 
 
 6375 
 
 6955 
 
 135 
 
 4500 
 
 6375 
 
 7339 
 
 136 
 
 4125 
 
 6000 
 
 6799 
 
 138 
 
 5100 • 
 
 7500 
 
 9141 
 
 TABLE 3 
 
 Chemical Analyses of Feces and Feeds 
 
 Sheep number 
 
 Dry 
 
 matter 
 
 Crude 
 protein 
 
 Nitrogen-free 
 extract 
 
 Ether 
 extract 
 
 Crude 
 fiber 
 
 Feces: 
 
 137 
 
 Per cent 
 
 38.65 
 37.88 
 36.72 
 35.52 
 
 85.38 
 83.60 
 
 Per cent 
 
 5.10 
 4.94 
 4.74 
 
 4.77 
 
 15.47 
 3.81 
 
 Per cent 
 
 16.56 
 16.19 
 15.69 
 14.95 
 
 35.72 
 61.94 
 
 Per cent 
 
 1.45 
 1.43 
 1.42 
 1.36 
 
 1.66 
 0.71 
 
 Per cent 
 12.37 
 
 135 
 
 136 
 
 138 
 
 Feeds: 
 
 Alfalfa hay 
 
 Dried pineapple pulp. ... 
 
 12.28 
 11.85 
 11.54 
 
 24.14 
 
 13.88 
 
 TABLE 4 
 
 Coefficients of Digestibility of Dried Pineapple Pulp and Alfalfa Hay 
 
 Sheep 
 number 
 
 Dry 
 
 matter 
 
 Crude 
 protein 
 
 Nitrogen-free 
 extract 
 
 Ether 
 extract 
 
 Crude 
 fiber 
 
 
 Per cent 
 
 Per cent 
 
 Per cent 
 
 Per cent 
 
 Per cent 
 
 137 
 
 75.566 
 
 23.011 
 
 80.070 
 
 0.583 
 
 72.775 
 
 135. 
 
 73.842 
 
 19.783 
 
 79.148 
 
 -8.475 
 
 68.154 
 
 136 
 
 75.554 
 
 26.273 
 
 80.294 
 
 -6.497 
 
 71.438 
 
 138 
 
 73.266 
 
 13.926 
 
 79.482 
 
 -14.593 
 
 66.105 
 
 Average 
 
 74.557 
 
 20.748 
 
 79.748 
 
 Negative 
 
 69.618 
 
 Alfalfa hay 
 
 63.928 
 
 75.909 
 
 77.304 
 
 25.236 
 
 42.977 
 
 To test the palatability of plain dried pineapple pulp, it was fed 
 to dairy cows. During the first two weeks of the test it was necessary 
 to add 1 pound of wheat bran to every 3 pounds of the pulp in order 
 to induce cows to consume any considerable amount of it. At the 
 
BUL. 439] DIGESTIBILITY OF CERTAIN FRUIT BY-PRODUCTS 7 
 
 end of this period, each cow consumed 6 pounds daily of the dry pulp. 
 In the digestion trial the pulp was readily eaten by sheep. Dried 
 pineapple pulp as sold on the market contains a small amount of 
 cane molasses which greatly increases its palatability. 
 
 The data from the digestion trial with pineapple pulp fed in 
 combination with alfalfa hay are given in tables 2, 3 and 4. 
 
 RESULTS OF THE DIGESTION TRIAL WITH DRIED LEMON PULP 
 
 Lemon pulp is a by-product in the manufacture of citric acid and 
 pectin and consists of the rind, pulp and seeds which are the residue 
 after extraction. Calculated on the dried basis, between 3000 and 
 6000 tons are produced annually. At the present time less than a 
 fourth of this amount results from the manufacture of pectin. It 
 seemed advisable, therefore, to determine the digestibility of the citric 
 acid pulp only. Dried lemon pulp compares favorably with dried 
 orange pulp in total digestible nutrients though it contains 3 per cent 
 less digestible protein. In both digestible protein and total digestible 
 nutrients it is equal to dried beet pulp as shown in table 11. 
 
 On account of its bitter taste, dried lemon pulp is not relished by 
 livestock. Both dried lemon pulp and dried orange pulp must be 
 mixed with more palatable feeds to induce stock to consume any 
 appreciable amount. In a palatability test with dried lemon pulp, 
 dairy cows were finally induced to consume 2 pounds per day when 
 the lemon pulp was mixed with an equal weight of a concentrate 
 mixture consisting of 4 parts barley, 2 parts rice bran and 1 part 
 cottonseed meal, plus salt. 
 
 The data from the digestion trial with lemon pulp fed in combina- 
 tion with alfalfa hay are given in tables 5, 6 and 7. 
 
 TABLE 5 
 Total Feed Consumed and Feces Collected 
 
 Sheep number 
 
 Alfalfa hay- 
 
 Dried lemon pulp 
 
 Feces 
 
 
 Grams 
 
 Grams 
 
 Grams 
 
 717 
 
 8775 
 
 4500 
 
 10174.5 
 
 600 
 
 10050 
 
 5175 
 
 12245.5 
 
 736 
 
 8775 
 
 4500 
 
 9259.0 
 
 686 
 
 7800 
 
 3975 
 
 8046 5 
 
 
 
UNIVERSITY OF CALIFORNIA EXPERIMENT STATION 
 
 TABLE 6 
 
 Chemical Analyses of Feces and Feeds 
 
 Sheep number 
 
 Dry 
 
 matter 
 
 Crude 
 protein 
 
 Nitrogen-free 
 extract 
 
 Ether 
 extract 
 
 Crude 
 fiber 
 
 Feces: 
 
 717 
 
 600 
 
 736 
 
 686 
 
 Feed: 
 
 Alfalfa hay 
 
 Per cent 
 
 34.23 
 33.76 
 37.95 
 39.19 
 
 87.28 
 92.90 
 
 Per cent 
 4.91 
 
 4.85 
 4.89 
 5.31 
 
 15.76 
 6.39 
 
 Per cent 
 
 9.70 
 
 9.42 
 
 10.66 
 
 10.22 
 
 37.26 
 65.24 
 
 Per cent 
 
 1.30 
 1.34 
 1.46 
 1.70 
 
 1.54 
 1.23 
 
 Per cent 
 
 14.04 
 13.48 
 15.65 
 15.92 
 
 23.43 
 
 Dried lemon pulp 
 
 15.00 
 
 
 
 TABLE 7 
 Coefficients of Digestibility of Dried Lemon Pulp and Alfalfa Hay 
 
 Sheep 
 number 
 
 Dry 
 
 matter 
 
 Crude 
 protein 
 
 Nitrogen-free 
 extract 
 
 Ether 
 extract 
 
 Crude 
 fiber 
 
 
 Per cent 
 
 Per cent 
 
 Per cent 
 
 Per cent 
 
 Per cent 
 
 717 
 
 82.776 
 
 42.132 
 
 91.659 
 
 43.568 
 
 62.056 
 
 600 
 
 79.824 
 
 35.789 
 
 91.006 
 
 23.999 
 
 60.326 
 
 736 
 
 82.033 
 
 58.407 
 
 91.656 
 
 38.305 
 
 59.014 
 
 686 
 
 81.106 
 
 48.377 
 
 93.724 
 
 3.904 
 
 59.935 
 
 Average 
 
 81.484 
 
 46.176 
 
 92.011 
 
 27.444 
 
 60.332 
 
 Alfalfa hay 
 
 63.928 
 
 75.909 
 
 77.304 
 
 25.236 
 
 42.977 
 
 RESULTS OF THE DIGESTION TRIAL WITH DRIED OLIVE PULP 
 
 Olive pulp is a by-product in the manufacture of olive oil. It con- 
 sists of the whole olive minus most of the oil. At present it is being 
 utilized largely as fuel in the plants manufacturing olive oil. The 
 estimated production is 2000 to 4500 tons annually. Requests were 
 made for information concerning its possible value as a feed for live- 
 stock. The olive pulp was supplied by P. F. Nichols of the Division 
 of Viticulture and Fruit Products. It had been dehydrated and 
 ground to a fine meal. As shown in table 10 the pulp used was found 
 to be practically valueless as a feed for livestock, only 19 per cent of 
 the dry matter being digested. Since a large amount of the digestible 
 matter was oil which has a value of 2.25 times that of an equal weight 
 
BUL. 439] DIGESTIBILITY OF CERTAIN FRUIT BY-PRODUCTS 9 
 
 of carbohydrates, 100 pounds of the material contain 36.6 pounds of 
 total digestible nutrients ; thus it has, as shown in table 11, a feeding 
 value similar to that of wheat straw. Dried olive pulp contains 
 approximately 60 per cent pit, the shell of which is largely crude fiber 
 of an indigestible nature. A great quantity of the ground pit was 
 found in an apparently unchanged condition in the feces. As shown 
 in table 9 the dried olive pulp had 36 per cent fiber or 12 per cent 
 more than was contained in the alfalfa hay used in the experiment. 
 
 This large amount of crude fiber apparently interfered with the 
 digestion of not only the olive pulp but also of the alfalfa hay which 
 was fed with the pulp, 7 ' 8 the digestion coefficients of which had pre- 
 viously been determined by a trial with alfalfa hay alone. In deter- 
 mining the value of dried olive pulp it was necessary to subtract from 
 the amount of total feed digested the calculated amount of alfalfa 
 digested allowing full value for alfalfa hay. This resulted in negative 
 values for crude protein and crude fiber in the olive pulp as shown in 
 table 10. If it were practical to feed dried olive pulp alone and 
 hence determine its digestibility directly the calculated coefficient 
 might have been slightly higher. However, when fed in combination 
 with a roughage, which would be the usual procedure, the figures 
 given in table 11 probably express very nearly the true value of this 
 material. 
 
 Since the olive pulp used in this trial was found to have a very 
 low nutritive value the question arose as to its value with the pits 
 removed. A sample of pulp with the pits removed was analyzed and 
 found to have the following composition: Dry matter 95.11 per cent, 
 crude protein 13.99 per cent, nitrogen-free extract 31.04 per cent, 
 ether extract 27.39 per cent, crude fiber 19.27 per cent and ash 3.43 
 per cent. 9 
 
 This material contains considerably less fiber than the original 
 pulp and it is reasonable to believe that the digestibility of all the 
 nutrients would therefore be increased. In view of the large amount 
 of highly , digestible ether extract and the expected increase in 
 digestibility of the other nutrients, the pit free pulp should have 
 approximately double the value of that used in the digestion trial. 
 
 7 Mumford, H. W., II. S. Gridley, L. D. Hall, and A. D. Emmet. A study of 
 the digestibility of rations for steers. Illinois Agr. Exp. Sta. Bui. 172:246-255. 
 1914. 
 
 s Armsby, Henry Prentiss. The nutrition of farm animals, pp. 613-623. 
 The Macmillan Company, New York. 1017. 
 
 9 These data were supplied by the Division of Viticulture and Fruit Products 
 at Berkeley. 
 
10 
 
 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION 
 
 Unless the pulp, free from pits, can be produced commercially and 
 in sufficiently large quantities to justify more complete data, no 
 further work will be conducted. The data from the digestion trial 
 with dried olive pulp fed in combination with alfalfa hay are given 
 in tables 8, 9 and 10. 
 
 TABLE 8 
 Total Feed Consumed and Feces Collected 
 
 Sheep number 
 
 Alfalfa hay 
 
 Olive pulp 
 
 Feces 
 
 
 Grams 
 
 Grams 
 
 Grams 
 
 726 
 
 8775 
 
 4500 
 
 13861 
 
 600 
 
 10050 
 
 5175 
 
 14217 
 
 736 :. 
 
 8775 
 
 4500 
 
 12201 
 
 717 
 
 8775 
 
 4500 
 
 12389 
 
 686 
 
 7800 
 
 3975 
 
 10376 
 
 
 
 TABLE 9 
 
 Chemical Analyses of Feces and Feeds 
 
 Sheep number 
 
 Dry 
 
 matter 
 
 Crude 
 protein 
 
 Nitrogen-free 
 extract 
 
 Ether 
 extract 
 
 Crude 
 fiber 
 
 Feces: 
 
 Per cent 
 
 Per cent 
 
 Per cent 
 
 Per cent 
 
 Per cent 
 
 726 
 
 44.86 
 
 4.57 
 
 3.45 
 
 1.59 
 
 22 AS 
 
 600 
 
 48.52 
 
 4.90 
 
 14.80 
 
 1.66 
 
 24.03 
 
 736 
 
 50.61 
 
 5.18 
 
 15.51 
 
 1.66 
 
 24.84 
 
 717 
 
 48.94 
 
 4.96 
 
 15.07 
 
 1.63 
 
 24.18 
 
 686 
 
 51.49 
 
 5.15 
 
 15.67 
 
 1.70 
 
 25.37 
 
 Feeds: 
 
 
 Alfalfa hay 
 
 86.84 
 
 15.24 
 
 36.50 
 
 1.64 
 
 24.14 
 
 Dried olive pulp 
 
 92.02 
 
 5.91 
 
 31.54 
 
 15.63 
 
 36.45 
 
 TABLE 10 
 
 Coefficients of Digestibility of Dried Olive Pulp and Alfalfa Hay 
 
 Sheep 
 number 
 
 Dry 
 
 matter 
 
 Crude 
 protein 
 
 Nitrogen-free 
 extract 
 
 Ether 
 extract 
 
 Crude 
 fiber 
 
 
 Per cent 
 
 Per cent 
 
 Per cent 
 
 Per cent 
 
 Per cent 
 
 726 
 
 16.219 
 
 -17.042 
 
 19.863 
 
 83.963 
 
 -16.326 
 
 600 
 
 21.253 
 
 - 7.130 
 
 22.094 
 
 86.057 
 
 - 7.774 
 
 736 
 
 17.260 
 
 -16.502 
 
 17.885 
 
 86.501 
 
 -11.130 
 
 717 
 
 19.959 
 
 - 9.916 
 
 19.671 
 
 86.586 
 
 - 8.992 
 
 686 
 
 20.737 
 
 - 5.562 
 
 21.851 
 
 87.002 
 
 - 7.578 
 
 Average 
 
 19.085 
 
 Negative 
 
 20.272 
 
 86.021 
 
 Negative 
 
 Alfalfa hay 
 
 63.928 
 
 75.909 
 
 77.304 
 
 25.236 
 
 42.977 
 
BUL. 439] DIGESTIBILITY OF CERTAIN FRUIT BY-PRODUCTS 
 
 11 
 
 TABLE 11 
 
 Digestible Nutrients Contained in Various Common Feeds Compared with 
 Dried Pineapple Pulp, Dried Lemon Pulp and Dried Olive Pulp 
 
 
 Total dry 
 matter in 
 100 pounds 
 
 Digestible nutrients in 100 pounds 
 
 Feeding stuff 
 
 Crude 
 protein 
 
 Carbo- 
 hydrates 
 
 Fat 
 
 Total* 
 
 Common barley f 
 
 Dried orange pulp J... 
 
 Pounds 
 
 90.7 
 87.5 
 92.9 
 91.8 
 83.6 
 91.4 
 91.6 
 92.0 
 88.7 
 
 Pounds 
 
 9.0 
 6.0 
 3.0 
 4.6 
 0.8 
 10.6 
 0.7 
 0.0 
 2.3 
 
 Pounds 
 
 66.8 
 70.4 
 69.1 
 65.2 
 59.1 
 39.0 
 35.1 
 6.4 
 27.3 
 
 Pounds 
 
 1.6 
 0.8 
 0.3 
 0.8 
 0.0 
 0.9 
 0.5 
 13.4 
 9.5 
 
 Pounds 
 
 79.4 
 
 78.2 
 
 Dried lemon pulp 
 
 72.8 
 
 Dried beet pulpj 
 
 Dried pineapple pulp 
 
 Alfalfa hayt, all analyses.. 
 
 Wheat strawf 
 
 Dried olive pulp. . .< 
 Raisin pulpj . y . 
 
 71.6 
 59.9 
 51.6 
 36.9 
 36.6 
 51.0 
 
 * Total includes fat times the factor 2.25. 
 tHenry, W. A., and F. B. Morrison Feeds and feedings. 
 Ed. The Henry-Morrison Company, Madison, Wis. 
 t Citation in footnote, page 1. 
 
 Table III, App. Eighteenth 
 
 192J