UNIVERSITY OF CALIFORNIA COLLEGE OF AGRICULTURE AGRICULTURAL EXPERIMENT STATION BERKELEY, CALIFORNIA THE VALUE OF ORANGE PULP FOR MILK PRODUCTION W. M. REGAN and S. W. MEAD BULLETIN 427 May, 1927 UNIVERSITY OF CALIFORNIA PRINTING OFFICE BERKELEY, CALIFORNIA 1927 THE VALUE OF ORANGE PULP FOR MILK PRODUCTION W. M. EEGANi and S. W. Mead2 Faced with the problem of disposing of thousands of tons of orange pulp, the annual residue from their manufacturing processes, the Exchange Orange Products Company, of San Dimas, California, appealed to the University for assistance in determining the value of this waste as a feed for livestock. The results of investigations begun for this purpose by the Division of Animal Husbandry in the fall of 1924 show that dried orange pulp is a satisfactory feed for dairy cows, having a value for milk production approximately equivalent to that of dried beet pulp, and that neither dried nor fresh orange pulp has any effect upon the butterfat tests. Orange pulp consists of the rind, flesh, and seeds of the orange, and a small amount of the unrecovered juice, oils, and other extracts. It is a heavy wet mass having the following approximate composition : Moisture 80.03 per cent; crude protein 1.71 per cent; nitrogen free extract 15.23 per cent; crude fiber 1.61 per cent; ether extract. 75 per cent; and ash .67 per cent. The manufacture of orange by-products is rapidly increasing with a consequent increase in residue which must be disposed of by the factory. During the year ending December 31, 1924, the Exchange Orange Products Company, the principal manufacturers of these by-products produced more than 9000 tons of the wet pulp at their San Dimas plant. They estimate that by 1930 the volume will be 50,000 tons. The disposal of this residue is, therefore, presenting yearly a more serious problem to the manufacturers. The first extensive attempt to utilize fresh orange pulp as a feed for livestock was made by Mr. Frank Pellissier on his dairy ranch near Whittier, California, in the summer of 1922. The results were so satis- factory that the demand for the wet pulp rapidly increased. However, because it decomposes so quickly and has such a high moisture con- tent, its use has been restricted to those dairy farms within trucking distance of the factory. These are able to use only a small portion of the total amount. i Associate Professor of Animal Husbandry, Associate Animal Husbandman in Experiment Station. 2 Assistant Professor of Animal Husbandry, Assistant Animal Husbandman in Experiment Station. 4 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION The Exchange Orange Products Company, therefore, conceived the idea of dehydrating the fresh pulp and marketing it as a livestock feed. For the purpose of determining its value as a feed for milk production, the first experiment described below was undertaken. DRIED ORANGE PULP The orange pulp used in this trial was obtained from the factory where it was dried in temporary equipment to approximately 12.5 per cent moisture. It was then ground. The resulting product had very much the appearance of fine corn meal. METHOD OF PROCEDURE Eight cows as nearly uniform as possible in weight, stage of lacta- tion, and gestation, were selected from the University herd. They were divided into two lots. Group A consisted of the following cows : Nos. 20, 108, 106, and 327 ; group B, of Nos. 121, 326, 334, and 357. Since the value of dried beet pulp for milk production is known, (1) and since its chemical analysis is similar to that of dried orange pulp, the former was used in this trial as the standard of comparison. The feeding trial was divided into two periods of 60 days each. During period 1 the animals in group A received alfalfa hay plus a concentrate mixture consisting of equal parts, by weight, of wheat bran and dried orange pulp. Group B, during the same time, received alfalfa hay plus a concentrate mixture consisting of equal parts, by weight, of wheat bran and dried beet pulp. During period 2, group A received the concentrate mixture containing dried beet pulp and group B that containing dried orange pulp. Every ten days throughout the experiment the requirements of each animal for both maintenance and milk production were cal- culated, and the amounts of feed adjusted. An attempt was made to supply the alfalfa hay in quantities sufficient to satisfy the mainten- ance requirements of each animal. The concentrate mixture fed was calculated to supply the requirements for milk production. Each cow was milked twice daily, her milk being weighed at each milking. A daily composite sample was taken and its percentage of butterfat determined. Chemical analyses were made of all feeds used, and an accurate account was kept of the feed consumed by each cow. To ascertain its weight at the beginning of the experiment, each animal was weighed on three consecutive days and the average taken. At ten-day intervals throughout the experiment, this procedure was repeated. BUL. 427] VALUE OF ORANGE PULP FOR MILK PRODUCTION PRESENTATION OF DATA Period 1 lasted from December 18, 1924, to February 15, 1925, and period 2, from February 16 to April 16, inclusive. To determine the amount of feed each cow should receive, the Armsby (2) standard for maintenance and milk production was used. The body weight and milk and fat production at the beginning of each ten-day period constituted the basis for calculating the individual daily requirements. The energy furnished by the feed was ascertained by the Armsby and Fries (3) method for computing the approximate net energy value of a feeding stuff. TABLE 1 Composition, Digestibility and Net Energy Values of Feeds Used Feeding stuff Wheat bran («) Period 1 Wheat bran Period 2 Dried beet pulp ( 4 ), Period 1 Dried beet pulp Period 2 Dried orange pulp (5), Period 1 Dried orange pulp, Period 2 Alfalfa hay ( 5 ) Both periods... Water Crude protein Nitrogen free extract Crude fiber Ether extract Per cent Per cent Coeffi- cient of digesti- bility Per cent Coeffi- cient of digesti- bility Per cent Coeffi- cient of digesti- bility Per cent Coeffi- cient of digesti- bility 13.94 15.73 78.0 52.06 72.0 9.50 31.0 2.98 68.0 9.93 17.37 78.0 52.69 72.0 9.18 31.0 4.85 68.0 11.61 8.52 52.0 58.30 83.0 18.31 83.0 0.86 10.24 8.86 52.0 57.13 83.0 20.17 83.0 0.97 12.75 7.56 78.5 66.81 95.4 7.87 83.7 1.68 48.9 11.44 7.85 78.5 68.03 95.4 8.24 83.7 1.03 48.9 9.73 15.49 77.0 38.46 73.5 25.66 48.5 1.85 20.3 Net energy Therms* 50.91 53.92 74.57 75.33 89.84 91.59 36.92 * Value per 100 pounds for ruminants, calculated according to Armsby and Fries. Table 1 gives the percentage composition, digestibility, and net energy values of the feeds used in this experiment. The net energy received by each animal during the feeding trial was derived by apply- ing the coefficients of digestibility to chemical analyses made at this station. The coefficients of digestibility for wheat bran and dried beet pulp were taken from Henry and Morrison. (4) Those for alfalfa hay and orange pulp were determined by Mead and Guilbert. (5) The accuracy with which the amount of feed needed by each cow was determined is shown in table 2. It was estimated that the four cows in group A would require 3404.3 therms of net energy during period 1. The feed they received actually furnished 3681.6 therms, thus exceeding the requirements by 277.2 therms or 8 per cent. UNIVERSITY OF CALIFORNIA EXPERIMENT STATION During period 2, they received an excess of 159.1 therms of net energy, or about 5 per cent. The four cows in group B received dur- ing period 1, 134.4 fewer therms than had been calculated for their requirements, or a deficit of approximately 5 per cent, and during period 2, 176.3 more therms than had been calculated, or an excess of almost 7 per cent. TABLE 2 Feed Consumed A comparison of net energy required and that received Period 1 Period 2 Cow No. Pounds of feed eaten Therms of net energy Pounds of feed eaten Therms of net energy Alfalfa hay Concen- trates Re- quired Re- ceived Differ- ence Alfalfa hay Concen- trates Re- quired Re- ceived Differ- ence 20 537.3 877.1 970.5 577.9 0) 789.8 1237.4 722.5 927.6 728.5 1097.0 720.7 858.1 754.2 1194.6 866.7 866.1 + 25.7 + 97.6 +146.0 + 8.0 596 .6 879.0 986.6 544.4 ( 2 ) 676.0 1024.0 608.0 842.1 668.4 915 5 629.7 772.9 657.1 986.2 757.1 745.2 - 11.3 108 + 70.7 106 +127.4 327 - 27.7 Group A, total... 2962.8 3677.3 3404.3 3681.6 +277.3 3006.6 3150.1 2986.5 3145.6 +159.1 121 590.8 534.1 561.2 647.4 ( 2 ) 795.5 522.1 552.3 1019.7 752.5 536.5 580.6 939.3 717.2 524.8 553.7 878.8 - 35.3 - 11 7 - 26.9 - 60.5 586.5 534.8 624.9 644.0 0) 710.3 462.0 417.1 884.1 697.3 505.1 479.0 824.2 733.3 533.6 534.2 880.9 + 36.0 326 + 28.5 334 + 55.2 357 + 56.7 Group B, total... 2333.5 2889.6 2808.9 2674.5 -134.4 2390.2 2473.5 2505.6 2682.0 +176.4 0) Dried orange pulp and wheat bran, equal parts by weight. ( 2 ) Dried beet pulp and wheat bran, equal parts by weight. The nutrients consumed by a dairy cow in excess of the amount required for maintenance result in either production of milk or increased body weight. Therefore, to determine the efficiency of dried orange pulp as compared with dried beet pulp for production, it was necessary to measure the effect not only upon milk and butterf at production but upon body weights as well. The total average weight of the cows in group A was 5029 pounds during period 1, as is shown in table 3. When the dried beet pulp re- placed the dried orange pulp in the ration during period 2, their total average body weight was 5049 pounds. For group B, the total average body weight during period 2, when dried orange pulp was being fed, was 4179 pounds ; during period 1, this weight was 4151 pounds. The difference of 20 pounds for group A and of 28 pounds for group B, when divided among the individual animals, is well within the error of weighing. BUL. 427] VALUE OF ORANGE PULP FOR MILK PRODUCTION TABLE 3 Individual Body Weights (Pounds) Group A Group B Weighing dates Cow No. Group total Cow No. Group 20 108 106 327 121 326 334 357 total December: 16-17-18 934 933 910 928 936 922 946 1449 1480 1458 1493 1484 1477 1483 1647 1665 1645 1681 1693 1674 1709 1003 965 947 952 931 910 949 5033 5043 4960 5054 5044 4983 5087 1077 1051 1025 1016 1023 1003 1027 917 914 893 905 891 899 918 1085 1053 1023 1043 1043 1073 1089 1172 1172 1161 1147 1147 1138 1155 4251 26-27-28 4190 January : 7- 8- 9 4102 17-18-19 4111 27-28-29 4104 February: 6- 7- 8 4113 16-17-18 4189 Average, period 1 930 1475 1673 951 5029 1032 905 1058 1156 4151 February: 16-17-18 946 955 959 962 965 980 971 1483 1478 1451 1430 1422 1396 1403 1709 1690 1725 1701 1709 1735 1737 949 931 957 926 911 942 921 5087 5054 5092 5019 5007 5053 5032 1027 1010 1036 988 1020 1037 1033 918 907 936 937 922 928 917 1089 1049 1093 1099 1108 1107 1125 1155 1144 1160 1132 1122 1128 1128 4189 26-27-28 4110 March: 8- 9-10 4225 18-19-20 4156 28-29-30 4172 April: 7- 8- 9 4200 17-18-19 4203 Average, period 2 963 -1438 1715 934 5049 1022 924 1096 1138 4179 TABLE 4 Total Milk and Butterfat Production Cow No. Milk in pounds Percentage of decline Butterfat in pounds Percentage of Period 1 Period 2 Period 1 Period 2 decline 20 1348 2205 995 1596 1091 1598 464 1395 19.1 27.5 53.4 12.6 59.2 97.3 29.7 82.0 49.5 70.9 16.5 67.6 16.4 108 27.1 106 44.4 327 17.6 6144 4548 26.0 268.2 204.4 23.8 121 1452 539 534 1631 1253 470 245 1261 13.7 12.8 54.1 22.7 57.9 33.5 35.0 87.9 51.1 26.9 16.4 70.1 11.7 326 19.7 334 53.1 357 20.3 4156 3229 22.3 214.3 164.5 23.2 8 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION A certain normal decline in milk and butterfat is expected with advancing lactation, and while there is considerable variation in the decline in production among the individuals within the groups, as shown by table 4, the total average percentages of decline for both groups are practically the same. Group A, on dried orange pulp, produced 6144 pounds of milk; on dried beet pulp, 4548 pounds, or 26.0 per cent less than during the first period. Meanwhile, group B, on dried beet pulp, produced 4156 pounds of milk, and on dried orange pulp, 3229 pounds representing a loss of 22.3 per cent. The declines in butterfat production also were practically the same. Group A, when on beet pulp, gave 23.8 per cent less butterfat than when on dried orange pulp. Group B, on the other hand, gave 23.2 per cent less butterfat when on dried orange pulp than when on dried beet pulp. The slight difference is not significant in either case. Figure 1 shows graphically the trend of milk and butterfat produc- tion during the entire experiment. That the rates of decline for both groups are similar in periods 1 and 2 has already been pointed out. Since the amount of energy furnished by the feed was almost exactly that necessary to satisfy the requirements for maintenance and production; since the total average weights of the groups remained about constant throughout the experiment; and since there was no significant increase or decrease in milk or butterfat, whether dried orange pulp or dried beet pulp was being fed, it is evident that the two are approximately equal in value as a feed for milk production. This observation is further substantiated by the results of a 25-day trial conducted with five grade wether sheep to determine the digestible composition of dried orange pulp for ruminants. (5) TABLE 5 Digestibile Nutrients Contained in Various Common Feeds Compared with Dried Orange Pulp Feeding stuff Total dry matter in 100 pounds Digestible nutrients in 100 pounds Crude protein Carbo- hydrates Fat Total" Dried orange pulp ( 5 ) Barley ( 4 ) Dried beet pulp ( 4 ) Alfalfa hay, all analyses ( 4 ). Pounds 87.5 90.7 91.8 91.4 Pounds 6.0 9.0 4.6 10.6 Pounds 70.4 65.2 39.0 Pounds 0.8 1.6 0.8 0.9 Pounds 78.31 79.40 71.60 51.60 Total includes fat X the factor 2.25. BUL. 427] VALUE OF ORANGE PULP FOR MILK PRODUCTION 9 According to the figures presented in table 5, dried orange pulp compares very favorably with barley in total digestible nutrients, though it is somewhat lower in amount of digestible crude protein. Dried beet pulp contains, on the average, 4.6 per cent digestible crude protein, whereas, the orange pulp used has 6.0 per cent. The total digestible nutrients in dried orange pulp is 78.3 per cent, and in dried beet pulp, 71.6 per cent. A difference in feeding value as small as these figures indicate could not be detected in a feeding trial for milk production. O L o C Period 1 •+- Period 2, ■ H 110 130 7 \- % 3 1 2 ^ Butte r fat OA ?ou p / 4 -^ \/30 \ Mi ^ Ik ^ 90 70 "i ' ' i ~i — c i - r- -i — i — i — i — i — r I i i "~i r 10 20 30 40 JO 60 70 SO 90 100 110 120 Number of Days k- — Period 1 — -*\ Period 2 — ^ 140 %/20 6 f ■1< o \ , (jA ?OL IP & \ A. Butter/at \ioo r 60 V V/M ^ O 1 1 1 1 1 | | | "1 1 "1 Fig. O 10 20 JO 40 JO 60 70 SO 90 /OO 110 120 Number of Days 1. — Trends in milk and butterfat production during the experiment. The figures used are five-day averages. Dried orange pulp is not a highly palatable feed. In a preliminary test, it was refused by dairy cows when unmixed with other feeds. However, during the feeding experiment as much as eight pounds of dried orange pulp were consumed daily when mixed with an equal weight of wheat bran. 10 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION \l 1 1 1 1 1 1 II 1 II 1 . ^No.X6 Group B ^ 1! 1 1 1 I " 5 ^..— ^ Zted A5 rvbtf •4o/r/<5 Period j r Oeriod E 7 6 /to. 33 4 <2/£ -tup £ X — / \ \ — ^ ^ •<» ^ Z5" ^^, /Vo.106 Oro . 1 1 1 1 y/?^» «■-— 1 ^ ■» — **^ s* ' Mini /0 BO 30 M) 30 QO 70 60 90 KX) IIO hlumber of Days Wheat Bran and Dried Orange Pulp Wheat Bran and Dried^deet Pulp Fig. 2. — Trends in butterfat tests. The figures used are five-day averages. BUL. 427] VALUE OF ORANGE PULP FOR MILK PRODUCTION 11 Data were studied to determine what effect, if any, the feeding of dried orange pulp had on the percentage of butterfat in the milk. To facilitate graphic presentation, the daily butterfat tests were averaged for each cow so as to cover every five days throughout the experiment. These are plotted in figure 2. No effect is evident when the curves for the individual cows are compared. Cow No. 20 in group A and cow No. 121 in group B show about the same increase in percentage of butterfat, an increase that is ordinarily expected with advancing lactation. Though the averages plotted for cow No. 357 in group B are irregular, the trend of her tests is approximately the same as that of cow No. 108 in group A. Cow No. 106 in group A and cow No. 334 in group B show much the same increase. Cow No. 327 in group A and cow No. 326 in group B decreased at about the same rate. While an increase is to be expected with advancing lactation, the reverse is not uncommon for individual cows over short periods of time. As shown in table 4, the total decline in butterfat production is 23.8 per cent for group A and 23.2 per cent for group B, a difference too small to be significant. As shown in figure 1, the curves for butterfat production are approximately the same for both groups and follow very closely those representing the trend of milk produc- tion. Thus, the feeding of dried orange pulp has no apparent effect on the percentage of butterfat in the milk. FRESH ORANGE PULP On the basis of dry matter, fresh and dried orange pulp should have, for all practical purposes, an equivalent feeding value. Had it not been for the case cited below, investigations with the feeding of the fresh pulp, therefore, would have been deemed unnecessary. In 1922, Woll, of this station, studied the records of milk and butterfat production of cows in the Pellissier herd, where fresh orange pulp was being fed. He concluded as follows: "There is a strong indication that the pulp feeding in the case of practically all of the cows resulted in a marked improvement in the fat content of the milk, which was apparently progressing up to the longest period of the experimental feeding, viz., three months. The increase in the per- centage of fat in the case of individual cows was frequently as much as one-half of one per cent, and in extreme cases over one per cent. ' ' Since there is no feed known (6) which will affect a permanent increase in the butterfat test, Woll's observation, if substantiated, 12 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION would be of great scientific importance. Though the trial reported in the first part of this paper showed no effect on the butter fat test attributable to the feeding of dried orange pulp, the possibility remained that the factor responsible for the increase in test noted by Woll had been destroyed in the drying process. The experiment described in the following pages was undertaken for the purpose of obtaining definite information on this point. METHOD OF PROCEDURE An attempt was made to carry on this experiment at Davis, but because of the perishable nature of fresh orange pulp, it became neces- sary to conduct the investigation near the factory. Mr. E. C. Bennett, who maintains a large dairy herd at Chino, California, kindly offered a portion of the herd for the trial. Twenty-four grade cows were selected for this purpose. All of these were in rather poor flesh but were considerably above the average in dairy qualities. They were divided into groups, A and B, which were placed in separate corrals. That the two lots were balanced is shown in table 6. The average body weight for group A was 825 pounds and for group B, 826 pounds. The average daily milk production for group A was 28.1 pounds, while that for group B was 27.5 pounds. Group A's average test was 3.86 per cent, and group B's, 4.07 per cent. In daily butterfat pro- duction both groups were the same. TABLE 6 Initial Records of Body Weights and Production Group A Group B Cow No. Weight Daily milk Butter fat Daily butterfat Cow No. Weight Daily milk Butter fat Daily butterfat Pounds Pounds Per cent Pounds Pounds Pounds Per cent Pounds 121 725 27.8 4.1 1.1 96 860 29.1 4.0 1.2 122 720 26.6 3.9 1.0 123 780 32.1 3.0 1.0 125 865 33.9 3.4 1.1 124 1020 19.3 4.8 0.9 126 800 25.7 4.2 1.1 134 795 25.7 3.7 1.0 128 985 39.1 3.9 1.5 139 770 29.8 4.9 1.5 129 830 24.2 4 4 1.1 140 670 25.0 4.7 1.2 131 945 40.7 3.7 1.5 141 825 30.7 3.6 1.1 132 1035 23.8 4.1 1.0 142 880 25.0 3.5 0.9 135 555 16.9 4.8 0.8 144 800 34.7 3.2 1.1 136 1000 35.4 3.6 1.3 145 700 24.1 5.1 1.2 143 780 28.8 3.1 0.9 147 970 29.3 5.0 1.5 172 665 14.0 4.0 0.6 171 840 24.8 4.0 1.0 Totals 9905 336.9 13.0 9910 329.6 13.6 Average 825 28.1 3.86 1.1 826 27.5 4.07 1.1 BUL. 427] VALUE OF ORANGE PULP FOR MILK PRODUCTION 13 The basal ration consisted of alfalfa hay and a concentrate mixture. The latter, which contained equal parts by weight of ground barley, ground corn, and dried beet pulp was fed according to production. In addition, each cow was given two pounds of cottonseed cake daily. The hay which was fed according to the average initial body weight, was placed daily in racks to which all cows of the respective groups had free access. All feeds refused were weighed and deducted from the amount given in order to arrive at the total consumption. The feeding trial covered a period of 110 daj^s. During the first 10 days, both groups received only the basal ration. During the next 30 days, each cow in group A received daily 20 pounds of fresh orange pulp, which replaced two pounds of alfalfa hay. As a check, group B was continued on the basal ration. During the next 30 days, the rations were reversed, group A receiving the basal ration and group B the fresh orange pulp. During the following 30 days, the rations were reversed again. During the last 10 days, only the basal ration was fed. The cows were milked twice daily. A competent man was detailed to oversee the feeding and handling of the animals and to do all weigh- ing, sampling, testing, and recording of data, The milk from each cow was weighed at each milking and a daily composite sample was taken for the determination of the percentage of butterfat. The cows were weighed every 30 days. The atmospheric temperature in the milking barn was recorded each morning and evening. PRESENTATION OF DATA For the purpose of presenting the data, the experiment was divided into periods of 10 days each. In table 7 are shown the body weights, average feed consumed, percentage of butterfat in the milk, and pounds of milk and butterfat produced. The total production of the two groups was remarkably uniform. The difference between the average percentages of butterfat for the total experimental period was only 0.01. Because of the irregular fluctuations that are normal in the per- centage of butterfat found from day to day in the milk of any dairy cow, a study of the daily tests, gives very little indication of the general trends. In table 8 the individual tests are compiled according to the rations fed. There is no consistent indication that the feeding of fresh orange pulp has any effect upon the percentage of fat in the milk. The 14 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION tendency to increase shown in the table can logically be explained by the effect of advancing lactation. Variations as small as those between the successive periods will usually be found in any set of similar tests regardless of the ration fed. TABLE 7 Feed Consumed, Body Weights and Production Becords (Group averages by ten-day periods) Period Hay Concen- trates* Cotton- seed cake Orange pulp Body weight Total milk Butterfat Pounds | Pounds Pounds \ Pounds Pounds Pounds Per cent \ Pounds Group A 1 . 190 176 170 170 190 190 190 170 170 170 190 76 69 67 70 70 70 64 61 63 63 56 20 20 20 20 20 20 20 20 20 20 10 825 270.9 269.7 254.5 284.8 272.6 260.6 246.7 254.7 255.9 249.3 226.0 3.87 3.90 3.96 3.89 3.85 4.05 4.14 4.40 4.39 4.65 4.76 10.5 2 157.9 195.2 199.7 10 5 3.. .. 10.1 4 11.1 5 873 10.5 6 10 5 7 10 2 8 187.8 193.8 197.3 938 11.2 9 . 11.2 10 . 11.6 11.. . 10.8 2845.7 4.16 118.2 Group B 1 .. 190 190 190 190 170 170 170 190 190 190 190 73 71 70 71 71 71 70 67 70 70 62 19 20 20 20 20 20 20 20 20 20 10 826 274.3 273.6 278.3 291.3 284.8 286.5 277.5 269.8 256.0 241.1 237.3 4.04 3.82 3.79 3.74 4.06 4.34 4.53 4.28 4.34 4.42 4.59 11.1 2 10 5 3 10 6 4 10 9 5 139.5 197.9 176.2 886 11.6 6 12 4 7 12.6 8 944 11.5 9 11 1 10 10 6 11 10.9 2970.5 4.17 123.8 * Equal parts by weight of ground barley, corn meal and dried beet pulp. In order to present a more detailed analysis of the data, the average daily butterfat tests for each group, together with average daily temperatures in the milking barn, are shown graphically in figure 3. While the temperature curve has many fluctuations, none of these correlate definitely with the variations in the butterfat curves (7) BUL. 427] VALUE OF ORANGE PULP FOR MILK PRODUCTION 15 TABLE 8 The Effect of Feeding Fresh Orange Pulp on the Fat Percentage in Milk Group A Group B Cow No. Basal ration 10 days Orange pulp 30 days Basal ration 30 days Orange pulp 30 days Basal ration 10 days Cow No. Basal ration 10 days Basal ration 30 days Orange pulp 30 days Basal ration 30 days Basal ration 10 days 121 4.28 4.37 4.70 5.40 5.58 96 3.98 3.51 4.02 4.18 4 51 122 3.91 4.30 3.97 4.48 4.66 123 3.76 3.75 4.14 4.21 4.51 125 3.63 3.69 3.59 3.85 3.93 124 4.42 4.37 4.93 4.99 5.27 126 4.01 3.98 4.04 4.44 4.76 134 4 00 3.91 4.29 4.66 5.20 128 3.90 4.00 3.84 4.28 4.49 139 4.27 3.92 4.43 4.49 4.56 129 4.43 4.45 4.36 4.89 4.91 140 4.52 4.50 5.78 5.73 6.31 131 3.86 4.09 4.33 4.88 5.02 141 3.40 3.08 3.24 3.23 3.38 132 3.93 3.81 3.85 4.22 4.47 142 3.47 3.56 3.80 3.83 3.97 135 4.99 5.42 5.71 6.10 6.27 144 3.77 3.42 4.10 3.87 4.00 136 3.54 3.44 3.45 3.77 4.07 145 5.08 4.62 5.33 5.43 5.98 143 2.88 2.80 2.89 3.07 4.23 147 4.82 4.72 5.39 5.13 5.72 172 3.90 3.73 4.38 5.20 5.26 171 Group average 3.50 3.09 3.66 3.88 3.99 Group average 3.94 4.01 4.09 4.55 4.80 4.08 3.87 4.43 4.47 4.78 90 * f V A 8-* \j K \/ 1 \ ^y \^ ^N A J V/ \ \ "\i [^ A Ah ( \ N E7D GO O - • 7 ~EMt effA ■ tupl — V — — V f V \ J ... . V \ i *JUHE as opange pulp reo TO GPOUP A OPANpe PULP F ED TV i GPOUP A k OPAHOE PULP TO GPOUP 3 J? •* 3 "*~~ ~ c Ipoup 3 1 1 I . O L=_n — O IO uune as JO so so DAY3 IOO IIO oct /a Fig. 3. — Trends in butterfat tests, and barn temperatures. 16 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION PALATABILITY Fresh orange pulp seemed to be relished by the animals. As much as twenty pounds a day were consumed for a period of thirty days. The palatability is considerably better than that of dried orange pulp or of cull oranges. In a palatability test, incidental to the experi- ments recorded here, difficulty was met in inducing cows to consume more than four or five pounds of cull oranges daily. However, after a considerable time, the cows might have acquired a taste for them. CONCLUSIONS 1. Dried orange pulp is approximately equivalent to dried beet pulp as a feed for milk production. 2. One hundred pounds of dried orange pulp contains approxi- mately 78 pounds of total digestible nutrients. 3. Neither fresh nor dried orange pulp influenced the percentage of fat in the milk produced. 4. While fresh orange pulp was readily eaten, it was necessary to mix the dried pulp with a more palatable feed. LITERATURE CITED 1 LlNDSEY, J. B. 1913. The food value of plain and molasses beet pulp. Mass. Agr. Exp. Sta. Bpt. 1913 (Part 1): 129-140. 2 Armsbt, Henry Prentiss 1917. The nutrition of farm animals, p. 711, 714. Appendix tables I and V. The MacMillan Company, New York. 3 Armsby, Henry Prentiss, and J. August Fries 1915. Net energy values of feeding stuffs for cattle. Jour. Agr. Eesearch 3:486-487. 4 Henry, W. A., and F. B. Morrison 1923. Feeds and feeding. 18th ed., p. 722-723. Appendix table II. The Henry-Morrison Company, Madison, Wisconsin, s Mead, S. W., and H. B. Guilbert 1926. The digestibility of certain fruit by-products as determined for ruminants. Part I. Dried orange pulp and raisin pulp. Cali- fornia Agr. Exp. Sta. Bui. 409:1-11. e McCandlish, Andrew C. 1921. The use of cottonseed meal to increase the percentage of fat in milk. Jour. Dairy Science, 4:310-333. 7 Hays, W. P. 1926. The effect of environmental temperature on the percentage of fat in cow's milk. Jour. Dairy Science, 9:219-235. 12m-6,'27