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Effects of Pelleting and Varying Grain Intakes on Milk Yield and Composition
EFFECTS
OF PELLETING AND VARYING GRAIN INTAKES YIELD AND COMPOSITION
ON M I L K
S. E. BISHOP,* J. K. LOOSLI, G. W. TRIMBERGER, AND,~ . L. TURK Department of Animal Husbandry, Cornell University, Ithaca, :New York SU/E[MAR¥
Twelve cows were used in three replicates of a 4 × 4 Latin-square design, to study the effects of meal as compared to pelleted concentrate, fed with two ratios of grain and roughage, on the yield and composition of milk and the relative proportions of rumen VFA. Feeding pellets resulted in a highly significant increase (P < 0.01) in milk yield and a decrease (P < 0.05) in fat percentage when compared to meal concentrate. There were very small differences in feed intake in favor of the meal, but the efficiency of utilization of TDN for the production of FCM was slightly better for pellets. Feeding low roughage-high concentrate rations resulted in a highly significant (P < 0.01) increase in milk protein content and a significant (P < 0.05) decrease in milk fat percentage, when compared to the high roughage-low concentrate rations. There were no appreciable effects on the solids-not-fat. TD• intake was 30% greater for the high concentrate rations. No differences in body weight changes were observed. The molar percentage of acetic acid was greater and butyric acid lower on the high-roughage rations than on low-roughage (P < 0.01). The proportion of the rumen propionic acid was not appreciably altered. Of the many factors that affect the yield and composition of milk, the use of pelleted concentrates and high-level grain feeding is currently of great interest to dairymen. Each of these, however, exerts its effect on several different milk constituents and sometimes in opposite directions. A 1956 study (1) compared a typical 16% protein meal with the same feed in the form of ½-inch pellets. I t was reported that a high milk fat percentage and more FCM favored the meal concentrate. F o r most of the cows there was no difference in milk yield, feed intake, or palatability; however, some cows refused the pellets entirely. A later study (14) reported that some cows ate pelleted concentrate faster, which might be an advantage in some milking parlors, but the observed difference was small. An increased plane of nutrition as a result o£ high-level grain feeding will cause marked increases in milk yield with no effect on the fat content (7) and, at the same time, will increase the milk protein percentage (7, 11-13, 21). The extent of this change in milk protein
content varies with the ratio of roughage to concentrate in the ration (7, 19-21). This experiment was undertaken to study simultaneously the influence of pelleted concentrates and different hay and concentrate levels of intake on milk yield and composition. EXPERI:gE~TAL
PROCEDURE
Twelve cows were selected in three groups of four, with each group located in a different barn. The four cows in one barn were Brown Swiss, the other eight were Holstein. The cows ranged in age from 2 to 10 yr, in size from 950 to 1,600 lb, and all had calved between November 1 - a n d December 31, 1961. The cows within groups, the groups, and the four experimental rations were all randomly assigned to a 4 × 4 Latin-square design with three replicates, as outlined by Federer (10). The four feeding periods were each 4 wk in length, with the first week as the changeover period. The experiment started on J a n u a r y 16 and ended May 22, 1962. The treatments were in the fol~l of a 2 × 2 factorial design and the four rations and daily feed allowances were as follows: Hay, ad lib. ; silage, 30 lb; pellets, 1 lb per 4 lb milk ttay, ad lib. ; silage, 30 Ib; meat 1 tb per 4 lb milk
l~eceived for pub]icatlon August 18, 1962. , Present address: University of California Agricultural Extension Service, l~oom 7, Post Office Building, Riverside, California. 22
EFFECTS
OF
PELLETING
AND
Ha)-, 5 lb; silage, 15 lb; pellets, ad lib. Hay, 5 lb; silage, 15 lb; meal, ad lib. Daily amounts of feed were held at a constant level for each cow during each 3-wk feeding period, but the concentrates, when fed at the low level, were reduced at a standard rate of I lb per cow between periods to compensate for the normal decrease in milk production. The l~-inch pellets and the meal concentrates were both made from the following formula: 800 lb ground yellow corn, 200 lb ground oats, 200 lb wheat bran, 400 lb corn distillers dried grains, 200 lb soybean oil meal (50% protein), 160 lb cane molasses, 20 lb dicalcinm phosphate, and 20 lb trace-mineralized salt. The hay and silage were fed from the available supplies at the three barns and were of fair quality. The chemical composition and estimated TDN content of all feeds are shown in Table 1. Records were kept of the daily feed intakes and milk production. Composite samples from two successive milkings were tested each week for percentages of fat, protein, and solids-notfat (SNF). Test procedures used were Babcock, Orange G dye (2), and Lactometer, respectively. Samples of tureen liquor were drawn from each cow by stomach tube during the last week of each period. The samples were taken 8 hr after grain and 6 hr after roughage feedings. Two milliliters of saturated mercuric chloride were added to each 100-ml bottle of rumen liquor and the samples were stored at 5 C until analyzed. Acetic, propionic, butyric, and valeric acids were separated chromatographically by the procedure of Wiseman and Irvin (25), as modified by Stewart (23) and Reynolds (18) and were expressed as molar per cent of rumen volatile fatty acid ( V F A ) .
GRAIN
ON
23
PRODUCTION
The valerie acid portion (C~) included small amounts of higher acids. Changes in body weight were determined from an average of weights taken the last three days of the pretest and at each feeding period. Treatment differences were determined using the analysis of variance technique of Federer (]0) and evaluated by the F test. RESULTS AlqD DISCUSSIOlq Considering all of the data~ the differences in the milk yield between high and low roughage and pellets and meal (Table 2) were found to be highly significant (P < 0.01). However, the milk fat percentages were affected inversely to the changes in milk yield, resulting in smaller differences when equated to 4% FCM. Table 2 also shows the very large differences in milk yield between the high- and the low-roughage rations and the smaller differences between the pellets and meal concentrate. Both differences were highly significant (P < 0.01). Mastitis infections in four cows caused rather marked reductions in milk yield for a few days; however, the average yields during those feeding periods were not greatly different from normal, so the yield figures were used without being adjusted or corrected for the effects of the mastitis. Significant differences (P < 0.05) of 0.23 percentage units in milk fat were observed between the high- and the low-roughage rations, whereas the differences due to pellets as compared to the meal concentrate (0.1 percentage unit) were not statistically significant (Table 2). These results are in close agreement with previous work and are largely explained by the low levels of roughage fed, and especially when accompanied by high levels of concentrate in the ration (3-5, 9, 15-17). The slight depres-
TABLE 1 Chemical composition of the feeds Feed
Dry matter
Crude protein
Ether extract
I'(FE
Crude fiber
Ash
TDN a
(%) Barn
1 :
Alfalfa hay Corn silage Barn 2 : Alfalfa hay Corn silage Barn 3 : Mixed hay b Corn silage Concentrate : Pelleted Meal
90.9 26.3
12.7 2.0
2.0 0.8
31.4 17.4
40.1 5.2
4.7 0.9
50.3 16.2
91.3 26.3
13.9 2.1
2.0 0.7
3,5.4 16.7
34.1 5.7
5.9 1.1
50.3 17.2
90.9 20.3
10.1 1.8
2.1 0.5
39.8 11.4
33.7 5.7
5.2 0.9
49.5 12.9
87.5 87.3
17.2 17.5
2.7 3.4
54.4 53.2
7.1 7.2
6.1 6.0
75.9 75.9
a Estimated from Feeds and Feeding, 22nd ed. (Morrison, 1956). b Mixed grass and alfalfa hay, good quality, more than 30% legumes.
S. E.
24
BISHOP ET AL
TABLE 2 Mea~l daily values of milk yield, fat, p•otein, and s'olid~-not-fat
Pretest High roughage + pellets High roughage -t- meal Low roughage + pellets Low roughage ÷ meal All values for: High roughage Low roughage Pellets Meal a~b, d~e, g~h
Milk
Fat
FCM
Protein
SNF
(tb)
(%)
(Zb)
(%)
(%)
51.21 42.68 42.02 47.12 ~4.93
3.73 3.65 3.73 3.41 3.50
49.14 40.44 40.32 42.95 41.56
............ 3.16 3.16 3.26 3.28
8.91 8.99 9.05 9.05
42.35a 46.02b 44.90c 43.48d
3.69e 3.46f 3.53 3.61
40.38 49.26 41.75 40.94
3.16g 3.27h 3.21 3.22~
8.95 9.05 8.98' 9.02
(P~O.01); f~e
(P~O.05).
sion caused by the pellets may possibly be reIated to the fine grinding of the pelleted feed (1, 4, 9, 14). The milk protein content showed a highly significant difference of 0.1 percentage unit (P < 0.01) betnveen the high- and the low-roughage rations. There was no difference between the effects of pellets and meal (Table 2). This difference would be accounted for by the large variation in the plane of nutrition between the high- and the low-roughage rations (7, 11-13, 21). The changes in milk protein content varied inversely with the changes in milk fat percentage and at approximately one-half the amount of the fat change. The difference in SNF percentage due to the high- as compared to the low-roughage rations was small (8.95 vs. 9.05%) and was statistically significant only at the 10% level. There was no difference between the effects of meal and pelleted concentrate (Table 2). This slight difference would be expected, as any change in SNF is almost entirely due to the change in the protein portion (19). Most of the differences in milk yield can be easily accounted for by the almost 30% difference in levels of TDN intake (Table 3) between the high- and low-roughage rations (7). However, the increased milk yield due to the pellets as compared to meal suggests a slightly better feed conversion for the pellets.
There was very little refusal of any of the feeds when offered at the low level of feeding or of the silage when offered at the higher (30 lb) rate. There was, however, great variability in the consumption of hay and both pellets and meal when fed at the high rate (Table 3). The daily hay consumptions, when fed at the high level, averaged 16.6 lb, and individual cows varied from 8.9 to 21.3 lb, the pellets intake at free choice feeding averaged 29.3 lb, with a range from 20.6 to 35.5 lb, and the meal consumed averaged 31.4 lb and ranged from 24.0 to 36.5 lb. Most of the differences in feed intake were due to the between cow variations in ability to consume large amounts of either the hay or the concentrates. There were some within cow differences in consumption between pellets and meal, but they can be largely accounted for by the mastitis infection that caused some cows to go off feed for short periods of time. There were no observed differences in palatability between the pellets and meal. The feed consumption, when converted to TDN intake, showed highly significant differences (P < 0.Ol) between the means of the high-roughage (21.7 lb) and the low-roughage (28.0 lb) rations. TDN intake averaged 24.4 lb for pellets and 25.3 Ib for meal. The efficiency of utilization of TDN for the production of FCM, milk protein, and SNF appeared to be slightly greater for pellets than for meal, par-
TABLE 3 Mean daily intakes of feeds and total digestible nutrients Ration
Hay
Silage
Grain
TDN
TDN/FCM
21.5 21.9 2.7.4 28.6
0.53 0.54 0.64 0.69
(lb) Nigh roughage + pellets High roughage + meal Low roughage ~- pellets Low roughage ~ meal
16.2 17.0 4.8 4.8
29.2 29.5 14.8 14.9
Daily TDN intake divided by daily FCM produced.
11.7 11.7 29.3 31.4
EFFECTS OF PELLETING AND GRAIN ON PI%ODUCTION
ticularly at the high rate of feeding. The lowconcentrate rations were more efficiently utilized than were the high-concentrate rations. In spite of the 30% difference in TDN intake between the high- and the lo~-ronghage rations, there were no significant differences in body weight changes. Some of the cows showed rather wide variations in body weight between feeding periods, but there were no consistent patterns for any of the rations fed. The highroughage ration would probably result in more rumen fill than the high-grain ration. The feedLug periods were not long enough for ~ny appreciable changes in body tissue to show up. Both the acetic and butyric acid proportions of the rumen Y F A showed highly significant changes (P < 0.01) between the high- and lowroughage rations (Table 4). Proplonic acid
25
I~EFERENCES
(1) ADAMS, H. P., ~ND WARD, R. E. The Value of Pelleting the Concentrate Part of the Ration for Lactating Cattle. J. Dairy Sci., 39: 1448. 1956. (2) AS]=IWOI%TH,U. S., SE~LS, R., AND ERB, R. E.
An Improved Procedure for the Determination of Milk Proteins. by Dye Binding. J. Dairy Sci., 43: 614. 1960. (3~) BALCH, C. C., BALCn~, D. A., BARTL~.TT, S., Cox, C. P., ANn ROWLAND, S. J. Studies of the Secretion of Milk of Low F~t Content by Cows on Diets Low in Hay and High in Concentrates. I. The Effect of Variations in the Amount of Hay. J. Dairy Research, 19: 51. 1952. (4~) BALC't{, C. C., BALCtI, D. A., BA~T~TT, S., BARTRU~, PATI~IOIA,J-O~NS0N, V. W., RowLAND, S. J., AND TUI%IWF~, JILL. Studies of
TABLE 4 Mean molar percentages of rumen volatile fatty acids
Ration
Acetic C2
Propionic Ca
Butyric C~
Valeric C~
C=/C~
High roughage + pellets High roughage + meal Low roughage + pellets Low roughage + meal
61.9a 61.8a 54.8b 55.8b
20.0 20.8 21.5 22.4
16.7e 16.2e 21.4d 20.6d
1.4 1.2 2.3 1.3
3.10 2.97 2.55 2.49
a>b,
d>c
(P <0.01).
showed no appreciable changes between these rations and none of the acids reflected any differences due to pellets as compared to meal. Several studies (4, 6, 8, 9, 20, 22, 24) have shown that restricting the roughage intake results in a decrease in the molar percentage of rnmen acetic acid and increases in both the propionie and butyric acid percentages. I n this experiment, the intake of roughages at the low level (5 lb hay plus 15 lb silage) apparently was low enough to cause marked differences in the proportions of acetic and butyric acids but was not sufficiently low to cause more than very small changes in the propionic acid content. The time of sampling after feeding would also have an effect on the proportions of each of the acids (6). I t is recognized that the 4-wk feeding periods used here may be too short for the maximum responses to the experimental rations to show up. Also, longer periods would allow more samples to be obtained, which would tend to reduce the rather large variations in milk fat and protein content and in the V F A of the rumen ingesta. The experiment should be repeated using longer feeding periods, which should result in more precise measurements.
the Secretion of Milk of Low Fat Content by Cows on Diets Low in Hay and High in Concentrates. V. The $mportanee of the Type of Starch in the Concentrate. J. Dairy Research, 22: 10. 1955. (5) BALOtt, C. C., BALGtt, D. A., BARTLE~TT,S., HOSKING, Z]~NA,JOIINBOI~,V. W., ROWLAND, S. J., AND TU~NF~, Jm•. Studies of the Secretion of Milk of Low Fat Content by Cows on Diets Low in Hay and High in Concentrates. III. The Effect of Variations in the Amount and Physical State of the Hay and a Comparison of the Shorthorn and Friesian Breeds. ft. Dairy Research, 21: 172. 1954. (6) BALClZ, C. C., AND ROWnAND, S. J. Volatile Fatty Acids and Lactic Acid in the Rumen of Dairy Cows Receiving a Variety of Diets. Brit. J. Nutrition, 11:288. 1957. (7) BVRT, A. W. A. The Effect of Variations in Nutrient lntake upon the Yield and Composition of Milk. J. Dairy Research, 24: 283. 1957. (8) ELLIOT, J. M., AND LOOSLI, J. g . Relationship of Milk Production Efficiency to the
Relative Proportions of the Rumen Volatile Fatty Acids. J. Dairy Sei., 42: 843. 1959. (9) ENSOR, W. L., SHAW, J. C., AND T~L~C~F~, ]I. F. Special Diets for the Production of
26
(10) (11)
(12)
(13)
(14)
(15)
(16)
(17)
S. E. BISHOP ET AL Low F a t Milk and More Efficient Gains in Body Weight. ft. Dairy Sci., 42: 1. 1959. FEDERE~,W. T. Experimental Design. p. 444. Macmillan Company, New York. 1955. FLUX, D. S., AND P~TC~LL, IV[. R. The Effects of Short Periods of Under-nutrition After Calving on the Establishment of Lactation in Dairy Cows. New Zealand J. Sci. Technol., 38: 689. 1957. HOt,MES, W., REID, D., MAcLUsKY, D. S., WAI~m, R., AN~ WATSON, J. N. Winter Feeding of Dairy Cows. IV. The Influence of Four Levels of Concentrate Feeding in Addition to a Basal Ration of Grass Products on the Production Obtained from Milking Cows. ft. Dairy Research, 24: ]. ]957. HOLMES, W., WAITS, R., MAoLuSK¥, D. S., AI~I~ WATSON, J. N. Winter Feeding of Dairy Cows. I. The Influence of Level and Sourse of Protein and of the Level of Energy in the Feed on Milk Yield and Composition. J. Dairy Research, 23: 1. 1956. LOOSLI, J. K. Pelleted Feeds for Ruminants. Prec. Distillers Feed Conf. Distillers Feed Research Council, C~ncinuati, Ohio. 1959. LoosLI, J. K., LUCAS, H. L., AN]) MAYIqAR,D, L . A . The Effects of Roughage Intake upon the F a t Content of Milk. ft. Dairy Sci., 28: 147. 1945. P o w ~ L , E. B. One Cause of F a t Variation in Milk. p. 40. Prec. Am. Soc. Animal Production. 1938. POWELL, E. B. Progress Report on the Relation of the Ration to the Composition of Milk. J. Dairy Sci., 24: 504. 1941.
(18) RZYNOLDS," P. J. The Separation and Estimation of the Volatile P a t t y Acids in the Rumen Fluid. Mimed, Animal Husbandry Dept., Cornell Univ. 1962. (19) RONNINO, MAGNAR. Effect of Varying Alfalfa Hay-Concentrate Ratios in a Pelleted Ration for Dairy Cows. J. Dairy Sci., 43: 811. 1960. (20) ROOK, 5. A. F. Variations in the Chemical Composition of the Milk of the Cow. P a r t I. Dairy Sci. Abstrs., 23: 251. 1961. (21) ROOK, J. A. F., AN~ LIN~, C. The Effect of the Plane of Energy Nutrition of the Cow on the Secretion of the Constituents of the Solids-not-fat Fraction and on the Concentrations of Certain Blood-Plasma Constituents. Brit. J. Nutrition, 15: 109. 1961. (22) SI~AW,J. C., ROBINSOI% R. R., SzI~om%,iV[. E., LAKSHMA/qAlq, S., AND LEWIS, T. R. Effect of Quality and Quantity of Concentrate on Volatile F a t t y Acids of Rumen and on the Composition of Milk. J. Nutrition, 69: 235. 1959. (23) Sa~WART, D. G. Continuous Culture as a Method for Studying Rumcn Fermentation. Ph.D. thesis, Cornell University. 1959. (24) VA~ SOEST, P. J., AND ALL,I% N. N. Studies on the Relationships Between Rumen Acids and F a t Metabolism of Ruminants Fed on Restricted l~oughage Diets. J. Dairy Sci., 42: 1977. 1951. (25) WISE~AN, H. G., AND I~VI~, H. IV[. Determination of Organic Acids in Silage. J. Agr. Food Chem., 5: 213. 1957.
OF PELLETING AND VARYING GRAIN INTAKES YIELD AND COMPOSITION
ON M I L K
S. E. BISHOP,* J. K. LOOSLI, G. W. TRIMBERGER, AND,~ . L. TURK Department of Animal Husbandry, Cornell University, Ithaca, :New York SU/E[MAR¥
Twelve cows were used in three replicates of a 4 × 4 Latin-square design, to study the effects of meal as compared to pelleted concentrate, fed with two ratios of grain and roughage, on the yield and composition of milk and the relative proportions of rumen VFA. Feeding pellets resulted in a highly significant increase (P < 0.01) in milk yield and a decrease (P < 0.05) in fat percentage when compared to meal concentrate. There were very small differences in feed intake in favor of the meal, but the efficiency of utilization of TDN for the production of FCM was slightly better for pellets. Feeding low roughage-high concentrate rations resulted in a highly significant (P < 0.01) increase in milk protein content and a significant (P < 0.05) decrease in milk fat percentage, when compared to the high roughage-low concentrate rations. There were no appreciable effects on the solids-not-fat. TD• intake was 30% greater for the high concentrate rations. No differences in body weight changes were observed. The molar percentage of acetic acid was greater and butyric acid lower on the high-roughage rations than on low-roughage (P < 0.01). The proportion of the rumen propionic acid was not appreciably altered. Of the many factors that affect the yield and composition of milk, the use of pelleted concentrates and high-level grain feeding is currently of great interest to dairymen. Each of these, however, exerts its effect on several different milk constituents and sometimes in opposite directions. A 1956 study (1) compared a typical 16% protein meal with the same feed in the form of ½-inch pellets. I t was reported that a high milk fat percentage and more FCM favored the meal concentrate. F o r most of the cows there was no difference in milk yield, feed intake, or palatability; however, some cows refused the pellets entirely. A later study (14) reported that some cows ate pelleted concentrate faster, which might be an advantage in some milking parlors, but the observed difference was small. An increased plane of nutrition as a result o£ high-level grain feeding will cause marked increases in milk yield with no effect on the fat content (7) and, at the same time, will increase the milk protein percentage (7, 11-13, 21). The extent of this change in milk protein
content varies with the ratio of roughage to concentrate in the ration (7, 19-21). This experiment was undertaken to study simultaneously the influence of pelleted concentrates and different hay and concentrate levels of intake on milk yield and composition. EXPERI:gE~TAL
PROCEDURE
Twelve cows were selected in three groups of four, with each group located in a different barn. The four cows in one barn were Brown Swiss, the other eight were Holstein. The cows ranged in age from 2 to 10 yr, in size from 950 to 1,600 lb, and all had calved between November 1 - a n d December 31, 1961. The cows within groups, the groups, and the four experimental rations were all randomly assigned to a 4 × 4 Latin-square design with three replicates, as outlined by Federer (10). The four feeding periods were each 4 wk in length, with the first week as the changeover period. The experiment started on J a n u a r y 16 and ended May 22, 1962. The treatments were in the fol~l of a 2 × 2 factorial design and the four rations and daily feed allowances were as follows: Hay, ad lib. ; silage, 30 lb; pellets, 1 lb per 4 lb milk ttay, ad lib. ; silage, 30 Ib; meat 1 tb per 4 lb milk
l~eceived for pub]icatlon August 18, 1962. , Present address: University of California Agricultural Extension Service, l~oom 7, Post Office Building, Riverside, California. 22
EFFECTS
OF
PELLETING
AND
Ha)-, 5 lb; silage, 15 lb; pellets, ad lib. Hay, 5 lb; silage, 15 lb; meal, ad lib. Daily amounts of feed were held at a constant level for each cow during each 3-wk feeding period, but the concentrates, when fed at the low level, were reduced at a standard rate of I lb per cow between periods to compensate for the normal decrease in milk production. The l~-inch pellets and the meal concentrates were both made from the following formula: 800 lb ground yellow corn, 200 lb ground oats, 200 lb wheat bran, 400 lb corn distillers dried grains, 200 lb soybean oil meal (50% protein), 160 lb cane molasses, 20 lb dicalcinm phosphate, and 20 lb trace-mineralized salt. The hay and silage were fed from the available supplies at the three barns and were of fair quality. The chemical composition and estimated TDN content of all feeds are shown in Table 1. Records were kept of the daily feed intakes and milk production. Composite samples from two successive milkings were tested each week for percentages of fat, protein, and solids-notfat (SNF). Test procedures used were Babcock, Orange G dye (2), and Lactometer, respectively. Samples of tureen liquor were drawn from each cow by stomach tube during the last week of each period. The samples were taken 8 hr after grain and 6 hr after roughage feedings. Two milliliters of saturated mercuric chloride were added to each 100-ml bottle of rumen liquor and the samples were stored at 5 C until analyzed. Acetic, propionic, butyric, and valeric acids were separated chromatographically by the procedure of Wiseman and Irvin (25), as modified by Stewart (23) and Reynolds (18) and were expressed as molar per cent of rumen volatile fatty acid ( V F A ) .
GRAIN
ON
23
PRODUCTION
The valerie acid portion (C~) included small amounts of higher acids. Changes in body weight were determined from an average of weights taken the last three days of the pretest and at each feeding period. Treatment differences were determined using the analysis of variance technique of Federer (]0) and evaluated by the F test. RESULTS AlqD DISCUSSIOlq Considering all of the data~ the differences in the milk yield between high and low roughage and pellets and meal (Table 2) were found to be highly significant (P < 0.01). However, the milk fat percentages were affected inversely to the changes in milk yield, resulting in smaller differences when equated to 4% FCM. Table 2 also shows the very large differences in milk yield between the high- and the low-roughage rations and the smaller differences between the pellets and meal concentrate. Both differences were highly significant (P < 0.01). Mastitis infections in four cows caused rather marked reductions in milk yield for a few days; however, the average yields during those feeding periods were not greatly different from normal, so the yield figures were used without being adjusted or corrected for the effects of the mastitis. Significant differences (P < 0.05) of 0.23 percentage units in milk fat were observed between the high- and the low-roughage rations, whereas the differences due to pellets as compared to the meal concentrate (0.1 percentage unit) were not statistically significant (Table 2). These results are in close agreement with previous work and are largely explained by the low levels of roughage fed, and especially when accompanied by high levels of concentrate in the ration (3-5, 9, 15-17). The slight depres-
TABLE 1 Chemical composition of the feeds Feed
Dry matter
Crude protein
Ether extract
I'(FE
Crude fiber
Ash
TDN a
(%) Barn
1 :
Alfalfa hay Corn silage Barn 2 : Alfalfa hay Corn silage Barn 3 : Mixed hay b Corn silage Concentrate : Pelleted Meal
90.9 26.3
12.7 2.0
2.0 0.8
31.4 17.4
40.1 5.2
4.7 0.9
50.3 16.2
91.3 26.3
13.9 2.1
2.0 0.7
3,5.4 16.7
34.1 5.7
5.9 1.1
50.3 17.2
90.9 20.3
10.1 1.8
2.1 0.5
39.8 11.4
33.7 5.7
5.2 0.9
49.5 12.9
87.5 87.3
17.2 17.5
2.7 3.4
54.4 53.2
7.1 7.2
6.1 6.0
75.9 75.9
a Estimated from Feeds and Feeding, 22nd ed. (Morrison, 1956). b Mixed grass and alfalfa hay, good quality, more than 30% legumes.
S. E.
24
BISHOP ET AL
TABLE 2 Mea~l daily values of milk yield, fat, p•otein, and s'olid~-not-fat
Pretest High roughage + pellets High roughage -t- meal Low roughage + pellets Low roughage ÷ meal All values for: High roughage Low roughage Pellets Meal a~b, d~e, g~h
Milk
Fat
FCM
Protein
SNF
(tb)
(%)
(Zb)
(%)
(%)
51.21 42.68 42.02 47.12 ~4.93
3.73 3.65 3.73 3.41 3.50
49.14 40.44 40.32 42.95 41.56
............ 3.16 3.16 3.26 3.28
8.91 8.99 9.05 9.05
42.35a 46.02b 44.90c 43.48d
3.69e 3.46f 3.53 3.61
40.38 49.26 41.75 40.94
3.16g 3.27h 3.21 3.22~
8.95 9.05 8.98' 9.02
(P~O.01); f~e
(P~O.05).
sion caused by the pellets may possibly be reIated to the fine grinding of the pelleted feed (1, 4, 9, 14). The milk protein content showed a highly significant difference of 0.1 percentage unit (P < 0.01) betnveen the high- and the low-roughage rations. There was no difference between the effects of pellets and meal (Table 2). This difference would be accounted for by the large variation in the plane of nutrition between the high- and the low-roughage rations (7, 11-13, 21). The changes in milk protein content varied inversely with the changes in milk fat percentage and at approximately one-half the amount of the fat change. The difference in SNF percentage due to the high- as compared to the low-roughage rations was small (8.95 vs. 9.05%) and was statistically significant only at the 10% level. There was no difference between the effects of meal and pelleted concentrate (Table 2). This slight difference would be expected, as any change in SNF is almost entirely due to the change in the protein portion (19). Most of the differences in milk yield can be easily accounted for by the almost 30% difference in levels of TDN intake (Table 3) between the high- and low-roughage rations (7). However, the increased milk yield due to the pellets as compared to meal suggests a slightly better feed conversion for the pellets.
There was very little refusal of any of the feeds when offered at the low level of feeding or of the silage when offered at the higher (30 lb) rate. There was, however, great variability in the consumption of hay and both pellets and meal when fed at the high rate (Table 3). The daily hay consumptions, when fed at the high level, averaged 16.6 lb, and individual cows varied from 8.9 to 21.3 lb, the pellets intake at free choice feeding averaged 29.3 lb, with a range from 20.6 to 35.5 lb, and the meal consumed averaged 31.4 lb and ranged from 24.0 to 36.5 lb. Most of the differences in feed intake were due to the between cow variations in ability to consume large amounts of either the hay or the concentrates. There were some within cow differences in consumption between pellets and meal, but they can be largely accounted for by the mastitis infection that caused some cows to go off feed for short periods of time. There were no observed differences in palatability between the pellets and meal. The feed consumption, when converted to TDN intake, showed highly significant differences (P < 0.Ol) between the means of the high-roughage (21.7 lb) and the low-roughage (28.0 lb) rations. TDN intake averaged 24.4 lb for pellets and 25.3 Ib for meal. The efficiency of utilization of TDN for the production of FCM, milk protein, and SNF appeared to be slightly greater for pellets than for meal, par-
TABLE 3 Mean daily intakes of feeds and total digestible nutrients Ration
Hay
Silage
Grain
TDN
TDN/FCM
21.5 21.9 2.7.4 28.6
0.53 0.54 0.64 0.69
(lb) Nigh roughage + pellets High roughage + meal Low roughage ~- pellets Low roughage ~ meal
16.2 17.0 4.8 4.8
29.2 29.5 14.8 14.9
Daily TDN intake divided by daily FCM produced.
11.7 11.7 29.3 31.4
EFFECTS OF PELLETING AND GRAIN ON PI%ODUCTION
ticularly at the high rate of feeding. The lowconcentrate rations were more efficiently utilized than were the high-concentrate rations. In spite of the 30% difference in TDN intake between the high- and the lo~-ronghage rations, there were no significant differences in body weight changes. Some of the cows showed rather wide variations in body weight between feeding periods, but there were no consistent patterns for any of the rations fed. The highroughage ration would probably result in more rumen fill than the high-grain ration. The feedLug periods were not long enough for ~ny appreciable changes in body tissue to show up. Both the acetic and butyric acid proportions of the rumen Y F A showed highly significant changes (P < 0.01) between the high- and lowroughage rations (Table 4). Proplonic acid
25
I~EFERENCES
(1) ADAMS, H. P., ~ND WARD, R. E. The Value of Pelleting the Concentrate Part of the Ration for Lactating Cattle. J. Dairy Sci., 39: 1448. 1956. (2) AS]=IWOI%TH,U. S., SE~LS, R., AND ERB, R. E.
An Improved Procedure for the Determination of Milk Proteins. by Dye Binding. J. Dairy Sci., 43: 614. 1960. (3~) BALCH, C. C., BALCn~, D. A., BARTL~.TT, S., Cox, C. P., ANn ROWLAND, S. J. Studies of the Secretion of Milk of Low F~t Content by Cows on Diets Low in Hay and High in Concentrates. I. The Effect of Variations in the Amount of Hay. J. Dairy Research, 19: 51. 1952. (4~) BALC't{, C. C., BALCtI, D. A., BA~T~TT, S., BARTRU~, PATI~IOIA,J-O~NS0N, V. W., RowLAND, S. J., AND TUI%IWF~, JILL. Studies of
TABLE 4 Mean molar percentages of rumen volatile fatty acids
Ration
Acetic C2
Propionic Ca
Butyric C~
Valeric C~
C=/C~
High roughage + pellets High roughage + meal Low roughage + pellets Low roughage + meal
61.9a 61.8a 54.8b 55.8b
20.0 20.8 21.5 22.4
16.7e 16.2e 21.4d 20.6d
1.4 1.2 2.3 1.3
3.10 2.97 2.55 2.49
a>b,
d>c
(P <0.01).
showed no appreciable changes between these rations and none of the acids reflected any differences due to pellets as compared to meal. Several studies (4, 6, 8, 9, 20, 22, 24) have shown that restricting the roughage intake results in a decrease in the molar percentage of rnmen acetic acid and increases in both the propionie and butyric acid percentages. I n this experiment, the intake of roughages at the low level (5 lb hay plus 15 lb silage) apparently was low enough to cause marked differences in the proportions of acetic and butyric acids but was not sufficiently low to cause more than very small changes in the propionic acid content. The time of sampling after feeding would also have an effect on the proportions of each of the acids (6). I t is recognized that the 4-wk feeding periods used here may be too short for the maximum responses to the experimental rations to show up. Also, longer periods would allow more samples to be obtained, which would tend to reduce the rather large variations in milk fat and protein content and in the V F A of the rumen ingesta. The experiment should be repeated using longer feeding periods, which should result in more precise measurements.
the Secretion of Milk of Low Fat Content by Cows on Diets Low in Hay and High in Concentrates. V. The $mportanee of the Type of Starch in the Concentrate. J. Dairy Research, 22: 10. 1955. (5) BALOtt, C. C., BALGtt, D. A., BARTLE~TT,S., HOSKING, Z]~NA,JOIINBOI~,V. W., ROWLAND, S. J., AND TU~NF~, Jm•. Studies of the Secretion of Milk of Low Fat Content by Cows on Diets Low in Hay and High in Concentrates. III. The Effect of Variations in the Amount and Physical State of the Hay and a Comparison of the Shorthorn and Friesian Breeds. ft. Dairy Research, 21: 172. 1954. (6) BALClZ, C. C., AND ROWnAND, S. J. Volatile Fatty Acids and Lactic Acid in the Rumen of Dairy Cows Receiving a Variety of Diets. Brit. J. Nutrition, 11:288. 1957. (7) BVRT, A. W. A. The Effect of Variations in Nutrient lntake upon the Yield and Composition of Milk. J. Dairy Research, 24: 283. 1957. (8) ELLIOT, J. M., AND LOOSLI, J. g . Relationship of Milk Production Efficiency to the
Relative Proportions of the Rumen Volatile Fatty Acids. J. Dairy Sei., 42: 843. 1959. (9) ENSOR, W. L., SHAW, J. C., AND T~L~C~F~, ]I. F. Special Diets for the Production of
26
(10) (11)
(12)
(13)
(14)
(15)
(16)
(17)
S. E. BISHOP ET AL Low F a t Milk and More Efficient Gains in Body Weight. ft. Dairy Sci., 42: 1. 1959. FEDERE~,W. T. Experimental Design. p. 444. Macmillan Company, New York. 1955. FLUX, D. S., AND P~TC~LL, IV[. R. The Effects of Short Periods of Under-nutrition After Calving on the Establishment of Lactation in Dairy Cows. New Zealand J. Sci. Technol., 38: 689. 1957. HOt,MES, W., REID, D., MAcLUsKY, D. S., WAI~m, R., AN~ WATSON, J. N. Winter Feeding of Dairy Cows. IV. The Influence of Four Levels of Concentrate Feeding in Addition to a Basal Ration of Grass Products on the Production Obtained from Milking Cows. ft. Dairy Research, 24: ]. ]957. HOLMES, W., WAITS, R., MAoLuSK¥, D. S., AI~I~ WATSON, J. N. Winter Feeding of Dairy Cows. I. The Influence of Level and Sourse of Protein and of the Level of Energy in the Feed on Milk Yield and Composition. J. Dairy Research, 23: 1. 1956. LOOSLI, J. K. Pelleted Feeds for Ruminants. Prec. Distillers Feed Conf. Distillers Feed Research Council, C~ncinuati, Ohio. 1959. LoosLI, J. K., LUCAS, H. L., AN]) MAYIqAR,D, L . A . The Effects of Roughage Intake upon the F a t Content of Milk. ft. Dairy Sci., 28: 147. 1945. P o w ~ L , E. B. One Cause of F a t Variation in Milk. p. 40. Prec. Am. Soc. Animal Production. 1938. POWELL, E. B. Progress Report on the Relation of the Ration to the Composition of Milk. J. Dairy Sci., 24: 504. 1941.
(18) RZYNOLDS," P. J. The Separation and Estimation of the Volatile P a t t y Acids in the Rumen Fluid. Mimed, Animal Husbandry Dept., Cornell Univ. 1962. (19) RONNINO, MAGNAR. Effect of Varying Alfalfa Hay-Concentrate Ratios in a Pelleted Ration for Dairy Cows. J. Dairy Sci., 43: 811. 1960. (20) ROOK, 5. A. F. Variations in the Chemical Composition of the Milk of the Cow. P a r t I. Dairy Sci. Abstrs., 23: 251. 1961. (21) ROOK, J. A. F., AN~ LIN~, C. The Effect of the Plane of Energy Nutrition of the Cow on the Secretion of the Constituents of the Solids-not-fat Fraction and on the Concentrations of Certain Blood-Plasma Constituents. Brit. J. Nutrition, 15: 109. 1961. (22) SI~AW,J. C., ROBINSOI% R. R., SzI~om%,iV[. E., LAKSHMA/qAlq, S., AND LEWIS, T. R. Effect of Quality and Quantity of Concentrate on Volatile F a t t y Acids of Rumen and on the Composition of Milk. J. Nutrition, 69: 235. 1959. (23) Sa~WART, D. G. Continuous Culture as a Method for Studying Rumcn Fermentation. Ph.D. thesis, Cornell University. 1959. (24) VA~ SOEST, P. J., AND ALL,I% N. N. Studies on the Relationships Between Rumen Acids and F a t Metabolism of Ruminants Fed on Restricted l~oughage Diets. J. Dairy Sci., 42: 1977. 1951. (25) WISE~AN, H. G., AND I~VI~, H. IV[. Determination of Organic Acids in Silage. J. Agr. Food Chem., 5: 213. 1957.