Effect of Quantity of Protein in the Concentrate Mixture on the Growth, Reproductive Development, and Semen Production of Dairy Bulls1

E F F E C T O F Q U A N T I T Y O F P R O T E I N ]N T H E C O N C E N T R A T E M I X T U R E ON T H E G R O W T H , R E P R O D U C T I V E D E V E L O P M E N T . AND SEMEN PRODUCTION OF DAIRY BULLS 1 R. J. FLIPSE A.~D J. O. ALMQUIST Dairy :Breeding l%search Center, Department of Dairy Science The Penns~-lvania State University, University Park SUSIMARY

Holstein bull calves 1-2 wk of age were assigned to three levels of dietary protein, with the low protein, nornml protein, and high protein groups receiving concentrate mixtures containing 10, 16, and 22% protein, respectively. A single source of hay was used for all groups. Data were collected on growth (body weight, height at withers, and heart girth), onset of semen production, and semen quantity and quality until the bulls reached 104 ~ k of age. At 104 wk of age the 18 unrelated bulls were removed from experiment; the three sets of monozygous twins were kept on experiment and data collected to 208 wk of age. No statistically significant differences among experimental treatments were noted in any of the criteria used in evaluation. It is concluded that when goodquality hay is fed liberally, a concentrate nfixture containing 10% protein is adequate for normal growth and reproductive development of dai~a.- bulls.

The effects of nutrition on reproductive performanee of farm animals have been studied rather extensively, but for the most part these studies have involved the plane of nutrition or level of feeding rather than specific nutrients (3, 15). While there is justification for attributing results in such studies to the energy intake (5, 15), a need exists for determining specific effects of other nutrients. Branton et al. (1) have shown a 12% protein concentrate mixture adequate for mature breeding bulls, and Reid et al. (16) reported a simple concentrate mixture containing 12% protein adequate for bulls as young as 18 months. Protein requirements for the younger, rapidly developing dairy bull have not been ascertained, although Jones et al. (8) stated that rations adequate for normM growth probably were adequate for normal reproductive performance. The young sire procurement and testing programs now in use at many breeding organizations involve the feeding and management of young bull calves as well as mature sires. The study reported herein was undertaken to determine the role of protein quantity in the growth and reproductive development of young dairy bulls. This was done by varying the protein Received for publication September 1, 1963.

intake but not the TDN intake of the experimental groups. EXPERI~IF~NTAI,PROCEDURE Grade Holstein bull calves front Pennsylvania farms were started on the experiment at 1 to 2 wk of' age. Six unrelated calves were allotted at random to each of' three experimental groups, LP (low protein), NP (norlnal protein), and H P (high protein). In addition, three sets of monozygous Holstein twin bulls were utilized in the study. One each of the three sets of twins was used in comparing NP attd LP, LP and HP, and H P and NP. The control group (NP) was fed a concentrate mixture containing 16% protein, whereas the LP and H P concentrate mixtures contained 10 and 22% protein, respectively. Ingredients of the three concentrate mixtures and the calculated values for TDN and digestible protein are given in Table 1. The same source of hay was used for all three groups: second-cutting alfalfa with an average analysis of 12.5% protein was fed until hulls reached 52 wk of age and a timothyclover mixture (7.4% protein) was fed thereafter. Hay was fed at the rate of 1 lb per 101) lb of body weight per day; sufficient concentrate nfixture was fed to maintain the total digestible nutrient intake at the recommended allowance established by the National Research Council (10). Bulls were weighed at weekly intervals; the individual weights were used to determine the TDN requirement and feed all()-

1 Authorized for publication as Paper No. 2817 in the Journal series of the Pennsylvania Agricultural Experiment Station, August 27, 1963. 1416

E E F E C T OF P R O T E I N

TABLE 1 Ingredients of the concentrate nfixtures LP

NP

HP

1417

ON R E P R O 1 ) U C T 1 O N

hulls were removed f r o m e x p e r i m e n t , whereas the identical twins were continued on to 208 wk (4 yr) of age. RESULTS

- - ( 9 ~ ) 30 30 26.5 30 30 11 26 12 0.5 0.5 1.0 1.0 1.5 100.0 100.0 72.4 72.6 7.8 13.0

Ground yellow corn Corn and cob meal Crushed oats Wheat bran Soybean oil meal Salt Bone meal Mineral mix ~ Total TDN Digestible protein

13 30 27 28 0.5 1.5 100.0 71.9 18.1

Commercial mixture containing calcium, magnesium, copper, iron, phosphorus, manganese, iodine, and cobalt. cation f o r the e n s u i n g week. H e i g h t at withers a n d h e a r t g i r t h were m e a s u r e d a t m o n t h l y intervals. S t a r t i n g a t 24 wk of age the calves were tested at biweekly intervals f o r ability to re(rant a n d ejaculate, u s i n g a h e i f e r of a p p r o p r i a t e size. Semen was collected with the artificial v a g i n a a n d semen e v a l u a t i o n tests were perf o r m e d in the l a b o r a t o r y as p r e v i o u s l y described (6). A f t e r collection of the first semen c o n t a i n i n g motile s p e r m a t o z o a , a single ejaculate was collected f r o m each bull at biweekly intervals. A t 72 wk of age, the collection frequen(T was increased to one e j a c u l a t e at weekly intervals, a n d at 104 wk to one e j a c u l a t e semiweekly. D a t a were collected on eight bulls p e r g r o u p to 104 wk of age; at this time the u n r e l a t e d

Feed intake.

U n d e r the conditions of this e x p e r i m e n t , i.e., h a y was fed as a c o n s t a n t f r a c t i o n of body weight, b o t h h a y a n d conc e n t r a t e i n t a k e were increased d u r i n g the period of r a p i d growth. Later, as bulls g r a d u a l l y shifted f r o m a g r o w t h to a m a i n t e n a n c e basis, c o n c e n t r a t e i n t a k e beeame c o n s t a n t whereas h a y i n t a k e continued to increase. Thus, concent r a t e made u p 6 2 % of the d r y m a t t e r i n t a k e at 20 wk, whereas at 104 wk it h a d decreased to 35%. The c o n t r i b u t i o n of c o n c e n t r a t e to p r o t e i n i n t a k e at 20 w k was 56, 58, a n d 7 5 % of the total, a n d a t 104 wk it was 44, 57, a n d 6 5 % f o r LP, N P , a n d H P , respeetively. Calculated intakes of digestible protein, expressed as p e r eent of the r e c o m m e n d e d allowa n t e s f o r digestible p r o t e i n (10), a r e shown in Table 2. E v e n with the 1 0 % p r o t e i n concent r a t e m i x t u r e ( L P ) , a n a d e q u a t e p r o t e i n intake was o b t a i n e d a f t e r the first few weeks. Growth. A s stated in E x p e r i m e n t a l Proeedure, bulls were weighed weekly a n d o t h e r m e a s u r e m e n t s were m a d e monthly. The d a t a for selected ages t h r o u g h o u t the e x p e r i m e n t are s u m m a r i z e d in Table 2. T h e r e was a n app a r e n t tendency, t h r o u g h o u t the trial, f o r N P hulls to be slightly l a r g e r t h a n bulls of the o t h e r two g r o u p s . The differences, however, did not approach statistical significance. G r o w t h of all three g r o u p s exceeded the Morrison s t a n d a r d (14) t h r o u g h o u t the trial.

TABLE 2 Digestible protein intake and I)ody measurements (Mean of eight bulls per group ~) Age in weeks Group LP NP HP LP NP HP LP NP HP LP NP Ht )

2

20

40

60

80

104

Digestible protein consmned (gk of recommended allowance) 90 97 137 120 125 117 92 123 175 169 170 155 100 160 220 210 205 187 Body weight (lb) 1 0 6 ~ 5 b 307 ~ 8 651+~ 13 961 -4- 21 1,209~+ 27 1,504+--39 108 -4-4 3 1 4 ± 1 1 641--+ 14 979+_ 15 1,232 4- 21 1 , 5 1 3 ± 2 0 105~2 310+--11 621~-- 18 939 +-- 19 1,197 ~+ 29 1,471+__39 Height at withers (cm) 77 98 116 129 138 145 78 98 118 130 139 146 76 97 115 127 138 144 Heart girth (cm) 84 119 155 176 191 205 84 119 154 178 192 206 83 118 151 175 188 204

Except at 208 wk, which includes two bulls per group. " Standard error of the mean.

208 120 145 170 2,293 ± 253 2,340--+ 101 2,147 +-- 87 162 161 158 232 234 232

1418

R . J . FIAI'SE ANI) .l.O. ALMQUIST

R e p r o d , c t i r e ph.q.,'i~;logy. The average age. body weight, height ~lt withers, and heart g i r t h at the time the first ejaculate containing motile spermatozoa was collected are shown in Tahle 3. Obviously there were no differences among g r o u p s in the age at first ejaculation, and the differences in body measurements were not statistically significant. Data on semen characteristics and the o u t p u t of motile spermatozoa are p r e s e n t e d in Table 4. No statistically significant differences associated with the e x p e r i m e n t a l t r e a t m e n t s were obtained in total s p e r m o u t p u t m" in a n y of the individual semen ehai'aeteristies. Data on semen characteristics other than those listed in Table 4 (namely, rate of sperm motility, eosin live-dead stain, and p e r cent motility a f t e r storage at 5 C f o r 5, 10, and 15 days) were

tabulated throughout the experiment. These data are not presented, because the amongg r o u p differences were negligibh,.

I)ISCI'SSION F r o m an examination of the data presented, it is a p p a r e n t t h a t p r o t e i n content of the concentrate m i x t u r e was of little consequence; thus, as long as ha?" of good quality is fed in liberal amounts, eoneentrate m i x t u r e s rangino' f r o m 10 to 22% p r o t e i n a p p e a r to s u p p o r t normal g r o w t h and r e p r o d u e t i v e development of d a i r y bull calves. F r o m a practical standpoint, breeding organizations with average to good hay available need not invest in special concentrate mixtures f o r g r o w i n g bull calves. They should be able to use the concentrate mixture recommended i'm' breeding bulls, since

TABLE 3 Age and measurements of lmlls at time first ejacub~te containing motile sl)el'm was collected (Mean of eight bulls per group) First ejaculation Height at withers

Weight

Heart girth

Group

Age

Orb)

(lb )

(era)

(cm )

L1) NP tip

48 ± 1.8" 48 ± 1.2 47 ± 1 . 4

786 ± 34 776 ± 31 733 ± 23

122 ± 2.3 123 ± 1.7 119 --+ 1.2

365 ± 2.3 165 --+ 2.3 160 ± 2.0

" Standard error of the me'm. TABLE 4 Sllnllllary of semen characteristics and sperm output Age in weeks Group LP NP HP LP NP HP LP NP HP LP NP KP LP NP HP

53-78

"

79-104

"

105-156 b

Volmne of ejaculate (ml) 3.6 ± 0.2" 4.1 ± 0.2 4.7 4.2 ± 0.4 4..5 ± 0.4 4.3 4.2 ±_ 0.4 4.5 ± O.4 3.9 Nmnber of spermatozoa (× 10'; lwr ml) 1,051 ± 96 1,181 ± 108 1,327 771±57 1 , 1 7 8 ± 88 1,536 820 ± 74 1,221± 84 1,562 Initial motility ( % ) 65± 1 67± 1 67 63 ± 2 65 ± 2 6(; 65± 1 68± 1 66 Fru(,tose (m.q per l(;d ml) 595 ± 46 565 ÷ 37 512 680 ± 48 587 ± 41 472 634_+ 45 590 ± 47 433 Output of motile sperm (× 10" p,'r ,.jacldat(') 2.50 ± 0.25 3.16 --+ 0.30 4.21 2.16 ± 0.29 3.38 ± U.31 4.42 2.28 ± 0.24 3.79 ± o.33 4.17

157-208 " 5.5 5.2 5.5 1,481 1,735 1,78o d7 6~ 69 446 419 394

5.t7 6.11 d.75 Mean of eight bulls 1)er group; one ejaculate per bull 1)iweekly to 72 wk of age, one ejaculate weekly from 73 to 104 wk of age. bMean of two bulls per group; mw ejaculate per Imll semiweekly. Standard error of the mean.

EFFECT ()F I'li:OTEIN ON III':PR()I)U('T|ON

y o u n g bulls do not need a high 1)ratein conc e n t r a t e mixture. The a p p r o a c h in this s t u d y has l)een from the p r a c t i c a l side, a n d no a t t e m p t has been made to d e t e r m i n e the lower limit of p r o t e i n i n t a k e compatible with norlnal r e p r o d u c t i v e f u n c t i o n of the bull. I f L e a t h e m ' s work with the r a t (9) is a n indication of w h a t can be expected in the bovine, it would be difficult to d e m o n s t r a t e , with r a t i o n s of common feed: stuffs, i m p a i r m e n t to r e p r o d u c t i v e p e r f o r m a n c e in the bull due to i n a d e q u a t e a m o u n t s of protein. Leathern reduced the p r o t e i n content of the r a t i o n to 5 % before o b s e r v i n g a n interference with spermatogenesis. Usi~g semipm'ifled r a t i o n s with less t h a n 2 % protein, 5 I e a c h a m et al. (13) d e m o n s t r a t e d reduced volume and s p e r m o u t p u t in beef bulls. I n a s m u c h as feed i n t a k e was d r a s t i c a l l y reduced on t h e i r low p r o t e i n rations, the results can not be a t t r i b u t e d unequivocally to p r o t e i n deficiency. Results of the p r e s e n t s t u d y s u p p o r t the r e p o r t s of B r a n t o n et al. (1) a n d Reid et al. (16) with older bulls, a n d indieate t h a t w i t h i n r a t h e r wide limits p r o t e i n is not a restrictive n u t r i e n t in n o r m a l r e p r o d u c t i v e d e v e l o p m e n t of the bull. Considered in e o n j u n e t i o n w i t h o u r p r e v i o u s r e p o r t on the role of e n e r g y in r e p r o d u c t i v e d e v e l o p m e n t of bulls (5), the data are h e l p f u l in i n t e r p r e t i n g those studies in which level of feeding or p l a n e of n u t r i t i o n was the variable, r a t h e r t h a n a single n u t r i e n t (2, 4, 7, 11, 12, 17). Reid's suggestion (15), t h a t in p l a n e of n u t r i t i o n studies the results should be a t t r i b u t e d to e n e r g y r a t h e r t h a n protein or o t h e r n u t r i e n t s , a p p e a r s to be valid. A t p r e s e n t , however, t h e r e is little basis f o r r u l i n g out the possibility of i n t e r a c t i o n s produced by s u p e r i m p o s e d deficiencies not a p p a r ent when a single deficiency is involved. REFERENCES (1) BRANTOX, C., BRATTON-, R. W., AND SALISBre, Y, G. W. Total Digestible Nutrients and Protein Levels for Dairy Bulls Used in Artificial Breeding. J. Dairy Sei., 30: 1003. 1947. (2) BR.A:PTON, R. W., MVSGRAVE, S. D., I)L'XN, H. O., AXD FOOTE, R. tI. Causes and Prevention of Reproductive Failures in Dairy Cattle. II. Influence of Underfeeding and Overfeeding from Birth to 80 Weeks of Age in Growth, Sexual Development, and Semen Produetion of Holstein Bulls. Cornell Univ. Agr. Expt. Sta., Ball. 94o. 1959. (3) CASID-X,L. E. Effect of Feed Level on Some Reproductive Phenomena in Cattle, Sheel), and Swine. Reproductive Physiology and Protein Nutrition. p. 35. Rutgers University Press. 1959,.

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(4) DAVlF.S, D. V., .M..~NN, T., AXe) I{OWSOX, L. E. A. Effect of Xutrition on ~he Onset of Male Sex l[ormone Activity and Sperm Formation tit ~[onozygous Bull Calves. Proc. Roy. Sos., 147: .332. 1957. (5) FLIPSE, R. J., AND AL~rQ;-IST, J. O. Effect of Total Digestible Nutrient Intake from Birth to Four Years of Age on Growth and Reproductive Development and Perfornmnce of Dairy t~ulls. J. Dairy Set., 44: 905. 1961. (W) FI~IPSE, ]l. J., SX';I)ER, J. W., TH3.CKEI~, D. L., AXD Al.arOl'lS:P, J. O. Effect of Total Digestible Nutrient Intake on Grmvtb and Ret>roductive Develol>ment of Dairy Bulls. Pennsylvania Agr. Expt. Sta., Progress Rept. 104. 1.953. (7) .la.~F,S, J. P. The Effect of Level of Nutrition on the Sexual Capacity of Dairy Bulls. Proe. New Zealand Soc. Aninml Production, 10: 84. 1950. (R) JONES, I. R., DOVGI.IERTY, l{. W., AND HAAG, J . R . Relation of Nutrition to Growth and Breding Performance in Dairy Bulls. I. Alfalfa Itay Rations. J. Dairy Sci., 28: 311. 1945. (9) LEXT~E~, J. It. Male l~eproduetive S.~stem and Protein Nutrition. Reproductive Physiology and Protein Nutrition. p. 12. Rntgers University Press. 1959. ( l o ) LOOSLI, J. K., HVFFMAN, C. F., PET.EP~SF.N, W. n., AND I-)I-IILLIPS, P. H. Recommended Nntrient Allowances for Domestic Animals. 111. Recommended Nutrient Allowances for Dairy Cattle. Natl. Res. Council Rept. 5950. (111 MAXX, T., .xxI) RowsoN, L. E. A. Effect of Different Planes of Nutrition on the Con> position of Bull Semen. 3rd Intern. Congr. Animal Reproduction, 1: 25. 1956. (12) Mxxx, T., AXD WALTON, A. The Effect of Underfeeding on the Genital Functions of a Bull. J. Agr. Set., 43: 343. 1953. (13) MEACItAM, T. X., C('x~=t, T. J., WaRXl('K, A. C., HEXTGF,S, J. F., aXD HaRGKOW:, D. D. Influence of Low Protein Rations on Growth and Semen Characteristics of Young Beef Bulls. J. Animal Set., 02: 115. 1963. (14) MoaaIsox, 15'. B. Feeds and Feeding. 22nd ed. Morrison Pu|)l. Co., Ithaca, N. Y. 195(i. (15) REIn, J. T. Effect of Energy intake upon Reproduction in Farm Animals. ,l. I)airy Sci., 43 (Supl)l.): i03. 1960. (Ill) REI1), d. T., W.\t~D, G. 5I., _tXB S.tLSm:RY, R. L. Simple versus Complex Concentrate Mixtures for Young Breeding Bulls. II. Semen Production. d. Dairy Set., 31: 439. 1948. (17) WINCHESTER, C. F., AND ttOV~'E, P. E. Relative Effects of Continuous and Interrupted Growth of Beef Steers. USDA Bull. ll(IS. 1955.