Genetic and environmental control of first-lactation milk yield in cows and buffaloes

Livestock Production Science, 17 (1987) 225-233

225

Elsevier Science Publishers B.V., Amsterdam - - Printed in The Netherlands

Genetic and E n v i r o n m e n t a l Control of FirstLactation Milk Yield in C o w s and Buffaloes M.A. SHARABY*, I.S. ELKIMARY and M.A. AZIZ

Department of Animal Production, Faculty of Agriculture, Alexandria University, Alexandria (Egypt) ( Accepted 21 April 1987)

ABSTRACT Sharaby, M.A., Elkimary, I.S. and Aziz, M.A., 1987. Genetic and environmental control of firstlactation milk yield in cows and buffaloes. Livest. Prod. Sci., 17: 225-233. Sire evaluations, heritabilities, genetic and time trends and seasonal variation for first lactation records of 1680 buffaloes and high grades of Friesian cows were estimated by means of best linear unbiased prediction (BLUP) and approximate maximum likelihood procedures. Cows produced higher milk yields than buffaloes. Herd differences were higher for actual lactation yield produced between calving and termination of lactation compared to the standard lactation yield in 305 and 335 days for cows and buffaloes. Seasonal variation had no particular trend. The estimated transmitting abilities of sires were calculated from sire and genetic group solutions within the herd. Few buffalo sires had high estimated transmitting abilities for milk production, compared to cow sires. Correlations between sire values for the two measures of first lactation yield were positive. Genetic and time trends indicated low actual gain in milk production, which necessitates the application of effective breeding plans for improving milk production of cows and buffaloes. Heritability estimates were between 0.20-0.67 and 0.21-0.42 for the two measures of first-lactation yield, indicating that selection for increasing milk yield from cows and buffaloes under Egyptian conditions is quite possible. Sire selection on the basis of actual lactation yield may prove highly efficient in buffaloes.

INTRODUCTION T o f o r m u l a t e m o d e r n b r e e d i n g p r o g r a m m e s f o r d a i r y c a t t l e i m p r o v e m e n t , it is e s s e n t i a l t o c o l l e c t b a s i c i n f o r m a t i o n a n d t o d e t e r m i n e t h e g e n e t i c a n d n o n genetic influences on milk yield and the related traits. Previous studies ( S h a r a b y et al., 1984a, b ) h a v e a s s e s s e d t h e c h a r a c t e r i s t i c s o f age a t first c a l v i n g a n d l a c t a t i o n l e n g t h a n d t h e i r r e l a t i o n t o l a c t a t i o n yield. T h e p o t e n t i a l *Present address: Department of Animal Production and Breeding, College of Agriculture and Veterinary Medicine, King Saud University, Gassim Branch, Bureidah P.O. Box 1482, Saudi Arabia.

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ability to improve milk production through selection is largely a function of how heritable it is and how much variation is exhibited by the trait. Studies on cows and buffaloes indicated that milk yield is highly variable due to sires and some environmental factors as well (Henderson, 1973; Schaeffer et al., 1974; Basu and Ghai, 1979). Heritability estimates of milk yield are usually moderate to high ( Gill and Allaire, 1975; Van Vleck and Bradford, 1965; Seykora and McDaniel, 1983). Under Egyptian conditions, heritability estimates of milk yield from cows and water buffaloes were moderate (Asker et al., 1965; E1Itriby and Asker, 1975). These estimates were obtained from daughter-dam pairs. There have been few, if any, studies aimed at estimating genetic parameters by methods of variance component estimation or evaluating sires using mixed models. Schaeffer (1976) described the applicability of the maximum likelihood procedure (ML) of variance component estimation for dairy sire evaluation using mixed models (Henderson, 1973), with one random factor nested within another. The purpose of this study was to determine the seasonal variation and time trend and to estimate sire breeding values, heritabilities and genetic trends in sires, for first lactation milk production of cows and buffaloes, as depicted by actual and standard lactation yields, using ML as described by Schaeffer (1976) and Henderson's mixed model equations. MATERIAL AND METHODS

The data used were 1680 first-lactation milk yield records obtained from the University high grades of Friesian cows and water buffalo herds (denoted H1 and He, respectively) and an institutional buffalo herd located near Alexandria (denoted H3) for calving years 1958-1982. Milk yield was recorded daily to the nearest 0.1 kg. Data were analyzed on the basis of the actual lactation yield and the standard lactation yield. Actual yield was the amount of milk produced by a cow or a buffalo from the fourth day after calving until termination of lactation, with no projection made for incomplete records. A standard lactation yield was the yield in 305 and 335 days for cows and buffaloes, respectively. Table I presents a summary of the data. Best linear unbiased prediction (BLUP) evaluations (Henderson, 1966) were computed for sires for actual and standard first lactation yields. Evaluations were computed with the model:

Yijkl =gi q-Sij q-hk + eijkl Where Yiikz= actual first lactation record or standard first lactation record of cow or buffalo l, daughter of sirej (in sire group i) for calving year-season k; gi = the fixed effect of sire group i; s o = the random effect of sire j in sire group i; hk = the fixed effect of year-season k; eokt= residual, sij and e0ht are assumed uncorrelated and normally distributed with mean zero and variance azs and a2e, respectively. Sires were grouped by year of birth to account for genetic

227 TABLE I Structure of data in different herds Item

H1

H2

Ha

Daughters Sires Year-seasons Summer calvings Winter calvings

445 51 36 201 244

406 45 37 182 224

829 83 28 350 479

trends in sires over time (Szkotnicki et al., 1978). This grouping was chosen as an initial exploratory method of determining the a m o u n t of genetic change in these herds. A more effective means of accounting for genetic trend is to utilize the additive genetic covariances among sires. Each sire had at least eight daughters in a herd. Analysis was executed separately for each herd. Each year was divided into two seasons of calving: (a) winter calvings from September to the end of February and (b) s u m m e r calvings from March to the end of August. Errors to sire variance ratios were set to 8 and 14 for actual and standard lactation milk yields, respectively, corresponding to heritability values previously estimated {Asker et al., 1965) and were an appropriate start for dairy sire evaluation (Henderson, 1973 ). The within-herd evaluations of sires were forced to sum to zero and the variance of prediction error was calculated with the diagonal element of the inverse of the coefficient matrix (Henderson, 1973). Sire estimated transmitting abilities and breeding values were calculated from the sire and group solutions. Estimates of sire and error components of variance were obtained by the approximate m a x i m u m likelihood procedures with a priori assumed sire-to-error variance ratio ( Schaeffer, 1976; Harville, 1977 ). Heritability estimates were obtained from sire and error components of variance and standard errors of heritability were approximated according to Turner and Young (1969). Genetic trends in sires were the change in their genetic values by time, calculated as the difference between averages of sire breeding values in two successive groups and regressing the averages on time. RESULTS AND DISCUSSION Although reared under different climatic and management conditions, differences between buffaloes of the two herds for milk yield were not significant. Cows, however, produced significantly higher milk yield than buffaloes (Table II). This could be attributed to both herd and species effects. Variations in milk yield due to herd are common and have been frequently reported ( T o m a r et al., 1972; Gill and Balaine, 1971 ). Differences were higher for actual

228 T A B L E II Average (2) a n d time trend* (b) in actual and standard first lactation milk (kg) in herds under investigation Herd

1 2 3

Actual

Standard

x

b

x

b

2535 + 130 1321 _+ 56 1043 _+ 23

- 1.92 _+1.00 0.24 _+0.24 2.54 _+0.93

2107 _+61 1902 _+63 1322 + 14

1.21 _+0.14 0.83 _+0.10 2.06 _+0.44

*Peryear.

milk yield than for standard lactation yield. Sharaby et al. (1984a) reported a longer lactation length for cows than for buffaloes of the same herds. The actual lactation yield of cows was higher than their standard lactation yield, but the opposite trend was observed in buffaloes. About 61% of cows had a lactation length > 305 days, but most of the buffaloes terminated lactation before reaching their normal standard lactation length (Sharaby et al., 1984a).

Year-season of calving and time trend Herd differences for actual lactation yield were high until 1965 and essentially remained constant at a lower level and with less fluctuation thereafter. Those for standard lactation yield, however, remained low and constant throughout the whole period, suggesting that variations in the former were mainly due to longer lactation length. Time trend, estimated by the regression of average milk yield on time (Table II ), indicated that actual and standard lactation yields of all herds had a positive increase with time, except for the actual lactation yield of cows. The estimates were generally higher and their standard errors were lower for standard lactation yield compared to those of actual lactation yields. Effects of season of calving were significant for actual and standard lactation milk yield ( P < 0.05 ). Lactations initiated during winter were characterized by significantly higher actual lactation yield in buffaloes and lower yield in cows. Variation was also observed on standard lactation yield initiated in either season, but it was difficult to pinpoint any particular pattern in either case in cows or buffaloes. This agrees generally with the observation that milk production is subject to environmental influence associated with the season of calving ( Tomar et al., 1972; Szkotnicki et al., 1978; Verde and Bodisko, 1978). Favourable environmental conditions usually available during winter encourage buffaloes to produce more milk, especially during early lactation when they produce most of their lactation yield ( Sharaby and Elshafie, 1986 ). On the other hand, cows initiating lactation during summer usually reach their peak milk produc-

229 T A B L E III Ranges of sire averages (kg) and evaluations (kg) for actual and standard lactation yields in different herds Herd

Actual

1 2 3

Standard

Average

Evaluation

Average

Evaluation

463:7222 562:3334 398:1685

-563:924 -230:311 -178:263

1147:3235 1293:2036 1141:1552

- 171:107 - 148:42 - 49:53

T A B L E IV Variance components (104 kg2), heritability estimates, regression of sire genetic values on time (b) and correlations (r) between sire values for actual and standard first lactation yield Item Actual H1 a~ a~ h2 b r1

Standard H2

H3

H,

H2

H3

79.40 12.40 2.30 13.50 3.23 0.39 391.10 102.40 43.30 121.50 52.70 7.10 0.67_+ 0.22 0.43_+ 0.21 0.20_+ 0.07 0.40_+ 0.18 0.23_+ 0.16 0.21_+ 0.08 17.2 +__20.5 10.0 _+11.01 31.7 ___15.71 37.2 _+10.7 - 2 6 . 0 -+15.4 31.3 _+10.98 0.73** 0.37 Ns 0.33 Ns

~Between actual and standard lactation yields. **(P<0.01). NS, not significant.

milk production during winter. Year-to-year fluctuations were much less for standard than for actual lactation yield.

Sire values and genetic trend The range of sire averages and BLUP evaluations for actual and standard lactation yields are presented in Table III. Wide ranges of sire averages and sire estimated transmitting abilities were observed on cow sires compared to buffalo's for both actual and standard lactation yields. The same ranges were narrow for standard lactation yield compared to those for actual lactation yield in both species, indicating differences in the genetic merit of sires for the two traits. The estimated transmitting abilities of sires were the sum of the sire solution and the corresponding genetic group solution ( Schaeffer, 1974; Szkotnicki et al., 1978). In H1, nearly 40% of sires had negative estimated transmitting abilities, 15% had values< 100 kg of milk and 45% had rather higher values for

230

X

A

I

400 ! i

~.

i

000 ....

1"

-400

/ l

II

-800

/

,

-1200 I

-& -~ >-

I

I

I

I

I

4OO

o°,# ooo

x

•

-400 %%

. -"

iI

i H I .....

-800

H 2 ~ H 3 .... -1200 I

56

I

60

I

64

I

I

68

72

I

76

YeGr

Fig. 1. Genetic trend in sires for actual (A) and standard (B) first lactation yield in different

herds ( H ~-Ha) under investigation. actual lactation yield. In H2 and H3, however, the corresponding percentages were 45, 30 and 25 for low, medium and high sire values, respectively. The correlations between sire estimated transmitting abilities for actual and standard lactation yields were positive (Table IV). Cow sires were found to have a strong association between the two traits, but those of the two buffalo herds had a weak association, probably due to differences in sire selection. Genetic trends in sires, calculated bi-yearly on the basis of estimated breeding values of sires within genetic groups ( Fig. 1 ), were quite similar for actual and standard lactation yields with higher consistency and less fluctuations observed in the latter. Regressions of average estimated breeding value on time ( Table IV) were significantly different from zero ( P < 0.05 ) and indicated an

231

overall positive trend in all cases, except the standard lactation yield of sires in H2. Annual change in milk yield indicated low genetic gain compared to theoretical breeding schemes. This necessitates the application of effective selection schemes for achieving higher actual progress in milk yield. Herds under investigation had no excess for a long-term genetic improvement plan and any changes were due to cu41ing decisions made on the basis of the animals' phenotypic values. Sire variance and heritability estimates Sires accounted for 16.9, 10.8 and 5.0% of the total variation in actual lactation yield in H1, H2 and H3, respectively. The corresponding values for standard lactation yield were 10.0, 5.8 and 5.2. The heritability estimates of actual and standard lactation yields were almost equal in H3 and were slightly lower than those reported by Asker et al. (1965). In H1 and H2, the heritability estimates of actual yields were higher than those of standard lactation yields. In both cases, heritability estimates were higher than those reported by Gill and Allaire (1975) and Van Vleck and Bradford (1975). Results of this study indicated that herd variation, year-to-year fluctuations and response to season of calving were high for actual lactation yield compared to standard lactation yield, but time trends were lower. Moreover, sire estimated transmitting abilities for the two traits were different and possessed a slight positive correlation, especially in buffaloes. This suggests possible differences in the genetic merit of sires for the two traits. Projection of the incomplete records may not present the real milk production ability and could be misleading, especially in buffaloes, which had a high tendency to terminate lactation before reaching the normal standard lactation length. This, along with the high heritability estimates and the wide range of sire-estimated transmitting abilities for actual lactation yield, may suggest that sire selection on the basis of the latter would be more efficient than that on the basis of the standard lactation yield. Variation in lactation length of buffaloes, which is mainly due to long service and gestation periods and, in some cases, to the high persistency of milk production, could be considerably reduced through improving the notably low breeding efficiency of buffaloes.

REFERENCES Asker, A.A., Bedeir, L.H. and El-Itriby, A.A., 1965. The inheritance and relationships between some dairy characters in the Egyptian buffaloes. J. Anita. Prod. U.A.R., 5: 119-130. Basu, S.B. and Ghai, A.S., 1979. Studies on milk production in Murrah buffaloes. Indian Vet. J., 59: 208-212. El-Itriby, A.A. and Asker, A.A., 1975. Repeatability and heritability of dairy characters in cattle and buffaloes in Egypt. Indian J. Dairy Sci., 9: 157-161.

232 Gill, G.S. and Allaire, F.R., 1975. Genetic and phenotypic parameters for a profit function and selection method for optimizing profit in dairy cattle. J. Dairy Sci, 59: 1325-1330. Gill, G.S. and Balaine, D.S., 1971. Effect of genetic and non genetic factors on lactation yield and lactation length in Haryana cattle. J. Res. Punjab Agric. Univ., 8: 263-269. Harville, D.A., 1977. Maximum likelihood approaches to variance component estimation and to related problems. J. Am. Stat. Assoc., 72: 320-337. Henderson, C.R., 1966. Sire evaluations which accounts for unknown genetic and environmental trends, herd differences, seasons, age effects and differential culling. Presented at National Technical Symposium and Workshop of Estimating Breeding Values of Dairy Sires and Cows, ADSA. Henderson, C.R., 1973. Sire evaluation and genetic trend. Proceedings of the Animal Breeding and Genetics Symposium in honour of Dr. J.L. Lush, at Champaign, IL, ASAS, ADSA, p. 10. Schaeffer, L.R., 1976. Maximum likelihood estimation of variance components in dairy cattle breeding research. J. Dairy Sci., 59: 2146-2151. Schaeffer, L.R., Freeman, M.G. and Burnside, E.B., 1974. Evaluation of Ontario Holstein dairy sires for milk and fat production. J. Dairy Sci., 58: 109-115. Seykora, A.J. and McDaniel, B.T., 1983. Heritabilities and correlations of lactation yields and fertility of Holsteins. J. Dairy Sci., 66: 1486-1493. Sharaby, M.A. and Elshafie, O.B., 1986. Sire evaluation and genetic trends for partial lactation yields of buffaloes and high grades of Friesian cows. Indian J. Vet. Sci., in press. Sharaby, M.A., E1 Kimary, I.S. and Aziz, M.A., 1984a. Sire evaluation and genetic parameters of first lactation length in Egyptian buffaloes and high grades of Friesian cows. Alex. J. Agric. Res., 31: 418-426. Sharaby, M.A., E1-Kimary, I.S. and Aziz, M.A., 1984b. Genetic control and sire evaluation for age at first calving in Egyptian buffaloes and Friesian cows. Alex. J. Agric. Res., 31: 8-15. Szkotnicki, W.J., Tong, A.K.W., Sharaby, M.A., Krotch, K.M., Johnson, L.P. and Schaeffer, L.R., 1978. Sire and cow evaluation in Brown Swiss, Canadienne and Milking Shorthorn. J. Dairy Sci., 61: 497-505. Tomar, S.P.S., Sharma, R., Dutt, M. and Singh, B.P., 1972. Least square analysis of some environmental factors affecting first lactation milk yield in Haryana. Indian Vet. J., 49: 316-324. Turner, H.N. and Young, S.S.Y., 1969. Quantitative genetics in sheep breeding. Cornell University Press, Ithaca, New York, p. 112. Van Vleck, L.D. and Bradford, G.E., 1965. Comparison of heritability estimates from daughter-dam regression and parental half sib correlation. J. Dairy Sci., 48: 1372-1379. Verde, S.O. and Bodisko, V., 1978. Genetic trend in milk production of Venezuelan herd. Dairy Sci. Abstr., 40: 131. RESUME Sharaby, M.A., Elkimary, I.S. et Aziz, M.A., 1987. Effets g~n~tiques et environnementaux sur la production laiti~re en premiere lactation des vaches et des bufflonnes. Livest. Prod. Sci., 17: 225-233 (en anglais). On a estim~ la valeur g~n4tique des p~res, les h~ritabilit~s, l'~volution g~n~tique et chronologique et les variations saisonni~res sur les productions en premiere lactation de 1680 bufflonnes et vaches Frisonnes amglior~es, ~ l'aide des m~thodes BLUP et du maximum de vraisemblance. Les vaches ont produit plus que les bufflonnes. Les differences entre troupeaux ont St~ plus ~lev~es pour la production effective entre la mise bas et le tarissement que pour les lactations standard en 305 jours pour les vaches et en 335 jours pour les buffionnes. Il n'y a pas eu de tendance saisonni~re nette. Les valeurs g~n~tiques transmises estim~es ont ~t~ calcul~es intra troupeaux. Peu de p~res

233 buffles ont eu une valeur g~n~tique transmise ~levSe pour la production laiti~re par comparaison avec les taureaux. Les correlations entre valeurs des p~res pour les deux mesures de la production en premiere lactation ont ~t~ positives. Les tendances g~n~tiques et chronologiques montrent une faible amelioration de la production laiti~re des vaches et des buffionnes; celle-ci requiert donc des plans de s~lection efficaces. Les estimations de l'hSritabilit~ se sont situSes entre 0.20 et 0.67 et 0.42 et 0.21 pour les deux mesures de la production en premibre lactation; la s~lection pour l'augmentation de la production laitibre des vaches et des buffionnes est donc tout ~ fait possible dans les conditions de l'Egypte. La s$1ection des p~res ~ partir des productions laitibres effectives peut ~tre trbs efficace chez le buffle.

KURZFASSUNG Sharaby, M.A., Elkimary, I.S. und Aziz, M.A., 1987. Genetische und umweltbedingte Einfltisse auf die erste Laktation von Kiihen und Btiffeln. Livest. Prod. Sci., 17:225-233 ( auf englisch).

Mit Hilfe von B L U P und approximierten Maximum-Likelihood-Verfahren wurden V~iterZuchtwerte, Heritabilita'ten,genetischerund ph~inotypischerTrend sowie saisonaleSchwankungen Rir Erstlaktationsergebnissevon 1 680 Biiffelnund Kreuzungskiihe mit hohem HF-Anteil gesch~itzt.Kiihe produzierten mehr Milch als Biiffel.Die Herdenunterschiede waren bei Betrachtung der gesamten LaktationsleistunggrGsseralsRir Standard-Laktationsleistungenbis zum 305. bzw. 335. Laktationstag bei Kiihen bzw. Btiffeln.Die jahreszeitlichenSchwankungen zeigtenkeinen festen Trend. Die Zuchtwerte wurden aus den Innerhalb-Herden-LGsungen fiirVater-und genetische Gruppen-Komponenten gesch~itzt.Wenige Btiffel-ZuchtwerteffirMilchleistung lagen ~ihnlichhoch wie die ftirKuh-Vtiter. Die Korrelationen zwischen den Vater-Zuchwerten in den zwei Masszahlen der Erstlaktation waren positiv.Der schwache genetische und ph'~inotypischeTrend in der Milch|eistung unterstreichtdie Notwendigkeit wirksamer Zuchtprogramme Rir Kiihe und B~iffel.Heritabilit~itenim Bereich 0.20-0.67 bzw. 0.42-0.21 ftirdie zwei Masszahlen der Erstlaktation belegen, dass eine Selektion auf Milchleistung zur Steigerung der Milchleistung unter ~igyptischenVerhiiltnissen durchaus machbar ist.Die Selektion von Bullen aufgrund aktuellerLaktationsleistungenkGnnte bei Biiffelnsehr effizientsein.