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Genetic trends in the production of brazilian dairy crossbreds^*

Ary Ferreira de Freitas^I; Charles J. Wilcox^II; Claudio Napole Costa^I

^ICentro Nacional de Pesquisa Gado de Leite, EMBRAPA, Coronel Pacheco, MG, Brasil - CNPq
^IIDepartment of Dairy and Poultry Sciences, University of Florida, Gainesville, FL 32611, USA. Send correspondence to C.J.W.

ABSTRACT

Data on lactation performance of crossbred dairy cattle on 20 farms in southeastern Brazil were analyzed to estimate genetic, phenotypic and environmental trends. Records resulted from the herd testing program of progeny testing of crossbred dairy sires by Centro Nacional de Pesquisa Gado de Leite (EMBRAPA) for 1977 to 1992. Represented were 2,343 records from 1,402 cows by 80 sires; cows were European x Zebu crossbreds (2/8 to 7/8). European breeds were Holstein (major contributor) plus Jersey and Brown Swiss (minor contributors). Traits studied were milk, fat and protein yields, and fat and protein percentages, each based on total lactation and 305-day performance. Mean total and 305 day performance was: milk yield, 2027 and 1865 kg; fat yield, 67.7 and 62.7 kg; protein yield, 53.5 and 53.4 kg; fat percentage, 3.59 and 3.59%; and protein percentage, 2.84 and 2.84%. All annual trends were curvilinear. Expressed as linear changes per year, changes in yields were negative; changes in percentages were variable, some negative and some positive. Linear negative annual trends for yields averaged 2.3% (phenotypic), 0.5% (genetic) and 1.7% (environmental).

Keywords: genetic trends; brazilian dairy; crossbreds.

REFERENCES

Burnside, E.B., Jansen, G.B., Givati, G. and Dadoti, E. (1992). Observed and theoretical genetic trends in a large dairy population under intensive selection. J. Dairy Sci. 75: 2242-2253.

Harvey, W.R. (1990). User's guide for LSMLMW PC-1 version. Ohio State University Press, Columbus, pp. 59.

Ledic, I.L. (1992). Investigação sobre produção de leite e peso ao parto em gado Gir. Rev. Soc. Bras. Zoot. 21: 815-826.

Lobo, R.B., Duarte, F.A.M., Bezerra, L.A.F. and Wilcox, C.J. (1982). Genetic trends in milk production following formation of a tropical dairy breed (Pitangueiras). Rev. Brasil. Genet. 2: 353-361.

Meinert, T.R. and Pearson, R.E. (1992). Estimates of genetic trend in an artificial insemination progeny test program and their association with herd characteristics. J. Dairy Sci. 75: 2254-2264.

Moya, J., Wilcox, C.J., Bachman, K.C. and Martin, F.G. (1985). Genetic trends in milk yield and composition in a subtropical dairy herd. Rev. Brasil. Genet. 3: 509-521.

Murdia, C.K. and Tripathi, V.N. (1991). Estimation of trends in various first lactation traits of different Jersey bull mother farms in India. Indian J. Dairy Sci. 44: 594-597.

Polastre, R., Pons, S.B. and Baccari Jr., F. (1990). Avaliação do programa de seleção e tendências ambientais de algumas características de produção e reprodução em um rebanho mestiço Holandes-Zebu. Rev. Soc. Bras. zoot. 19: 31-38.

Robertson, A. and Rendel, J.M. (1950). The use of progeny testing with artificial insemination in dairy cattle. J. Genet. 50: 21-31.

Strandberg, E. and Danell, B. (1988). Genetic trends in milk production and days open in the first three lactations of Swedish dairy cattle. Act. Agric. Scand. 38: 89-100.

Valente, J., Lemos, E.M., Freitas, A.F., Rehfeld, O.A.M., Martinez, M.L. and Madalena, F.E. (1982). Desenvolvimento de Mestiço Leiteiro Brasileiro. 1 - Vacas-elites e touros em test. Pesq. Agropec. Bras. 17: 143-148.

* Florida Agricultural Experiment Station Journal Series No. R-03619.