Autoria: BIASSUS, I. de O.; COBUCI, J. A.; COSTA, C. N.; RORATO, P. R. N.; BRACCINI NETO, J.; CARDOSO, L. L.

Resumo: The objective of this study was to estimate genetic parameters for milk, fat and protein yields of Holstein cows using 56,508; 35,091 and 8,326 test-day milk records from 7,015, 4,476 and 1,114 cows, calves of 359, 246 and 90 bulls, respectively. The additive genetic and permanent environmental effects were estimated using REML. Random regression models with Legendre polynomials from order 3 to 6 were used. Residual variances were considered homogeneous over the lactation period. The estimates of variance components showed similar trends, with an increase of the polynomial order for each trait. The heritability estimates ranged from 0.14 to 0.31; 0.03 to 0.21 and 0.09 to 0.33 for milk, fat and protein yield, respectively. Genetic correlations among milk, fat and protein yields ranged from 0.02 to 1.00; 0.34 to 1.00 and 0.42 to 1.00, respectively. Models with higher order Legendre polynomials are the best suited to adjust test-day data for the three production traits studied.

Ano de publicação: 2011

Tipo de publicação: Artigo de periódico

Unidade: Embrapa Gado de Leite

Palavras-chave: Fat yield, Herdability, Protein yield, Test-day, milk yield