




Cobuci,Jaime Araujo; Euclydes,Ricardo Frederico; Lopes,Paulo Sávio; Costa,Claudio Napolis; Torres,Robledo de Almeida; Pereira,Carmen Silva. 
Testday milk yield records of 11,023 firstparity Holstein cows were used to estimate genetic parameters for milk yield during different lactation periods. (Co)variance components were estimated using two random regression models, RRM1 and RRM2, and the restricted maximum likelihood method, compared by the likelihood ratio test. Additive genetic variances determined by RRM1 and additive genetic and permanent environmental variances estimated by RRM2 were described, using the Wilmink function. Residual variance was constant throughout lactation for the two models. The heritability estimates obtained by RRM1 (0.34 to 0.56) were higher than those obtained by RRM2 (0.15 to 0.31). Due to the high heritability estimates for milk yield throughout lactation and... 
Tipo: Info:eurepo/semantics/article 
Palavraschave: Random regression models; REML method; Genetic parameters; Testday milk yield; Holstein cows. 
Ano: 2005 
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S141547572005000100013 
 

 

 


