Genetic evaluation by animal model techniques of first lactation length and mean daily milk yield of the Caracu breed

Abstract

The objective of this study was to estimate genetic and environmental effects on first lactation length (DL) and daily milk production (PDL) of Caracu Criollo cows of the Recreio Farm herd in Poços de Caldas, State of Minas Gerais. Data from 1 323 lactations of cows that calved from 1983 to 1990, were analysed by least squares methods for data with unequal subclass numbers. Least squares means and standard errors were 289.7 ± 7 days for DL and 4.95 ± 0.12 kg for PDL. The fixed effects of season and year of parturition were significant (P<0.01) for both traits. Estimates of variance components and heritabilities, obtained by the algorhythm Derivative Free Maximum Likelihood (DFREML), were: 0.24 ± 0.08 for DL and 0.57 ± 0.09 for PDL.