Genetic analysis of Sind cows using test day milk and fat yield

Abstract

Data were used from 373 lactation of 4.476 controls of the Sind cows, controlled between 1986 and 2004 with the objectives of estimating the genetic parameters and to predict the genetic values for the production of milk (PLDC) and fat (PGDC) on the day of the control and to compare to the classification of the animals, for estimates obtained by ordinary test-day model. PLDC and PGDC were analyzed through an animal model, in ordinary test-day model, considering the first four lactations (repeatability model). The statistical models to analyze PLDC and PGDC included the genetic effects direct and of permanent ambient, as random, the fixed effect of contemporary group, formed by the year and month of the control, and covariances the age of dam at kidding as, linear and quadratic regression. In general way, the dear herdabilidades (0,36 and 0,47) estimated and the order of correlations (0,74 and 0,68) among the genetic values for PLT and PLDC and between PGT and PGDC were larger in the intermediate phase of the lactation indicating response possibility to the selection in substitution to the total production.