Estimation of the genetic parameters for test-day milk yield in Holstein cattle

The objective of this study was to determine the genetic parameters represented by heritability for test-day milk yield, the genetic correlations between test-day milk yield and the breeding value for Holstein cows. The model used was random regression test-day animal model. the data set consist of 216 test day records from 30 cows. The average number of test day per lactation was seven. The heritability estimates for test-day milk yield ranged from 0.43 at 250 th day in milk to 0.60 at 10 th day in milk. Genetic correlations between individual test-days milk yield were high and positive.