Estimates of Genetic and Phenotypic Parameters for Milk Production in Moroccan Holstein-Friesian Cows

Abstract

Heritabilities, repeatabilities and genetic and phenotypic correlations among milk yield, fat yield and fat percentage were estimated using an animal model and 20,140 records of 11,618 Holstein-Friesian cows enrolled in the Moroccan official milk-recording program between 1990 and 1999. Heritabilities for milk yield, fat yield and fat percentage were 0.29, 0.27, and 0.39, respectively, and their repeatabilities were 0.33, 0.32, and 0.39, respectively. Genetic correlations of milk yield with fat yield and with fat percentage were 0.96 and –0.32, respectively, and correlation of fat yield with fat percentage was –0.06. Phenotypic correlations were 0.96 between milk and fat yields, –0.28 between milk yield and fat percentage, and –0.03 between fat yield and percentage. It was concluded that these genetic and phenotypic parameters could be used for the genetic evaluation of dairy cattle in Morocco.