93. Estimation of genetic parameters for milk-related traits derived from automatic milking systems in Holstein cattle

Abstract

We estimated genomic-based genetic parameters for daily milk yield (MY), milk electrical conductivity (EC), and somatic cell score (SCS) from automatic milking systems (AMS) in North American Holstein cattle. Random regression models (RRM) enable the estimation of genetic parameters for each lactation day as well as the genetic correlation coefficients among MY, SCS, and EC. The data contained records of 4,118 cows genotyped with 72,820 SNP. The heritabilities and genetic correlations for MY, SCS, and EC and were estimated fitting third-order Legendre orthogonal polynomial. The daily heritability estimates ranged from 0.07-0.28 for MY, 0.03-0.08 for SCS, and 0.39-0.50 for EC. The genetic correlation among MY and other traits had high variation, whereas the genetic correlations between SCS and EC were moderate and positive. These results contribute to a better understanding of the genetic variability of longitudinal traits derived from AMS and can be used when refining dairy cattle selection indexes.