Estimation of genetic parameters for fat: protein ratio trait in Iranian dairy cows

The aim of this research was estimation of genetic parameters for the fat: protein trait (FPR) in daily milk test records of Iranian dairy cow. From a total of 295,820 monthly daily milk test records, 29,582 first-parity cows in 622 herds were used which were calved from 1997 to 2012. The trait was analyzed using a covariance function. Orthogonal Legendre polynomials with a 3th order were implemented to take account of genetic and environmental aspects of milk production over the course of lactation. The data were analyzed with the help of DXMRR software. Maximum phenotypic and genetic correlations (0.209 and 0.988) was obtained between the ninth and tenth month Maximum permanent environment correlation (0.938) was observed between the seventh and eighth months. The lowest (0.029) and highest (0.064) heritability’s were obtained for the third and first months of the lactation, respectively. Low heritability magnitudes showed that there is a low genetic variation for FPR trait which is suggesting much more effects of environmental factors.