Genetic Parameters of Residual Energy Intake and Its Correlations with Other Traits in Holstein Dairy Cattle

Residual energy intake (REI) or residual feed intake (RFI), defined as the difference between actual energy intake, is predicted on the basis of requirements for maintenance, milk production, and body weight change of an animal. Genetic variationof REI and its relationships with dry matter intake, milk yield, fat corrected milk yield and milk fat, and protein yields wasinvestigated using 3503 monthly records collected from 906 Holstein lactating cows. Variance components were estimated using univariate and multivariate animal models with the derivative-free approach of restricted maximum likelihood algorithm, fittinganimal models with fixed effects of herd-year-season, parity number and stage of lactation, and random effects of animal additivegenetic and permanent environment. The estimated heritability and repeatability for REI were 0.15 and 0.53 from univariate, and0.21 and 0.60 from multivariate models, respectively. REI had a genetically weak and negative correlation with yield traits (from -0.05 to -0.08) and a positive correlation with dry matter intake (0.61). Moderate heritability estimate for REI, along with negligiblegenetic correlations with yield traits and high genetic correlation with dry matter intake, might reveal that selection against REIimproves feed efficiency by reducing feed intake and increasing yield traits a little.