Energy efficiency of grazing Hereford heifers classified by paternal residual feed intake.

Residual feed intake (RFI) has become a widely spread index of feed efficiency. Although most of beef cattle systems in the world are pasture based, RFI evaluation and research is usually performed in confinement conditions. In this context, residual heat production (RHP) estimated as the difference between actual and expected heat production (HP), could allow to identify efficient animals.

Genotype-environment interaction for milk production of Gyr cattle in Brazil and Colombia.

Background: Genotype by environment interactions (G × E) can play an important role in cattle populations and should be included in breeding programs in order to select the best animals for different environments.

Objective: The aim of this study was to investigate the G × E for milk production of Gyr cattle in Brazil and Colombia by applying a reaction norm model used genomics information, and to identify genomic regions associated with milk production in the two countries.

Methods: The Brazilian and Colombian database included 464 animals (273 cows and 33 sires from Brazil and 158 cows from Colombia) and 27,505 SNPs.