Possibilities of Shortening the Number Days on Feed for Calculating NFI in Cattle

Abstract

Feed efficiency is an important trait in many beef cattle breeding programs. The current measure of feed efficiency used in beef cattle is net feed intake (NFI). Current measurement protocols stipulate a 70 day test period to obtain a reliable NFI phenotype, incurring a significant economic cost. This study examined the phenotypic and genetic implications of shortening the number of days on feed in the calculation of NFI phenotypes. Phenotypic and genetic parameters were estimated for 5 trial lengths (14, 28, 42, 56 and 70 days) for NFI and its component traits; average daily gain (ADG), metabolic mid weight (MMWT) and daily feed intake (DFI). For NFI, 56 days on feed was highly genetically correlated with 70 day estimates. For shorter periods correlations reduced and variance components changed substantially. In contrast, daily feed intake could be measured well in short periods of time with genetic correlations of > 0.95 for lengths greater than 14 days. To substantially reduce the time on feed it is suggested that breeders consider collecting DFI information rather than NFI. If this was seen to be desirable an alternative way of balancing feed intake and weight gain would need to be explored.