An Alternative Approach to Modeling Genetic Merit of Feed Efficiency in Dairy Cattle

Abstract Text: Genetic improvement of feed efficiency (FE) in dairy cattle requires greater attention. A commonly used measure of FE in dairy cattle is residual feed intake (RFI); however, the use of RFI may be limiting for a number of reasons. We propose an alternative multiple-trait modeling strategy that exploits the Cholesky decomposition (CD) to provide a potentially more robust measure of FE.  We assessed both approaches by simulation as well as by application to 23,770 mid-lactation weekly records on 1,967 cows from a dairy feed efficiency consortium study involving 7 different research stations within US. Although the CD model fared better than the RFI approach when simulated genetic and non-genetic associations between dry matter intake and component traits were substantially different from each other, there were no meaningful differences in predictive performance between the two models on application to the consortium data.

Keywords: Feed efficiency, Residual feed intake, Cholesky decomposition