Short communication: estimation of genetic parameters for residual feed intake and feeding behavior traits in dairy heifers.

Data from a 2-yr feeding trial of Holstein-Friesian heifers (n=842) were used to examine the heritability of feeding behavior traits and their relationships with residual feed intake (RFI), a measure of feed efficiency. Five traits were assessed: number of meals, feeding duration, dry matter intake (DMI), eating rate, and average meal size. For estimating genetic parameters, all traits were simultaneously fitted in a multivariate model with a genomic relationship matrix calculated from heifers' high-density genotype data. All 5 traits were moderately heritable (0.45-0.50), which was slightly higher than the estimate for RFI (0.40 ± 0.09). Two traits had modest genetic correlations with RFI (DMI and feeding duration; 0.45 ± 0.13 and 0.27 ± 0.15, respectively), and 2 traits had modest phenotypic correlations with RFI (DMI and eating rate; 0.52 ± 0.03 and 0.23 ± 0.04, respectively). The results indicate that feeding behavior (1) may differ between efficient and inefficient animals and (2) may be useful for selecting animals with better feed efficiency. However, the limitation is that measurements on DMI are still essential. It is therefore possible that a more efficient selection tool for RFI may be the use of high-density DNA markers to make direct genomic predictions for RFI.