The benefits of carcass estimated breeding values for pasture-finished cattle are not as great as for long-fed cattle

Abstract

Context BREEDPLAN reports estimated breeding values (EBVs) for many traits, but there are few EBVs specifically for the inputs into the Meat Standards Australia (MSA) index for producers, so as to make genetic progress. It is not known how selection on current BREEDPLAN EBVs influences the MSA index and whether these relationships are the same for different market end-points. Aims The aim of the present study was to examine the extent to which the MSA index of commercial animals is related to sire EBVs. Methods Data from 12 industry or research datasets (6997 animals) from four breeds (Angus, Charolais, Hereford and Limousin), three feeding regimes (pasture-, short- and long-fed) and 433 sires have been included for analysis. Carcass traits (intramuscular fat (IMF), MSA marbling, eye-muscle area, MSA index, rib, ossification and hot standard carcass weight) were regressed on BREEDPLAN sire EBVs (IMF EBV, eye-muscle area EBV, 600-day weight EBV, rib EBV). Sire ariance components were estimated for each of the 12 datasets, to determine whether the genetic variance in the MSA index and its indicator traits changed with carcass weight. Key results Sire variation in carcass traits changed with market end-point (or feeding regime) for all carcass traits except ossification, where there was no difference between long- and pasture-finished systems. One of the biggest differences between market end-points was observed in marbling where there was a 5.5-fold increase in the sire standard deviation for a long-feedlot finish system relative to pasture (1619 long vs 352 pasture finish). The sire EBV that had the greatest effect on the MSA index was IMF. A 1-unit increase in IMF EBV was associated with an improvement in the MSA index by only 0.34 units for long-fed cattle or 0.12 units for cattle finished on pasture. Furthermore, the regression coefficient between carcass traits and the sire EBV for the same trait was significantly lower for pasture-finished than for long-fed cattle. Conclusions and implications This means that commercial producers are unlikely to be receiving the full benefits of purchasing superior eating-quality sires unless they receive a premium from the finishing or wholesale meat sectors where the benefits are captured or they retain ownership through to heavier finish weights.