Evaluation of the Angus BREEDPLAN IMF% EBV in 100d-fed Angus x Hereford steer progeny

Abstract

The Angus BREEDPLAN IMF% (intramuscular fat %) EBV was evaluated in 320 100d-fed Angus x Hereford steer progeny of 25 sires. Results showed using the EBV to select among sires would significantly increase marbling scores and IMF%, and that this was unaffected by growth regime to feedlot entry or by whether slaughter was at a constant age or weight. For the production system studied, Angus breed average IMF% EBV level was associated with MSA-scale marbling scores of 1.6 and 1.5, and IMF% levels of 4.6 and 3.9 in 'fast' and 'slow' grown steers (0.71 and 0.48 kg/d, respectively). The ability of the sire IMF% EBV to explain differences among individual steers was low but in line with expectation. The same expectation limits how effective any EBV can be in sorting individual animals of a breed for a management or marketing purpose.