Breeding for a good score
Sarah Burke, Edward O’Riordan, Paul Crosson and Mark Mcgee of the Teagasc Animal and Grassland Research and Innovation Centre, Grange, Co. Meath, report on exploiting genetic divergence for carcass fat score.
Irish suckler cattle are mostly from breeds that take longer to mature. It’s harder for these cattle to reach the right level of fat (a score of 2+ or higher) at a young age when they’re raised mainly on grass. This is especially true compared to breeds that mature faster. Recent research at Teagasc Grange looked at how genetics affected carcass fat score, growth, and conformation (shape) of Charolais crossbred steers finished from grass-based systems at 19, 23, and 26 months of age.
Lean vs fat
The study compared cattle bred to be leaner versus those bred to gain more fat. They found that cattle bred to gain fat had higher carcass fat scores at all ages. The fat scores were higher by 1.7, 2.4, and 2.0 points (15-point scale) at 19, 23, and 26 months, compared to the leaner cattle. However, these fatter cattle had slightly lower carcass conformation scores (~1.0 point) and their carcasses weighed a bit less – about 9kg less on average at 19 and 23 months, but there was no weight difference at 26 months.
The takeaway is that late-maturing cattle that are bred to gain more fat can still reach the right fat level at a younger age. The slight drop in shape and weight isn’t as much of a concern as it would be with breeds that mature earlier.