14 April 2023

Decreasing age at slaughter

Aidan Moloney, Edward O’Riordan, Mark McGee and Paul Crosson of the Animal and Grassland Research and Innovation Centre, Teagasc Grange, report on decreasing the age at slaughter of early maturing suckler heifers in the recent Teagasc Beef Advisory newsletter.

Slaughtering animals at a younger age is one strategy suggested to decrease methane emissions from beef cattle. There is also a view that younger animals have superior meat eating quality. This study examined the effect of decreasing the slaughter age of early maturing breed sired suckler heifers on carcass fatness, feed conversion efficiency and meat quality, when slaughtered at the same carcass weight from a similar ration.

Yearling heifers were finished either on ad-libitum concentrates and 5kg grass silage for 174 days and slaughtered at 17.7 months of age, or a restricted amount of the same ratio of concentrates and silage such that they were 19.7 months of age at slaughter. As planned, the younger slaughter group grew faster (0.97 v 0.79kg/day), had a similar carcass weight (259kg) but had a poorer feed conversion efficiency (9.1 v 7.9kg dry matter/kg bodyweight gain) compared to the older slaughter group.

The carcasses of the younger slaughter group were fatter (average fat score = 10.8 v 9.4 on 1-15 scale) and 77% of the carcasses graded 4= or higher, which would be considered too fat for some markets. In contrast, only 14% of the carcasses of the older slaughter group graded 4= or higher.

When assessed by trained tasters, there was no difference in meat tenderness, texture and overall liking between the two slaughter age groups. It is concluded that for early maturing suckler heifers, achieving a commercially acceptable fat score in younger animals will result in a lower carcass weight. The economic implications of this finding for the producer and the processor are under investigation.