Penny Young, ASAP/ASAS Intern
An article recently published on Farm Online highlighted the benefits offered by performing and recording more ultrasound scans on heifers. Catriona Millen from Southern Beef Technologies Services was interviewed to provide insight.
While producers often perform ultrasound testing for EBV traits on some of their bulls, Ms Millen stresses that there are benefits to extending this testing to heifers. Scanning heifers is potentially more beneficial for a few reasons. Firstly, because the heifers mature earlier than bulls, scanning them at the same age is likely to give a greater indication of their traits because the variation in rib and rump fat depth and marbling is often more obvious. This allows more accurate EBVs to be calculated. Research by S. Walkom et al. concluded that scanning cattle earlier and when they are leaner results in a decreased correlation between scan intramuscular fat and carcass intramuscular fat, which decreases the efficacy of the scanning in terms of its application in selection for genetic improvements. However, the reduction in strength of prediction is not as great in heifers compared to bulls. Thus scanning heifers may help to mitigate the disadvantage of measuring earlier due to their earlier maturity.
Scanning heifers is also beneficial because generally a larger proportion of heifers are retained in the herd relative to bulls and these heifers are less likely to be culled for carcass traits. This means that scanning the heifers probably gives a better indication of the differences in rib and rump fat depths and marbling in a herd.
Yet despite these advantages, Southern Beef Technologies Services reports that the scanning of heifers generally lags behind that of scanning bulls. They recommend giving preference to scanning heifers where scanning is limited due to costs, and also remind producers that even pregnant heifers can be ultrasound scanned for carcass traits.