Mature cow weight (MWT) is an important trait in cattle production because it influences feed requirements and overall efficiency. However, MWT is closely related to body condition score (BCS), which reflects a cow’s nutritional status and energy reserves. Because of this relationship, how BCS is accounted for can affect which animals are selected for breeding. This study compared two approaches for analyzing MWT: one that adjusts MWT for BCS before using it in national genetic evaluations, and another that separates the genetic effects of MWT and BCS during analysis via a recursive method. The goal was to determine whether these approaches identify different underlying genetics or simply produce statistical differences. Both methods detected many of the same key genetic regions, showing they capture the main biological drivers of MWT. However, the recursive approach identified more genes and biological pathways related to growth, skeletal development, feed efficiency, and carcass traits. In contrast, the pre-adjustment method may have missed some smaller genetic effects and introduced signals not detected in the unadjusted MWT. These findings suggest that despite the small differences in identified regions, both methods pointed to the same core biological factors affecting MWT.

Read the full article in the Journal of Animal Science.