Summary
A concern in the beef industry is that genetic change in growth and carcass quality has led to cows that have compromised productivity when under limited feed supply resulting from high stocking rate or dry seasons. The project scanned 7,760 cows in 15 Angus or Hereford stud herds. There were also over 500 cows run on research centres in WA and SA with intensive measurement including feed intake over 3 calving cycles. There was large variation in cow size and body composition due to both genetic and nutrition effects. The current carcass EBVs can be used to select for changes on cow body composition if desired. However, genetic effects on mature cow productivity or efficiency were small. Heifer management targets have been produced to aid management. Genetically lean heifers did have reduced fertility and the challenge of achieving heifer fertility EBVs on young bulls remains.
