Replacement Index Delivering on Weaning and Carcass

Lighter cows, heavier weanlings and better carcass performance.

In last week’s article, we examined the fertility performance of suckler females that calved for the first time in 2018. The analysis showed that 5-star Replacement Index cows produced more than 1 extra calf over 1-star cows between 2018-2024, due to calving down younger, shorter calving intervals and surviving longer in herds. But what about the quality of the calves they are producing?

Using the same 145k females from last week’s analysis, we look at the weaning performance of these females and the carcass performance of their progeny.

Weaning performance

When analysing the weaning performance of a suckler cow, you look at both her own weight and the weight of her calf. While it is the calf’s weight which generates income, the cow’s weight is also important as it affects input costs – bigger cows generally eat more.  Table 1 outlines the average weights of 5-star vs 1-star cows, the weights of their progeny and their average Weaning Efficiency %. Calves were an average of 7.5 months at weighing.

Table 1. Weaning Efficiency performance of 5-star vs 1-star cows.

The Weaning Efficiency % is calculated by dividing the calf weight by the cow weight (325/670 = 48.5%). 5-star cows were 50kg lighter, weaned calves 15kg heavier, resulting in a 5.4% higher Weaning Efficiency % (figure 1).

Figure 1. Additional Weaning Efficiency % from 5-star cows.

Carcass performance

To get a more complete picture of progeny performance, we also looked at the progeny slaughter data. Table 2 outlines the slaughter performance of both steers and young bulls. Progeny of 5-star cows slaughtered as steers were 5kg lighter at slaughter, leaving €4 less/carcass, however, they were slaughtered 21 days younger (0.7 months) when compared to progeny of 1-star cows. On the young bull data, carcass weights were the same, but progeny from 5-star cows were slaughtered 12 days younger (0.4 months). Young bull progeny from 5-star cows also left €51 more at slaughter.

Table 2. Comparison of 5-star vs 1-star cows on steer and young bull carcass performance.

Key points:

  • 5-star cows produced more than 1 extra calf over 1-star cows between 2018-2024.
  • 5-star cows were 50kg lighter while producing calves 15kg heavier.
  • This resulted in a 5.4% higher Weaning Efficiency %.
  • 5-star cows produced steers 5kg lighter but slaughtered 21 days younger.
  • 5-star cows produced young bulls with the same carcass weight but slaughtered 12 days younger.