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Recent analysis of statistics from the ICBF Weaning Performance Report shows that high Replacement Index (5 star) cows are performing best on key output and maintenance traits such as ‘calf 200-day weight’ and ‘cow liveweight’. This new weight report was generated for 4,000 herds last December (herds with ≥5 calves weighed) and posted to 2,000 herds (herds with ≥10 calves weighed).

Calf Weight

There were just under 52,000 calf weights available for analysis. Table 1 details the performance of calves based on the star rating of the cow. The 5-star cows produced calves with a 200-day weight of 291 kg (1.24 ADG) which was 13 kg heavier than calves from 1-star cows at 278 kg (1.17 ADG).


No. Cows Calf 200 day Wgt (kg) Calf ADG (kg)
5 Star 19746 291 1.24
4 Star 10075 288 1.22
3 Star 8095 285 1.21
2 Star 7124 282 1.2
1 Star 6956 278 1.17
Nat Avg 286 1.22

Table 1. Breakdown of calf performance by cow star rating. The 5-star cows had the highest average performance.

Cow Efficiency

Suckler cow efficiency is something that is continuously scrutinised within the beef sector. The age which a cow has her first calf, how often she subsequently calves and how long she lasts in a herd are all important performance metrics. A relatively new concept in the analysis of cow efficiency is to measure the weight of her calf at 200 days as a percentage of the cow’s own weight. Figure 1 shows how this is calculated.

Figure 1. How the weaning efficiency metric is calculated. It is a simple calculation which gives the calf’s 200-day weight as a percentage of the cow’s mature weight.

5-star Cows Most Efficient

Further analysis of the weight data showed that the 5-star cows were also the lightest and had the highest weaning efficiency percentage. Table 2 details cow liveweight and efficiency by star rating. The 5-star cows had an average mature weight of 659 kg which was 52 kg lighter than the 1-star cows at 711 kg. The weaning efficiency trend was also the same, with progeny from 5-star cows weighing in at 44.2% of the cow weight. This was over 5% better than the 1-star cows at 39.1%.

No. Cows Weighed Cow Wgt (kg) Weaning Efficiency (%)
5 Star 3574 659 44.2
4 Star 1215 664 43.4
3 Star 1136 677 42.1
2 Star 1115 679 41.5
1 Star 1305 711 39.1
Nat Avg 673 42.5

Table 2. Cow liveweight and efficiency performance by star rating. 5-star cows were, on average, the lightest and had the best weaning efficiency percentage.

Weighing of Animals

Farmers that would like to measure the weaning efficiency performance of their suckler cows will need to weigh all cows and calves at least once per year. Calves should be weighed between 100-300 days of age. For a spring calving herd, the optimum time to weigh is late summer, but this will vary depending on an individual herd’s calving pattern. Cows should be weighed on the same day as calves as this represents a mid-season “working” weight for the cow. For a more accurate prediction of the 200-day weight, calves should be weighed a second time closer to weaning (September/October).

Weaning Performance Report

The Weaning Performance Report is available to all HerdPlus customers. Once weights are recorded, a new report can be generated online. This report will show a herd’s best and worst performers as well as detailing the performance of each individual cow and calf in the herd. Click here for more information on this report.

If you have any queries on weighing animals or the Weaning Performance Report please contact us on 023-8820452 or email [email protected].