Posted October 3, 2023
by Tom Brink, RAAA CEO
We recently conducted some data analysis for a long-time Red Angus breeder located in the Northern Plains. He was interested in understanding how the Weaning Weight EPDs in his herd correlate to actual scale weights. For example, could EPDs help him avoid light-weaning calves? Good question.
This breeder has been raising Red Angus seedstock for more than 20 years. During that time, he has produced almost 4,000 calves.
With plenty of data available, we set out to determine if lightweight calves appeared more often among cattle with lower WW EPDs. In other words, did calves with lower-ranking growth genetics produce unacceptably light-weaning weights with greater frequency? The answer to that question turned out to be YES.
To define a lightweight calf, we drew the ‘acceptability line’ at 500-lb. for 205-day adjusted weight on bull calves and at 450-lb. on heifers. Calves below those weight thresholds are undesirable in most seedstock operations. Such calves do not fit the rest of the calf crop and are less likely to become a marketable bull or a replacement female. The fewer of them, the better.
The accompanying table presents the results of our analysis. For this herd, from 2000-2022, low WW EPDs were associated with a greater frequency of lightweight calves. Higher WW EPDs produced a lower percentage of calves below the weight threshold.
The probability of getting lightweight calves decreased steadily as WW EPDs increased. When calf WW EPDs reached breed average (near 60) or above, the percentage of calves weaning below the threshold was significantly reduced.
Takeaway message: Red Angus WW EPDs are directionally correlated to actual weaning weights. WW EPDs, therefore, can be used to help reduce the number of light-weaning calves and thereby increase average calf crop weights.