Last week Dr. Selk wrote about management of bulls in multi sire pastures to achieve the highest fertility levels possible. Continuing that theme, I want to increase awareness of a genetic management practice that can be performed after the breeding season that will help evaluate a bull’s reproductive performance as part of a multi sire breeding program. A bull’s worth in a commercial cattle operation is relative to his abilities to sire calves, with additional value captured when he sires calves with superior performance. The second objective can be evaluated and selected for using EPDs. However, in multi-sire pastures, the bull’s ability to sire calves can be hard to pinpoint without additional information.
Genetic testing to establish parentage in multi-sire pastures can be an invaluable tool. Knowledge of which bulls are making you money and which are a drain on limited resources is an effective, if not essential, risk management tool. Data from the California Commercial Ranch Project showed that calves sired by groups of bulls in multi-sire pastures resulted in large differences in gross revenue per sire. Due to vast differences in the number of calves each bull sired in a breeding season, the gross revenue varied from $4,881 to $55,889 between sires.
All bulls in this scenario were declared sound breeders, but some bulls sired as few as 7 calves out of a total of 5 calf crops, and as a consequence, generated only $4,881 in gross revenue during this period. The use of genetic testing for parentage determination would allow identification of bulls that are not pulling their weight so that they may be replaced. Regardless of whether a sire possesses superior EPD’s, a bull that doesn’t sire very many calves is still a drain on available resources. Additionally, if the bull that sires the largest number of calves has the worst set of EPDs, the average performance of the resulting progeny may be lower than expected. To increase performance in the calves, you may wish to cull that bull either to allow bulls with better EPDs to breed more cows, or to replace him with another bull with better performance data. In either scenario, the numbers speak for themselves. Knowing the quantity of calves that are being sired by each bull in multi-sire pastures can help to better manage bulls to maximize return on your investment.
Source: Alison VanEenennaam, “Uses of DNA information on commercial cattle ranches”