Bull management at the end of the breeding season
August 6, 2010
Typical recommendations for the length of the breeding season are 60 days for mature cows and 45 days for yearling heifers. Some producers use shorter breeding seasons to make age and weight at weaning more uniform. For example, if one assumes a conservative average daily gain (ADG) for calves of 2-lbs. per day, a calf born on the 60th day of the calving season will be 120-lbs. lighter than a calf born on the first day of the calving season. Obviously, differences in growth potential, dam milk production, etc. will alter actual results for each calf, but the overall difference between early- and late-born calves is substantial.
Another reason for a short breeding season in heifers is to apply selection pressure on those that are most fertile and likely to breed back early throughout a long life as a cow. Some producers shorten heifer breeding to 20 to 25 days (about one estrous cycle) to intensify this selection pressure. This approach requires that a larger number of heifers be exposed to breeding because the overall pregnancy rate will be reduced to only those that were pubertal and fertile at the beginning of the breeding season. Excess heifers can be marketed as though they were stockers, creating an added-value income stream from these feeder heifers. Ultrasound pregnancy diagnosis can be used to reveal pregnancy success relatively early after breeding to allow market timing flexibility for the open heifers.
Often, producers don’t remove bulls from the cow or heifer herd at the end of a defined breeding season. In this way, they avoid the labor and effort to gather the bulls and the need to manage bulls as a separate group after breeding. There are concerns with this approach. It is dependent upon culling late-bred (bred after 60 days) cows as though they were open. Depending on the time of pregnancy diagnosis, estimation of fetal age by rectal palpation can be difficult when determining the difference between a cow bred on the 60th vs. 70th day. Again, ultrasound diagnosis could improve this accuracy.
Another reason to remove bulls from the cows is to avoid problems they can get into. If neighboring cows are in an adjacent pasture, it may be difficult to keep idle bulls in, leading to extra effort to manage them and repair fences. Additionally, not everyone is fortunate to have neighbors with healthy herds and thus bulls can contract reproductive (e.g. trich) and other diseases and bring them back to the cow herd. Separating the bulls at the end of a defined breeding season and isolating them from other cattle can greatly reduce these problems.
Once the breeding season is over, it will be important to determine the future of each bull. Basically, there are three options: market cull bulls, maintain mature bulls and grow young bulls to maturity. With the current strong cull bull market, deep culling in the bull battery should be considered. Buying replacement bulls next winter or spring should accelerate genetic improvement compared to keeping “old genetics.” It will also eliminate the feeding and other costs of maintaining these bulls. Early marketing of culls will be a desirable option.
If these bulls are thin at the end of the breeding season, which is typical, a short feeding period to put weight and condition on them can add considerable value. This high salvage value can be tremendously important in reducing overall bull depreciation costs. Early marketing can further reduce bull ownership costs such as feed.
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For mature bulls that you intend to keep, a maintenance ration should be adequate. A person needs to be careful not to overfeed bulls. Being too fat will reduce fertility, as well as waste feed. Management of these bulls is probably as simple as turning them out to a pasture and watching body condition to determine when to provide supplemental feed this fall or winter. Bulls can be scored for body condition in the same manner as cows on the nine-point scale wherein a body condition score (BCS) of one is emaciated (extremely thin) and nine is obese (extremely fat). Ideal BCS during the fall and winter would be five (moderate).
Young bulls need a better ration that will allow them to resume growth to their mature size. Again, overfeeding needs to be avoided as much as underfeeding to ensure that they don’t get too fat. Bulls should be on a forage-based ration (pasture or hay) with supplemental energy or protein to support an appropriate level of gain (probably 1.5- to 2-lbs. per day) to reach mature weight. Assistance with ration balancing can be provided by your local Extension Educator.
Beef producers need quality beef bulls that are capable of breeding cows and are physically able to seek out cows and heifers on pasture. Management practices after breeding such as culling decisions, nutritional management of culls and breeding bulls, and future bull selection decisions are important to genetic capability of the cow herd and beef enterprise economics, particularly in relation to bull breeding costs.