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Preparing Bulls for the Breeding Season

March 14, 2017

Winter is a stressful time for cattle. They are regularly exposed to extended periods of cold stress and snow. Producers often pay less attention to the bull battery through the winter than the cow herd. After all, the cows are pregnant and obviously need some TLC. However, bulls that have been carried through the winter have been impacted with the stress of winter weather as well. Following are some management considerations to ensure that your bulls are ready to go when the breeding season arrives.

Nutritional Status
A major concern is the nutritional status of the bulls. Mature bulls can typically do well through the winter on a maintenance diet. In fact, the concern in mild winters is bulls being overfed so that they are too fat, which can have negative effects on reproductive capacity. This winter, the situation has been the opposite in many areas that had deep snow and cold temperatures because a lot of energy has been expended to maintain body temperature. This has caused total energy expenditure to exceed normal maintenance requirements. Add to that the likelihood that nutrient intake has been reduced in bulls that were turned out to graze through the winter because deep snow limited forage access. Either situation alone can lead to negative nutritional status, but the combination guarantees it.

Body Condition Score
Body condition scoring (BCS) can be performed on bulls in the same manner as cows. On the scale of 1 to 9, bulls should be in moderate condition at this time of year, meaning at or near BCS of 5. As the breeding season approaches, bulls in moderate BCS should maintain or slightly increase condition so they are slightly above moderate at the beginning of breeding. However, if bulls are thinner than a BCS of 5 at this time, improved feeding should be considered now to improve their BCS from now until the breeding season. Alternatively, bulls that have been overfed through the winter and have excess BCS (7 or greater) can be given a lower quality diet to gradually decrease BCS to a moderate level by initiation of breeding. For more information, see Don’t Ignore the Bulls on the Ranch.

Breeding Soundness
Ensuring that they are fertile and reproductively sound is the biggest concern. The opportunity for frostbitten testicles has been high this winter. This can cause reduced sperm production that may be temporary, but is likely to be permanent. Conducting breeding soundness exams on all bulls is recommended in all years, but it will be particularly critical this year because of the increased probability of cold stress injuries.

Timing of the breeding soundness exam can play a role in the value of the results. Doing the exam early can be useful to determine which bulls fail and need to be replaced while there are still plenty of bull sales to find replacements. On the other hand, bulls still have the opportunity to become injured or contract diseases that impact fertility later in the spring and thus become infertile after having passed the exam. Additionally, bulls that fail the exam early may recover. Thus, follow-up testing may be needed if the initial breeding soundness exams are done early. In other words, timing of the exam is a balancing act that needs to be based on the health and body condition of the bulls, opportunities to find replacements after the exam for bulls that fail, and probably other issues that are unique to each situation.

The Bottom Line
Managing the situation now will be tremendously important to avoiding unpleasant surprises next fall when the cows are pregnancy checked. For further information, view Bull Check Up on iGrow.

Source: South Dakota State University