Summer Breeding Bull Health

Establishing herd genetics that fit your environment and operation are critical for the success of cow-calf operations, especially those who keep their own replacements.  If natural service is used in the breeding program, the bull plays a crucial role in this process, spreading new genetics quickly across the herd. 

Because of this oversized role, making sure the bull is in good health and able to perform going into the breeding season deserves some time and effort.  We manage nutrition programs to ensure bulls head into breeding at a BCS 6 and bring out the vet to perform breeding soundness exams.  But once the bull is turned out, is there anything left to do?

The obvious task is keeping an eye on the bull’s physical health.  With a somewhat one track mind this time of year, a bull’s body condition is expected to drop during breeding. Typically a bull can expect to lose 100-200 lbs. Because the bulls are intermixed with the herd at this point, any options we have to manage their nutrition is limited.  Whatever the cows get, they get.

However, we can still ensure that nothing has happened to limit mobility or that their condition hasn’t dropped so much that vigor and performance is impacted.  If a bull does get too thin, we may consider replacing him as his ability to service the cows is most likely impacted.

Young bulls are most impacted by the nutrient demand of breeding season.  Because these animals are not yet full size, the added nutritional demands from growth means yearling bulls shouldn’t be left in the cow herd for 60 days max. 

Young animals will also be most impacted by social hierarchy that is mostly influenced by bull seniority.  Older bulls are typically more dominant, limiting a younger bull’s opportunity to cover females. Dominance is most notable in herds where the bull:female ratio is low.  Correctly calibrating the bull to female ratio can avoid issues with fertility, bull fighting, and prevent bull fatigue.  There is a sweet spot here we want to try and hit and bull age plays a role.  Animals under 16 months of age may be expected to only cover 15 females, while a bull 2.5 years or older can cover double that.

To manage dominance, consider separating bulls by age, running younger bulls (under 4 years of age) in a group separate from older bulls.  Rotating bulls or adjusting the bull to female ratio during the breeding season may also help.  Adjusting the bull to female ratio is especially helpful for herds that have utilized a synchronization protocol, starting with a high bull:female ratio and removing animals after the first 21 day cycle and fewer females remain open.  When rotating bulls, start with more mature animals early and swap out for a younger battery during the second half of the season.  This strategy can eliminate dominance issues and also prevent young bulls from losing too much body condition during breeding.

The last thing I want to cover today is the impact weather has on breeding and fertility, especially during the summer.  Typically the testes need to be kept 3.6 to 10.8°F cooler than a bull’s natural body temperature of 101.9°F.  Increased testicular temperature and heat stress can influence semen quality both short and long term.  Providing shade and adequate water during heat events are instrumental in limit environmental impacts.  Refrain from handing, moving, or transporting bulls during these periods, especially during the heat of the day, to further prevent overheating.

Breeding success is equal parts bull and cow, and while a lot of the work from the bull’s side can be done prior to breeding, management during the breeding season is still important.  Watch bull health, consider adjusting male to female ratios, and mitigate the impacts of heat to have a successful breeding season this year.

-Ben Beckman is a beef systems Extension Educator serving the counties of Antelope, Cedar, Knox, Madison and Pierce.  He is based out of the Cedar County Extension office in Hartington.  You can reach him by phone: (402) 254-6821 or email: