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- A realistic reproductive performance goal is for a 95% conception rate with 75% of the calves born in the first 21 days of the calving season. In order to achieve this, it is essential that bulls are managed properly.
- A complete breeding soundness exam should assess reproductive and seminal characteristics as well as an assessment of the eyes, feet, and legs. The examination should be approximately 60 days prior to the breeding season to give time to correct problems or to replace bulls.
- Feed growing bulls appropriate rations. Too much energy can temporarily harm sperm morphology and motility due to poor heat regulation of the testes from fat in the scrotum.
- Overfeeding predisposes bulls to certain reproductive disorders such as lameness.
- Ideally bulls should be in a body condition score of 3.5 to 4 before the breeding season. Often young bulls purchased at sales are to fat requiring a dietary "let down" before the breeding season. Over-fat and over-thin bulls have reduced libido and fertility. During the breeding season, old or thin bulls benefit from small amounts of grain, given daily or every other day.
- The standard recommendation for a bull-to-cow ratio is 1:25 which gives allowance for sub-standard bulls. At this ratio, bulls are under utilized where the stock density is high, forage quality is high and when the bull is highly fertile. Knowing the libido and serving capacity is helpful to optimize the bull to cow ratio.
- If the bull to cow ratio is larger than desired, consider rotating out the working bulls with bulls that have been rested during the breeding season. A rested bull will have more libido for days to come compared to simply adding bulls into the herd. Even if bulls are not breeding, they still travel within the herd focusing on cows in heat resulting in fatigue.
- Health care for bulls varies according to their age. In yearling bulls, establish a long-term immune base for the common viral and reproductive diseases. Administer vaccines to yearlings at the time of semen evaluation and booster two to three weeks prior to the breeding season. Mature bulls only require an annual booster at semen evaluation.
- Parasite control will vary from region to region. Generally, bulls require deworming and louse control once yearly. Fly control may also be essential.
- Observe bulls closely during the breeding season to ensure that penetration takes place. Observation is most important in the first several days of the breeding season in multiple sire pastures while dominance is established. Bulls are prone to back, feet and leg injuries as well as cuts and breaks to the penis.
- Age is a major consideration when making culling decisions. Semen quality and social dominance changes after age 6. Other considerations are vision, conformation and disposition. Older bulls with exceptional value should be in single-sire pastures.
Beef Bull Fertility
Beef Sire Selection Recommendations - available in PDF format
Bull Nutrition and Management
Choosing and Managing Young Bulls - available in PDF format
Determining Reproductive Fertility in Herd Bulls - available in PDF format
Feeding Young Beef Bulls Can Influence their Reproductive Capacity
Guidelines For Developing And Testing Beef Bulls On-Farm
The Reproductive and Nutritional Management of Beef Bulls - available in PDF format
Let us know of good research papers relating to beef bull management.