It is time for bull turnout for herds that calve in January. As we prepare for breeding season it is critically important to address bull to female ratios and answer the question, do you have adequate number of bulls on hand to get females bred promptly?
The first goal of breeding season is to get cows bred early in breeding season resulting in more calves born earlier in calving season, shorter breeding/calving seasons, older calves at weaning and ultimately, more pay weight at weaning due to calf age. The typical beef calf gains about 2 pounds/day up until weaning; accordingly, a calf born one heat cycle (21 days) earlier will wean off about 40 lbs. heavier.
How do we get this accomplished? By having an adequate number of bulls to get cows serviced. The following shows a conservative expectation of the number of cows we should expect bulls to cover in a defined breeding season (45-90 days).
• 12-15-month-old bulls: 10-12 females.
• 15-18-month-old bulls: 12-18 females.
• 18-24-month-old females: 18-25 females.
• 24 months and older: 25-35 females.
• 2-6-year-old bulls: 25-35 females.
The rule of thumb is one female per month of age at turnout for yearling bulls after passing a breeding soundness exam (BSE). For example, if you have 60 heifers to breed and plan to turn out 15-month-old bulls, you will need four bulls.
What is the typical life expectancy of a breeding bull? Typically, up to 6 years old is “prime of life” for breeding bulls. This isn’t to say that all bulls will break down at this age, but it is more likely to happen after 6 years old. Often when an older bull goes bad, it isn’t discovered until after breeding season when we are doing pregnancy checks.
Get prepared, make sure your herd bulls have passed a BSE prior to turnout and take measures to have an ample number of bulls with females to ensure prompt breed up this season. — Mark Z. Johnson, Oklahoma State University Extension beef cattle breeding specialist
