Breeding season
Bull to cow ratio calculator
Enough bull power before turnout costs less than open cows at preg check.
A young bull can be put with about as many cows as his age in months: 12 or 13 for a true yearling, 15 to 18 at 18 months and 24 or 25 at two years (Oklahoma State University Extension). For 100 cows and 18-month-old bulls, that is 18 cows per bull, so 6 bulls.
Example numbers. Change them to your own.
Using the rule
- Count every female to be bred. Cows and replacement heifers in the same pasture and season.
- Go by the bull’s age in months. Oklahoma State University Extension puts a true yearling with 12 or 13 females, an 18-month-old with 15 to 18, and a two-year-old with 24 or 25.
- Test before turnout. Bulls vary a great deal, and a few fail even with very few cows. A breeding soundness exam and close watching early in the season catch most of them.
- Keep young and old bulls apart. In multi-sire pastures older bulls dominate, and some young bulls end up breeding only a small share of the cows.
How many cows can a yearling bull breed?
Oklahoma State University Extension says a true yearling bull should be exposed to 12 or 13 females, following the rule of about one cow per month of the bull’s age.
How many cows per bull for a two-year-old?
By two years of age a bull should be able to breed 24 or 25 cows, according to Oklahoma State University Extension. An 18-month-old bull should handle 15 to 18.
Does the rule always hold?
No. Extension specialists note that bulls vary widely: some breed many more cows than the rule suggests and a few fail with very few. A breeding soundness exam before the season and watching the bulls work early on are the safeguards.