It's not easy to keep up with bull breeding activity, but with a keen eye, you can detect the difference between inactive and active bulls, says Kris Ringwall, NDSU Extension beef specialist, Dickinson, N.D.
• Remember that the average estrous cycle of the cow is 21 days. If all the cows are cycling, about 5% should be expressing "heat" each day (one day divided by 21 days).
• Let's assume one has 100 cows. An average of five cows should be in heat or estrus on any given day. Realizing that not all the cows calve the first 21 days of the calving season, this number can be adjusted. In fact, typically, only 63% of the cows calve the first 21 days of the calving season. For typical producers who expose mature bulls to 100 cows, at least three to four cows should be in heat every day early in the breeding season.
• As the second-cycle cows (those cows that calved later in the calving season) start to cycle, the typical producer should have 23% of the cows just starting to cycle within the second 21 days of the breeding season. Those same mature bulls that were exposed to 100 cows should have 23 cows to breed the second 21 days of the breeding season, or roughly one cow per day.
In summary, three to four cows should be cycling every day during the first 21 days of the breeding season, but only one cow per day should be cycling during the second 21 days, Ringwall says.
After 42 days, breeding activity should be sporadic.
So, in the last seven days, how many times did you check the cows and how many appeared to be cycling?
"Given the average turnout dates in the Dakotas, most cows should be bred by now. If there are cows cycling now, do some checking and bring in a reserve bull," Ringwall advises.