Cows undergo a period of anestrus after each calving. During this anestrous period, cows will not have an estrus and will not stand for a bull. Usually the length of time they are anestrus (called the postpartum interval, or PPI, the time from calving to the first estrous cycle) ranges from 50 to 60 days if the cows are in good body condition. If the cows are in poor condition, the PPI would be longer. First-calf heifers have a longer PPI compared to mature cows, about 20 days longer if she has no calving difficulty and is in good body condition. If cows are exposed to bulls after calving, then the PPI may be as much as 10 days shorter.

Pasturing your bulls with your cows during calving is not recommended. Bulls need to be pastured with the cows for only the 60 to 70 days of the breeding season. Removing the bulls prevents pregnancies from occurring at unwanted times and prevents conception in young heifers (6 to 7 months of age).