All four are of equal importance and testing would be a recommended procedure where practical before a bull is used. The average scrotal circumference will vary according to breed. Bull to Cow Ratio Table 4. These figures vary considerably with the condition of the pasture, the sex drive of the bull, the fertility level of the cow herd and the length of the breeding season. Cows in moderate or good condition at calving time.
Cows gain in weight for three weeks before the start of breeding season and during breeding season.
Calves removed from cows for 48 hours at start of breeding season. Cows bred to fertile bulls. This factor may not be practical to the majority of commercial producers. Eighty percent of the cows were pregnant after 30 days of breeding in the O'Connor herd that utilized these five factors. The length of the breeding season is an important factor in determining pregnancy rate.