Managing reduced-fertility beef herds.

Many beef herds with less than ideal reproductive efficiency have an 85-90% pregnancy rate, a breeding season longer than 90 days, and less than 60% of the calf crop born in the first 21 days of the calving season. The previous years' fertility levels should be used as a guideline for estimating calf losses and assessing improvement after implementation of reproductive programs. Acute infectious causes of reproductive inefficiency tend to be expressed as abortion or delayed conception. Management-related reproductive problems are common and involve inadequacies in nutrition, replacement heifer development, bull fertility and cow culling.