Body condition: Influences on beef cattle reproductive performance

This observational study of beef cows had as its objectives to evaluate the relationship of body condition score (BCS) to pregnancy rate, time-to-conception and to evaluate animal variables associated with body condition. Beef cows in the state of Florida (USA), over several years and localities, were evaluated relative to age, breed-type, BCS (al prebreeding and at pregnancy examination), change in BCS prebreeding to pregnancy examination, pregnancy status (60 to 100 days of bull removal) and gestational age. BCS by pregnancy rate showed a consistent, significant pattern (p<0.01) in all herds, with pregnancy rate improving with increasing BCS. Pregnancy rate increased with increasing BCS category in all age groups, but low BCS had the most adverse effect on pregnancy rate in young cows. As BCS increased, time to conception within the breeding season and subsequent calving interval decreased. Cows losing BCS during the breeding season had a significantly lower pregnancy rare than cows maintaining or gaining BCS during the same interval, and, had a lower though not significant pregnancy rate than cows remaining in marginal condition. Cow nutrition, as reflected in BCS, is closely associated with reproductive performance of beef cows.