Relationship of parity and body condition score to pregnancy rates in Florida beef cattle.

Pregnancy rates, determined by per rectum palpation, were analyzed with respect to cow parity (range 1 to >8 calvings) and body condition score (BCS, 1=thin to 9=fat) at pregnancy examination for 3734 beef cattle females on 3 commercial beef operations (8 herds) in 3 Florida counties in 1989 and 1990. The means and standard deviations for the herds were the following: pregnancy rate, 81.3 +/- 39% (range 62.1 to 91.5%); BCS, 4.7 +/- 0.6 (range 4.3 to 4.9); and parity, 3.9 +/- 2.3 (range 2.8 to 4.8). Significant associations were found between pregnancy rate, parity, BCS and herd (P < 0.001); and between the variable interactions, parity with BCS, herd with BCS, and herd with parity (P < 0.001). Cows with a BCS </=4 had a pregnancy rate of 59%; those with a BCS >/=5 had a pregnancy rate of 90%. Cows having a parity of <4 had a PR of 80%, while cows having a parity >/=4 had a PR of 85%. The interaction of parity with BCS was significant, resulting in pregnancy rates as follows; parity <4 and BCS </= 4 was 51%; parity < 4 and BCS >/= 5 was 88%; parity >/=4 and BCS </= 4 was 66%; and parity >/=5 and BCS >/= 5 was 93%. Body condition, parity, and the interaction of body condition and parity play important roles in the reproductive performance of commercial beef cows in Florida.