A beef cow, to maintain a calving interval of 365 days must conceive within 85 days after calving. Cow body condition at calving greatly determines the rebreeding performance of beef cows in the subsequent breeding season.

Research has shown that cows calving in a body condition of four or less had a rebreeding rate of sixty percent. A cow in body condition four will be thin with ribs and backbone showing. The spinous processes along the loin edge will be barely visible. Muscle tissue is not depleted through the shoulders and hindquarters. Cows in a thin condition have low amounts of body fat, which is an important energy source for a beef cow in times of physiological stress such as the process of fetal development, giving birth, lactation and repair of the reproductive tract. Thin cows at calving, because readily available stored energy (fat) is very, limited, will have difficulty rebreeding in 85 days post calving.

Cows in a body condition score of five at calving had an 81 percent rebreeding rate. A body condition score five cow will be described as moderate to thin. The last two ribs can be seen and little evidence of fat will be present over the ribs or around the tail head. The spinous processes at the loin edge will be smooth and no longer individually identified.

Cows in a body condition score of six are cows that exhibit a good smooth appearance throughout. Some fat deposit will be evident over the tail head and brisket. The back appears rounded over the ribs. Cows in this body condition were able to rebreed in the 85 day period after calving at a rate of 92%.

Cows that conceive early in the breeding season calve early in the calving season. Calves born early in the calving season will be older at weaning. Older calves (early born) will be heavier at weaning. A goal for commercial cow-calf operators is to calve 70 percent of their cows in the first 21 days of their calving season.