Missouri researchers found young cows that calve in thin body condition (body condition score 3 or 4) cannot gain enough body condition after calving to return to heat cycles as quickly as cows that calve in moderate body condition (BCS 5.5).

Oklahoma State University extension animal scientist Glenn Selk reports heifers that calved in poor body condition and were fed well did not return to estrus as quickly (111 days versus 102 days) as the heifers that were in good body condition and lost a small amount of body condition after calving.  

Self remarks that it is very dificult to add body conditon on young lactating cows in most range situations.

"Cows must be rebred by 85 days after calving to calve again at the same time next year," says Selk. "Notice that none of the averages for two year-old cows that calved in thin body condition were recycling in time to mantain a 12-month calving interval."

Selk adds that this is why many ranches breed yearling heifers two to three weeks ahead of the start of the breeding season for adult cows.  It gives the heifer group extra days to return to heat cycles and be bread back to calve at about the same time as the mature cows in the herd.  

Adapted from: Ontario Farmer Tuesday April 17, 2012