Relationships Among Changes in Body Condition Score and ReproductiveEfficiency in Lactating Dairy Cows

摘要

This manuscripts summarizes research, with emphasis on 3 recent publications, relating body condition score (BCS) or changes in BCS with reproductive performance in dairy cows. Cows with lower BCS have greater likelihood of anovulation with reduced reproductive performance due to decreased service rate in cows bred to estrus and reduced pregnancy per AI (P/AI) in cows bred to synchronized ovulation. Evaluation of BCS at first AI predicted P/AI in cows bred either to Ovsynch or Double Ovsynch with relative improvements of 30 to 50% in P/ AI ( BCS > 2.5 vs BCS < 2.5). Loss of BCS (calving to 21 days postpartum) was associated with a dramatic reduction in P/AI in cows bred to Double Ovsynch. One recent study found that cows with high BCS at 21 days before expected calving were more likely to lose BCS during transition period (21 days before calving to 21 days after calving) and cows that lost BCS had greater health problems and a large reduction in P/AI. Finally, one recent study showed that loss of BCS during the dry period (dry off to calving) was a critical predictor of health and reproductive performance. Excessive BCS at dry off (> 3.25) was the primary predictor of subsequent BCS loss. Thus, dairy herds need to implement evaluation of BCS at dry off, calving, 21 days after calving, and at first AI to diagnose nutritional and management factors associated with BCS change and thereby improve health and reproduction in these dairy herds.