Negative Energy Balance and Reproduction: A Review

The peripartum period is of critical importance to subsequent health and fertility. Most cows enter a state of negative energy balance (NEB) associated with many metabolic changes which have carry over effects on the resumption and normality of estrous cyclicity and the success of subsequent inseminations. High producing dairy cows need to mobilize body reserve to be able to sustain their milk production. In early lactation, until energy intake assures the requirements, dairy cows, especially high producing breeds, enter a state of negative energy balance (NEB), losing high amounts of body condition. The NEB is detectable by measurement of body condition score (BCS), which has been useful in the past and by more sophisticated ways to measure the relationship between adipose tissue and fertility, like metabolic hormones: IGF-I, leptin. The aim of this study is to summarize the effect of negative energy balance and the risk for reproductive disorders in dairy cows.