Transition XXXX : interaction with fertility.

@entity1522 @entity5852 @entity1420 @entity4208 @entity1474 @entity2670 @entity291
In recent years a progressive worsening of fertility indices in dairy @entity291 herds has been observed. Several factors (genetic, dietary and management) seem to be more related to poor fertility than milk yield level. The degree and the length of the energy deficit during the transition period are inversely related to reproductive indices (e.g. conception rate is <30% for BCS decreases over one unit). A serious energy deficit reduces (or suppresses) pulsatile secretion of gonadotrophins ( @entity2670 and/or smaller follicles): @entity4208 and insulin plasma levels (slower follicle growth and higher embryonic mortality); and @entity1420 production from the corpus luteum (higher rate of @entity5852 ). The diet influences fertility in several ways. Excess of rumen degradable proteins, apart from negative energy balance, negatively affects reproductive activity. Conversely, some nutrients (i.e. some @entity1474 or some @entity1522 ) seem to show positive effects on fertility. Finally, the relationship between health status, often compromised during the transition period, and fertility efficiency is discussed. The release of cytokines seems to be related directly and indirectly (mainly by the change in usual hepatic metabolism to the malfunction of reproductive apparatus. Quick recovery of reproductive activity requires the adoption of strategies around calving to cover the higher environmental and nutritive requirements and to prevent disorders of any kind.
