ABSTRACT
Dairy cattle industry has gone through a series of changes during the last decades to improve competitiveness. However, this has correlated to a detriment in reproductive parameters. Efforts in improving and understanding this situation have meant in practice changes in many fields. Milestones have been: (1) a deeper study and understanding of the estrus cycle of the cow, with the development of synchronization and resynchronization protocols more and more detailed and with improving fertility results after insemination; (2) better insight of how cow’s parity affects reproduction; (3) the consideration of the length of the voluntary waiting period as an essential decision in order to maintain an optimal reproductive efficiency in farms; (4) the understanding of the process and relevance of the pregnancy loss during the early fetal phase; (5) improvement in estrus detection rates through novel technologies. These advances in technology have resulted also in earlier and more precise pregnancy diagnoses.
But reproduction control alone is not enough. Nutrition, genetics, and welfare have a deep effect on reproductive performance. A better 88understanding of the energy during the production cycle and its effects have been pivotal in the improvement of dairy cattle fertility in high-yielding animals. In recent years, fertility has been added as a trait to be taken into account in selection programs, since they are fundamental for maintaining farm’s profitability. Animal welfare, with growing importance in animal production, has been focused on an increase of published studies, studying the effect of stress (social, environmental) on reproduction, helping to give strategies to minimize it or even to void it.
All in all, changes in veterinary advice in farms have been accomplished by this better understanding of the dairy production systems, transforming the trend of reproductive efficiency up to figures even better than the historically 50% fertility after artificial insemination.
