ABSTRACT
Approximately 150 million households around the world produce milk with up to one billion people deriving their livelihood from the dairy sector. Concurrent with increasing milk production, dairy cow fertility is generally declining in North America and elsewhere. Breeding and management strategies to improve reproductive efficiency in dairy cattle a cause-and-effect relationship. The cow-to-person ratio usually increases with herd size, which may reduce reproductive efficiency. Therefore, it is essential to assess reproductive performance, identify key problems and deficiencies, and plan and deliver corrective actions. An excellent attitude, interest and knowledge are extremely important for achieving reproductive success in dairy herds. Vaginal bleeding during metoestrus is more common in heifers than in cows and is attributed to extravasation of blood after oestrogen concentrations decrease. Many factors, either independently or through their interactions, can influence reproductive efficiency. Breeding soundness evaluation should be performed by an experienced veterinarian before first using a bull and subsequently perhaps once annually.
