Abstract

Reproductive efficiency in dairy cows has been decreasing in recent years, in parallel with the increase in milk production per cows and the intensification of dairy systems. Reproductive efficiency in dairy herds has a marked effect on profitability. Several factors influence reproductive performance, the important ones being accurate detection of oestrous using efficient systems with low input. Appropriate knowledge of cow behaviour during oestrous, evaluation methods and modification factors is important to design observation routines of heat detection and determine the precise timing for artificial insemination. This paper reviews the literature on this subject from the first descriptive reports to the latest results.