Abstract
It is documented that the reproductive performance of postpartum dairy cows is influenced by both internal and external factors. One of the most important reproductive performance indices is the first ovulation postpartum. This review aimed to describe factors affecting first ovulation postpartum in dairy cows, particularly those raised under tropical climates. Negative energy balance and its consequences; metabolic disorders; uterine pathology; udder health; lameness; and heat stress are discussed for their potential effects on the first ovulation postpartum. Understanding the underlying mechanisms of those affecting factors would assist in justifying the treatment and prevention plans in order to optimize the reproductive performance of postpartum dairy cows.

Key words: Dairy cows, First ovulation, Heat stress, Reproduction, Tropical condition