ABSTRACT
Small ruminants from mid and high latitudes have a seasonal pattern of reproductive activity. These animals are sexually active during short days (autumn-winter), while during long days (spring), they enter a period of sexual rest-a mechanism of adaptation that allows birthing and lactation to occur at a time (normally spring) more favorable in terms of climatic conditions and food and water availability. Domestication has nearly abolished seasonal reproduction in cattle and pigs, but it is still seen in most breeds of sheep and goat originating from higher latitudes [1-4]. Melatonin has been shown as the hormone that controls such reproductive activity.
