Reproductive seasonality in creole hair sheep in the tropic.

The objective of the present study was to evaluate the annual ovulatory activity of hair sheep at 15° N. Nineteen Creole ewes with body weight of 40.8 ± 0.3 kg were used. The ovulatory activity was monitored for a year by quantifying progesterone concentrations in blood samples obtained from all the ewes every 7 days. The differences in monthly proportions of ewes with ovulatory activity were analyzed by the chi-square test. Ovulatory activity decreased from May to July and in September, and 42% of ewes ovulated year round. It is concluded that at 15° N, a high proportion of ewes is capable of ovulating throughout the year in the tropical southeastern region of Mexico.