RESUMO
The objective of this study was to determine the seasonal ovarian activity of domestic queens under the tropical conditions of southern Mexico (19° 30' and 21° 35' N latitude). A total of 250 reproductive tracts were evaluated, and the frequencies of queens with ovarian activity (oestrus, dioestrus or pregnant), anoestrus, pregnancies and ovulation rate by season of the year (spring, summer, autumn and winter) were calculated. Ovarian activity was observed throughout the year, but a significant reduction occurred during the winter; conversely, anoestrous cases were lower during spring and showed an increase during summer, autumn and winter. Pregnancies were most common during spring and decreased during summer, autumn and winter. Ovulation rate varied from 2.5 to 2.8 during the four seasons. Cystic endometrial hyperplasia, pyometra and ovarian follicular cysts were the most common lesions found. The results demonstrate that domestic queens are not seasonal in tropical conditions, but a clear effect of the season of the year reducing ovarian activity is present.