Effect of the combination of male effect with PGF2α on estrus synchronization of hair sheep in Mexican tropic

The aim of this study was to evaluate the "male effect" at the end of protocol with prostaglandins (PG) on estrus synchronization of hair sheep during breeding season (November-December) in Yucatan, Mexico. Twenty female Pelibuey sheep (weighting 38.2 +/- 1.6 kg and body condition score of 2.5 +/- 0.5) were randomly distributed in two groups (n = 10). Group T1 (control, PG), two doses of 50 mu g of cloprostenol with 12 days between applications were applied; in the second group T2 (PG-ME), ewes received the same PG protocol plus the introduction of a male at the end of treatment. The interval of end treatment-onset of estrus was analyzed using survival test; the number of sheep with presence/absence of estrus was analyzed using Fisher's exact test. Ewes in estrus for groups T1 and T2 were 5 vs. 8, respectively. No significant differences were found as regards the interval end of treatment-onset of estrus (P > 0.05), as well as in total proportion of ewes with estrus and likewise in the duration of it (P > 0.05). We conclude that the protocol based on double dose of PGF2 alpha with interval of 12 days combined with the male effect is efficient to induce luteolysis and estrus synchronization in hair sheep.