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 µg 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 PGF2α with interval of 12 days combined with the male effect is efficient to induce luteolysis and estrus synchronization in hair sheep.

Short communication: estrus synchronization using progestogens or cloprostenol in tropical hair sheep.

The objective of the experiment was to compare the use of a PGF2α analogue (Cloprostenol) IM, with an intravaginal progestagen sponge, flurogestone acetate (FGA), and equine chorionic gonadotropin (eCG) IM application protocol. A total of 30 cyclical hair ewes (54.07 ± 0.5 kg live weight, body condition score 3.5 ± 0.5, and age 3 ± 1 years) were used. For the control group ewes (n = 15), intravaginal sponges (IS) impregnated with 20 mg of FGA were inserted for 12 days with 500 IU of eCG IM at sponges withdrawal. For the PG group ewes (Treatment group n = 15), two injections of Cloprostenol (75 mcg) were given 12 days apart. The presence of estrus was detected using two rams with 8 h interval beginning at the end of the treatment. Progesterone concentrations in blood were measured by solid phase radioimmunoassay. A student's t test was performed to analyze the duration of estrus and the interval between the ends of the treatment and the onset of estrus (ET-OE) presentation. Progesterone levels were compared with two-way ANOVA, with treatment, and day of menstrual cycle as fixed factors. Treatment costs ratio was calculated by dividing the total costs of FGA IS application between total costs of Cloprostenol application. Significant differences (P < 0.05) were found in the (ET-OE) interval and estrus duration. For the control group, estrus was presented at 30 + 8.2 h; in treatment group, at 44 h after the last application, duration of estrus was 54.9 + 8.34 h, and 41 + 1.83 h for the control and treatment group, pregnancy rates were 53.3 and 60.0 %, respectively. Significant differences (P < 0.001) were found from days 9 to 13 on Progesterone levels in both treatments. Treatment costs of Cloprostenol protocol were 2.63 cheaper than FGA including disposable material, biological products, and labor. It was concluded that Cloprostenol could be an effective tool in estrus synchronization in hair sheep in tropical areas.