Aim.

This study looked to assess the effect of different oral doses of progesterone (P4) on estrus synchronization and ovulation of covies.

Methods:

The study was conducted in the high Ecuadoran tropical areas, on a commercial farm located at 2 500 meters above sea level. A total of 35 multiparous Peruvian female covies and five male covies were used in the experiment. The procedure consisted of five treatments: T1= 0.33mg/kg (n=7). T2=0.28mg/kg (n=7). T3=0.22mg/kg (n=7). T4=0.17mg/kg (n=7). T5=0.11mg/kg (n=7). The vaginal membrane aperture was evaluated on the last day (15d) of P4 administration every 24 hours (h). A vaginal cytology test was performed to establish the moment of ovulation, which helped determine the moment of estrus and ovulation. A simple ANOVA was performed to analyze the vaginal membrane aperture, the vaginal cytology, estrus, and ovulation. A 5% Tukey test was conducted for multiple comparisons.

Results:

The T1, T4, and T5 covies showed 100% vaginal membrane aperture, whereas T2 and T3 underwent 85.7% vaginal aperture, with a general mean of 94.3%. More than 50% vaginal cells from T1 were superficial at 37.7 ± 4.84 hours following P4 withdrawal; T2 and T3 needed 14.3 additional hours. Ovulation in T1 was observed at 85.7 ± 4.84 hours, with a value similar to T2 (88.0 ± 5.05 hours), and no differences between them (p>0.05). The T3 and T4 animals ovulated 20.6 hours after. However, the T5 animals needed more hours for ovulation (113.1 ± 4.42).

Conclusion:

The oral administration of 0.33 mg of progesterone for 15 days in a row helped synchronize estrus at 48 hours following the administration of progesterone.