Progesterone concentrations during the estrous cycle in sheep in the Colombian tropics

Objective. Efficiency in heat detection, determination of the duration and type of estrous cycle and progesterone concentration in sheep racial biotypes in the high tropics was evaluated. Materials and methods. In 32 adult ewes, biotype Criolla, Hampshire, Romney Marsh and Corriedale, during the postpartum period, Heat Detection Efficiency - EDC, cycle type: Short - CC, Regular - CR and Long - CL, Cycle Duration was determined. Oestrus – DCE and progesterone concentrations – CP4. CP4 were assessed by ELISA technique. Statistical analysis used a completely randomized model and repeated measures over time. Results. The average EDC was 64.88%, presenting 35.12% CC, 59.92% CR and 4.96% CL. The average of regular DCE was 16.9±0.89 days. The Criollo group presented the highest ranges of variation of CP4, showing changes in its steroidogenic activity of the corpus luteum similar to that observed with the Hampshire group. Between days 4 and 12, the Romney Marsh group presented the lowest CP4., being similar to the behavior of the Corriedale group. Conclusions. CP4 increases from days 2 to 6, remaining high and constant between days 10-12, gradually decreasing until day 18, progressively evidencing a possible functional luteolysis that leads to structural luteolysis. The CP4 may be associated with adaptation phenomena of some racial groups, which affect the reproductive efficiency that is observed to be differentiated between them.