Efficacy of Prostaglandin for Oestrus Induction in Sub-estrus Cows

Sub-oestrus cows were evaluated pre-rectally, cows having palpable corpus luteum on either of the ovaries were enrolled in the study. Out of eighty (80) sub-oestrus cows, forty (40) post-partum sub-oestrus cows (group-I) were treated with Prostaglandin (Dinoprost tromethamine 25 mg, I/M) and another forty (40) sub-estrus cows were kept as control animals (group-II). Observations regarding number of cows exhibiting oestrus after prostaglandin treatment, mean time interval for oestrus onset, oestrus duration and number of cows became pregnant in two groups were recorded. In treatment group-I, 33 cows (82.50 percent) exhibited oestrus following corpus luteum regression within four days after treatment. Five cows (12.50%) exhibited oestrus on second day (48 hours), 11 cows (27.50 percent) exhibited oestrus on third day (72 hours) and 17 cows (42.50 percent) exhibited oestrus on fourth day (96 hours) after prostaglandin treatment. The mean time interval required to show oestrus was 80.72±3.102 hours. The oestrus duration observed in group-I was 12–24 hours. The average estrus duration was 16.84±0.533 hours. 21 out of 33 (63.63 percent) cows were found pregnant. Overall conception rate was 52.50 percent. In control animals, fourteen cows (35.00 percent) exhibited subsequent cyclic oestrus at an average interval of 28.28±0.301 days after previous recorded oestrus. The duration of oestrus observed in this group was 18–24 hours. The average oestrus duration was 20.71±0.401 hours. Remaining cows showed no cyclical activity throughout the experimental period. Six out of 14 cows (42.85 percent) were found to be pregnant. Overall conception rate in control group was 15.00 percent.