Journal of Veterinary and Animal Sciences (Jan 2008)
PATTERN OF INDUCED OESTRUS AND FERTILITY RATE FOLLOWING hCG INJECTION AT EARLY LUTEAL PHASE IN PGF2a TREATED REPEAT BREEDER COWS
Abstract
A total of 48 repeat breeder cows were divided into three groups viz., group 1, ll and Ill. Cows in group l and 11 were treated with 0.98mg of Tiaprost (PGF2a) on day 70 following natural oestrus (day 0). Group 111 cows, served as control without any treatment. A! was done at 72 and 96 h following PGF2a therapy in group I and ll. Group 111 cows were artificially inseminated twice at 24 h interval during natural oestrus. Group ll cows were injected with 1500 IU hCG on day four following first Al. There was cent per cent oestrus response in PGF2a treated cows. The mean onset of oestrus was 59.3810.81 and 59.63±0.74 h and the mean duration of induced oestrus was 28.50±0.56 and 27.50±0.70 h in group 1 and 11, respectively. In control, the mean duration of oestrus was 29.38±0.77 h. The occurrences of very good and good oestrus intensities were 12.50 and 87.50 (group I) and 25.00 and 75.00 (group ll and ll!) per cent. The first service conception rate obtained was 43.75, 37.50 and 18.75 per cent, in group 1, ll and Ill, respectively. It is concluded that administration of PGF2a on day 10 following natural oestrus may improve the conception rate in repeat breeder cows and that injection of hCG on day four after fixed time Al is unnecessary.
