Effect of Different Doses of Hcg at Ai on Pregnancy Rates of Repeat Breeder Nili-Ravi Buffalo

The efficacy of different doses of hCG administered at the time of artificial insemination (AI) for the treatment of repeat breeder buffaloes was evaluated by using a total of 140 Nili-Ravi buffaloes. The animals were assigned at random to four treatments (n=35) administered i.m at the time of artificial insemination (AI) following estrus synchronization with a single dose of PGF(2)alpha. The treatments were, 3000 IU hCG (group A), 2250 IU hCG (group B), 1500 IU hCG (group C) and 2ml saline (control group D). AI was performed about 12 hours following the onset of observed estrus. Blood samples were obtained from all buffaloes 5 and 12 days after AI. The conception rate at first service in group A, B, C and D was 48, 28, 25, 17 percent respectively. Conception rate increased as the dose of hCG increased at first service. The differences between treatment A and other treatments were significant (P< 0.05). The treatment effects followed the same pattern at the second and third AI but the differences were not significant. Mean progesterone concentrations were significantly higher (P< 0.05) in animals that become pregnant to the first AI for between group A on day 5 (1.90 ng/ml) and day 12 (2.10 ng/ml) than treatments group B, C and D on day 5 (1.01-1.02 ng/ml) and day 12 (1.02-1.03 ng/ml). It was concluded that administration of hCG at the time of insemination increased progesterone concentrations and improved the pregnancy rate of repeat breeder buffaloes.