Effect of Presuperovulatory Treatment of Buserelin on Superovulatory Response and Embryo Recovery in Cattle under Subtropical Conditions of Meghalaya

Abstract

An experiment was conducted with 24 healthy cyclic cows between 2^nd to 5^th lactation by under intensive system of rearing. The animals were randomly divided into Control (C) and Experiment (E) groups with 12 animals in each The control and experiment groups were again further subdivided in groups C₁ and C₂ & E₁ and E₂ comprising six in each. Onset of oestrus was considered as day 0 for superovulatory treatment. The animals of groups C₁ and C₂ & E₁ and E₂ were injected with 5 ml NSS (i/ml) & 21μg GnRH (i/m) (Buserelin acetate) on day 8 of the oestrous cycle, respectively. Each of the experimental animals of groups C1and E₁ was superovulated with 400 mg FSH (i/m) in divided and equal doses at 12 h intervals for four days on day 10 to 13 of the oestrous cycle and consequently, each of the experimental animals of groups C₂ and E₂ was also superovulated with 2000 I.U.PMSG injection (i/m) as single dose on day 10 of the oestrous cycle. PGF₂α 2ml was injected (i/m) at morning time on day 12 of oestrous cycle. At the superovulatory oestrus, all the animals were bred three times at 12 h intervals using frozen semen. The animals were examined per rectally on day 6 of the induced oestrus after first insemination to detect the superovulatory response. Flushing was performed on day 7 of induced oestrus to retrieve embryos from the superovulated cows. In the present experiment, superovulatory response in GnRH treated groups of cows (groups E₁ and E₂) were found to be better as compared to that of the animals of control groups but the duration of induced oestrus (h) recorded in groups C₂ (49.02 ± 0.07 h) and E₂ (50.40 ± 0.27 h) were found to be significantly higher (P<0.05) than the value recorded in groups C₁ and E₁