Effect of GnRH on Enhancement of Pregnancy Rates of Artificial Insemination in Cross-Bred Cattle
Keywords:Crossbred cattle, Estrus, GnRH, Pregnancy rates
Though large number of cross-bred cattle are available, their productivity still remained marginal due to low conception rate and more repeat breeding problems with artificial insemination (AI). Therefore, the aim of the study was to evaluate the effect of supplementation of different doses of Gonadotropine Releasing Hormone (GnRH) along with AI and twelve days post AI in cross-bred dairy cattle on enhancement of pregnancy rates. Fifty five cross-bred dairy cattle that exhibited estrus and apparently healthy were randomly selected. The cattle were randomly divided into five equal groups, G1 (n=11) cattle were treated intramuscularly with each 20 µg GnRH, Buserelin acetate, at the time of AI. G2 (n=11) cattle have the same procedure as G1 but with the dose of 10µg Buserelin acetate. G3 (n=11) cattle were given the 10 µg GnRH (Buserelin acetate) twelve days post AI. The G4 (n=11) cows were given double insemination with 6-12 hours interval. The last group was given a single service which was considered as the control group. Pregnancy diagnosis was conducted after three months rectally. The pregnancy rates were 72.72%, 63.63%, 54.54%, 45.45% and 36.36 % in the cattle grouped with G1, G2, G3, G4 and G5, respectively. The pregnancy rates of the treated groups were higher than the control by 36%, 27%, 18% and 9 % from the first to the fourth group, respectively. The first two groups showed a significant statistical variation (P<0.05). The other finding that was observed was that treated heifers became more responsive to the therapy than the treated cows with a significant variation (P<0.05). The study concluded that the supplementation of GnRH at the time of AI can enhance pregnancy rate; and is helpful and cost effective to minimize financial losses incurred from milk production lost, managemental, and feed cost; by reducing the calving interval and treating repeat breeding cases.
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