Effects of hCG or GnRH Treatment on Embryonic Mortality and Reproductive Performance in Buchi sheep of Cholistan Desert, Pakistan

Abstract The present study was conducted on Buchi sheep at Government livestock farm, Jugaitpeer, district Bahawalpur. The objectives of this study were to investigates the genetic potential, birth and adult body weights, growth and turnover rates, and seasonal reproductive performance, the effect of Dalmazin (PGF2α) on synchronization, the effect of GnRH and hCG treatment given on the mating day on pregnancy rate, and embryonic mortality after plasma hormone concentrations and embryo development to improve litter size. Male lambs exhibited significantly higher (P<0.05) birth (3.40 ± 0.16 kg) and adult weights (61.67 ± 0.95 kg) compared to females (3.00 ± 0.00 kg and 39.67 ± 0.41 kg, respectively), along with faster growth and higher turnover rates. Seasonal variations showed superior pregnancy rates in spring (62.83%) but higher reproductive efficiency and lower mortality in autumn. In a second experiment, 30 ewes divided into hCG, GnRH, and control groups. hCG and GnRH groups were mated to ram at synchronized estrus by two injections of 2ml PGF2α analogue (Dalmazin) given at 11 days apart. The control group received only saline. The blood samples were collected from jugular venipuncture (3ml) with a disposable syringe from day 2 to 16 after treatment. Plasma progesterone concentrations detected by ELISA were higher (P<0.05) in sheep as compared with saline treated controls and improved reproductive outcomes. The hCG group showed the best performance with a litter size of 1.28%, no embryonic mortality, and increased twinning and fecundity rates. The GnRH group also demonstrated enhanced reproductive efficiency with a litter size of 1.25% and no embryonic loss. The control group had the lowest reproductive outcomes, including a higher embryonic mortality rate. Overall, hCG proved more effective than GnRH in enhancing progesterone levels, fecundity, and prolificacy in Buchi sheep.