BREED-ASSOCIATED DIFFERENCES IN OOCYTE RECOVERY AND IN VITRO EMBRYO PRODUCTION IN GAOLAO AND SAHIWAL CATTLE

Abstract

The present study was undertaken to evaluate and compare the in vitro embryo production potential of Gaolao and Sahiwal cattle using ovum pick-up (OPU) and in vitro embryo production (IVEP) techniques. A total of 16 OPU sessions were conducted, involving eight donors from each breed. Following follicular wave synchronisation and FSH stimulation, oocytes were recovered, graded morphologically, and subjected to in vitro maturation (IVM), fertilisation (IVF) and culture (IVC). A total of 126 oocytes were recovered, of which 62 developed into blastocysts, resulting in an overall blastocyst production rate of 49.20%. Breed-wise comparison revealed significantly (P<0.05) higher oocyte recovery in Sahiwal donors (101) than in Gaolao donors (25). Similarly, the mean number of oocytes recovered per donor was higher in Sahiwal (12.63 ± 2.96) compared to Gaolao (3.13 ± 0.67). Sahiwal donors also produced a significantly (P<0.05) higher mean number of blastocysts (6.63 ± 1.90) than Gaolao donors (1.13 ± 0.35). Although the blastocyst conversion rate was numerically higher in Sahiwal (43.37 ± 9.77%) than in Gaolao (31.40 ± 7.54%), the difference was not statistically significant (P> 0.05). A total of 62 blastocysts were produced, of which 28 were selected for embryo transfer due to the limited availability of recipient cows. Embryo transfer resulted in eight pregnancies, with an overall pregnancy rate of 28.57%. The pregnancy rate was numerically higher in Sahiwal (36.8%) than in Gaolao (11.1%), although the difference was not statistically significant. The findings indicate that Sahiwal donors exhibited better oocyte recovery and blastocyst production potential under the conditions of the present study compared to Gaolao donors.