In Vitroenergy Requirements of in Vitro and in Vivo Derived Embryos of Cross Bred Cows Synchronized and Super Ovulated with Crestar and Porcine Follicle Stimulating Hormone

The considerable progress made during the last decade in the development of the synchronization and superovulatory responses in animals and this worked was plane to study on the cross bred cows and the characterization of energy requirements of the pre implantation embryos from the 8- cell embryos onward after being produced invitro and invivo. Animals were kept in different private farms under strict supervision of the JahadKeshavarzi and government veterinary section in the Damghan city, Semnan province in Iran as a joint work carried out by the Zabol veterinary college and Haryana Agricultural college , India . Cross bred cowsin winter (n=12) and summer (n=12) seasons between 2-5 years of aged were assigned randomly to receive a total dose of 75 International Unites of Super-ov(FSH-P)for 3 days in a descending -orders from Day -2 through Day 0 (-day of implant removal) to induce superovulation . Estrus synchronization was done by insertion of a 3 mg synthetic progestogene (Crestar) on the external surface of the ear for 14 days. In the middle of heat, after first mating with fertile bull, each cow was injected with 2.5 mL of receptal(Gn-RH) to ensure that the cows ovulated . Non invading embryo collection wasdone on Days 6 and 8 post estrus (Day0) and collected embryos were subjected to comparison of energy requirement by the same stage of in-vitro derived embryos. A majority of cross bred cows (19/24) exhibited estrus within 8 hr after implant removal . Theeffect of the seasons on the CL numbers, un-ovulated follicles and overall ovarian activity, estrus behavior, super ovulation and embryos quality for summer and winter seasons were recorded. While the pattern of energy requirement from the 12 -cell stage onward was constant among invitro and invivo derived embryos, lower ratio ofpyruvate substratewas preferred by the embryos in vitro. Lactate consumption reached up to 50% of pyruvate level,except at8- cell and early morula stages which required glucose, and glucose concentration has steady increased up to blastocysts stages.Oxidation and CO2 production of lactate invitro was significantly higher as compared toin vivo. Low viability of collected embryos at the morula and blastocysts stages was due to the thawing of freeze sperm and fertilization invitro and after embryo transfer into the receiver uterus, but level of CO2 production from glucose after freezing process in in vitro remained unchanged.