Preliminary study of factors affecting the superovulatory response of high producing dairy cows superstimulated regardless of the stage of estrous cycle in Egypt

This work was conducted as a first time commercial production of embryos from lactating Holstein and Brown Swiss cows using multiple ovulation embryo transfer (MOET) technology in Egypt. We studied factors affecting the superovulatory response (SR) in superovulated cows and effects of propylene glycol (PG) on embryo quality. Daily milk production at flushing had significantly negative effects on SR and embryo yields in superovulated cows. In addition, Brown Swiss cows had better SR than Holstein cows. Moreover, cows having more than 3 parities yielded better response, compared to cows in the first three parities. However, factors such as body weight at flushing, body condition score (BCS) at flushing and days in milk (DIM) at flushing did not have any association with SR in cows. In addition, drenching of PG prior to and during the superovulatory treatment improved SR (Right CL number, P < 0.05; Left CL number, P < 0.05), total embryos per flush (P < 0.05), first grade embryos per flush (P < 0.01) and tended to improve transferable embryos (P = 0.13) and second grade embryos per flush (P = 0.11). However, it tended to increase the number of degenerated embryos per flush (0.06). In conclusion, commercial production of embryos from lactating Holstein and Brown Swiss cows regardless of stage of estrous cycle by MOET proved successful under Egyptian conditions. Milk yield was negatively associated with SR and embryo yields in superovulated cows. Moreover, drenching of PG prior to and during the superovulatory treatment improved SR and embryo yields