Seasonal results of transfer of fresh and frozen embryos and the effectiveness of superovulation in cows

Seasonal differences were found in the rate of fertilisation in 1641 cows implanted with fresh embryos. The rate of fertilisation was higher (P<0.01) than the respective mean values in October, January, April, June and February and lower (P<0.01) in July and November. However, the rate of fertilisation differed insignificantly in cows implanted with frozen embryos. The month of superovulation significantly affected the number of produced embryos and oocytes, embryos suitable for transfer and total embryos; the number of embryos was lowest in Summer, and highest in January, February, and March.