Ovarian activity and embryo yield in relation to the postpartum period in superovulated dairy cows

The aim of this study was to evaluate superovulation response in cows at various postpartum periods (early postpartum period up to 3.5 months; middle postpartum period 3.7–7 months; later postpartum period above 7.5 months after calving). The data included observation of 55 Holstein cows superovulated at one farm in the Czech Republic during the years 2010 and 2013. Reproduction traits (dependent variable) were represented as number of the corpora lutea, number of transferable embryos, morulae, blastocysts, total number of embryos and embryo recovery. For statistical evaluation we used the PROC GLM of SAS？ with fixed effect - breeding value of milk production. The study results show significant differences (P < 0.05–0.01) in the three postpartum periods (early, middle, and later postpartum periods) and the number of corpora lutea (4.6; 7.4; 10.8), number of total embryos (3.2; 2.9; 6.5) and transferable embryos (1.8; 1.7; 4.4). Effective timing of embryo transfer in the later postpartum period resulted in greater ovarian activity and embryo yield compared to early lactation periods.