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

Abstract

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.

Cow metabolic status assessed from fat/protein ratio in milk affected ovarian response and number of transferable embryos after superovulation

“…These differences in metabolic status could be the reason behind better results for the group with a low F/P ratio than for the group above 1.3, but worse compared to the group with an ideal F/P ratio of 1.1 to 1.3. The optimal timing of embryo flushing seems to be outside of the deep NEB period, as was also confirmed by Stadnik et al (2017), when they observed that timing of embryo transfer in the later postpartum period resulted in greater ovarian activity and embryo yield compared to early lactation periods. Noya et al (2020) made the opposite finding in their nutritional experiment.…”