EN
The objective of this study was to evaluate effect of the season on the yield and viability of embryos recovered from superovulated and flushed Holstein cows (n = 56). The embryo recovery rate (ERR, %) was determined as the proportion of totally flushed embryos (TFE, n) to the number of corpora lutea detected. The embryos were evaluated as transferable (TRANS) or non-transferable and analysed for occurrence of apoptotic cells (T+, TUNELindex) as well as actin cytoskeleton quality (ACG). TFE and ERR were the highest during spring vs summer (149 embryos, 59.6% vs 20 embryos, 37%; P < 0.001), while they insignificantly differed in autumn (57 embryos, 48.3%). The autumn embryos presented a higher proportion of TRANS (P < 0.05, +10.56% vs spring; +18.94% vs summer). The occurrence of apoptosis in these embryos was lower (–1.38 T+ cells and –1.75% T-index; P < 0.05) and the percentage of the best ACG was higher (+35%; P < 0.05). These findings identified autumn as the best season for collection of high-quality bovine embryos.