Delayed Ovarian Cyclicity Does not Reflect Blood Metabolites Irregularity in Postpartum Holstein Cows

An experiment was conducted to investigate the effect of different types of ovarian cycles on reproductive indices and blood metabolites in 61 Holstein cows. Blood samples were taken from each cow between day 12 and day 50 postpartum (PP). Serum progesterone concentrations were measured to determine the onset of luteal function and different types of luteal dysfunctions in cows. Serum glucose, cholesterol and blood urea nitrogen concentrations were measured in the cows with normal and abnormal ovarian cyclicity. In this study, 29 (47.5%) cows showed normal ovarian cyclicity with first luteal activity detected before day 50 days PP, whereas 32 (52.5%) cows showed abnormal cyclicity. Of the 32 cows with abnormal patterns, 13 (21.3%) had prolonged luteal phase (PLP), 7 (11.5%) had short luteal phase (SLP) and 12 (19.7%) had delayed first ovulation (delayed ovulation).Progesterone concentration at different times was considerably varied from day to another day (P≤0.01), while the main effect of the group on the progesterone concentration was significant (P≤0.01). Cows that had normal cyclicity showed earlier luteal activity (P≤0.01) and shorter interval to first ovulation (P≤0.01) compared to cows with abnormal cyclicity. There were no significant differences in different blood metabolites between cows with normal or abnormal cyclicity. In conclusion, a high percentage (52.5%) of the postpartum cows had abnormal ovarian cycles. The abnormal ovarian cycles reduced the reproductive performance of dairy cows, including the onset of luteal activity and interval to first ovulation. Blood metabolites were not associated with postpartum abnormal cycles in cows.