Effects of dietary supplementation of pioglitazone on metabolism, milk yield, and reproductive performance in transition dairy cows.

The objective of this study was to investigate the effect of dietary supplementation of pioglitazone (PGT), a specific ligand for PPARγ, on metabolic dynamics, milk production, and reproductive performance of transition dairy cows. Eighty multiparous Holstein cows in their second or more lactations were blocked by the calving date and parity and assigned randomly to four dietary groups (n = 20 cow/treatment) including control (no PGT-/-), supplemented with PGT (6-mg PGT/kg body weight) from Day -14 to +21 relative to parturition (PGT+/+) or only during prepartum (PGT+/-) or postpartum periods (PGT-/+). Postpartum body condition score and body weight loss decreased (P < 0.05) in all PGT-supplemented groups. Milk yield was not affected by PGT supplementation (P > 0.05). Percentage of milk fat decreased (P < 0.05) in all PGT-treated groups; however, milk fat yield was lower (P < 0.05) in PGT (+/+) and PGT (+/-) groups compared with PGT (-/-). Peripartum (Day -7 to +7) concentrations of plasma nonesterified fatty acids and β-Hydroxybutyrate decreased in PGT (+/+) but not in the PGT (-/-) group (P < 0.05). During the postpartum period, PGT reduced (P > 0.05) plasma concentrations of nonesterified fatty acids in all PGT-treated groups but did not affect β-Hydroxybutyrate level. Plasma concentrations of triglycerides decreased in all PGT-supplemented groups. Supplementation of PGT increased the peripartum concentrations of plasma glucose in PGT (+/+) and PGT (+/-) groups compared with control. Plasma concentrations of insulin-like growth factor 1 were higher in PGT (+/+) compared with the control group during both the peripartum and postpartum periods. Plasma concentrations of growth hormone and insulin were not affected by PGT treatment (P > 0.05). Mean days to ovulation were lower in PGT (+/+) and PGT (-/+), and the proportion of cows ovulating by Day 14 postpartum was higher in PGT (+/+) compared with control. Days open were shorter in PGT (+/+), PGT (+/-), and PGT (-/+) groups compared with control. However, the proportion of pregnant cows at 120 days in milk were higher in all PGT-supplemented groups. The results showed positive effects of dietary supplementation of PGT, especially supplementation during both the prepartum and postpartum periods, on metabolic dynamics, ovarian function, and reproductive performance in transition dairy cows.