Rumen-protected glucose hastens uterine involution and increases numbers of ovarian follicles in early postpartum dairy cows.

The primary objectives were to investigate effects of feeding a new rumen protected glucose (RPG) on uterine involution and ovarian follicular dynamics in recently calved dairy cattle. From 4 to 30 d after calving, 16 Holsteins (first to third lactation, mean parity 1.75), were randomly assigned to be fed either a basal diet top-dressed with either 600 g rumen protected glucose (RPG group) or 600 g of the coating material and glucose (CONT group). Based on transrectal ultrasonography, conducted every 3 d starting 20 d after calving, the interval from calving to complete uterine involution was shorter in RPG versus CONT (27.1 vs 30.4 d, P < 0.01). Furthermore, based on transrectal ultrasonography conducted every 2 d, cattle fed RPG had more small (3.0-4.9 mm) ovarian follicles (2.96 vs. 0.9, P < 0.001) and more total follicles (5.26 vs. 2.85 P < 0.01). Feeding RPG increased serum insulin concentrations (4.59 ± 0.54 vs 3.13 ± 0.57, P < 0.05), but had no significant effects on serum glucose concentrations, dry matter intake or milk yield. In conclusion, we inferred that cattle fed RPG had increased glucose turnover that was responsible for higher insulin concentrations, faster uterine involution, and more ovarian follicles.