Lactobacillus plantarum and supernatant: vaginal health and reproductive parameters of ewes synchronized with fluorogestone or medroxyprogesterone acetate.

This study investigated the effects of Lactobacillus plantarum (LAC) and its cell-free supernatant (CFS) on vaginal health and reproductive performance in ewes. The ewes were synchronized using fluorogestone acetate (FGA) or medroxyprogesterone acetate (MPA) impregnated intravaginal sponges. A total of 196 Merino ewes were randomly assigned to four groups in a 2 × 2 factorial design. Intravaginal sponges remained for 14 days, and vaginal discharge, sponge weight change, estrus response, and pregnancy rates were evaluated. No adverse health effects were observed following intravaginal probiotic treatment. There was a tendency (p = 0.07) for higher sponge loss in the FGA group (13.2%) compared to the MPA group (5.7%). On the day of sponge removal, 90.8% of ewes exhibited vaginal discharge. Although not statistically significant, mean vaginal discharge scores were lower in LAC-treated groups compared to CFS-treated groups. While L. plantarum had no significant effect on vaginal discharge scores in the MPA group (40.7% in MPA + LAC vs. 41.7% in MPA + CFS for score 2; p > 0.05), it significantly reduced purulent/hemorrhagic discharge in the FGA group (29.7% in FGA + LAC vs. 47.6% in FGA + CFS; p < 0.05). Estrus initiation occurred significantly earlier in the FGA group (36.8 ± 1.9 h) compared to the MPA group (49.1 ± 1.2 h; p < 0.01), although neither the probiotic treatment nor its interaction with progestagen type significantly influenced estrus timing. Pregnancy rates were significantly higher in the FGA + LAC (71.7%) and FGA + CFS (75.6%) groups compared to the MPA + LAC (49.0%) and MPA + CFS (50.0%) groups (p < 0.01). Our findings suggest that FGA-based synchronization improves pregnancy rates, while treatment with L. plantarum may enhance vaginal health, providing a potential non-antibiotic approach for reproductive management.