244 Fertility Outcomes Associated with Reproductive Tract Cytokines and Microbiota in Postpartum Beef Cows

Local immune activity in the reproductive tract is crucial in the response to uterine diseases, normal reproductive functions, and establishing pregnancy. Few studies have evaluated the influence of the local immune environment of the reproductive tract on fertility outcomes. The objectives were to 1) evaluate reproductive cytokine concentrations in postpartum cows undergoing estrus synchronization followed by timed artificial insemination (TAI) and 2) correlate reproductive bacterial communities with cytokine concentrations. Angus cows (n = 20) were subjected to a 7-Day Co-Synch protocol with pre-synchronization beginning 21 days prior (d -21) to TAI (d 0). Uterine and vaginal flushes were collected on d -21 and -2. Pregnancy was determined by transrectal ultrasound on d 30. Bacterial community profiling and analyses were conducted targeting the V1 to V3 hypervariable regions of the 16S rRNA gene. Cytokine concentrations for interleukin (IL)-1b, IL-6, IL-10, and transforming growth factor beta (TGF-β) were determined by commercial ELISA kits. Concentration data were analyzed using PROC MIXED and correlations using Pearson correlation in SAS. No differences were detected in vaginal samples (P >0.05). No differences in IL-10 or IL-1b concentrations were detected in uterine samples (P >0.05). Uterine TGF-β concentrations were greater in resulting pregnant than non-pregnant cows (44.0 ± 13.4 pg/mL vs 14.7 ± 4.9 pg/mL; P = 0.05). Uterine TGF-β was negatively correlated with the relative abundance of genera Treponema (r = -0.668; P = 0.05) in resulting non-pregnant cows on d -21. Uterine IL-6 concentrations were greater in resulting non-pregnant than pregnant cows (198.7 ± 21.8 pg/mL vs 144.3 ± 16.1 pg/mL; P = 0.05). Uterine IL-6 and the relative abundance of genera Butyrivibrio were positively correlated (r = 0.742; P = 0.02) in resulting non-pregnant cows on d -21. These results suggest possible relationships between uterine bacterial communities and cytokines prior to TAI that may ultimately affect fertility outcomes in beef cattle.