The Impacts of Protein Supplementation and Semen Exposure on Uterine Cytokines in Beef Heifers

Reproductive efficiency is largely impacted during heifer development which generally requires nutrient supplementation for proper maturation. Nutritional status can also influence inflammation within the reproductive tract. Therefore, we hypothesized that cytokine concentrations in uterine luminal fluid (ULF) will be impacted by protein supplementation following artificial insemination (AI). Commercial heifers (n = 60) were utilized to determine the effects of protein supplementation and AI on cytokine concentrations in ULF. Heifers were randomly assigned to one of three supplemental treatments: 1) CON (10% crude protein [CP]), 2) P20 (20% CP), and 3) P40 (40% CP). All heifers underwent estrus synchronization and ULF was collected 14 d after insemination. Cytokine profiles were constructed in MetaboAnalyst 5.0 and R Studio was used for individual cytokine analyses. Control heifers had increased ( P = 0.05) MIP-1β concentrations (148.7 ± 123.9pg) over P20 heifers (42.3 ± 123.9pg) and P40 heifers (75.5 ± 123.9pg) were intermediate. Semen exposure (1877 ± 550pg) tended ( P = 0.06) to increase concentrations of IP-10 compared with heifers who were not inseminated (1556 ± 550pg). In conclusion, protein supplementation and exposure to semen had a limited impact on the cytokine profiles and individual cytokine concentrations in the ULF of heifers following AI but did identify three cytokines providing potential targets important in early gestation.