Changes in Vaginal Cytokines Concentrations during Artificial Insemination and Natural Service in Beef Heifers

Heifer development is crucial for the optimization of reproductive efficiency in beef production. Heifer development is largely influenced by nutrition, however, nutritional status can influence immunological responses crucial for reproduction. Commercial Angus heifers (n = 9) were utilized to elucidate the effects of sampling time, pregnancy status, and type of mating on individual cytokine concentrations and cytokine profiles in the vagina following breeding. A vaginal flush was collected by injecting 20 mL of sterile saline into the vagina via insertion of a Foley catheter and was collected on days 0, 7, 14, 21, 28, and 35. Cytokine profiles were analyzed using MetaboAnalyst 5.0 and one-way ANOVAs were performed in R Studio to identify differences in individual cytokines based on sampling time, pregnancy status, and type of mating. Cytokine profiles were different ( P = 0.05) 7 days after either mating type. Cytokines IL-1β, IL-17a, MCP-1, and TNFα were different based on the mating type and pregnancy status. Multiple cytokines, IL-1α, IL-1β, IL-6, IL-8, IL-10, IL-17a, VEGFa, and MIP1α, were different between days regardless of pregnancy status. In conclusion, vaginal cytokines differ based on pregnancy status, type of mating, and time which may be indicative of vital pathways that need to be activated for pregnancy.