PSIV-18 - Pro- and anti-inflammatory cytokines in the uterine environment throughout beef heifer development with supplemental protein

Nutrition is a major component in successful heifer development, influencing age at puberty and the uterine environment, therefore, impacting reproductive efficiency. Different diets can influence systemic inflammation, however, the effect on uterine cytokines has not been determined. Our objective was to evaluate the effect of varied levels of dietary protein on inflammatory cytokines in the uterine environment of developing heifers. Commercial Angus heifers (n = 60) were blocked by body weight, then allocated to receive one of three dietary protein supplementation treatments (n = 20 per group, n = 5 per pen): 10% crude protein (CP; 100% corn), 20% CP [75% dried distillers’ grains (DDG) 25% corn], or 40% CP (75% soybean meal 25% DDG). Supplements were provided four times weekly for six months with ad libitum native grass hay, mineral supplement, and water. Body weight, BCS, and blood was taken every 14d. Uterine fluid was collected every 28d to determine presence of cytokines IL1α, IL1β, TNFα, IFNγ, IL10, IL4, and IL6. The GLIMMIX procedure (SAS 9.4) was used with fixed effects of supplementation, month, and their interaction; random effects of block, interaction of block and supplementation, and heifer within the interaction; and repeated measure of month. Concentrations of IL1β, TNFα, IFNγ, and IL10 shifted throughout development (P < 0.0002). Cytokine IFNγ was also affected by month of development (P = 0.002) and tended (P = 0.06) to decrease as CP increased. Presence of each cytokine was then recorded as binary and analyzed by the frequency procedure (SAS 9.4) to determine a uterine cytokine profile. Pro-inflammatory cytokines IL1α, IL1β, and TNFα occurred together more frequently following the beginning of supplementation. In conclusion, inflammatory cytokines shift throughout heifer development, potentially leading to differences in future reproductive success. Further research is needed to determine the dietary influence for optimal uterine environment development.