Age and Body Condition Influence the Post-Prandial Interleukin-1β Response to a High-Starch Meal in Horses

SIMPLE SUMMARY: In horses, consumption of meals rich in nonstructural carbohydrate content transiently increase plasma concentrations of the pro-inflammatory cytokine interleukin-1β. The current experiment provides evidence that age and body condition score influence these results. For instance, younger and leaner horses only experienced this response after regular and prolonged intake of high-starch meals, whereas older and heavier conditioned individuals experience elevated post-prandial interleukin-1β concentrations on day 1 of feeding and thereafter. ABSTRACT: Older horses and those prone to obesity may be at a higher risk for inflammation than younger and leaner counterparts. Previous research indicated a postprandial elevation in plasma concentrations of interleukin-1β (IL-1β), a pro-inflammatory cytokine, after consuming 1.2 g of non-structural carbohydrates/kilogram of body weight. However, these studies utilized horses of mixed age and body condition. The current study evaluated post-prandial IL-1β concentrations in horses specifically comparing lean to over-conditioned and middle aged to older. Our results suggest that at least two weeks of daily consumption of a high non-structural carbohydrate diet is required to induce a post-prandial increase in IL-1β concentrations in younger and leaner horses. In opposition to this, older and over-conditioned horses experience plasma increased on the first day of feeding and thereafter. Feeding management practices of older and over-conditioned individuals should emphasize lower non-structural carbohydrate intakes and further research should elucidate mechanisms of IL-1β activation.