AbstractsBiology & Animal Science

Every year the equine industry spends millions of dollars on research to enhance equine performance, whether it be reproductive or athletic. Equine nutrition is a leading contributor to equine performance and health, with poor nutrition and diet being associated with an ever-increasing incidence of metabolic related disorders. However, there is a lack of clinical markers to diagnose disease processes associated with poor nutrition or nutrient absorption. It has been well established that changes in nutrient intake can have a direct impact on health, but new evidence has emerged indicating that diet can influence endogenous miRNA and consequently gene expression. Also, recent research has identified the presence of exogenous plant miRNA in mammalian serum as a result of food consumption, but the role these miRNAs have on physiology is unclear. miRNAs are small, non-coding RNA molecules that post-transcriptionally regulate mRNA to silence gene expression via translational repression or degradation. We first hypothesized that diet-derived plant miRNAs can be detected in serum and tissue. For this study, twelve horses were randomly assigned to one of three groups (n=4/group) and fed alfalfa hay, extruded corn and alfalfa hay, or rice bran and alfalfa hay. Additionally, multiple tissues were harvested from four necropsied horses for detection of plant miRNAs in tissue. Our results reveal the presence of plant miRNAs in the serum and tissue of horses. Using an mRNA target prediction database, we were able to identify several potential mRNAs that could be regulated by exogenous plant miRNAs. These results suggest that diet-derived plant miRNAs enter into the circulation of the horse and are capable of being taken up by tissues. This data is important for understanding the role diet-derived plant miRNAs may have on equine biological processes. Furthermore, these results suggest a novel way in which plant miRNAs function as not only a nutrient in equine diet but also as a potential regulator of endogenous mRNA. Due to the large influence diet can have on the health of horses, we were then interested in investigating the role of diet on endogenous miRNAs in the horse. We hypothesized that either a rice bran (high-fat) or corn (high-non-structural carbohydrate) diet will alter the relative endogenous miRNA profile in horse serum exosomes. For this study we utilized the same serum samples collected from the feed trial horses in the previous study. Our results discovered 37 differentially expressed (P≤0.05) miRNAs in horses fed the corn diet high in NSC (starch and simple sugars) 23 days after feed treatment began. Pathway analysis of significantly different (P≤0.05) miRNAs indicated gastrointestinal disease, hepatic system disease, connective tissue disorders and inflammatory diseases as the primary predicted networks in which the differentially expressed miRNAs are involved. The horses fed rice bran (high-fat diet) exhibited 11 miRNAs that were differentially expressed on day 23. Cellular development, growth and…