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Immunomodulation of Supplemental Omega-3 Fatty Acids in Horses Delivered Via a Commercially Available Molasses Lick Block
T.M. Horne, J.S. Drouillard, T.L. Douthit, C.I. Vahl, J.M. Lattimer
Kansas State University, Manhattan, KS
An experiment was conducted in which supplemental omega-3 (O3) and omega-6 (O6) fatty acids (FA) were provided ad libitum via molasses lick blocks (MLB) to evaluate their immunomodulatory effects after horses were exposed to a period of stress. Supplemental O3 FA were provided via a MLB containing flaxseed and flaxseed oil and O6 FA were provided by a MLB containing sunflower oil. After 51 d of supplementation, horses were subjected to a 60-min trailer ride, 10-min canter in an automated horse exerciser, and a 2-h head tie. Blood samples were collected at 6 h before stress challenge events and at h 1, 6, 12, 24, 48, 72, 96, and 168 post-challenge (PC) and were analyzed for an array of immunological and hematological parameters. Nasopharyngeal flush (NPF) samples were collected 6 h before stress and h 12 and 72 PC. At the end of the sampling week, horses were crossed over to the opposite treatment and the supplementation and sampling protocols were repeated. Serum was analyzed for hematocrit (HCT), white blood cell (WBC), red blood cell (RBC), interleukin-17 (IL-17), immunoglobulin M (IgM), and immunoglobulin G (IgG) concentration, as well as differential cell count and platelet count. NPF samples were analyzed for IgA. Treatment did not affect serum or NPF parameters (P > 0.05). All parameters changed with time (P < 0.05), with the exceptions of IgM and IgG. Treatment by hour interactions were observed for serum RBC and HCT (P < 0.05), with serum RBC and HCT being more concentrated in O3 treated horses at h 72 compared to O6 treated horses In both treatment groups, a peak (P < 0.05) was detected at 6 h PC in HCT and RBC, whereas a peak (P < 0.05) was detected in WBC, neutrophil, and IL-17 concentrations in serum 1 h PC. Lymphocyte, eosinophil, and platelet concentrations were greatest 96 h PC (P < 0.05). Monocytes were most (P < 0.05) abundant 24 h PC, and IgA concentration in nasal fluid was greatest at 12 h PC (P < 0.05). There was no clear impact of omega-3 supplementation on immunomodulation in horses subjected to transport and exercise stress.