Interaction between feed management systems and omega-3 fatty acid supplementation on bovine immunization parameters (VET1P.1116)

A trial was designed to investigate impacts of omega-3 fatty acid feeding regimes on bovine immunization responses. Dietary supplements contained either fish oil or microalgae as omega-3 fatty acid sources, and cattle were divided into 2 feed management systems; they either grazed pasture or were kept in barn tie stalls and fed total mixed rations (TMR). Cattle were immunized with keyhole limpet hemocyanin (KLH), a standard T cell dependent antigen. Dietary supplements and feeding systems influenced the response of cattle to immunization with KLH. Anti-KLH IgM, IgG and IgA antibody levels in serum were significantly higher in cattle grazing pasture than those fed TMR. Cattle consuming microalgae had consistently higher anti-KLH IgG2 and IgM antibody levels compared to cattle fed fish oil. Effects of omega-3 fatty acid supplements and TMR versus pasture-based diets were also apparent in cytokine profiles from spleen and cecal tissues. Levels of transforming growth factor-beta (TGF-β) were highest in cecal tissue of pasture-grazing cattle (P < 0.0001), and spleen TGF-β levels were highest in pasture-grazing cattle consuming microalgae (P = 0.0073).These findings suggest that effects of omega-3 supplements on bovine immunity are influenced by the feed management system, with heightened effects on antibody production observed with a pasture system relative to a confinement and TMR-based diet.