| Trial one: Objective was to determine the effects of duodenal infusion of a highα-linolenic acid (LNA) on the immune function of lactating dairy cows. Four primiparous lactating Chinese Holstein cows fitted with duodenal cannula were administered 2 treatments in a crossover design: rich-α-linolenic acid infusion at varying concentrations (0, 100, 200, 300, and 400 g/d) vs. basal infusate control. Blood was collected and serum IgA, IgG, IgM, prostaglandin E2 (PGE2) and Th1/Th2 cytokines were determined. Results showed that increasing the supply of LNA to the small intestine of dairy cows linearly increased serum IgG and quadratically enhanced interferon-γ(P < 0.05), whereas the concentrations of PGE2 declined linearly (P < 0.05) and that of interleukin (IL)-4 tended to decrease (P = 0.08). No difference was observed in serum IgA, IgM and other cytokines, such as IL-2, IL-6 and IL-10. This study demonstrated that post-ruminal infusion of LNA affected the na?ve T lymphocytes and modified the secrection of Th1/Th2 cytokines, which showed the immunomodulatory properties of LNA.Trial two: Evaluated effects of duodenal infusion of fatty acids with 18 C (18-C FA; C18:0, C18:1, C18:2 and C18:3) on immunity of dairy cows. The total concentration of immunoglobulin (Ig) in serum, T lymphocyte subsets in peripheral blood, the acount of white blood cell (WBC) and body temperature were determined. Duodenal infusion of 18-C FA did not affect Ig in serum and body temperature. Duodenal infusion of C18:2 tended to increase the amount of CD4+T lymphocyte. Duodenal infusion of C18:3 and C18:2 decreased the acount of WBC significantly. Duodenal infusion of C18:1 tended to increase the acount of monocyte. Duodenal infusion of C18:3 and C18:2 increase and regulate immunity of dairy cows.
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