Forty eight (48) Single Comb White Leghorn laying hens 24 wk of age were housed in cages and were fed wheat-soybean meal based diets with added oils [sunflower oil (SO), animal oil (AO), linseed oil (LO), or fish oil (FO)] at 5%. After 5 wk on experimental diets, spleen lymphocytes and peripheral blood lymphocytes were obtained from six birds and assayed for polyclonal mitogen Con A-induced proliferative response and the proportions of lymphocyte subsets. The IgG concentration in serum and egg yolk was also measured. Feeding LO and FO resulted in an increase in longer-chain n-3 polyunsaturated fatty acids (PUFA) (C20:5n-3, C22:5n-3, and C22:6n-3) with a concurrent decrease of C20: 4n-6 in spleen lymphocytes (P < 0.05). The highest enrichments of the longer-chain n-3 PUFA were achieved by feeding FO. The content of C20: 4n-6 was higher (P < 0.05) in the lymphocytes of hens fed AO and SO. Subsequently, Con A-stimulated proliferation of spleen and peripheral blood lymphocytes were significantly suppressed (P < 0.05) in the chicks fed high n-3 PUFA diets (LO and FO). The LO diet increased (P < 0.05) the IgG concentration in laying hen serum. The SO diet reduced (P < 0.05) IgY content in egg yolk. Dietary fatty acids did not affect (P > 0.05) the proportions of lymphocyte subsets in spleen and blood lymphocytes. It is indicated that the ratio of n-6 to n3 PUFA plays a major role in modulating cell-mediated and humoral immune responses of laying hens, and various n-3 fatty acids possess different potencies of immunomodulation. Key words: Laying hens, n-3 polyunsaturated fatty acids, lymphocyte proliferation, immunoglobulin G, immunoglobulin Y
The sequence of the Mycoplasma arthritidis superantigen, MAM: identification of functional domains and comparison with microbial superantigens and plant lectin mitogens.
