Dietary polyunsaturated fatty acids significantly affect laying hen lymphocyte proliferation and immunoglobulin G concentration in serum and egg yolk

Forty eight (48) Single Comb White Leghorn laying hens 24 wk of age were ho used 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 bl ood lymphocytes were obtained from six birds and assayed for polyclonal mit ogen Con A-induced proliferative response and the proportions of lymphocyte subsets. The IgG concentration in serum and egg yolk was also measured. Fe eding 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 de crease of C20: 4n-6 in spleen lymphocytes (P < 0.05). The highest enrichmen ts 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 hig h n-3 PUFA diets CLO and FO). The LO diet increased (P < 0.05) the IgG conc entration in laying hen serum. The SO diet reduced (P < 0.05) IgY content i n egg yolk. Dietary fatty acids did not affect (P > 0.05) the proportions o f lymphocyte subsets in spleen and blood lymphocytes. It is indicated that the ratio of n-6 to n-3 PUFA plays a major role in modulating cell-mediated and humoral immune responses of laying hens, and various n-3 fatty acids p ossess different potencies of immunomodulation.