Dietary polyunsaturated fatty acids alter lymphocyte subset proportion andproliferation, serum immunoglobulin G concentration, and immune tissue development in chicks

The effects of fat source on immune response of the offspring of the Single Comb White Leghorn laying hens were investigated. The laying hens were fed for 6 wk with a wheat-soybean meal basal diet with added sunflower oil (SO ), animal oil (AO), linseed oil (LO), or menhaden fish oil (FO) at 5% (wt/w t). Upon hatching, the chicks (30/group) were given the same types of diets for 8 wk. The dietary SO, AO, and LO provided different n-6 to n-3 polyuns aturated fatty acids (PUFA) ratios. The FO and LO had ratios of n-6 to n-3 PUFA that were close but had different components of n-3 PUFA. The results demonstrated that the chicks fed LO or FO had significantly lower (P < 0.05 ) splenocyte proliferative response to ConA than the chicks fed SO or AO at either 4 wk or 8 wk of age, with a stronger (P < 0.05) suppressive effect produced by LO at 4 wk. A significantly lower (P < 0.05) splenocyte respons e to PWM was produced by the chicks fed AO, LO, and FO compared with the ch icks fed SO at 8 wk. The thymus lymphocyte proliferation in response to Con A at 4 wk was lower (P < 0.05) in the chicks fed AO, LO, and FO than in the chicks fed SO. Both LO and FO elevated (P < 0.05) the proportion of IgM(+) lymphocytes in spleen, but only FO increased (P < 0.05) the serum IgG conc entration. The LO elevated (P < 0.05) the percentage of CD8(+) T-lymphocyte s but not the ratio of CD4(+) to CD8(+) cells (P > 0.05) in spleen. Growths of thymus, spleen, and bursa were impacted significantly (P < 0.05) by the amount of dietary PUFA, the ratio of n-6 to n-3 fatty acids, and n-3 PUFA components.