Effect of dietary polyunsaturated fatty acids ratios on immune response of laying hens

In order to study the effects of different polyunsaturated fatty acids (PUFA) ratios on the immune responses of laying hens, one hundred and sixty eight thirty week old laying hens were randomly assigned to ten diets containing five ratios (1∶1, 1∶4, 1∶8, 1∶16, 1∶32) n 3/n 6 PUFA supplemented with 30 or 300 mg/kg VE. Laying hens were injected with BSA at week 5 and week 7, antibody titers were measured at 10 d after primary and secondary challenge respectively. Concanavalin (ConA) and lipopolysaccharide (LPS) stimulated proliferation of lymphocyte in blood and IgY concentration of egg yolk were assessed at week 5 and week 10 respectively. At week 9, plasma IgG concentration was determined at 6 h, 12 h and 24 h after LPS was injected. Results demonstrated that as the ratios of n 3/n 6 decreased, anti BSA titers decreased significantly (P0.05), egg yolk IgY concentration also decreased but unsignificantly (P0.05). Ratios of n 3/n 6 and VE added level in diets can also affect IgG concentration of plasma. As the ratios of n 3/n 6 decreased, lymphocyte proliferation of blood to ConA increased significantly (P0.05) at week 10. N 3 to n 6 ratio at 1∶1 to 1∶8 can increase the immune responses of laying hens.