Effect of selection for phagocytosis in dwarf chickens on immune and reproductive characters

In current study, phagocytosis product (PP) of peripheral blood monocytes was detected among 920 dwarf chickens (460 per sex) at 20 wk of age, and based on discrepancies of PP, the flock was grouped (the highest group, the medium group, and the lowest group). Then serum hemagglutination inhibition antibody titers and subpopulations of T-lymphocytes of each group were examined after inoculations of avian influenza virus H5N2 inactivated vaccine (20 wk of age), avian influenza virus H9 inactivated vaccine (24 wk of age), and Newcastle disease virus-egg drop syndrome virus bigeminal inactivated vaccine (28 wk of age), respectively, to study the relationship between PP and immune response. To gain insight into effects of selection for PP on number of eggs, mean egg weight, fertilization rate, hatchability, and rate of healthy chicks, 9 (3 x 3) mating combinations were conducted. The results showed that (1) selection for higher PP in both sexes benefited to humoral immunity but not CD8(+) T-lymphocyte mediated immunity in dwarf chickens; (2) there were effects of selection for higher PP in hens on fertilization rate (P < 0.05), hatchability (P < 0.05), rate of healthy chicks (P < 0.05), and level of IgY antibody (P < 0.0001); however, hens' PP had no effects on number of eggs (P > or = 0.05) or egg weight (P > or = 0.05) and cocks' PP had no effect (P > or = 0.05) on any trait mentioned above. The results indicated that phagocytosis of peripheral blood monocytes might be an indicator of humoral immunity in dwarf chickens; furthermore, selection of hens with higher PP was not only beneficial to fertilization rate, but also benefited to hatchability and rate of healthy chicks in that the hens had stronger humoral immunity, which might contribute to maternal antibody in eggs.