Effect of selection on humoral and in vivo cell mediated immune responses in broiler chicken

Immunocompetence of broiler strain PB-2 and random bred control line was compared as humoral response to T cell dependent antigen SRBC and in vivo cell mediated response to mitogen Phytohaemagglutinin (PHA-P). Immune response to sheep red blood cells was measured as HA; MER and MES titre at 0, 4, 9, 14, 21 and 28 days post primary inoculation (PPI). In both strains peak titre was observed at 9 days post primary inoculation. The control line had higher total, MER and MES titres at all intervals (except MES titre at 9 days PPI) after post primary inoculation than PB-2 strain. PB-2 females had significantly higher HA, MES titres at 9, 14 and 21 days PPI and MER titre at 14 days PPI than PB-2 males. While in control line, females had higher HA and MER titres at 4, 9, 14, 21 and 28 days PPI and MES titre at 9 and 14 days PPI. The in vivo cell mediated response as measured by T-lymphocyte proliferation response to mitogen Phytohaemagglutinin was higher in control line than broiler line PB-2.