ANALYSES OF IMMUNE RESPONSE TO Salmonella typhimurium VACCINE OF THREE BROILER CHICKEN BREEDS RAISED UNDER HARSH ENVIRONMENT OF THE TROPICS

Abstract

This study examined the body weights and immune response to Salmonella typhimurium vaccine of three popular breeds of broiler chickens (Arbor acre, Ross 308 and Cobb 500) reared in the tropics. A total of 75-day old chicks comprising 25 each of Arbor acre, Ross 308 and Cobb 500 broiler chickens were used for the study. The birds were inoculated with Salmonella typhimurium vaccine on day 14. Body weights were taken on days 7, 14, 21 and 28 from 12 birds from each breed while the blood samples were collected on day 14, 17 and 21 for immunological studies. Cobb 500 showed superiority in terms of body weight at day 7 (147.60±3.16 g) (before inoculation) and 14 (553.07±13.68 g), 21(842.79±20.86 g) and 28 (1340.25±55.71 g). The IgA and IgG levels of the three breeds of broiler chickens were not affected by breed before inoculation with Salmonella vaccines. However, on the 3rd day post inoculation when the birds were 17 days old, the IgA level was significantly (P<0.05) at the highest in Cobb 500 chickens (0.92±0.15µg/ml) while Arbor acre and Ross 308 broilers had IgA levels of 0.38±0.06 µg/ml and 0.48±0.09 µg/ml respectively. The results revealed that there are breed differences in the immune response to Salmonella typhimurium vaccine across three broiler breeds