Comparative Study of Antibody Titers against Newcastle Disease in E.coli Infected and Non-Infected Broiler Chickens

Abstract

Colibacillosis in birds is primarily caused by avian pathogenic E.coli (APEC), leading to extra-intestinal infections. In many cases, birds infected with Newcastle disease virus (NDV) become susceptible to E.coli superinfection, resulting in immunosuppression and increased disease outbreaks. This study was conducted to compare the Anti-NDV-HI antibody titers in E.coli infected and non-infected broiler chickens with efficacy of various treatment regimens and the impact of E.coli on feed conversion ratio (FCR) of the birds. A total number of 35 day-old commercial Ross 308 broiler chicks were divided into seven equal groups (A-G). Groups A-E were orally infected with pathogenic E.coli (Strain O1) on day 3 (10⁴ CFU in 0.5 ml PBS), while A-D and F received NDV vaccine (Lasota strain) in drinking water (DW) on day 4 and booster on day 18. Groups B, C and D were treated with antibiotic (Tylosin tartrate @ 1g/2L in DW), prebiotic (Celmanax® liquid @ 0.5ml/L in DW) and herbal medicine (Cinnamomum cassia powder @ 2g/kg of feed) respectively. The groups E and F served as positive control for E. coli and ND vaccine, while group G served as negative control. Weekly FCR and antibody titers at days 0, 10, 20, 30, and 40 were monitored. Group B was found significantly similar to F with highest antibody titers, whereas group E was found significantly different from all other groups with lowest antibody titers. Similarly group D was found significantly similar to G. In terms of FCR, group F displayed the highest followed by B, whereas group E had the lowest. The study concluded that antibiotics and prebiotics have a better impact on immune boosting against NDV and growth performance of broiler chickens even in the presence of E.coli infection. It is recommended that prophylactic treatments for E. coli and immune boosters should also be practiced along with or before vaccinations to avoid the vaccine failure and NDV outbreaks in broiler chickens.