Sequential effects of experimental Newcastle disease virus on performance and severity of clinical manifestation of the disease in three indigenous Nigerian genotypes of chickens

Abstract

Newcastle disease has been identified as a killer viral infection associated with high case fatality in poultry. This study was conducted to evaluate the sequential effects of experimental Newcastle disease on the performance and severity of clinical manifestation of the disease in three indigenous Nigerian genotypes of chickens. A total of 180 day-old Nigerian indigenous chicks consisting of 60 Naked necks (NN), 60 Frizzle feathers (FF) and 60 Normal feathers (NF) (45 experimental and 15 control per genotype) were used for the study. These chicks had no symptoms of Newcastle disease at the commencement of the experiment. Birds were fed on starter ration (20% CP and 2800 Kcal ME/kg) from day-old to 8th week of age, and growers ration (16% CP and 2750 Kcal ME/kg) from the 9th to 16th week. Fifteen (15) vials of lyophilised Newcastle live virus Kudu 113 strain were obtained from National Veterinary Research Institute, Vom Plateau State, and each vial was diluted with 2 ml of sterile phosphate buffer saline (pH 7.2). Each experimental genotype was inoculated through intra-crop injection with 0.2 ml of the virus in the 5th week. The control group was inoculated 0.2 ml of normal saline. Post infection (PI) observable clinical signs were assessed and live weight changes were determined. Patent Newcastle Disease infection manifested clinical signs included greenish watery diarrhoea, insomnines, ruffled feathers, sneezing and coughing, wherein all of these obvious clinical signs manifested in 90, 31 and 25% of infected NN, NF and FF respectively by day 14 PI. The mortality pattern by day 42 was 94% NF, 100% FF and 79% NN. The study concluded that live-weight changes in the naked neck subsequently increased by day 35 and 42 post infection and the NF had the same sequential result. The study recommended that the NN genotype should be raised in places that are not endemic to Newcastle disease.