Antiviral efficacies of neem (Azadirachta indica J.) and scent (Ocimum sanctum L.) leaf meals against Newcastle and infectious bursal disease in broiler chickens

Abstract

The effects of neem (Azadirachta indica) and scent (Ocimum santum) leaf meals fed singly or in combination on the growth response, haemato-biochemical parameters and their antiviral potencies in broiler chickens were investigated. Two hundred 1-day old Ross 308 unsexed broiler chicks were randomly allotted to 5 treatments, consisting of 5 replicates with 8 birds each. Treatments 1 and 2 were basal diets with no leaf meals, treatments 3, 4 and 5 had the basal diets plus 3% neem leaf meal (NLM), 3% scent leaf meal (SLM) and the blend of 2% NLM + 2% SLM, respectively. Birds in treatments 2-5 were unvaccinated against Newcastle disease and Infectious bursal disease while birds in treatment 1 were vaccinated. On days 21 and 42, blood samples were randomly collected from 2 birds per replicate for haemato-biochemical assay, haemagglutination inhibition and agar gel precipitation tests. Data were subjected to descriptive statistics and ANOVA at p<0.05. At the starter phase, an improved feed conversion ratio (p<0.05) was recorded in birds fed the blend at the starter (1.83) and finisher (1.92) phases and the overall performance (1.88) compared to other treatment groups. The least platelet counts (11.08 ×104/µL) were recorded in birds placed on the blend of 2% neem leaf meal + 2% scent leaf meal while the 3% scent leaf meal group recorded the lowest lymphocyte counts (53.60%). At the finisher phase, lymphocyte counts of birds that received the blend of 2% neem leaf meal + 2% scent leaf meal (63.00%) were higher than the other treatments. In conclusion, birds fed diets supplemented with 3% neem and 3% scent leaf meals singly had haemagglutination inhibition titre values and conferred immunity above the protective threshold against Newcastle disease and produced antibodies against Infectious bursal disease. Birds fed the blend of 2% neem + 2% scent leaf meal diets had improved overall performance.