Herbal Mixture Supplementation Enhances Survival in Broiler Chickens Challenged with Newcastle Disease Virus and Infectious Bronchitis Virus
Description
The effectiveness of vaccines has decreased due to more virulent antigens. Therefore, this study aimed to evaluate the effects of a herbal mixture (HM) on performance, carcass composition, liver enzymes, intestinal morphology, and mortality rates in broiler chickens infected with Newcastle Disease Virus (NDV) and Infectious Bronchitis Virus (IBV) during the starter and finisher phases. 300 chicks based on a completely random design were divided into five treatment groups with six replicates of 10 chicks each. T1 received a basal diet, while T2, T3, T4, and T5 were supplemented with 1.5%, 3%, 4.5%, and 6% HM, respectively. On the 7th and 25th day of age, all chicks were infected with NDV and IBV, respectively. Supplementing the diet with HM resulted in improved (P<0.05) average weight gain (AWG) and feed intake (AFI) in the starter phase without affecting (P>0.05) AWG, AFI, or feed conversion ratio (FCR) during the grower phase, as well as FCR during the starter phase. Adding HM increased AWG and reduced mortality rates in NDV-infected chicks from 1 to 25 days old. However, in the finisher phase, HM did not significantly affect AWG, AFI, or FCR in IBV-infected chickens. Still, it significantly reduced the mortality rate compared to the control group. Over the total rearing period, supplementing HM at a 4.5% level significantly decreased mortality rates among chickens infected with NDV and IBV. Adding HM to the diets, there were no significant changes in liver enzymes, serum total protein, uric acid levels, or antibody titers for NDV and IBV. In conclusion, incorporating 4.5% HM into the diet of broiler chickens does not negatively impact their performance while positively affecting the immune system, enhancing the chickens' tolerance to NDV and IBV and reducing mortality rates.