Herbal Mixture Supplementation Enhances Survival in Broiler Chickens Challenged with Newcastle Disease Virus and Infectious Bronchitis Virus

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&lt;0.05) average weight gain (AWG) and feed intake (AFI) in the starter phase without affecting (P&gt;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.因抗原毒力增强，疫苗的保护效力有所下降。因此，本研究旨在评估中草药混合物（herbal mixture, HM）对育雏期和育肥期感染新城疫病毒（Newcastle Disease Virus, NDV）与传染性支气管炎病毒（Infectious Bronchitis Virus, IBV）的肉鸡的生产性能、胴体组成、肝脏酶活、肠道形态及死亡率的影响。本试验采用完全随机设计，将300羽雏鸡分为5个处理组，每组设置6个重复，每个重复含10羽雏鸡。T1组饲喂基础日粮，T2、T3、T4、T5组分别在日粮中添加1.5%、3%、4.5%、6%的HM。分别于雏鸡7日龄和25日龄人工感染NDV和IBV。日粮添加HM可显著提升（P<0.05）育雏期的平均增重（average weight gain, AWG）与平均采食量（average feed intake, AFI），但对育成期的AWG、AFI及料重比（feed conversion ratio, FCR），以及育雏期的料重比均无显著影响（P>0.05）。在1~25日龄阶段，HM可提升NDV感染雏鸡的平均增重并降低其死亡率。然而在育肥期，HM对IBV感染肉鸡的平均增重、平均采食量及料重比均无显著影响，但较对照组可显著降低死亡率。在整个饲养周期内，添加4.5%的HM可显著降低NDV与IBV混合感染肉鸡的死亡率。日粮添加HM对肉鸡的肝脏酶活、血清总蛋白、尿酸水平以及NDV和IBV的抗体滴度均无显著影响。综上，在肉鸡日粮中添加4.5%的HM不会对其生产性能产生负面影响，同时可正向调节机体免疫功能，增强肉鸡对NDV和IBV的耐受性并降低死亡率。