Assessing the effect of the probiotic in the effectiveness of the Newcastle disease vaccine in specific pathogen-free chickens

The present study aimed to assess the impact of a probiotic supplement on the effectiveness of the Newcastle disease ( ND ) vaccine in specific pathogen-free ( SPF ) chickens. A total of one hundred and twenty 7-day-old SPF chicks were randomly divided into six groups including: CNT (control group), PRO (probiotic), RCV (Razi Clone12IR vaccine), ICV (imported Clone vaccine), PRO + RCV (probiotic and Razi Clone12IR vaccine), and PRO + ICV (probiotic and imported Clone vaccine). Administration of the probiotic, either alone or in conjunction with ND vaccination, decreased cholesterol and increased total protein, albumin, calcium, and phosphorus concentrations ( P < 0.05). Increasing weight, length, and bone breaking strength were observed in chickens that were given the probiotic alone. The highest concentration of malondialdehyde ( MDA ) was recorded in the CNT, while MDA levels decreased in the PRO, PRO + RCV, and PRO + ICV ( P < 0.05). An increase in IgY anti-SRBC antibody titer was found in the PRO + RCV and PRO + ICV groups. Higher antibody titer against ND was observed in the PRO + RCV ( P < 0.05). The use of probiotics during ND vaccination led to increased lysozyme activity compared to other groups ( P < 0.05). The birds receiving probiotics exhibited significantly greater villus height, crypt depth, and villus height/crypt depth ratio in the duodenum ( P < 0.05). No histopathological lesions were observed in the trachea, lungs, liver, or bursa of Fabricius in vaccinated chickens, regardless of whether they received probiotic dietary supplementation. The study’s findings suggest that incorporating probiotics during ND vaccination can enhance the health-related parameters of SPF chickens.