Effect of in ovo administration of Newcastle disease vaccine conjugated with Astragalus polysaccharide on growth performance, intestinal development, and mucosal immunity in broiler chickens

This study was conducted to investigate the effect of in ovo administration of a mixture of Astragalus polysaccharide (APS) and Newcastle disease vaccine (NDV) on growth performance, intestinal development, and mucosal immunity in newly hatched chicks. Six hundred specific‐pathogen‐free (SPF) Leghorn fertilised eggs were incubated in a commercial hatchery and divided into four groups: (a) control group injected with 1 ml of 0.9% physiological saline, (b) APS group injected with 1 ml of 1 mg/ml APS solution, and (c) NDV group injected with 1 ml of 104.0 EID50/dose of NDV solution, and (d) APS + NDV group injected with a mixture of 0.5 ml of 2 mg/ml APS plus 0.5 ml 104.0 EID50/dose ND vaccine (NDV) on Day 18.5 of incubation. The results showed that in ovo injection of APS or the mixture of APS and NDV increased the body weight at 1 day (IW) and final weight (FW) at 28 days and increased the feed conversion ratio (FCR) at 1–7, 8–14, 15–21, and 1–28 days of age. The villus height (VH) was increased (p