Effect of nucleotides on growth performance, gut health, and some immunological parameters of broiler chicken exposed to high stocking density

Abstract

The current study was conducted to investigate the effect of dietary nucleotides inclusion rate on growth performance, gut health, and immunity of broiler chickens exposed to high stocking density-induced stress. A total of 315 one-day-old mixed broiler chickens were randomly assigned to a 2 × 3 factorial arrangement of treatments with 2 different stocking densities, low stocking density (LSD; 0.073 m2/2.2 kg broiler chicken; 15 broiler chickens/replicate) and high stocking density (HSD; 0.05 m2/2.2 kg broiler chicken; 20 broiler chickens/replicate), and 3 dietary inclusion rates of nucleotides at 0, 0.05, and 0.1%, with 3 cages per treatment. The experiment lasted for 35 days. At the end of the experiment, intestinal histomorphology, digestive enzymes production, immune status, and growth performance of broiler chickens were determined. The results showed that intestinal histomorphological picture, immune indices, and digestive enzymes production were negatively affected (P < 0.05) with HSD, resulting in a decreased (P < 0.001) body weight gain (BWG), feed intake (FI) (P < 0.001), and an increased (P < 0.001) feed conversion ratio (FCR). While the intestinal and pancreatic enzymes production and intestinal histomorphology, including villus height, mucosal thickness, and goblet cell number increased linearly (P < 0.001) with the increased nucleotides supplementation rate, which resulted in a linear increase in BWG (P < 0.001) and FI (P < 0.001), and a decrease in FCR (P = 0.026). However, the effect was more prominent at LSD than HSD. In addition, immune indices, including antibody against NDV, IL-2 and INF-γ gene expression, and lysozyme production, linearly increased (P < 0.001) with the increase of dietary nucleotides inclusion rate, resulting in partial mitigation of immune compromise in broiler chickens at HSD. We concluded that dietary nucleotide supplementation, particularly at 0.1%, partially attenuated the negative effect of HSD on broiler chicken performance through improving intestinal histomorphology, digestive enzyme production, and immune status.