Dietary phytosterols supplementation improves the growth performance and decreases the abdominal fat of broiler chickens by regulating intestinal epithelial structure and microbiota

Phytosterols, plant-derived fatty compounds, were reported to be bioactive for animals and promote the growth of broilers. Whether dietary phytosterols could improve the growth performance of broilers by regulating intestinal morphology and microbiota is still unclear and limited. Thus, our experiment aimed to evaluate the effects of dietary phytosterols on the growth performance, intestinal morphology, and microbiota of broilers. A total of 200 male Arbor Acres broiler chickens (1 day old) were randomly assigned to 2 treatment groups with 5 replicates of 20 birds each, (1) basic corn-soybean diet; (2) basic corn-soybean diet supplemented with 25 mg/kg phytosterols. Dietary supplementation of phytosterols at 25 mg/kg increased the average daily gain and reduced the feed conversion rate of broilers (P < 0.05), but did not affect average daily feed intake (P > 0.05). It reduced the abdominal fat yield and serum triglyceride and low-density lipoprotein cholesterol levels in broilers (P < 0.05). Phytosterols treatment increased villus height to crypt depth ratio and up-regulated the mRNA expression of tight junction-related genes in both jejunal (i.e., ZO-2, ZO-3, and claudin-3) and ileal (i.e., claudin-1 and claudin-2) tissues (P < 0.05). Additionally, dietary phytosterols significantly down-regulated the mRNA expression of proinflammatory cytokine (IL-1 beta and IL-6) in the jejunal tissues (P < 0.05), and up-regulated that of anti-inflammatory cytokine (IL-4 and IL-10) in the ileal tissues (P < 0.05). Moreover, broilers fed with dietary phytosterols had a higher concentration of lactic acid in the caecal digesta (P < 0.05). Dietary supplementation with phytosterols decreased the alpha diversity of the bacterial community (P < 0.05) and increased the relative abundance of probiotics (i.e., Lactobacillus) in the intestinal digesta of broilers (P < 0.05). PICRUSt2 analyses revealed that phytosterols enhanced the bacterial metabolic pathways of amino sugar and nucleotide sugar metabolism and fatty acid metabolism. Dietary supplementation of phytosterols could improve the growth performance and reduce the abdominal fat yield of broilers by altering their intestinal epithelial structure, lipid metabolism and bacterial community.