Effect Of Chronic Heat Stress On Intestinal Mucosal Barrier Function In Broilers

Broilers have thick feathers but no sweat glands.High temperature can easily induce fever stress.The purpose of this study was to investigate the effects of chronic heat stress on intestinal morphology,oxidative stress and cecal flora in broilers.The change of production performance,organ index,serum biochemical indexes,intestinal mucosal barrier,cecal flora and intestinal antioxidant enzymes of broilers under chronic heat stress were studied,so as to provide a theoretical basis for early warning,comfort evaluation and heat stress relief measures of broilers.The main results are as follows:1.Compared with the Control group,ADG(average daily gain)and ADFI(average daily feed intake)decreased,while FCR was not significantly affected.Chronic heat stress significantly reduced the organ index of heart,liver and spleen,but had no effect on organ index of bursa of Fabricius.The contents of CK(creatine kinase),AKP(alkaline phosphatase)and MDA(malondialdehyde)in serum increased significantly,while the activities of GSH-PX(glutathione peroxidase)and superoxide dismutase(SOD)decreased significantly.2.Effects of chronic heat stress on intestinal morphology of broilers.Compared with the control group,Chronic heat stress leads to the shedding of duodenal epithelial cells in broilers;Inflammatory cell infiltration,glandular hyperemia and disorder of intestinal glandular cells were found in the crypts in duodenum,jejunum and ileum,Edema of lamina propria in jejunum and ileum.3.Effects of chronic heat stress on the structure of cecal intestinal flora in broilers.16 S r RNA Illumina high-throughput sequencing results showed that chronic heat stress changed the richness and diversity of cecal flora.At the genus level,eight cecal microbiota associated with high temperature were screened out :Parabacteroides、Saccharimonas、Romboutsia、Weissella、Anaerofustis、Rikenella Pseudonocardia and Tyzzerella.4.Correlation analysis between local oxidative stress and villus height in small intestine.Compared with the control group,GSH-Px,SOD and T-AOC contents in duodenum,jejunum and ileum were significantly decreased,while MDA content was significantly increased.Pearson correlation analysis showed that MDA content in duodenum,jejunum and ileum was negatively correlated with villus height.In conclusion,chronic heat stress can damage the intestinal barrier function of broilers,affect the production performance,organ index(heart,liver,spleen),abundance and diversity of intestinal flora of broilers,and provide support for the prevention and control of heat stress in broilers.