Heat stress impairs growth performance and alters body protein and amino acid metabolism. This study was investigated to explore how body protein and amino acid metabolism changed under heat stress (HS) and the stress adaptation mechanism. A total of 144 broilers (28 d old) were divided into 3 treatment groups for 1 wk: HS group (32°C), normal control group (22°C), and pair-feeding group (22°C). We found that HS elevated the feed-to-gain ratio, reduced the ADFI and ADG, decreased breast muscle mass and plasma levels of several amino acids (glycine, lysine, threonine, and tyrosine), and increased serum glutamic oxaloacetic transaminase (GOT) activity and corticosterone (CORT) level and liver GOT and glutamic pyruvic transaminase activities. Heat stress elevated muscle atrophy F-box mRNA expression and reduced mRNA expression of the 70-kD ribosomal protein S6 kinase in the breast muscle of broilers. Broilers in the HS group exhibited striking increases of mRNA expressions of solute carrier family 1 member 1, family 3 member 1, family 7 member 1, and family 7 member-like in the liver and liver gluconeogenesis genes (PCKc, PCKm, PC, and FBP1) in comparison with the other 2 groups. In conclusion, HS increased the circulating CORT level and subsequently caused muscle protein breakdown to provide amino acid substrates to liver gluconeogenesis responsible for energy supply.

Chronic heat stress can enhance fat synthesis in broilers, and excessive triglyceride (TG) synthesized by the liver needs to be transported to extrah

Wooden breast (WB) has emerged as a dramatically increasing myopathy in the poultry industry over the past few years. The objective of this study was

This study was designed to evaluate the effects of γ-irradiated Astragalus polysaccharides (IAPS) on growth performance, cecal microbiota populations, and concentrations of cecal short-chain fatty acids of immunosuppressed broilers. A total of 144 one-day-old broiler chicks were randomly assigned into 3 groups: nontreated group (control), cyclophosphamide (CPM)-treated groups fed either a basal diet or the diets containing 900 mg/kg IAPS, respectively. On day 16, 18, and 20, broilers in the control group were intramuscularly injected with 0.5 mL sterilized saline (0.75%, wt/vol), and those in the CPM and IAPS groups were intramuscularly injected with 0.5 mL CPM (40 mg/kg of BW). The trial lasted 21 d. Compared with the control group, CPM treatment decreased the broiler average daily gain (ADG) and feed intake (P < 0.05) but did not affect the overall microbial diversity and compositions, as well as the concentrations of cecal acetate, propionate, and butyrate in cecum of broilers (P > 0.05). Dietary IAPS supplementation increased broiler ADG, Shannon index, and decreased Simpson index (P < 0.05). Specifically, broilers fed diets containing IAPS showed lower abundances of Faecalibacterium, Bacteroides, and Butyricicoccus and higher proportions of Ruminococcaceae UCG-014, Negativibacillus, Shuttleworthia, Sellimonas, and Mollicutes RF39_norank, respectively (P < 0.05). The IAPS treatment also increased butyrate concentration (P < 0.05) and tended to elevate acetate concentration (P = 0.052) in cecal digesta. The results indicated that IAPS are effective in increasing the cecal beneficial bacteria and short-chain fatty acids production, contributing to improvement in the growth performance of immunosuppressive broilers. These findings may expand our knowledge about the function of modified Astragalus polysaccharides in broiler chickens.