Effect of glucose supplementation on protein biosynthesis in chickens reared under thermoneutral or heat stress environment

Heat stress (HS) impacts broilers by reducing feed intake which impairs nutrient availability and energy levels, subsequently affecting protein biosynthesis. We hypothesize that an exogenous supply of glucose could provide extra energy resources that enhance protein biosynthesis in broilers reared under HS. Our experimental design involved two levels of temperature (25 °C [thermoneutral, TN]); 35 °C (8.00 AM to 8.00 PM, [Heat Stress, HS]), and two glucose levels (0 % and 6 %). We randomly assigned a total of 456 four-week-old Cobb500 broilers to four different treatment groups (TN₀, TN₆, HS₀, and HS₆), respectively. After 7 days post-HS, we observed an inverse relationship between the avian target of rapamycin (avTOR) and autophagy-related genes. The phosphorylation of mTOR and S6K1 at Ser2448 and Thr421/Ser424 respectively was higher (p < 0.05) in the TN₀ group than in the HS groups. Additionally, the phosphorylation of Foxo3a at Ser253 was higher (p < 0.05) in the HS₀ group than in the HS₆ groups, indicating an adaptive response to HS. Thus, the combined effect of HS and glucose could influence the phosphorylation status of key signaling genes in the mTOR pathway. The expression levels of mRNA genes in the mTOR pathway were more pronounced (p < 0.05) in HS₆ birds than in HS₀ birds except for avTOR, Akt1, and S6K1.