As heat stress levels increase, poultry exhibit various physiological responses, including panting, reduced feed intake, and decreased activity. While these signs are easily recognized, the metabolic changes occurring in the liver often go unnoticed, despite their significant impact on growth, feed efficiency, and overall production performance.

Recent studies have shown that bile acids not only enhance fat digestion but also support liver function by regulating lipid metabolism and improving antioxidant capacity. In one study, broilers supplemented with 200 mg/kg of bile acids during heat stress conditions achieved higher average daily weight gain compared to birds that did not receive supplementation.

Bile acid supplementation was also found to preserve intestinal villus structure, increase the expression of the Farnesoid X Receptor (FXR) in the ileum, enhance glutathione peroxidase (GSH-Px) enzyme activity, and help restore gut microbiota balance disrupted by heat stress.

In addition, bile acids reduced hepatic lipogenesis by suppressing the expression of key genes involved in fat synthesis, including sterol regulatory element-binding protein 1 (SREBP-1) and fatty acid synthase (FASN) (Figure 1). Total cholesterol levels and liver fat accumulation were also reduced (Figure 2), indicating improved hepatic lipid metabolism and greater protection against liver damage caused by heat stress.

Figure 1. Effects of bile acid supplementation on the expression of lipogenic genes in the livers of heat-stressed broiler chickens (Yin et al., 2021).

Figure 2. Liver lipid deposition in broilers supplemented with 0 or 200 mg/kg bile acids under thermoneutral (TN) and heat stress (HS) conditions. (A) TC = total cholesterol; (B) TG = triglycerides; (C–F) adapted from Yin et al., 2021.

These findings demonstrate that the role of bile acids extends far beyond fat digestion. By supporting liver health, maintaining the integrity of the gut–liver axis, and reducing oxidative stress, bile acid supplementation helps poultry adapt more effectively to heat stress conditions.

As rising environmental temperatures continue to challenge the global poultry industry, the use of bile acids represents a practical nutritional strategy for improving bird resilience while maintaining production performance.