Targeted intestinal delivery of luteolin microcapsules as a precision nutritional strategy to alleviate heat stress and enhance growth performance in broilers

Heat stress ( HS ) poses a significant threat to poultry production by impairing the growth and health of broilers. Luteolin ( Lut ) is a natural flavonoid with potent antioxidant properties. In vitro , Lut mitigated HS-induced oxidative injury and reactive oxygen species accumulation, decreased p38 MAPK phosphorylation, and downregulated Hsp70 expression. To improve its delivery, pH‑dependent spray‑dried microcapsules were engineered using tributyrin as a functional carrier. A 30-day oral toxicity study in mice confirmed the safety of Lut microcapsules at doses up to 10 g/kg/day. The efficacy of Lut microcapsules was then evaluated in broilers subjected to HS. Dietary supplementation with Lut microcapsules significantly increased average daily feed intake and average daily gain, while significantly reducing the feed/gain ratio compared with the HS group. In addition, Lut microcapsules alleviated metabolic disturbances and multi-organ histopathological damage. Lut microcapsules also reduced hepatic p38 MAPK phosphorylation and lowered Hsp70 and Hsp90 expression. However, because the in vivo study did not include Lut‑only or tributyrin‑only control groups, despite the convincing in vitro work it is not possible to definitively attribute the responses noted to Lut alone. Collectively, these findings suggest that Lut microcapsules may improve growth performance and heat tolerance in broilers. Therefore, the Lut microcapsule formulation shows potential as a feed supplement to mitigate heat stress‑related losses in broilers.