Evaluation of an Extract Derived from the Seaweed Ascophyllum nodosum to Reduce the Negative Effects of Heat Stress on Broiler Growth and Stress Parameters

This study evaluated whether supplementing broiler diets with an extract of Ascophyllum nodosum could mitigate the negative effects of prolonged heat stress on bird welfare and performance. Broilers were exposed to high temperatures during the finishing phase, with half receiving the seaweed extract. Heat stress significantly impaired growth, feed efficiency, and uniformity, while increasing physiological stress markers such as corticosterone, heterophil-to-lymphocyte ratios, and heat shock proteins. Birds supplemented with the seaweed extract showed consistently lower stress markers compared to unsupplemented heat-stressed birds, indicating improved resilience. Notably, under heat stress conditions, the seaweed extract significantly enhanced both body weight and feed conversion ratio (FCR) compared to heat-stressed control group. These findings suggest that A. nodosum extract can support bird welfare and mitigates performance losses during heat stress events through modulation of stress pathways and immune responses.