Dietary Supplementation with GBE and TP Alleviates Heat Stress-Induced Lung Oxidative Damage in Broilers

Heat stress is a major environmental stressor in poultry production that reduces growth performance and induces oxidative stress, inflammatory responses, and lung tissue injury. This study investigated the protective effects of dietary supplementation with Ginkgo biloba extract and tea polyphenols against heat stress-induced lung injury in broilers. A total of 320 one-day-old broilers were reared under standard management conditions until 21 days of age. Subsequently, 300 birds with similar body weight were selected and randomly allocated into six groups: a thermoneutral control group, a heat stress group, a heat stress group supplemented with 300 mg/kg tea polyphenols, and three heat stress groups receiving 300 mg/kg tea polyphenols combined with 100, 300, or 600 mg/kg Ginkgo biloba extract. The analysis of the results showed that heat stress significantly reduced the average daily gain and feed intake while increasing the feed conversion ratio. It also markedly increased serum lactate dehydrogenase activity and malondialdehyde levels, while decreasing antioxidant-related indicators, indicating the occurrence of oxidative stress and inflammatory responses. Histological examination revealed lung injury characterized by alveolar wall thickening, epithelial cell shedding, and disruption of the endothelial barrier, accompanied by upregulated expression of heat shock proteins and inflammation-related signaling genes. Supplementation with tea polyphenols alone partially alleviated these changes. Notably, the combined supplementation of Ginkgo biloba extract and tea polyphenols exerted more pronounced protective effects, significantly enhancing antioxidant capacity, attenuating inflammatory responses, and maintaining pulmonary barrier integrity. Among the tested levels, the groups receiving 300 mg/kg Ginkgo biloba extract in combination with tea polyphenols showed the most evident improvements. These findings suggest that the combined use of these plant-derived extracts effectively mitigates heat stress-induced lung injury in broilers.