This study examined whether 3% dietary Spirulina platensis supplementation could mitigate the negative effects of heat stress in broilers across three treatment groups: normal temperature, heat stress, and heat stress with microalgae. Heat stress appeared to reduce final body weight and daily weight gain relative to normal conditions, while microalgae-supplemented birds showed improvements in body weight and feed conversion ratio compared to heat-stressed controls. Beyond growth performance, microalgae supplementation was associated with improved villus height and villus height-to-crypt depth ratio, increased expression of antioxidant-related genes including GPX3, and changes in immune-related and tight-junction genes, suggesting potential support of gut structure, nutrient absorption, and the bird's natural defense system. Gut microbiome analysis further indicated higher microbial diversity and elevated levels of bacteria associated with gut health and volatile fatty acid production — including Ruminococcus, Lactobacillus, and Oscillospira — collectively suggesting that dietary microalgae may support gut function, microbial balance, and broiler performance under heat stress conditions.
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