ISSUE FOCUS FEED & ADDITIVE MAGAZINE July 2025 61 OXIDATIVE STRESS’ EFFECTS ON THE GUT In the gastrointestinal tract, oxidative stress and the consequent tissue damage lead to increased intestinal permeability. This facilitates the translocation of toxins and pathogens from the intestinal tract into the bloodstream (Figure 3). Under oxidative stress conditions in the gut, there is a demand for antioxidants to counteract the excess of ROS; hence, dietary antioxidants can help reduce ROS and improve animal performance.15 Research shows that certain phytomolecules have antioxidant properties and improve performance under conditions of oxidative stress.14, 18-20 Thermoregulation: Changes in blood flow The gastrointestinal tract is profoundly affected by heat stress in poultry: to help with heat dissipation, the thermoregulatory mechanism of the animal shifts visceral blood flow towards peripheral circulation. Organ ischemia and hypoxia follow, limiting gut motility, nutrient utilization, and feed intake.5,14 Enterocytes are particularly sensitive to hypoxia and nutrient restriction, which leads to oxidative stress.2, 12 Changes in intestinal barrier’s tight junctions Several studies indicate that both acute and chronic heat stress increase gut permeability, partly by increasing oxidative stress and by disrupting the expression of tight junction proteins.5,21 Heat and oxidative stress in the gut result in intestinal cell injury and apoptosis. When the tight junction barrier is compromised, luminal substances leak into the bloodstream, which constitutes the condition described as “leaky gut”.4, 21 Changes in intestinal morphology Heat stress in poultry affects intestinal weight, length, barrier function, and microbiota, resulting in animals that have lower total and relative weight of the small intestine, with shorter jejunum and duodeFigure 3. Simplified effects of head stress in intestinal functions 2 3 4 5 1 ROS Normal condition Leaky gut 1. Visceral blood flow is directed to the peripheria 2. Intestinal cell damage through oxidative stress 3. Disruption of tight junctions 4. Alteration of the microbiome 5. Leaky gut and translocation of toxins (mycotoxins, endotoxins) and pathogens into the bloodstream Photo: ew | nutrition
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