Effects of lactoferrin and probiotic supplementation on intestinal morphology and gut microbiota of broilers after exposure to heat stress condition

Abstract
Structured Abstract
Background:
Heat stress is a major environmental challenge that markedly impairs broiler health and productivity. It disrupts intestinal morphology, alters gut microbiota composition, and promotes systemic endotoxemia. Nutritional interventions with biofunctional agents such as lactoferrin and probiotics have been proposed to mitigate these adverse effects by enhancing intestinal integrity and maintaining microbial homeostasis.
Objective:
This study aimed to evaluate the efficacy of lactoferrin, either alone or in combination with probiotics, in alleviating heat stress–induced intestinal injury and microbial dysbiosis in broiler chickens.
Methods:
Eighty day-old Ross 308 chicks were randomly assigned into four groups: (1) control (thermoneutral), (2) heat-stressed (36 ± 1 °C, days 7–14), (3) lactoferrin-treated (250 mg/kg feed, days 14–21), and (4) lactoferrin + probiotics-treated (250 mg/kg lactoferrin + 5 × 10¹² CFU/kg probiotics, days 14–21). At day 21, intestinal ultrastructure was examined using transmission electron microscopy (TEM), and cecal bacterial populations (Lactobacillus spp., Escherichia coli, and Clostridium perfringens) were quantified by qPCR. Serum lipopolysaccharide (LPS) and D-lactate (D-LA) levels were measured as indicators of intestinal permeability and barrier dysfunction.
Results:
Exposure to heat stress caused severe intestinal epithelial degeneration, depletion of beneficial bacteria, overgrowth of pathogens, and significant elevations in serum LPS and D-LA concentrations (p < 0.05). Supplementation with lactoferrin markedly improved epithelial morphology, increased Lactobacillus counts (~5 log CFU/g), reduced pathogenic bacteria, and mitigated endotoxemia. The combined lactoferrin + probiotics treatment produced additive benefits, showing superior preservation of villus architecture, microbial equilibrium, and serum biochemical indices compared with single supplementation.
Conclusion:
Lactoferrin, particularly when administered together with probiotics, effectively mitigates heat stress–induced intestinal and microbial disturbances in broilers. These findings highlight its potential as a sustainable nutritional intervention to improve gut health, antioxidant defense, and thermotolerance in poultry exposed to high environmental temperatures.