Effects of piperine-loaded chitosan nanoparticles on growth and health of heat-stressed rabbits: a dose-response analysis

This study aims to identify the optimal dosage of piperine-loaded chitosan nanoparticles (PIP-CHNPs) for enhancing growth performance and health status in heat-stressed fattened rabbits. Eighty healthy 6–week-old rabbits were randomly divided into four groups of 20, each receiving dietary supplements of 0, 50, 100, or 200 mg PIP-CHNPs per kilogram of diet. The dietary intervention significantly improved growth performance, feed conversion efficiency, physiological responses, dressing percentage, and liver weight. PIP-CHNPs supplementation led to a linear reduction in total cholesterol, low-density lipoprotein, very low-density lipoprotein, interleukin-4, nuclear factor kappa B, and hydrogen peroxide levels. Conversely, there was a linear increase in immunoglobulins (IgG, IgA, IgM), lysozyme activity, total antioxidant capacity, and glutathione peroxidase activity. The levels of total protein, albumin, interferon-gamma (IFN-γ), tumour necrosis factor-alpha (TNF-α), nitric oxide (NO), superoxide dismutase (SOD), and catalase (CAT) demonstrated a quadratic increase, reaching their peak at specific doses of PIP-CHNPs: 150 mg/kg for total protein and SOD, 135 mg/kg for albumin, 130 mg/kg for NO and IFN-γ, and 100 mg/kg for TNF-α and CAT. Conversely, liver enzymes activities (ALT, AST) and malondialdehyde (MDA) levels showed a quadratic decline, with the greatest reductions at 120 mg/kg for ALT and MDA, and 115 mg/kg for AST. PIP-CHNPs supplementation alleviated liver damage caused by heat stress, restoring normal hepatic morphology. The hydrophobic interactions of piperine with antioxidant enzymes and cytokines reduced oxidative damage. In conclusion, 100–150 mg/kg of PIP-CHNPs enhanced growth, oxidative balance, immunity, and inflammation control in fattened rabbits during summer.