Nutritional Immunology of Tropical Livestock: Mechanisms Linking Micronutrient Status to Innate Immunity in Nigerian Ruminants

This study investigates the mechanisms linking micronutrient nutritional status to innate immune function in Nigerian ruminants, developing an original understanding of nutrition-immunity interactions that is relevant to improving disease resistance in nutrient-limited tropical production systems. Micronutrient deficiencies are widespread in Nigerian ruminants due to poor soil mineral status, seasonal feed quality variation, and low dietary diversity in rangeland-dependent systems. The consequences for immune function are poorly understood, creating a gap between nutrition science and animal health management. This study characterises selenium, zinc, copper, and vitamin E status in 400 cattle, sheep, and goats sampled from four contrasting production environments in Borno, Niger, Delta, and Kano States, using blood and liver tissue analyses. Innate immune function is comprehensively characterised using neutrophil oxidative burst capacity, macrophage phagocytic activity, natural killer cell cytotoxicity, acute phase protein concentrations, and pattern recognition receptor expression. A controlled depletion-repletion experiment supplementing deficient animals with individual and combined micronutrients tests the causal pathway from deficiency to immune impairment and its reversibility. Transcriptomic analysis identifies the molecular pathways mediating micronutrient-immunity relationships. Findings reveal significant deficiencies of selenium (68 percent of sampled animals below physiological thresholds), zinc (52 percent), and copper (44 percent) in the surveyed populations. Selenium deficiency shows the strongest association with impaired neutrophil function, explained by mechanistic evidence through glutathione peroxidase pathway characterisation. Supplementation restores neutrophil function within 21 days. The study contributes an original Nigerian ruminant nutritional immunology model and recommends targeted selenium-zinc supplementation as a disease resistance enhancement strategy.

Keywords: nutritional immunology, micronutrients, innate immunity, Nigerian ruminants, selenium deficiency.