Physiological Basis and Molecular Determinants of Heat Tolerance in Nigerian Indigenous Cattle Breeds: A Multi-Omics Investigation

Nigerian indigenous cattle breeds, including the N'Dama, White Fulani, and Keteku, have evolved under intense selection pressure from thermal stress, haemoparasitism, and nutritional scarcity, developing physiological and molecular mechanisms of resilience that remain insufficiently characterised compared with temperate breeds. Understanding the physiological basis of heat tolerance is critical for informed crossbreeding decisions and conservation of indigenous genetic resources. This study conducted a multi-omics investigation integrating physiological phenotyping, transcriptomics, and proteomics to characterise heat tolerance mechanisms in N'Dama, White Fulani, and Friesian crossbred cattle from South South, North West, and South West Nigeria respectively. Ninety cattle, 30 per breed, were subjected to standardised heat stress challenges of 40 degrees Celsius for four hours in climate-controlled stalls at facilities in Ibadan. Physiological measurements including respiratory rate, rectal temperature, sweating rate, and skin surface temperature were collected. Blood samples were taken for serum cortisol, thyroid hormones, and oxidative stress markers. Peripheral blood mononuclear cells were collected for RNA sequencing and quantitative proteomics by iTRAQ labelling. N'Dama cattle showed significantly superior thermoregulation, returning to baseline rectal temperature 42 percent faster than Friesian crossbreds. Transcriptomic analysis identified significantly higher constitutive expression of heat shock protein 70 isoforms in N'Dama cattle, alongside lower expression of pro-apoptotic genes. Proteomics revealed higher anti-oxidant protein concentrations in indigenous breeds. These molecular signatures of resilience provide targets for marker-assisted selection and validate N'Dama as a thermotolerant genetic resource for sustainable beef production in a warming Nigerian climate. Keywords: heat tolerance, indigenous cattle, transcriptomics, heat shock proteins, multi-omics.