Zebu Bos indicus

Zebu are the humped, tropically adapted cattle that carry production wherever heat and ticks rule: over 65 percent of the world's cattle live in tropical and subtropical climates, and Brazil alone, working largely with zebu, supplies about 18 percent of global beef with 23 percent projected by 2028. Zebu and taurine cattle separated long before domestication, by mitochondrial estimates 117,000 to 275,000 years ago and by microsatellite estimates 610,000 to 850,000. Their thermotolerance is structural rather than behavioural: denser, larger sweat and sebaceous glands sitting closer to the skin surface, a slick pale coat that reflects sunlight, a lower metabolic rate and smaller heart and liver. They eat less, extract more from poor forage, and lose less condition under water restriction, but gain more slowly in the feedlot and grade below taurine carcasses. The veterinary point that defines them is tick resistance: resistance to Rhipicephalus microplus is associated primarily with zebu and is both acquired through challenge and heritable, so it responds to selection. That matters because the same tick transmits Babesia bovis and B. bigemina, where young calves in endemic areas build lasting immunity and outbreaks follow interrupted exposure or the arrival of naive cattle. Handling design matters too: zebu are more excitable and mount a larger cortisol response to restraint.