Table 1.

Some important functions of Zn, Cu, and Mn in livestock and associated dietary recommendations.

Trace Mineral	Functions	Example of NRC [9,10] Recommendations	Example of Commercial Specifications (average)	Reference (s)
Zinc	Fat absorption (phospholipase A2) Antioxidant activity (superoxide dismutase) Hydrolysis of phosphate esters (alkaline phosphatase) Formation of carbon dioxide (carbonic anhydrase)	Growing pigs 50–100 mg/kg	Up to 534 mg/kg	[11]
		Broiler chickens 40 mg/kg	110 mg/kg	[12]
Copper	Copper transport (caeruloplasmin) Cellular respiration (cytochrome oxidase) Antioxidant activity (superoxide dismutase) Iron absorption and transport (hephaestin, caeruloplasmin) Pigmentation (tyrosinase) Connective tissue (lysyl oxidases)	Growing pigs 3–6 mg/kg	Up to 82.5 mg/kg	[11]
		Broiler chickens 5–8 mg/kg	16 mg/kg	[12]
Manganese	Lipid and carbohydrate metabolism (pyruvate carboxylase) Antioxidant activity (superoxide dismutase) Proteoglycan synthesis (e.g., cartilage) (glycosyltransferase)	Growing pigs 2–4 mg/kg	Up to 70.3 mg/kg	[11]
		Broiler chickens 60 mg/kg	120 mg/kg	[12]