Trace Mineral Function

USDA-ARS Image # K3627-16. Photo by Keith Weller

Zinc. Zinc is an essential component of over 200 enzyme systems of which the metabolic actions include carbohydrate and energy metabolism, protein synthesis, nucleic acid metabolism, epithelial tissue integrity, cell repair and division, and the absorption and utilization of vitamins A and E (1). In addition zinc plays a major role in the immune system and certain reproductive hormones (1, 2). Adequate zinc nutrition is crucial for normal development, maintenance, and function of the immune system and associated cells, including heterophils, basophils, macrophages, and T-lymphocytes (3). Zinc plays a role as cofactor for the enzyme keratinase in formation of the eggshell membrane and carbonic anhydrase that is involved in the formation of the eggshell.

Zinc is known to be essential for proper sexual maturity and reproductive capacity. Zinc deficiency has resulted in poor semen quality (4, 9). Improved zinc status also improves fertility by reducing footpad ammonia burns and foot lesions allowing the hens to stand and walk comfortably (6, 7).

Recommended dietary supplementation of zinc for breeder hens is typically 100 to 160 ppm in broiler breeder diets in the USA. Other regions of the world will feed zinc in a range of 60 to 120 ppm mainly in the sulfate and oxide forms.

Manganese. In general, manganese is an activator of enzyme systems in the metabolism of carbohydrates, fats, proteins and nucleic acids (11). It is also essential for normal brain function, and plays a role in collagen formation, bone growth, urea formation, synthesis of fatty acids and cholesterol, protein digestion, eggshell formation, and the function of the immune system (12, 13). Manganese is a cofactor in superoxide dismutase and required for the synthesis of chondroitin-4-sulfate, which is required for proper wound healing (33).

Manganese is typically supplemented at 120 to 180 ppm in the broiler breeder diet in the USA. Other regions will supplement manganese at 60 to 120 ppm in the diet mainly in the form of sulfates or oxides.

Copper. Copper is a necessary component of a number of enzymes. Many of these enzymes play a role in the immune system. These include superoxide dismutase, lysyl oxidase and thiol oxidase (14, 15), which function to eliminate free radicals that increase tissue susceptibility to bacterial infections. These enzymes also are necessary to increase structural strength and elasticity of connective tissue and blood vessels and increase strength of bone. Copper also is involved in the metabolism of iron and the maturation of red blood cells.

The copper requirement provided in the National Research Council (10) nutrient requirements for broilers is 8 ppm; the nutritional requirement of broiler breeders for copper is unknown. Copper typically is supplemented at 8 to 25 ppm in broiler breeder diets, almost exclusively in sulfate form.