Ingredients and calculated chemical composition of the diets.

1 Mineral and Vitamin Premix (Spezialfutter Neuruppin Ltd., Neuruppin, Germany), containing per kg dry matter: 130 g Sodium (as sodium chloride), 55 g Magnesium (as magnesium oxide), 210 mg Retinol, 3 mg Vitamin D3, 8 g DL-a-Tocopherol, 300 mg Menadione, 250 mg Thiamine, 250 mg Riboflavine, 400 mg Vitamin B6, 2 mg Vitamin B12, 2,5 g Nicotinic acid, 100 mg Folic acid, 25 mg Biotin, 1 g Pantothenate, 80 g Choline chloride, 5 g Iron (as Iron-(II)-carbonate), 1 g Copper (as Copper-(II)-sulfate), 6 g Manganese (as Manganese-(II)-oxide), 45 mg Iodine (as Calcium-iodate), 35 mg Selenium (as Sodium-selenite).2 Corn starch in the basal diet was partially replaced in the three diets containing 50, 150, and 2500 mg/kg zinc with analytical grade zinc oxide (Sigma Aldrich, Deisenhofen, Germany) to adjust for the zinc level.3 Analyzed concentration of zinc in the basal diet without ZnO supplementation. The experimental diets contained zinc at 57, 164, and 2,425 mg/kg, respectively.Ingredients and calculated chemical composition of the diets.