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.