Excess calcium reduces zinc absorption and may speed its removal from the tissues. The zinc requirement on a corn-soy ration is about 50 to 100 ppm with normal levels of calcium for growing to finishing pigs. Zinc toxicity results in reduced growth, arthritis, hemorrhage in axillary spaces, gastritis and death. Selenium Selenium should be included in swine diets. Careful mixing to ensure adequate but not excess concentrations is important.
Selenium deficiencies result in sudden death, liver necrosis, mulberry heart and pale muscles.
Selenium toxicity can occur at 5 to 8 ppm and is characterized by reduced feed intake, depressed growth, loss of hair, stiffness or pain upon movement, cirrhosis of the liver, anemia, separation of the hoof from the foot, impaired embryo development, and a high percentage of stillbirths. In the following example, Step 1 . Using the chemical analysis in Table 4, calculate the amount of calcium and phosphorus available from the 80 lb of corn and 20 lb of soybean meal, which results in 0.088 lb of calcium and 0.354 lb of phosphorus. Total supplied 0.088 0.354 Step 2 . You will still be short 0.512 lb of calcium and 0.146 lb of phosphorus.