Zinc Requirement of Baby Pigs on Casein Diets

Abstract

In 2 trials to determine their zinc requirement 27 baby pigs were fed diets in which casein supplied the protein. Casein was treated with disodium ethylenediaminetetraacetate to remove zinc and insure a subrequirement dietary level in the first trial. Since deficiency symptoms appeared in pigs on the untreated basal casein diet, in trial 1, this procedure was discontinued in trial 2. Levels of dietary zinc used were 4, 10 and 14 ppm in trial 1 and 10, 14 and 20 ppm in trial 2. All pigs receiving 10 ppm or less of dietary zinc in either trial exhibited symptoms of zinc deficiency, including parakeratotic lesions and a reduction of growth rate, food utilization, serum zinc, calcium and alkaline phosphatase levels, bone size and strength, allometric weight of thymus, tissue zinc level and zinc and calcium balance. The pigs which received 14 ppm or more of dietary zinc in either trial showed no parakeratotic lesions, and rate of growth and food utilization were normal. Pigs receiving 14 ppm of dietary zinc gave evidence of zinc repletion with serum zinc and alkaline phosphatase slowly returning to near normal values for nursing pigs of this age. Values of serum zinc and alkaline phosphatase were more readily restored to normal in pigs receiving 20 ppm of dietary zinc. Zinc retention data indicated that a dietary zinc level of between 14 and 20 ppm was required to maintain total body tissue levels similar to those of the nursing pig.