Zinc Utilization in the Chick as Influenced by Dietary Concentrations of Calcium and Phytate and by Eimeria acervulina Infection

Abstract

Experiments were performed to investigate the effects of Eimeria acervulina infection (duodenal coccidiosis) on the zinc (Zn)-calcium (Ca)-phytate interrelationship in the chick. Three supplemental levels of Ca (0, .91, and 1.82%), two of Zn (0 or 52 mg/kg), and two of sodium phytate (0 or 1.2%) were evaluated as to their effects when added to completely adequate corn-soybean meal diets. Duodenal coccidiosis was produced by multiple crop inoculations of 4 × 105 sporulated E. acervulina oocysts. Calcium supplementation depressed gain and efficiency of feed utilization, while Zn content of tissue and plasma was also lowered. Coccidial infection tended to reduce these values further. The addition of dietary phytate also depressed performance and deposition of Zn in tissue. Both excess dietary Ca and phytate addition to the diet markedly reduced plasma Zn concentration of birds fed corn-soybean meal diets unsupplemented with Zn. Addition of 52 mg/kg Zn, however, prevented excess Ca or phytate from exerting this effect. Parasitized chicks responded markedly with increased gain and gain/feed ratios when 52 mg/kg supplemental Zn was added to a 24% protein corn-soybean meal diet containing 1.82% total dietary Ca. It is evident, therefore, that the Zn-antagonizing effect of excess Ca (in the presence of phytate) is exacerbated by duodenal coccidiosis.