Effects of dietary selenite, copper, and zinc on tissue trace mineral levels in chicks

Studies were conducted to determine whether nutritional selenium (Se) status affects the nutritional status of the chick with respect to other trace elements, particularly copper (Cu) and Zinc (Zn). Severe Se deficiency was produced in chicks by the use of diets that contained exceedingly low contents (less than 0.010 ppm) of Se, but contained adequate amounts of all other known essential nutrients. This diet was based upon corn and soybean meal produced in areas of China with endemic Se deficiency of geobotanical origin. A level of at least 0.10 ppm Se was found to be required to maintain normal Se status of chicks fed this diet, and Se deficiency resulted in decreased levels of Cu, Zn, and molybdenum in the pancreas (liver and plasma levels were not affected). High dietary supplementation of Zn nor Cu did not affect the short-term utilization of Se, as indicated by the 18-h responses of Se-dependent glutathione peroxidase in plasma and liver.

Uncomplicated selenium deficiency produced in chicks fed a corn-soy-based diet

Day-old chicks were fed a practical-type diet based on corn- and soybean meal produced in a severely Se-deficient area of northeastern China. The diet contained 0.007 ppm Se and resulted in marked decreases in the activities of Se-dependent glutathione peroxidase in plasma and pancreas within 6 days of feeding. Chicks fed this basal diet showed histological signs of acinar atrophy of the pancreas, hyaline body formation, vacuolation and cytoplasmic shrinkage by 18 days and significantly elevated activities of amylase in plasma by 30 days. Each of these changes was prevented by supplementing the basal diet with Se to bring it to a level of 0.20 ppm. Chicks fed a Se-deficient purified diet based on crystalline amino acids also showed decreased Se-dependent glutathione peroxidase activities in plasma and pancreas, pancreatic damage as evidenced by histological examination and increases in plasma amylase activities. However, these signs of nutritionally induced pancreatic atrophy occurred sooner and were of greater magnitude than those observed in Se-deficient chicks fed the practical diet within the 30-day experimental period. These results, therefore, constitute the first report of nutritionally induced pancreatic atrophy in Se-deficient chicks fed a diet containing intact protein, and we suggest that a factor(s) associated with the practical diet acts to partially protect the chicks from this pathological consequence of severe Se deficiency.