Zinc antagonizing effects of fish meal, wheat bran and a corn-soybean meal mixture when added to a phytate-and fiber-free casein-dextrose diet

Abstract

Two levels of dietary zinc (Zn), 68 and 318 mg/kg, were fed to young chicks in the presence or absence of 10% dietary additions of fish meal (FM), wheat bran (WB) or a corn-soybean meal mixture (C-SBM). As determined by Zn deposition in pancreas, bone and liver, Zn utilization was severely depressed by addition of FM, WB or C-SBM to the phytate-and fiber-free casein-dextrose basal diet. The increase in pancreatic Zn concentration upon supplementing the basal diet (68 mg/kg Zn) with 250 mg/kg Zn from ZnCO 3 was only 1.7% (C-SBM), 4.8% (FM) and 2.0% (WB) of that which resulted when the same quantity of Zn was added to the phytate-and fiber-free basal diet. Tibia and liver uptakes of Zn were also markedly depressed by feed ingrediet supplementation. Liver Zn concentration double when 250 mg/kg Zn was added to the basal diet, but C-SBM, FM or WB addition totally prevented the increase in liver Zn resulting from Zn supplementation. With 318 mg/kg dietary Zn, chicks fed the diet with no feed ingredient supplementation had three times more Zn in bone than in liver and over twice as much Zn in pancreas as bone. In the presence of any one of the supplemental feed ingredients, however, Zn concentration in bone actually exceeded that present in pancreatic tissue. The data support the conclusion that phytate-and/or fiber-furnishing feed ingredients markedly reduce Zn utilization, but not all tissue storage sites of Zn are affected similarly.