EFFECTS OF CANOLA MEAL ON ABSORPTION AND TISSUE LEVELS OF TRACE MINERALS IN RATS

Abstract

The possibility that supplemental trace minerals (TM) might be less available in the presence of canola meal (CM) compared with other protein sources was investigated using growing rats fed a barley-wheat (BW) diet alone or with 20% added CM, soybean meal or ammoniated mustard meal for 28 d. A purified diet was used as a control diet. Femur Zn concentrations were lowest (P < 0.05) in rats fed the BW + CM diet (306 μg g−1femur ash) followed by the BW diet (329 μg g−1); both groups showed lower Zn levels than for all other diets (control diet 345 μg g−1). Plasma Zn concentrations were lowest (P < 0.05) in rats fed the BW + CM diet (1.07 vs. 1.35 μg mL−1 for control diet). Differences in concentrations of copper, iron or manganese in plasma and liver were minor. Apparent absorption of Zn from the BW and BW + CM diets tended to be less than from the other diets. Some differences were observed in weight gains and feed efficiency but were apparently unrelated to a TM deficiency. The results indicated that while dietary levels of copper, iron and manganese were adequate, there was evidence of a marginal deficiency of Zn particularly in the BW + CM diet, a result of reduced availability of supplemental Zn due to the CM in the diet. Key words: Trace mineral, zinc, canola meal, rat