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

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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