Trace mineral deficiencies in rats caused by feeding rapeseed flours during growth, gestation and lactation

The present study determined the effect of duration of feeding and dietary levels of rapeseed flours on growth, outcome of gestation and lactation and blood trace element content of rats. In the first two experiments, female rats were fed either casein or rapeseed flour diets during gestation and lactation, or prior to and during gestation. In the last two experiments, weanling male rats were fed for 4 weeks either casein or rapeseed flour diets with or without added zinc. Feeding rapeseed flours prior to and/or during gestation caused a reduction in weight gains and food consumption but did not affect the number or weight of the pups born. Plasma zinc levels were low in the mother rats at parturition and plasma zinc and iron levels were low in weanling rats after 4 weeks of feeding the rapeseed diets. Adding 300 ppm zinc to the diet prevented the decrease in food consumption, weight gains and plasma zinc levels in the weanling rats. It is concluded that the recommended levels of trace elements in the rat diet are inadequate for the purpose of bioassay and toxicological evaluation or rapeseed preparations. In order that the nutritional potenital of new protein sources be correctly evaluated, guidelines for adequacy of mineral in such diets should be determined.