Abstract
The influence of krill feeding on iron absorption and hematologic factors related to iron nutrition was studied with male growing Wistar rats. Experimental diets containing 20% and 30% protein from freeze-dried raw or precooked krill were given to rats for 4 weeks. Control diets contained 20% and 30% protein from casein. The control diet of each protein level contained an almost equal iron level to that of a corresponding krill diet. The weight gain, count of blood cell, hemoglobin concentration and serum iron concentration were lower in both krill groups, especially in the precooked krill groups, than those as compared with the control groups. The apparent iron absorption rate during the last 9 days of the experimental period was estimated from ingested dietary iron and fecal iron contents. These rates in the raw krill groups were nearly equal to those of the control groups, but in the precooked krill groups these absorption rates showed a negative sign, indicating a remarkable inhibition of iron absorption. To confirm the relation between iron absorption and ingested exoskeleton, rats were fed a diet containing raw or boiled shrimp exoskeleton for 3 weeks, and the concentrations of hemoglobin and serum iron in these rats were compared with those of rats fed a control diet containing cellulose powder. Although these concentrations in the raw exoskeletongroup were similar to those of the control group, a significantly lower serum iron concentration was observed in a boiled exoskeleton group. The results indicated that the krill contained an inhibitory factor of dietary iron absorption, and it was postulated that the inhibitory factor was probably krill exoskeleton which might be activated by a heating treatment.
