Studies on Intermittent Supplementation

Abstract

A discontinuous casein supplementationat 24-hour intervals of an only-gluten diet was reported previously to result in an incomplete growth recovery, as well as a delayed liver-cell maturation when the protein level in the diet was 10%. When such a discontinuous supplementation was carried out at 14% protein level, the growth recovery was sufficient to ensure a practically normal terminal body weight; but a delay in liver-cell multiplication was found. Moreover, at both protein levels, the recovery rate on the day of supplementation appeared to depend on the level of nitrogen intake rather than on the balance existing between non-supplemented and supplemented diets. The effects of 24- and 48-hour intervals between successive casein supplements of a 30-percent only-gluten protein diet on growing rats have now been investigated. The results indicate that, at this artificially high protein level, the utilization of the dietary protein, as indicated by several criteria (PER, NGI, NPU), does not appear to be impaired by discontinuity in the supplementation, even when the intervals are as long as 48 h. The growth recovery is complete, and the carcass and liver composition values fall within the normal range. In the liver, at the cellular level, the results indicate a lack of interference with both the cell maturation and multiplication. In addition, the liver cell ability to ‘store’ nitrogen in high-protein diets appears unimpaired by discontinuity in supplementation under the conditions investigated in the present study.