Abstract
Daily utilization and digestibility of nitrogen in food by the silkworm, Bombyx mori, were determined, and quantitative distribution of digested nitrogen into the cocoon-shell, pupa and eggs was estimated. The amount of nitrogen ingested and digested by a single larva in the 4th and 5th instars was 16.5 and 10.8 mmoles for the male, and 18.7 and 12.7 mmoles for the female, respectively. The digestibility of nitrogen was 65.1% (male) and 67.6% (female). The increase of nitrogen in the whole body and silkglands in the 5th instar was 8.9 and 6.1 mmoles in the male, and 11.0 and 6.4 mmoles in the female, respectively. Approximately 46 and 70% of nitrogen ingested and digested were stored in the coccon-shell in the male, and 43 and 63% of nitrogen ingested and digested were stored in the cocoon-shell in the female, respectively. Approximately 10 and 15% of nitrogen ingested and digested were used for egg formation. These results clearly show that the efficiency of conversion of nitrogen in the coccon-shell is conspicuously high in the silkworm.
