Effect of Various Mulberry Leaf Powders on the Quality of Artificial Diet for Domestic Silkworm, Bombyx mori

This study aimed to investigate how mulberry leaf powders from different mulberry varieties influenced the quality of artificial diet for domestic silkworms. Using metabolomics, we examined the possible reasons why silkworm rearing performance varied, and provided new research ideas for improving diet quality. Forage mulberry leaves differed from grafted mulberry leaves in metabolic pathways related to fatty acids, amino acids, and vitamin C. Forage mulberry leaf powder showed considerably decreased amounts of vitamin C, serine, linoleic acid, and linolenic acid, all of which are required for the production of silk proteins and their intermediates. A considerable increase in 1-deoxynojirimycin (DNJ) content was observed. The feeding characteristics of silkworms led to decreased DNJ tolerance and lower quality of silkworm diet made from forage mulberry leaf powder compared to that made from grafted mulberry leaf powder. Furthermore, the body weight during the silk-spinning stage, cocoon weight, and Cocoon shell ratio of the reared silkworms were all markedly reduced. Using mulberry leaf powder would require addressing the problem of reduced DNJ tolerance in silkworms owing to the changes in their diet, in addition to improving the composition of the silkworm diet based on the characteristics of the mulberry leaf powder.