Food is a factor of paramount importance, which regulates its growth, development and silk yield in commercial sericulture. Food intake and silk production in silkworm are very closely related to nutritional factors. Dietary efficiency of silkworm plays a major role in converting the mulberry leaves consumed by them to silk. Efficiency of Conversion of Ingested (ECI) mulberry leaves into silk or leaf silk conversion rate is a better economic index in cocoon production. 

Retarded growth in insects may not be only due to the nutritional inadequacy of the diet, but also may be due to the effect of various environmental conditions and it also depends on the digestion and utilization of food, which varies from species to species, and even between different sexes of the same species. Developed sericulture countries have realized the importance of dietary efficiency, and they are engaged in finding effective ways to enhance leaf silk conversion rate. This can be improved by breeding programmes for evolving new breeds. The paper deals on ingestion, digestion, assimilation and feed conversion efficiency of exotic as well as Indian silkworm races and also on nutritional efficiency of silkworm under different environmental, feeding and nutritional conditions. 

But it is rather pertinent to note that in nutritional studies repeatability of results is very scare because of variability of many factors. To get consistent results in nutritional studies further more studies and methodologies are required to be standardized. Further, nutritional studies should be continued to work out dietary efficiency of new breeds to be released by var­ious research organization. 

It was felt and also it would be appropriate and suitable to screen the improved productive hybrids to understand the conversion efficiency of ingested mulberry leaf in to silk. Another important study need to be undertaken on feed conversion efficiency of a particular breed/hybrid by feeding leaves of different mulberry genotypes and its effect on food ingestion, digestion and conversion efficiency of breed under different feeding regime, environ­mental and climatological conditions. Further rapid development of biotechnology will be open up vast vistas and spawn a revolution in sericulture in the future, the gene controlling the character of high leaf-silk conversion rate could be transplanted into some silkworm races and it consequently improve the leaf silk conversion rate of new race.