In ericulture the by-products are not marginal. In the standard one-acre castor model, pupae account for about 82 % of gross revenue — the cocoon is, in strict financial terms, the by-product. Everything the system produces has a use.
Products and their value
| Product | Source | মূল্য |
|---|---|---|
| Cut cocoon / shell | Eri rearing | Spun yarn — the primary product |
| Pupa | Eri rearing | About 16 g protein and 8 g fat per 100 g fresh; amino acid score 99–100 with leucine limiting; PDCAAS 86. Defatted meal is about 75 % protein with 44 % essential amino acids — suited to protein concentrates and animal feed. |
| Pupal oil | Eri pupae | High in α-linolenic acid; found nutritionally comparable to common vegetable oils in feeding trials. |
| Castor seed and oil | Castor plantation | Industrial oil and cake from the same plants that feed the worms |
| Sericin | Degumming liquor | Recoverable protein with cosmetic and biomedical applications |
| Seed cocoon | Both systems | Sold to grainages as certified DFL stock |
| Ghicha and spun grades | Non-reelable muga cocoons | Hand-spun yarn; the 20 % flimsy fraction still earns about ₹ 400 per thousand cocoons |
Pupae are eaten widely in Assam — reported at about 88 % of surveyed households for
eri, 57 % for muga and 25 % for mulberry. Composition figures above are from published
nutrition research, not institute trials.