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close this bookBioconversion of Organic Residues for Rural Communities (UNU, 1979)
close this folderPerspectives on bioconversion of organic residues for rural communities
View the document(introduction...)
View the documentIntroduction
View the documentSources of available nutrients
View the documentThe most suitable materials for bioconversion
View the documentCharacteristics of residues
View the documentBioconversion systems
View the documentPhysical and chemical treatments
View the documentMicrobial conversion
View the documentThe animal conversion phase
View the documentSummary
View the documentReferences

Physical and chemical treatments

The alkali treatment of cellulose-rich materials like straw (1,800 million tons in rural areas) deserves special attention (Table 5). Digestibility for ruminants improves from 45 to 68 per cent when straw is treated. What does that imply? in the major rural areas of India, untreated rice straw provides hardly enough nutrients to maintain the live weight of cattle; in other words, it barely covers the animals' maintenance requirements Assuming that 90 per cent of the feed is used for maintenance, 10 per cent is available for increasing weight, for producing offspring, and for milk production. If digestibility were increased by 50 per cent, it would provide, as in the Table 5 example, a fivefold increase in nutrients available for meat and milk production.

TABLE 5. Effect of Treatment on Straw Digestion in Sheep

Treatment Organic matter Digestibility (%)
Alkali untreated 45
  treated 68
Ammonia untreated 38 (56)
  treated 52 (69)