1. FIBRE FRACTIONS 2. ENERGETIC EVALUATION OF FEEDS

Question 1

How to separate hemicelluloses, cellulose, and lignin?

Answer 1

1. BOILING IN NEUTRAL DETERGENT SOLUTION
   (Na-lauryl-sulphate), pH: 6.9-7.1
   A: Soluble fraction („cell contents”): minerals, CP, EE, soluble carbohydrates, starch, pectin;
   B:Insoluble residue (cell wall) NDF: Neutral Detergent Fiber hemicelluloses, cellulose, lignin
2. BOILING IN ACID DETERGENT SOLUTION 
   (0.5 mol H2SO4 + 2% cetil-trimetil-ammonium-bromid)  A: hemicelluloses(NDF-ADF)
   B: ADF: Acid Detergent Fiber cellulose, lignin;
3. TREATMENT IN CONCENTRATED (72%) H2SO4   A:Cellulose (ADF-ADL)
   B:ADL: Acid Detergent Lignin lignin.

Question 2

Crude Fibre (CF) =/= NDF

Answer 2

E.g. Alfalfa hay; CF: 25%; NDF: 39%; ADF: 31%; ADL: 7%; NDF˃CF!

Question 3

ENERGETIC EVALUATION OF FEEDS

What are the nutrients required for?

Answer 3

• For the synthesis of body tissues and animal products;

- as sources of energy (for maintenance and production).

Question 4

ENERETIC EVALUATION OF FEEDS

Aims:

Answer 4

to express 
the energy requirements of animals and 
the energy contents of their feeds by the same energy terms.