Starch equivalent

STARCH EQUIVALENT

Definition

  • Starch equivalent is the number of kilograms of starch that would be required to produce the same amount of fat as that of 100 kg of feed.
  • eg:- When we say starch equivalent of groundnut cake is 74 kg, it means that 100 kg of the groundnut cake, can produce as much animal fat as 74 kg of pure starch, when fed in addition to maintenance ration. In other words 100 kg of groundnut cake contains as much net or productive energy as 74 kg of the starch. 
  • The starch equivalent (SE) is essentially the same as net energy of the feedstuffs since both expressions aim at stating the productive value of the feed. The only difference being that, net energy is expressed as calories and starch equivalent is expressed in terms of starch,which is regarded to be a source of net energy to the animal.

Calculation of Starch equivalent

  • Kellner has given starch equivalent factor for one kg of digestible nutrients.

One kg of digestible nutrient
Starch equivalent factor
Carbohydrate
1.00
Fibre
1.00
Protein
0.94
Fat from Roughages
1.91
Fat from Cereals
2.12
Fat from oil cakes
2.40

  • The correction factor for concentrate is known as Value number or Golden number and it is 0.98 and the correction factor for roughages is known as crude fibre correction factor.

E.g.

    • Calculate the S.E of Barley with following digestible nutrients.
        • Digestible protein                  5.6
        • Digestible ether extractive  1.2
        • Digestible fibre                      2.5
        • Digestible NFE                      60.5
    • Multiply the digestible nutrients by respective starch equivalent factor. Totaling of this will give the starch equivalent of Barley as shown here.

    Digestible protein
      5.6 x 0.94
    =
    5.26
    Digestible ether extractive
      1.2 x 2.12
    =
    2.4
    Digestible crude fibre
      2.5 x 1
    =
    2.5
    Digestible NFE
      60.5 x 1
    =
    60.5
    _____
    70.80
    _____
    • 70.80 is known as calculated SE( uncorrected SE value). The corrected SE is obtained after the application of the correction factor. ie. 70.80 x 0.98 = 69.38

For Roughages

  • In case of roughages, deductions are to be made from calculated starch equivalent value to obtain the actual SE. For each % of crude fibre in the material, the calculated SE is less by 0.58.

          Eg: Calculate the S.E. of oat straw with 30% crude fibre:

Digestible protein
  0.5 x 0.94
=
0.47
Digestible ether extractive
  0.3 x 1.91
=
0.57
Digestible fibre
  18.5 x 1
=
18.50
Digestible NFE
  20.0 x 1
=
20.00
_____
39.54
____

Crude fibre content is 30 %

  • Crude fibre correction is 30 x 0.58 = 17.4
  • Calculated starch equivalent           = 39.54
  • Correction factor                               = 17.40

      Actual starch equivalent    39.54-17.40   = 22.14

Exercise

    1
    Calculate the starch equivalent of an oil cake.
    Digestible protein
    =
    40.6
    Digestible fat
    =
    5.8
    Digestible NFE
    =
    18.5
    Digestible fibre
    =
    0.16
    2
    Calculate the starch equivalent of hay
    Digestible protein
    =
    1.2
    Digestible fat
    =
    0.6
    Digestible NFE
    =
    25.8
    Digestible fibre
    =
    13.6
    Note : Crude fibre content is 26.8
    3
    Calculate the starch equivalent of Maize
    Digestible protein
    =
    7.6
    Digestible ether extract
    =
    1.2
    Digestible NFE
    =
    61.5
    Digestible fibre
    =
    2.0

Last modified: Monday, 2 April 2012, 7:30 AM