Difference between physiological fuel value and gross fuel value
Answers
Based on the composition of carbohydrate, fat and protein the heat of combustion of the feed sample can be worked out using appropriate factors.
From the gross chemical composition of the feed samples the amount of energy yielding nutrients namely carbohydrate, fat and protein are estimated.
If the amount of each is known it is easy to workout the heat of combustion of the feed sample using appropriate factors.
The heat of combustion of individual carbohydrates, proteins and fats differ with their composition. (Eg.) As determined by Atwater GE of sucrose is 3.96 Kcal/gram and that of starch is 4.23 Kcal/gram.
Energy yield of butterfat was found to be 9.21 Kcal/gram and that of lard, 9.48 Kcal/gram.
For practical use individual figures were averaged to apply to the major food stuffs (carbohydrate, fat and protein) as gross energy of food.