First, I would't use moisture to the NFE formula, it is assumed you are working on a Dry Matter basis. I

Second:

Even though I don't know the formula,  it seems it assumes a certain amount of energy (ME) /x g of CP, NFE nd Fat. Off course, Fat contains more energy than NFE and CP, that's why you multiply by 85 instead of 35 (85/35 = 2.42 fold). I guess 35 is 35 kcal x %CP, otherwise it wouldn't be possible, the same for the rest.  For example: feed with 10% CP, 10% Fat and 50% NFE would have: 35 kcal x 10 + 85 kcal x 10 + 35 kcal x 50 = 2950 kcal/ kg DM. 

Where does the 35 comes from? Well, the gross energy of Carbohydrates is 4.4 Mcal/kg DM. If you assume 3.5 Mcal/Kg are metabolisable, you are assuming that approx 20% is lost because it is undigestible or like enteric gases or in urine. I know it is complex, but that is how you derive the metabolisable energy. In case of fat, you have to consider fat has approx 9.2 Mcal GE/kg DM. 

Dear Prabhani,

Energy content of a feedstuffs depends on 2 multiplicative factors:

1/ individual nutrient content (= there is more energy from a nutrient if there is more of this nutrient - obvious)

2/ individual nutrient digestibility (= there is more energy from one nutrient if it is more digestible)

From this remark, it is obvious that you cannot have a single formula for all raw materials, because you cannot assume that their digestibility is the same. Some general formula can be found for complete feeds (because their overall digestibility is more or less stabilized) but NOT for raw materials.

In "European Table of Energy Values for Poultry Feedstuffs" by Janssen et al, (link to the pdf below) you will find coefficients for the estimation of energy values for various feedstuffs.

An example of the use of your formula for two raw materials you mention (rice polish and Soybean meal) is given below, showing that it doesn't apply to raw materials.

Good luck,

Denis.

: your formula is in calories, literature is often in joules - take 1Cal = 4.184 joule).

RICE POLISH ----------------------------

(compo from Feedipedia rice bran, link below : 94 g/kg ASH, 148 g/kg PROTEIN, 172 g/kg FAT, 86 g/kg C FIBRE, 500 g/kg NFE)

Feedipedia value: 12.7 MJ/kg

Your equation: 35*14.8 + 85*17.2 + 35*50 = 3730kcal/kg=15.61 MJ/kg (23% overestimation)

Janssen equation (specific for rice byproducts): 19.54*organic matter - 29.1 * protein + 17.97*C fat -34.29* C fibre = 13.53 MJ/kg (6% overestimation)

SOYBEAN MEAL -------------------------------

(compo from Feedipedia SBM link below : 71 g/kg ASH, 518 g/kg PROTEIN, 20 g/kg FAT, 67 g/kg C FIBRE, 324 g/kg NFE)

Feedipedia value: 10.7 MJ/kg

Your equation: 35*51.8 + 85*2 + 35*32.4 = 3117kcal/kg=13.04 MJ/kg (18% overestimation)

Janssen equation (specific for SBM): 15.69 * protein + 19.41*C fat + 6.236*NFE = 10.54 MJ/kg (1.5% underestimation)

http://www2.svenskaagg.se/attachments/92/1425.pdf

http://www.feedipedia.org/node/750

http://www.feedipedia.org/node/674

Thank you very much for your valuble answers....

Hi guys, can i use the same formula to calculate the energy in fish feed?

no, as energy value are specific for type of animal spices as ruminants, poultry, pigs, rabbits and fish every spices has it value of energy, even energy value may be different with age of age, younger ages derived less energy value than adult and may be between sex laying hens and cockerels, thus you have to use the equation developed for each spices of animal

Hi, Prabhani Nisansala, yes the equation is correct, thus you can use for poultry feed production. It is developed by Pauzenga. Check out this paper.

Pauzenga, U. (1985). Feeding Parent Stock. Zootecnica Internation. Pp. 22-24.

The formula is correct because I have used it to verify some answers.