Chemical analysis:

Animal Nutrition and Fodder Production Essentials: Lomash’s Quick Guide for Master’s Prep

Chemical analysis:

 It is a scientific process that evaluates the composition of animal feed.

 It is starting point for determining nutritive value of any feed.

 Data like crude protein, ether extract, crude fiber, ash and nitrogen free extract are determined by this method.

 It is simple, economic and rapid.

1. Proximate Analysis:

 It is a method of evaluating nutrient content of forage grasses.

 This system divides food into 6 fractions; moisture, ash, crude protein, ether extract, crude fiber and Nitrogen-free extract (NFE)

 This method was first carried out at Weende, a village near University of Goettingen in Germany in 1865.

Fraction	Analysis	Main contributory component
Moisture	Sample are oven-dried to constant weight at 100-105°C	Water
Ash	Ignite in muffle oven at 454-550°C to improve organic compounds	Inorganic salts (minerals) (same Sulphur and phosphorus from protein and other organic compound
Crude protein (CP)	Kjeldahl digestion in sulphuric acid followed by distillation and NH₃ determination (CP= N x 6.25)	Protein, amino acid, amines, nucleic acid, nitrogenous glycosides, glycolipid
Ether extract (EE)	Reflux extraction with petroleum ether, sometimes following hydrolysis in strong acid	Fats, oils, waxes, sterol, lipid-soluble vitamin, organic acid, pigments.
Crude Fiber (CF)	Treatment of ether extract residues with boiling acid and boiling alkali	Cellulose, hemicellulose, lignin
Nitrogen free extract (NFE)	Estimated by difference NFE-100- (M+ Ash + CP + EE + CF)	Starch, sugars, pectins, fructans, resins, organic acids.

Advantages of proximate analysis:

 Comparison of feed on specific basis

 It is common basis for feed purchasing and for ration formulation.

 No substitute till today except for fiber component.

 It forms starting point for specific analysis.

 It is used for analysis of feed, feces, urine, body tissues, body fluids.

 It provides first-hand information about the potentiality of the feed to fulfill required nutrient.

Demerits/Limitations of Proximate Analysis:

 It broadly categorizes carbohydrate; CF, NFE, EE and CP

 It donot indicate type of mineral element

 It does not include vitamins

 Traditional conversion factor (6.25) is too large for most of wild vegetation.

 Values are approximate one.

 Partioning of CF and NFE are poor and questionable.

 CF method severely under estimates the total plant cell wall content of a feed.

 CF doesn’t account for some of hemicellulose and lignin components.

 CF of forages may be as well digested as protein.

 CP values gives no indication if heat damage has occurred which alter protein availability.

 The ash content is not true representation of inorganic material in feed.

P.J Van Soest working at USDA station at Beltsville, Maryland, USA developed a rapid technique of separating carbohydrates on basis of nutritional availability to ruminants and rumen bacteria.
This method divides feed into two fractions; (a) plant cell contents, highly digestible fraction and (b) plant cell wall contents having variable digestibility consisting of insoluble protein, hemicellulose, cellulose, lignin and bound nitrogen.
This method involves boiling sample in neutral detergent solution. Soluble fraction is called NDS- neutral detergent soluble, while fibrous residue is called NDF- Neutral detergent fiber.
This method has been further refined with addition of acid-detergent fibre analysis, which breaks down NDF into soluble fraction containing hemicellulose and some insoluble protein and insoluble fraction containing cellulose, lignin and bound nitrogen. Further, content of lignin in ADF can be determined by either treating fiber with H₂SO₄ to dissolve cellulose or by oxidation to degrade lignin.
Feed samples boiled in neutral detergent solution.