Proximate principles of feed analysis.pptx

Animal nutrition

1. PROXIMATE PRINCIPLES OF FEED ANALYSIS.

2. PROXIMATE ANALYSIS Weende System of Feed Analysis Origin Weende Experimental Station, Germany 1865 By Wilhelm Henneberg & Friedrich Stohmann Chemical analysis of feed & fodder

3. Contents Water Or Moisture Crude Protein Ether Extract Crude Fiber Ash Nitrogen Free Extractives (NFEs)

4. Weende System of Proximate Analysis Feed or biological samples Dry matter Moisture Inorganic Matter Inorganic matter Acid soluble Acid Acid insoluble Acid Crude protein Ether Extract Carbohydrates NFE CF

5. Water/ Moisture Principle Determined by drying feed sample in hot air oven at 100ºc for a specified length of time DM,% = ( wt after drying/ wt before drying)x100 % Moisture = 100 – DM.%

6. Significance of Moisture Determines the keeping quality of hay Determines loses in silage making Classification of feed into succulent & non succulent Significant in storage of feed Important while purchasing of feed Directly related to nutrition value of feed

7. Drawbacks Some volatile substances are also evaporated along with moisture Eg : Overestimation of moisture content on silage due to the evaporation of volatile fatty acids (VFAs) Highly Variable (High in young plants i.e around 80%) Difficulty in storage (Due to fungal infections)

8. Crude Protein Principle In the presence of sulphuric acid, sodium sulphate and a catalyst, amino nitrogen of many organic materials are converted into ammonim sulphate. Ammonia is distilled from an alkaline medium and absorbed in standardized mineral acid.

9. Include both true protein & non-protein nitrogen Estimated by using Johan Kjeldhal’s method Assumption: All protein is present as ‘N’ & all Food Protein contains !6% of N (100/16 = 6.25) Crude protein = N x 6.25 , where N = nitrogen content of the feed Merits & demerits + protein estimation -> method is cheap, Accurate values. - Protein estimation -> conc. H2SO4 -> Harmful

10. Ether Extract Fat content in a feed is determined by extracting feed sample in Soxhlet apparatus for 8-16 hrs It contains both true fats and pseudo fats hence called as crude fat. Psuedo fats includes wax, cholesterol, lecithin, volatile oils. p r i n c i p l e : - A dried ground sample is extracted with diethyl ether which dissolves fats, oils, pigments & other fat soluble substance.

11. Merits Instruments used are cheaper Ether can be reused Demerits Apart from fats, components like wax, cholesterol, lecithin are also soluble resulting in over estimation.

12. Total Ash Principle When a sample is burnt in muffle furnace at 600°C for 2 hours, only mineral matter is left behind. This is the total ash or mineral content of feed. % Ash = wt. after ashing /sample wt. x 100% Demerits No indication of amounts of individual minerals. Long time required (12-24 hours). Muffle Furnaces are quite costly to run. Loss of volatile minerals e.g., Cu, Fe, Pb, Hg, Ni, Zn.

13. Acid Insoluble ash When Hcl id added to ash, some Substance remains insoluble Called as Acid insoluble ash (AIA). AIA- indicates content of Silica & Sand in feed due to faulty handling. AIA -> Estimated to know the quality of the feed. Acid Soluble ash The Soluble protein of the total ash is Soluble ash which contains All macro & Micro molecules.

14. Fibre Estimation To See the digestible Component in the feed -> Merit fibres an estimated by using the Van Soest method. Acc. to this method, fibres are Characterised into 3 Components Neutral detergent fibre, Acid detergent fibre, Acid detergent lignin,

15. Neutral detergent fibre This procedure involves Separation of feed dry matter into 2 factor: One of high digestability , Other of low digestability . by boiling 0.5-1 gm Sample in Neutral detergent Solution for I hour & filtering Neutral detergent Solution - 3% Sodium Lauryl sulfate buffered to a pH of 7.0

16. Acid detergent fibrer It is a preparatory Step for the purpose of determing the lignin in the given Sample. Principle: Boiling 1 gm of feed in acid detergent Solution for an hour & filtering. The residue of insoluble molecules up ADF Acid detergent solution - 49.04 g of Sulphuric acid & 20gm of acetyl trimethyl ammonium bromide per litre. NDF - ADF – Hemicellulose + ( Limmited amount of protein)

17. Acid detergent lignin In order to determine the amount of lignin present, ADF is digested in 72% +H2S04 at 15 °C for 3 hrs & filtered. The residue remaining after washing & drying is weighed & ashed . The loss in weight during ashing approximates the lignin & reffered as Acid detergent lignin.

18. Nitrogen free extract (NFE) Principle NFE represents the soluble carbohydrate of the feed, such as starch and sugar. % NFE = % DM - (% EE + % CP+ % ash + % CF) Demerit NFE not determined analytically but is calculated by difference. Therefore, NFE accumulates all of the errors that exists in other proximate analysis components.

19. Major components Procedure Fraction Compoments Drying(100±20°) Moisture Water, other Volatile compounds Ignite (500-600°) Ash Minerals Elements Kjeldhal Digestion CP Protein, A.A.,NPN Ether Extraction EE Fats, Oils, Waxes Boiling with acid and alkali CF Cellulose, Lignin Remainder NFE Starch, Sugar

20. Advantages of Proximate Analysis Comparison of feeds on a specific basis It is a common basis for the feed purchasing and for ration formulation No substitute till today except for fiber component It forms Starting point for specific analysis Used for analysis of feeds, feces, urine, body tissues, body fluids

21. DEMERITS Broad categorization of carbohydrates, CF, NFE, EE & CP No indication of kind of mineral elements. It does not include vitamin. Traditional conversion factor (6.25) is too large for most of the wild vegetation. Values are approximate one and without actually using in feeding trials. The partitioning of CF & NFE as poorly and highly digestible respectively is questionable. The CF method severely underestimates the total plant cell wall content of a feed.

22. DEMERITS … CF-considered as indigestible-non nutritive residue. CF doesn't account for some of the hemicellulose and lignin components. The residue of alkali-acid digestion is not truly indigestible portion of feed rather is composed of cellulose and variable portion of non- cellulogic polysaccharides and lignin. The digestibility of carbohydrates does not follow its partitioning into CF & NFE with any marked certainty, especially for roughages.

23. DEMERITS … The CF of forages may be as well digested as the protein NFE includes pentosans, other polusacharides , soluble lignins thus overestimates. If EE contains large percentage of plant waxes, essential oils, resins etc., it has little value. CP values give no indication if heat damage has occurred which may alter protein availability. The ash content is not true representative of the inorganic material in the feed."

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