THE COMPOSITION OF FEEDING STUFFS 



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organic matter has been completely decomposed and the nitrogen has been 

 changed into ammonium sulfate. This is dissolved in distilled water, 

 and 50 c.c. of a concentrated soda solution are added, the flask being 

 connected with a distillation apparatus and heat applied. A certain 

 quantity of standard hydrochloric acid solution, more than sufficient to 

 neutralize the ammonia obtained in the oxidation of the protein, has been 

 previously added in the receiving flask, and the distillation is now con- 

 tinued till all ammonia has been distilled over. The excess of acid in the 

 receiving flask is then accurately titrated back (neutralized), and from the 

 volume of acid used the amount of nitrogen in the sample is obtained. 

 This is calculated in percentage of the amount of sample weighed out, 

 and by multiplying by 6.25 the percentage of protein contained in the 

 sample is obtained. 



FIG. 5. View of a chemical laboratory for analysis of feeding stuffs and other agricultural 

 products. (Wisconsin Station.) 



d. Fiber is determined in the residue from the ether extract by boiling 

 first with 200 c.c. of a 1.25 per cent sulfuric acid solution and then with 

 200 c.c. of a soda solution of the same strength. After filtering, drying, and 

 weighing, the residue is ignited, and the loss in weight, calculated on the 

 amount of the sample originally weighed out, shows the percentage of 

 fiber in the feed. This method, which is known as the Weende method, 

 gives pure cellulose or woody fiber, with some impurities like pentosans, 

 incrusting substances (lignin, cutin), and certain insoluble proteins. The 

 method does not give very satisfactory results, and is only used for want 

 of some better method of arriving at the amount of fiber present in feeding 

 stuffs. 



e. Ash or mineral matter is obtained by igniting at a low red heat 2 

 grams of the sample and weighing the residue after cooling in a desic- 

 cator. The crude ash thus obtained generally contains free carbon, as well 

 as carbonates and sulfates formed by oxidation of organic components of 

 plant materials. It is sometimes purified, and the amount thus found is 

 given as pure ash. 



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