CHAPTER IX 

 FEEDING STANDARDS: THEIR ORIGIN AND USE 



The process of analyzing a feeding stuff takes place in 

 chemical laboratories especially equipped for this work. The 

 chemist secures a fair sample of the feed and grinds it in a 

 mill to a powder as fine as flour. He then takes a small 

 sample of this and analyzes it in the laboratory. He dries 

 a weighed portion in an oven and finds j ust how much water 

 it contains, and the percentage of dry matter. Then with 

 ether he dissolves out the fat, (ether extract) and weighs this. 

 With other chemicals he also separates out the protein, the 

 nitrogen-free extract, and the fiber. Another sample of the 

 feed he burns to learn how much ash or mineral matter 

 remains. Thus the chemist is able to determine just how 

 many pounds of each of these substances there are in a given 

 amount of feed. This investigation of the chemical com- 

 position is the first step taken by the chemist in studying 

 the value of foods for animals. 



The amount of digestible nutrients in a food, the simple 

 chemical analysis, however, did not show. Then there was 

 another step forward by the chemist, whereby he learned 

 just how much of the total protein, carbohydrates, and fat 

 in a given food an animal digested. After analyzing a sample 

 of the feed, as much of it was fed as the animal would eat in 

 a given time. During the experiment, all the solid and liquid 

 excrement passed off by the animal was collected, and samples 

 of these were also analyzed. Having learned how much pro- 

 tein, carbohydrates, and fat were lost in the manure, the 

 chemist deducted these amounts from the total quantity con- 

 sumed in the feed, and the difference was regarded as the 

 amount digested by the animal. This method was not per- 



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