SECTION XXI. 



COMPOSITION AND DIGESTIBLE NUTRIENTS OF FEED STUFFS 

 AND THE NUTRITIVE RATIO. 



Composition of Feeds. We have already stated the meaning 

 and functions of the nutritive elements contained in plants and 

 animals. The next thing is to become more familiar with the 

 composition and digestibility of feeds. The chemist has already 

 worked out these for us and he expresses the composition as 

 follows : 



COMPOSITION OF CORN (GRAIN) IN PER CENT. 



The above analysis is very simply translated. It means that 

 in every 100 pounds of corn grain, there are 10.3 Ibs. of protein, 

 5 Ibs. of fat, 70.4 Ibs. of nitrogen free extract, 2.2 Ibs. of fiber, 

 10.6 Ibs. of water and 1.5 Ibs. of ash. Or there are 10.6 Ibs. of 

 water and 89.4 Ibs. of dry matter. 



Digestibility of Feeds. Knowing the composition of feeds, it 

 is now necessary to become acquainted with the actual amounts 

 of the nutrients (protein, fat, nitrogen free extract and fiber), 

 that the animal can assimilate. The digestibility of any food is 

 determined by analyzing and finding its chemical composition, 

 namely the per cent, of protein, ether extract, nitrogen free ex- 

 tract, fiber, water and ash, and feeding weighed portions of this 

 food to animals for a given period and at regular intervals. The 

 feces or manure is collected, weighed and analyzed. The differ- 

 ence between the dry matter fed and the dry matter cast off as 

 manure, is taken as digestible. This procedure seems very simple 

 but it requires a great deal of work, and the results received are 

 not always satisfactorily accurate. 



Digestibility not Always Accurate. The true digestibility of 

 the protein and fats is the most difficult to ascertain. We know 

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