DEFINITIONS AND TECHNICAL CONSIDERATIONS. 335 



consideration; however, as far as possible, it is desirable to have a general 

 knowledge of both sides of the question which will permit new fields of investi- 

 gation with fodders of which a farmer has had no previous experience. 

 The early formula generally adopted was : 



c _ Protein -f Fat -4- Nitrogen Free Extract 



Protein + Fibre -f Fat -f Kitrogen Free Extract 



Protein -j- Fat -f Nitrogen Free Extract 

 Organic Substances. 



But the organic substances are represented by dry matter less ash. Conse- 

 quently the formula reads: 



c > = Total Protein + Fat + Nitrogen Free Extract. 

 Dry matter Ash. 



If applied to meadow hay for example : 



c D _ 8.5 + 3.0 + 38.3 

 85.76.02 



Calculations based upon this formula give the following coefficients: hay 

 = 0.60; straw = 0.40; husks = 0.50. 



If it is desirable to replace a portion of hay by straw in a ration, owing to 

 special circumstances of the market, the amount of straw to be used may be 

 estimated by considering the coefficient of digestibility of the two fodders, hay 

 (0.60) straw (0.40) = 0.20, which means that 20 per cent, more straw must 

 be used to get the same effect as would have been realized with i less hay. 

 This is an excellent practical example of how a farmer can meet existing con- 

 ditions. The nutritive relations of a ration should also be considered as it 

 has an important influence; while this may be considered as a relative diges- 

 tibility, the absolute digestibility depends upon various causes. Between 

 these terms there exist frequent confusions. Two fodders, oats and hay for 

 example, may have the same absolute digestibility, but not the same value for 

 feeding unless their relative digestibility is also the same. The fodder that 

 yields the greatest amount of nutritive elements that are digested, has the 

 highest value. In such cases, it must not be forgotten that feeding stuffs when 

 alone, act very differently than when combined, and may produce a collective 

 depressing effect. The digestibility of the protein of a fodder may decrease by 

 the addition of starch, for example, and remain constant by a further addition 

 of some fatty substance. Hence there has been proposed a special factor known 

 as adipoprotein relation, which is a proportion between the protein and fatty 

 substances. Attention should be called to the fact that the best results are ob- 

 tained when the proportion is 1 to 2. (In hay it is to 7.) When there is 

 too much fat or too little, the effects are equally bad. When the nutritive 

 relation (relative digestibility) is i. the best combination then is 1 protein, 

 0.5 fatty substance and 4.5 carbohydrate. Some authorities maintain that the 

 proportion between fat and protein should never be lower than . 



In all these formulae, too little account is taken of the proportion between 



