VALUATION OF FEEDING STUFFS 225 



the foods, (2) to determine the rations for work from the 

 dynamic values, (3) to determine the rations for milk pro- 

 duction from the amounts of digestible protein and non- 

 nitrogenous nutrients, (4) to determine the rations for fattening 

 only from the starch equivalents. In each case the amounts 

 are to be calculated separately according to the formulae given 

 for the purpose not from feeding standards. The actual 

 foods can, of course, be mixed together if deemed advisable 

 on practical grounds. 



In all cases care must be taken to ensure that the calcu- 

 lated quantities of food contain the required amounts of 

 protein. When starch values are used, the protein is often 

 overlooked or counted twice over. Such mistakes should 

 not be attributed to any defect in the system, but rather to 

 misapprehension on the part of those who employ it. At 

 the same time, a system which readily lends itself to such 

 mistakes must be deemed something less than perfect. 



Nutritive Ratio. In feeding for any specific purpose 

 maintenance, work, milk production, or increase certain 

 minimum amounts of digestible protein and non-nitrogenous 

 nutrients are required, and these bear a certain definite ratio 

 to each other in each case. If there be a deficiency of either 

 kind of nutrient, the object of the feeding whatever it may 

 be will not be satisfactorily accomplished. If there be more 

 than is required of either kind of nutrient, the excess of that 

 one may be wasted. Excess of protein, it is true, can perform 

 most of the functions of the non-nitrogenous nutrients. It 

 has approximately the same value as an equal weight of 

 starch, but it is much more expensive. It is not desirable, 

 therefore, on pecuniary grounds to give any considerable 

 excess of protein. 



The ratio of non-nitrogenous to nitrogenous nutrients in 

 any food is called the " nutritive " or " albuminoid ratio " of 

 the food. The contracted form, N-ratio, is often used. In 

 order to determine this ratio, the non-nitrogenous nutrients 

 must all be expressed in terms of one of them starch. The 

 amount of fat must therefore be multiplied by a factor which 

 represents the value of the fat as compared with starch. The 



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