FEEDING. 45 



is called the albuminoid ratio. The ratio of 1:5, which has been found 

 by experience to be suitable for the feeding of adult cows, may be con- 

 sidered as a standard ratio for purposes of comparison. According as 

 the ratio is less or greater than 5, it is named a narrow or wide ratio. If 

 the ratio of nutrients is to be calculated, it is necessary, in the first place, 

 to reduce both the groups of non-nitrogenous nutrients, i.e. the fat and 

 the carbohydrates (digestible non-nitrogenous extract and digestible fibre) 

 to a common value. This is necessary in order that the quantity of fat 

 may be stated in its equivalent amount of carbohydrates. For this pur- 

 pose, the quantity of fat is multiplied by 2*5, which is called the starch 

 equivalent of fat, since it has been ascertained by experiments that by the 

 digestion of one part of fat (by weight) as much heat is produced approxi- 

 mately as from the digestion of 2 '5 parts of carbohydrates. In order, 

 therefore, to find the nutritive ratio of a ration, it is necessary to multiply 

 the amount of digestible fat by its starch equivalent. This is added to 

 the amount of digestible carbohydrates, and the total divided by the 

 amount of digestible nitrogenous substance. An example may serve to 

 make this clear. 



A ration consisting of 8 Ibs. of average clover, 10 Ibs. of oat straw, 

 20 Ibs. of roots, 6 Ibs. of oats, 1 Ib. of rape-cake, and 2 Ibs. of earth-nut 

 cake from shelled nuts, has to be examined. From tables which will be 

 found in any text-book of agricultural chemistry, 1 the following figures 

 may be found, which represent the average composition of the dry sub- 

 stance of the individual foods and their digestible nutrients. 



8 Ibs. clover hay, . . . 

 10 Ibs. oat straw, 

 20 Ibs. roots, 



6 Ibs. oats, ... 



1 Ib. rape cake, 



2 Ibs. earth-nut cake, 



Totals, 25-65 2'51 877 3'62 '67 



From the above we find that the ration contains 25*65 Ibs. of dry 

 matter, of which 15 '29 Ibs. are in the form of coarse fodder. The follow- 

 ing quantities are the amounts of digestible constituents: 2-51 Ibs. of 

 nitrogenous matter, 8'77 + 3-62 = 12-39 Ibs. carbohydrates, and -67 Ib. of 

 fat. The nutritive ratio is 1 : 5 '6 for 



67x2.5 + 12-39 



- = O'D 



2-51 



!See Johnston's Elements of Agricultural Chemistry, 17th edition, revised by Dr. Aikman r 

 pp. 382-85 and p. 465 (Blackwood & Sons). 



