2 3 o THE CHEMISTRY OF CATTLE FEEDING 



chemical composition of the substance. This may be expressed 

 in percentages of the several (digestible) nutrients, or as per- 

 centages of digestible protein and starch equivalents. The 

 latter probably gives a truer view of the properties of the food, 

 and it involves the use of a smaller number of separate figures 

 which is a great advantage for purposes of comparison. It is, 

 however, open to the objection that the protein is counted 

 twice over, and it is a troublesome business to determine 

 exactly and deduct that part of the starch equivalent which is 

 due to the protein. 



The author has found it convenient in practice to take 

 the percentage of digestible protein and of digestible non- 

 nitrogenous nutrients the latter being all reckoned as starch 

 (p. 172) and from these data to plot the positions of the 

 foods on a chart as shown in Fig. 14. For this purpose the 

 protein is plotted on the abscissae (vertical lines) and the non- 

 nitrogenous nutrients on the ordinates (horizontal lines). Con- 

 sequently, the greater the percentage of protein in a food the 

 higher up will be its position on the page, and the greater the 

 percentage of non-nitrogenous nutrients the further to the right. 



Three diagonal lines are draw from the point of origin 

 representing ratios of 2 to i, 4 to i, and 6 to i respec- 

 tively. The chart, therefore, shows the nutritive ratios 

 as well as the percentages of digestible protein and non- 

 nitrogenous nutrients ; and it is possible to compare any one 

 food with another, or all together, at a glance. 



On reference to the figure it will be found that several 

 natural groups can be distinguished as follows : 



(1) The succulent green fodders (grass, etc.) and roots 

 forming a close constellation l in the south-west corner. These 

 contain less than 5 per cent, of protein and less than 20 per 

 cent, of non-nitrogenous nutrients. 



(2) The dry coarse fodders (hays and straws) containing 

 less than 6 per cent, of digestible protein and from 35 to 45 

 per cent, of digestible non-nitrogenous nutrients. This can be 

 subdivided into (a) cereal straws and (b) hays and leguminous 



1 In order to compare these foods with each other they should be 

 plotted separately on a larger scale as in the N.E. corner of the chart. 



