DEFINITIONS AND TECHNICAL CONSIDERATIONS. 347 



mine the actual percentage of carbohydrates that is soluble; this being known, 

 the digestibility of crude fibre could be entirely ignored. Wolff discussing 

 the subject, says that no data can possibly be accepted unless shown to be true 

 by practical experiments upon living animals. Of all the carbohydrates hav- 

 ing the greatest influence upon digestion, starch heads the list. Numerous 

 experiments upon every kind of animal have demonstrated that when its pro- 

 portion in coarse fodder is higher than 10 per cent, of the dry matter, the in- 

 fluence is noticeable; when reaching 15 per cent. . the effect is slight, but is 

 very great when it attains 25 to 30 per cent. In the experiments of Schulze 

 and Maercker, 800 grams of meadow hay were fed with 230 grams of starch; 

 the digestibility of hay fell from 54 to 32 per cent. , or a loss of 41 per cent, of 

 the digestible proportion. Consequently, upon general principles, it may be 

 admitted that by the addition of starch in quantities representing of the 

 total dry substances of a coarser fodder, there is a depression of 15 per cent, in 

 the digestibility of crude protein and at least 25 per cent, for starch, and 40 

 per cent, wiien the starch is of the weight of dry substances. These results 

 depend upon the age and kind of fodder; if a by-fodder consisting mainly of 

 oil cake be added in sufficient quantities, the effect of starch may be entirely 

 neutralized. 



Sugar has very much the same effect as starch, but to a much smaller ex- 

 tent. Starch and sugar have a secondary effect upon the digestibility of 

 nitrogen-free extract and fat, so long as the by-fodder is digested, which occurs 

 when the fodder is poor in nitrogen as compared with non-nitrogenous sub- 

 stances. 



The feeding of sugar to animals in some countries is a very general practice, 

 not always in the form of pure sugar, but as molasses containing 50 per cent, 

 sugar. Starch on the other hand is seldom used, unless it be in the residuum 

 from starch factories or in potatoes. Roots contain percentages of sugar that 

 depend upon their variety. However, it must not be forgotten that starch 

 and sugar when presented in this shape, have a very different action than 

 when fed alone, due to the fact that they have other elements in combination, 

 among which may be mentioned protein. 



It is desired to call attention to some interesting experiments made by 

 Wolff, the results of which are given in the following table. The roots added 

 to the fodders are supposed to be entirely digestible, and the depression 

 noticed refers to other fodders making up the ration. W T hether roots 

 are wholly digested or not, does not influence the results obtained. It was 

 noticed that as the quantity of roots used increased, so did the depression 

 in the assimilation of the various elements of which the fodder is composed. 

 In the table herewith the quantities given refer to dry substances of by-fodder 

 as compared with coarse fodder. 



