n6 SCIENTIFIC FEEDING OF ANIMALS 



scopical examination. The first gives the quantities 

 of crude nutrients, and the second shows in what 

 form the products of the food are present. Both, 

 either together or separately, give information as 

 to the quality, purity, or falsification of the 

 material. 



Where it is a t question of grain, roots, tubers, 

 hay, or straw, the practical man can often distin- 

 guish various gradations in the quality of these, 

 particularly if the conditions of growth and harvest 

 are known. It is much more difficult to estimate 

 the feeding value of foods in the form of meals or 

 cakes, for much impurity may be invisible to the 

 naked eye. Inadmissible impurities and direct 

 falsification are often so frequent that an examina- 

 tion by a qualified person is absolutely necessary. 

 Special care should be taken with foods which are 

 sold under names which are not descriptive of the 

 article, for often they are mixtures of cheap by- 

 products with very little feeding value. Although 

 a guarantee as to the amount of protein and fat 

 which they contain may be given, this is not suffi- 

 cient, for there are plenty of materials rich in 

 protein, but it is not digestible. Such sub- 

 stances, owing to their cheapness, are largely used 

 in the manufacture of mixtures of this indefinite 

 nature. 



The composition of some waste products used 

 for this purpose is seen from the following 



