I9i i.] 



Concentrated Feeding-stuffs. 



221 



The chief function of the carbohydrates is to supply heat 

 and mechanical energy, and when fed in large quantity they 

 are also capable of producing animal fat. In this latter 

 respect starch appears to be superior to sugar, especially in 

 the case of ruminant animals. 



Fat and Oil. — The fats and oils are essentially heat-pro- 

 ducers, and, weight for weight, are nearly 2J times as valuable 

 for this purpose as the carbohydrates. When sufficient heat- 

 forming food has been consumed to maintain the tempera- 

 ture of the body, fats and oils may be converted into animal 

 fat, and so increase the body-weight. Whether for the pro- 

 duction of heat or fat, the fats and fatty oils are far superior 

 to either albuminoids or carbohydrates, but their use is re- 

 stricted to moderate quantities by practical considerations. 

 Of the foods in common use linseed, soy beans, linseed cake, 

 and decorticated cotton cake are the richest in fat, after which 

 come dried grains, soy bean cake, undecorticated cotton cake, 

 oats, and maize. 



Crude Fibre. — "Crude Fibre" is that portion of the food- 

 stuff which remains undissolved after boiling in weak acid 

 and alkali. It represents those ingredients which are of a 

 more or less woody character, and it is essentially an ad- 

 mixture of cellulose with highly indigestible substances 

 (lignin, cutin). Its value for feeding purposes varies widely 

 according to its mechanical character and the class of animal 

 to which it is fed. All farm animals have considerable 

 powers of digesting the soft fibre of green food, but only 

 cattle and sheep can derive appreciable nourishment from the 

 hard fibre of foods like straw. Horses occupy an intermediate 

 position in this respect, whilst pigs can only deal effectively 

 with the softest types of fibre. 



A high proportion of crude fibre, unless it is normal to 

 the food in question (e.g., undecorticated cotton cake), should 

 always be regarded with suspicion, since it usually indicates 

 the presence of husks or other highly indigestible material. 



In general, foods containing more than about 10 per cent, 

 of crude fibre will require special care in their use, especially 

 if the fibre is largely in the form of hairs or "woolly" 

 material. 



Mineral Matter. — Mineral matter, although performing an 



