PRODUCTION OF MILK 203 



sheep, freely exposed to weather, the quantity may be 

 15 per cent, or less. In a washed fleece the fat may 

 vary from more than 30 per cent, to 8 per cent., or less. 

 Short fine wool contains the largest proportion of fat. 

 Pure wool-hair contains about 16 per cent, of nitrogen. 

 The quantity of nitrogen and ash constituents in un- 

 washed and in washed wool, is given on page 108. 



A large proportion of the nitrogen of a sheep's body 

 occurs in the wool ; 20 per cent, of the whole nitrogen 

 was found in the fleece in the case of the four Hamp- 

 shire Down sheep analysed at Eothamsted. 



The production of wool-hair and of wool-fat is practi- 

 cally no greater when a full-grown sheep receives a 

 liberal fattening diet than when the diet only suffices 

 to maintain the ordinary condition of the animal ; 

 indeed, under poor treatment, the carcase may lose 

 weight to some extent without the production of wool 

 being seriously affected. With starvation, however, 

 the yield of wool is considerably diminished. In the 

 case of lambs, a liberal diet causes increased growth, 

 and with this a bigger fleece. If sheep are kept on a 

 poor diet for the mere production of wool, the amount 

 of albuminoids supplied must not fall too low, wool- 

 hair being formed entirely from this part of the food. 



Production of Milk. — Although milk is entirely 

 derived from the food which has been supplied to the 

 cow, yet the constant production of milk is of such 

 great importance for the nourishment of the calf that 

 it has been made as far as possible independent of the 

 immediate supply of food. If the food of a fattening 

 ox is suddenly reduced to a maintenance ration the 

 increase of carcase will at once cease ; but the food of 



