COMPOSITION AND YIELD OF MILK 181 



manuring, now standing at an average of 93 galls. 

 per acre. 



2. Breed. Milk from Jersey cows contains a much 

 higher percentage of butter-fat than is the case with that 

 from Shorthorns or Ayrshires, and the butter made 

 from it is both firmer and of a richer yellow colour. The 

 richer colour in butter from Jersey cows is largely due 

 to its containing a comparatively large proportion of 

 "volatile" fatty acids, which can very probably be 

 accounted for in two ways : 



(a) Careful selection through successive generations. 

 (b} The tethering system. 



In the latter case, the cows have been accustomed 

 to handling from their youth up, and through constantly 

 being tethered, have not developed such a wild disposi- 

 tion as, say, an Ayrshire. Excitability, or wildness of 

 any kind, on the part of the cow producing the milk 

 appears to affect the colour of butter-fat adversely. 



This is also an argument against using the dog 

 too freely when driving milking cows, as well as against 

 any rough treatment in the cowhouse. 



3. Individual Character of cows of the same breed. 

 This is sometimes called " individuality," and refers 



to the fact that both the quantity and quality of 

 the milk yielded by any particular breed of cows 

 varies very considerably with individual animals 

 of that breed. E.g., in the milk record tests carried 

 out by the Lancashire County Council with Dairy 

 Shorthorn cows during the lactation period of 1906, 

 one notices that one of the worst milkers gave 404 

 galls, of 4-1 per cent, milk, while the best yielded 

 as much as 928 galls, of 3-4 per cent, milk for the 

 year. In the former case, the cow produced about 



