VARIATION WITH SEASON. 



321 



quantity of the milk can clearly be detected when the food of 

 the cows is changed to a more nitrogenous ration. Thus in 

 tests including some 150 animals the following mean results 

 were obtained : 



Daily 



rations 



per 



head 



Average weight of cow 



'Digestible protein . . . 

 Fuel value of nutrients 

 Albuminoid ratio . . . 

 Total cost 

 .Net cost" ... 

 Average 

 daily 

 yield 



(to produce lOOlb. of milk, 



net :;: 



to produce lib. of butter, total 



net* 10 



of milk 

 of butter f 



Cost of 

 food 



It is very doubtful whether these changes, clear and distinct 

 though they are, are of more than a temporary character. 



The improvement in the amount and quality of milk which 

 usually ensues when cows are turned out to pasture in the 

 early spring is not to be attributed entirely to the change of 

 food, but largely to the more healthy and natural character of 

 the conditions of life. In England, the change in the milk 

 when the cows are turned out to grass is usually said to be an 

 increase in quantity, but with a lower fat content. Broadly 

 speaking, it may be said that if the cows are sufficiently fed 

 a change of food produces, at most, a temporary effect upon 

 the quality of the milk. 



Influence of season. -According to the numerous analyses of 

 Bichmpnd and ViethJ the winter's milk is richest, the sum- 

 mer's poorest, while milk in spring and autumn is of inter- 

 mediate quality. 



They found the average amount of fat to be at its maximum 



v Total cost of food, less value of obtainable manure. 



t Assuming butter to contain S2'4 % fat and that 96'3 % of the total fat of the milk 

 to be obtained as butter. 

 I Dairy Chemistry, 127. 



