Dr. Lyon Play fair on the Milk of the Cow. 291 



furnish the nitrogenous matter, in which the other foods are 

 deficient; and as they contain casein ready formed, they assist 

 in the formation of the milk. Their value is fully appreciated 

 by all Scotch dairymen, although their use is little known in 

 this country. The pot ale contains sugar and alcohol, and 

 therefore contributes to sustain the heat of the body. It thus 

 enables the other food to be formed into butter. But its princi- 

 pal use seems to be in diluting the secretions. Pure water does 

 not readily enter the blood ; we know that it destroys the blood- 

 globules. But acid water does not do so, and this pot ale is 

 generally very acid. Hence it dilutes the secretions. The great 

 object, therefore, in this kind of feeding, is to give the cows as 

 much unazotised food as possible; and the food which is pre- 

 ferred, consists of those very kinds in which fat exists in the least 

 proportion. Porter and beer are well known to be favourable 

 to the production of butter in the milk both of women and of 

 cows; yet these fluids do not contain fat. We are, therefore, 

 justified in asserting that practice is opposed to the theory of 

 Dumas, but highly favourable to that propounded by Liebig. 



During stall-feeding we have it in our power to alter the 

 composition of milk, even with respect to the casein. Thus 

 in the second day the cow received in its food 2^ lbs. of albu- 

 men, or of a substance of the same composition (28 lbs. of hay, 

 2^ lbs. of oatmeal). It produced 19 lbs. of milk, in which was 

 0*93 lb. of cheese. The next day it received 5 lbs., or double 

 the quantity, of albumen in its food, and the milk, which 

 amounted to 22 lbs., contained 1 lb. of casein*. Still theory 

 would have led us to anticipate a larger increase than actually 

 took place. The circumstance which favoured the produc- 

 tion of casein in the milk of the first day will afterwards be 

 considered. 



The cow received in the food given on the fourth day, 

 4 lbs. of casein and albumen (14 lbs. hay, 8 lbs. beans, 24 lbs. 

 potatoes), and yielded 23 "22 lbs. of milk, which contained 

 0'75 lb. of casein. The fifth day she received considerably 

 less albumen in her food, viz. 1»7 lb. (14 lbs. hay and 30 lbs. 

 potatoes), but the amount of casein in the milk, though in 

 less per centage than before, was equal in amount to the 

 other, from there being a greater flow of milk. The milk 

 amounted to 25 lbs., of which about 0*94 lb. was casein. Here, 

 although the food did not contain much casein, it was such as 

 to induce a great flow of milk, and the casein must have been 

 derived from the albumen of the blood. Had the cow been 

 continued on this food, there cannot be a doubt that the 



* Calculated according to the composition of the evening's milk, as that 

 of the morning had not been analysed. 



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