132 Testing Milk and Its Products. 



morning nor the evening milking is always the richer, 

 and even if the interval between the two milkings is 

 exactly the same, the quality as well as the quantity of 

 milk produced will vary considerably. Such cows are 

 mostly of a nervous, excitable temperament, and are 

 easily affected by changes in feed, drink, or surrounding 

 conditions. 



3. The milk of a sick cow, or of a cow in heat, as a 

 rule, tests higher than when the cow is in a normal 

 condition; the milk yield generally decreases under such 

 conditions; marked exceptions to this rule have, however, 

 been observed. 



4. Half- starved or underfed cows may give a small 

 yield of milk testing higher than when the cows are 

 properly nourished, probably on account of an accompa- 

 nying feverish condition of the animal. The milk is, 

 however, more generally of an abnormally low fat con- 

 tent, which may be readily increased to the normal per 

 cent, of fat by liberal feeding. 



5. Fat is the most variable constituent of milk, while 

 the solids not fat vary within comparatively narrow 

 limits. The summary of the analyses of more than 2400 

 American samples of milk calculated by Cooke 1 shows 

 that while the fat content varies from 3.07 to 6.00 per 

 cent., that of casein and albumen varies only from 2.92 

 to 4.30 per cent., or less than one and one-half per cent., 

 and the milk sugar and ash content increases but little 

 (about .69 per cent.) within the range given. 



6. A test of only one milking may give a very erro- 

 neous impression of the average quality of a certain 



i Vermont experiment station, report f. 1890, p. 97. 



