VARIATIONS IN COW'S MILK 37 



such variations may take place without external causes. 

 "With cows that have suckled their calves, after separa- 

 tion from the calf, there is usually a very noticeable de- 

 crease of fat in the milk, which is sometimes made good 

 by a subsequent considerable temporary increase. 



7. The influence of food. It is an old and, in some 

 places, still commonly accepted opinion that the compo- 

 sition and the tjuantity of the food have an important 

 influence on the composition of the milk and more espe- 

 cially on its fat content. Palm and cocoanut meal and 

 several other food stuffs, are said to eiicoura,i;e the pro- 

 duction of rich milk, while, on the other hand, distillery 

 slops, for exami)le, are said to cause the i)roduction of 

 l)oor milk. During icccnt years, numerous investiga- 

 tions undertaken abroad as well as in the experimental 

 laboiatory in ('o]i<mhagen, seem to have pi'()\en that it 

 is not possible by changes of food to brint;- about a 

 noticeable permanent cITect ui)on tlie composition of the 

 milk. The activity of the uddei- cells, as is shown from 

 the daily variation in the composition of milk, is casily 

 tbrown out of c(iuilibrium, Init such a condition is only 

 temporary. With changes of feeding, this condition 

 appears (piite plainly, nearly every change very 

 (piickly causing a variation in the composition of the 

 milk, es]H'cially the fat percentage, so that sometimes 

 this rises, sometimes, c.//., when distillery slojis and simi- 

 lar moist foods are fed, it falls off more or less. But 

 this variation always seems to be merely temporary: in 

 the ccnirse of a day or so, sometimes, however, not until 

 the end of a coui)le of weeks, the average percentage 

 returns. This is the t'ase even when food of only one 

 kind, as distillery slo]) and, indeed, when food especially 

 rich in fat, is fed; in these cases, also, the change in 

 pi'rcentage will l)e only temporary (Henriques and C. 

 TTansen). 



