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 quantity 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 encourage the pro- 

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

 slops, for example, are said to cause the production of 

 poor milk. During recent years, numerous investiga- 

 tions undertaken abroad as well as in the experimental 

 laboratory in Copenhagen, seem to have proven that it 

 is not possible by changes of food to bring about a 

 noticeable permanent effect upon the composition of the 

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

 the daily variation in the composition of milk, is easily 

 thrown out of equilibrium, but such a condition is only 

 temporary. With changes of feeding, this condition 

 appears quite plainly, nearly every change very 

 quickly causing a variation in the composition of the 

 milk, especially the fat percentage, so that sometimes 

 this rises, sometimes, e.g., when distillery slops and simi- 

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

 this variation always seems to be merely temporary; in 

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

 the end of a couple of weeks, the average percentage 

 returns. This is the case even when food of only one 

 kind, as distillery slop and, indeed, when food especially 

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

 percentage will be only temporary (Henriques and C. 

 Hansen). 



