314 SCIENTIFIC FEEDING OF ANIMALS 



If the milk is collected in different lots, it is found 

 that each successive portion is richer in solid matter 

 than the one before. In one experiment, where 

 six portions were collected separately successive, 

 they contained the following quantities of fat : 

 170, 176, 2-10, 2-54, 3-14, and 4-08%, whilst in 

 the mixed milk 2-55% fat was found. Similar 

 results were also got for the percentage amount of 

 dry matter. As cause of this phenomenon, it is 

 assumed that, owing to friction, the globules of fat 

 in the milk move more slowly along the very 

 narrow ducts leading from the alveoli than do the 

 constituents which are dissolved in the fluid of the 

 milk. The manner of milking has a very consider- 

 able influence upon the yield of milk, as is well known, 

 so that a clever and experienced hand is of much 

 value in milking. 



(b) Performance of work by cows. 



As every kind of work done by an animal is 

 associated with a corresponding utilisation of 

 material, the influence of work on the milk yield of 

 a cow will depend largely upon the amount of food 

 it has at its disposal. If the ration does not suffice 

 for the full supply of milk as well as for the work, 

 then under all circumstances it is the milk yield 

 that will suffer, and this has been repeatedly 

 proved. When, for example, a cow was made to 



