FARM DAIRYING 



of this fluid is directly absorbed into the blood, 

 but the greater part of it passes into the thoracic 

 duct which empties the fluid into the blood circula- 

 tion near the heart. The blood, as it rapidly 

 courses through the body, carries this digested 

 matter with it to the remotest parts, to nourish 

 and replace waste of bone and muscle and nerve. 



Thus is food made available for the sustenance 

 of the body. It will be noticed that the important 

 consideration with regard to a cow's ration is the 

 digestibility of the food; for it is only that portion 

 of the food which becomes dissolved and absorbed 

 that is available for the maintenance of the cow 

 and the production of milk. 



A strong circulation of healthy blood is essen- 

 tial in the dairy cow, if she is to give a heavy flow 

 of milk. A large artery carries the blood from 

 the heart along the back and gives off a branch 

 called the mammary artery, which supplies the 

 udder. The blood-vessels form a fine network 

 through the udder and emerge in large veins in 

 front of it. These are known as milk veins; but 

 it will be seen that they hold blood, not milk, and 

 that they are emerging from the udder, not enter- 

 ing it. When these veins are large and numerous 

 and extend well forward, they are supposed to in- 

 dicate a good milker. These veins show the 



[io6] 



