24 DAIRY CATTLE AND MILK PRODUCTION 



passes forward just beneath the skin. These veins crook 

 back and forth more or less, in some cases divide into two 

 or more divisions, and finally pass upwards through one or 

 more openings in the wall of the abdomen into the body 

 cavity. The portion of the veins from the udder to the 

 opening through which it passes into the abdomen is called 

 the milk vein. The opening in the abdomen through which 

 the vein passes is popularly known as the milk well. Fig. 

 10 shows exceptionally good development in this respect. 

 The milk vein is one of the most reliable indications of dairy 

 capacity, since a large production of milk calls for a large 

 quantity of blood to pass through the udder, and a large milk 

 vein denotes such a circulation. The size of the milk vein 

 is influenced to a great extent by the age of the cow. In 

 a young animal the vein is smaller and more elastic than in 

 the aged cow. When a cow is producing the maximum 

 amount of milk, the veins are larger than is the case 

 when the same animal is dry. The milk wells, on the 

 other hand, remain of practically a constant size after the 

 cow is once mature. In judging a dry cow, or one far ad- 

 vanced in the period of lactation, the size of the milk well is 

 of greater importance than the size of the milk veins. 



The Udder. The development of the udder is of the 

 greatest importance in selecting the cow, especially in regard 

 to its size and shape. In the manufacture of milk, the food 

 of the cow is first digested and becomes blood, then passes 

 through the circulation to the udder. Since this gland is 

 responsible for the secreting of milk from the blood, its size 

 and development are of the greatest importance of all as 

 indicating the dairy qualities of the cow. 



It is not the size of the udder alone that is important, 



