50 DAIRYING 



gland to begin the secretion of milk and this continues until the 

 gland is emptied or until some sudden excitement causes the 

 nerves surrounding the milk gland to check the milk secretion. 



After birth of the young the blood which was used to nourisji 

 the young mammal before birth is sent to the udder, and this 

 causes the glands to become active. The inside of the gland lobules 

 is covered with a layer of epithrelial cells which are swelled when 

 secreting milk and flat when no milk is given. The outside o f the 

 gland lobule is covered with a network of blood and lymph vessels 

 which nourish and build up the gland. The more of these glands 

 there are the more milk is produced, but a certain amount of the 

 milk is undoubtedly formed during milking, as the milk given at 

 one milking weighs more than the entire udder and its contents 

 before milking began. The cow's milk glands ordinarily weigh 

 between two and three pounds, and the solid matter alone in 20 

 pounds of milk will amount to about two and one-half pounds; 

 while with cows giving 50 pounds of milk, the solid or dry matter 

 amounts to six pounds. 



The activity of the milk glands in a cow is therefore influenced 

 by the inherited milk-giving capacity of the animal and by the 

 treatment the cow receives such as milking dry at each milking, 

 regularity of time between milkings, promptness and gentleness 

 during milking, protection from excitement, and an abundant sup- 

 ply of palatable feed at all times. These are points to which the 

 owner and the milker of cows should give close attention in order 

 to develop and maintain the maximum activity of the milk glands. 



The milk veins under the abdomen of the cow extend for- 

 ward from the udder to a point near the middle of the abdomen 

 where they enter the body, and then pass on to the heart. The 

 size of this opening which the blood passes through as well as 

 the size of the milk veins is some indication of the milking capacity 

 of the cow. 



207. Too Frequent Milking or too long a time between milk- 

 ings tends to diminish the activity of the gland like the tiring of a 

 muscle by excessive exercise, but with a normal amount of milk- 

 ing the emptying of the glands seem to be a stimulus to milk se- 

 cretion and a knowledge of this fact may aid cow owners in their 



