218 Cattle Problems. 



artery-walls by engorgement, are not observed or suspected 

 at the time they are taking place. 



In almost every stranger or new cow, and in home- 

 raised cows, the degree of increase in size, and extent 

 of relaxation, in the udder-supply arteries, varies. Cheese 

 making, and full-feeding, proceed without interruption till 

 November, or later. 



By November, with its dry feed, there is considerable 

 reduction in total yield and the bulk of blood made by the 

 cows ; but they are still milked. Some of them do not 

 shrink their yield much, if well fed, though their embryos 

 require more blood nutriment from day to day. 



Suddenly several of these new cows that hold out their 

 yield best, abort their embryos, say in the fourth month 

 of pregnancy. Several others abort a month later, 

 holding their yield fairly, if well fed ; while the cows that 

 dry up early do not abort. 



What is the reason of the first batch of abortions, when 

 the yield is fair ? And of the second batch a month later ? 

 We have space only to indicate the principal, or general 

 causes. 



The reason why cows — new cows more than others — 

 abort their embryos in such cases, is because the embryos 

 are starved to death, by reason of the udder-supply arteries 

 being relaxed at an enlarged size, causing the conveyance 

 of so much of the mammary blood to the udder, that the 

 supply to the embryo becomes deficient, but cannot be in- 

 creased, when increase is vitally necessary to maintain 

 embryo life; because the udder-supply arteries, being re- 

 laxed, cannot be contracted, nor the supply of blood to 

 the milk glands reduced. 



The greater the degree of engorgement in summer, and 

 relaxation in the udder-supply arteries, the earlier abortion 

 occurs, because the larger the share of blood flowing to the 

 udder, the earlier the supply to the embryo becomes in- 



