Abortion in Cows. 211 



from the rash haste in establishing large yield by great in- 

 crease of feed, that leads to abortion in many cows ; chief- 

 ly in the new or " stranger " class. To these cows, much 

 and rich feed is a great novelty, and causes great temp- 

 tation. Their over-consumption of feed leads to an over- 

 rapid increase in their udder-supply of blood, which of 

 course engorges their udder-supply arteries ; the weakest 

 muscled and least vigorous cows being most liable to the 

 artery relaxation, resulting from such excessive engorge- 

 ment in the arteries that supply the udder, which occurs 

 from such rapid rates of increase in food and blood, as are 

 over-rapidly produced during large and excessive degrees 

 of increase in yield, beyond the previous quantity of milk 

 produced. 



We here add a diagram, showing various degrees of in- 

 crease in diameter, or artery-size by engorgement in ex- 

 tents that may lead to abortion in cows under various dif- 

 ferent conditions, as explained in the references. 



In Plate VI., Fig. i, shows an increase of 70 per cent in 

 artery size made in two months, four months, or six 

 months, as happens in each period in cows, in dairy 

 herds. The diverging dotted lines show the much great- 

 er rapidity at which artery-size and blood are increased 

 when yield is increased 70 per cent in two months, com- 

 pared to 70 per cent in four months, and in four months, 

 compared with the six months rate of 70 per cent increase. 

 The more rapid the rate of engorgement, the more rapid 

 the process of expansive' relaxation. In many cows, the 

 udder-supply arteries are already expanded as much as they 

 will bear without becoming relaxed. In such cases, the 

 four, and six months rates of increase are likely to relax, 

 by over-straining the udder-supply artery walls. 



The thinning of the udder-supply artery walls, that re- 

 sults from greater engorgement, either in cows or heifers, 

 is shown, though imperfectly, in Fig. 2, where it appears 



