262 A STUDY OF FARM ANIMALS 



would be 50 cents, which is known as the "necessary margin" 

 to prevent loss. If the steer is sold for $8.00 per hundred, 

 then we have an actual margin of $1.50 per hundred, which 

 is the difference between the actual price received at sale 

 and the original purchase price. 



There are numerous things which influence the margin, 

 as already brought out, as first cost, first weight, cost of 

 gain, delivery to feed lot and later marketing, and time of 

 year and feed conditions. "The heavier the cattle to be fed, 

 and the better their condition when placed on feed, the nar- 

 rower will be the necessary margin. The higher the price 

 of feed stuffs, the wider should be the necessary margin, 

 while cattle on pasture, making inexpensive gains, naturally 

 require a narrower margin than winter-fed stock. 



Separate care of beef cattle of different ages and sexes 

 is given in all well-regulated herds. Young calves of both 

 sexes may run together until three or four months old, after 

 which time they should be fed and cared for separately. Heif- 

 ers to be retained for breeding should be fed and cared for 

 in lots by themselves. Cows with calves require very close 

 attention in feed and care, while dry cows require less feed 

 and supervision. Bulls should not run with the herd, but 

 should be provided good yards, affording plenty of exercise. 



Tuberculosis is one of the most common diseases affect- 

 ing cattle. It is caused by a form of bacteria known as 

 Bacillus tuberculosis, a very minute, slender rod-shaped 

 organism, or what we commonly term a germ. A tubercular 

 animal may be affected in various ways. The lungs, liver, 

 spleen, small glands, udder and intestines in well-advanced 

 stages develop lumps or tubers, containing cheesy-like matter. 

 When the lungs are affected, animals cough and expectorate 

 sputum, which contains the germs through which the disease 

 is spread. Germs are also passed off in the excrement, and 

 so may be found anywhere in manure that comes from tuber- 

 cular cows. In advanced stages of the disease, cattle may 



