198 The Diseases of Animals 
for breeding purposes. Excessive sexual intercourse in 
all animals tends to lessen the fertility of the animal. 
Breeding very young animals is likely to stunt the 
growth of females and to impair the vigor of the 
reproductive system in males. Stallions should not 
be used for breeding purposes until three years old, 
and should be limited to fifteen or twenty mares the 
first season, and not used very frequently even then. 
Bulls may be used for breeding at two years old, but 
should be limited to fifteen or twenty cows. A judi- 
cious use of young breeding males will greatly prolong 
their vigor and fertility. 
SIGNS OF PREGNANCY 
It is often important to determine whether a female 
is pregnant, as the value of the animal may be enhanced 
or lessened by such a condition. In its early stages, 
pregnancy is difficult to recognize. One of the first 
signs is the absence of the usual period of heat, or 
rutting, although in some cases a pregnant animal 
will take service by the male. Service is usually re- 
sented by the female. There is a tendency for the 
animal to be more quiet than usual, and to take on 
fat more readily. This fact is sometimes taken advan- 
tage of by unscrupulous persons who breed animals, 
when beginning to fatten them for the market. In 
some cases, a pregnant female becomes more cross 
toward other animals and will drive them away. As 
pregnancy advances, the belly becomes more pendulous 
and movements of the fetus (the young animal in the 
