PRINCIPLES OF LIVESTOCK BREEDING. 47 
METHODS OF SELECTION. 
GENERAL CONSIDERATIONS. 
In a broad sense the whole subject of practical breeding comes under 
the head of selection. The considerations which should determine 
the general policy of mating have been discussed in the previous 
section. 
In the present section, selection will be considered with respect to 
the characteristics which it is desired to improve rather than to the 
FrG. 13.— A Lincoln ram, an example of the long-wool type of sheep. The Corriedale breed was 
developed from crosses of rams of this type with fine-wool ewes. 
system of mating. The most obvious basis for such selection is the 
performance of the animals themselves. A dairy cow with a record 
of 1,000 pounds of butterfat in a year is more likely to produce a 
useful calf than one which produced only 200 pounds under the same 
circumstances. Unfortunately, the merits of most kinds of livestock 
can not be measured so directly. The study of conformation as an 
index of useful qualities has accordingly held a high place as a basis 
for selection of breeding stock. Livestock judging has this for its 
purpose. An animal of good stock is a better one to breed than one 
of equal individual merit but of mixed or common breeding. His 
prepotency is apt to be greater. The pure breeds were founded in 
recognition of the importance of the heredity back of the immediate 
