6 BULLETIN 1360, U. S. DEPARTMENT OF AGRICULTURE 
but rather an inherited trait or tendency. Quality in a live animal 
is a rather difficult thing to describe. By experienced stockmen it 
can, however, be judged with fair accuracy from certain external 
evidences such as fineness and softness of hair, thickness and plia- 
bility of hide, width of muzzle, refinement of head, and other similar 
characteristics. Frequently these external features are called 
quality. When this is done it simply amounts to mistaking the 
tangible, external evidences of a thing for the thing itself. 
MARKET GROUPS OF LIVESTOCK 
Present day market practice involves sorting livestock into seven 
general groups as follows: (1) Species or kinds, as cattle, hogs, and 
sheep; (2) classes, as steers, sows, ewes, etc.; (3) subclasses, as 
slaughter, feeder, stocker, etc.; (4) use selections, as butcher, bacon, 
packing, etc.; (5) age selections, as yearlings, two-year-olds, etc.; 
(6) weight selections, as lightweight, mediumweight, heavyweight; 
(7) grades, as, choice, medium, common, etc. 
BASIS OF CLASSES 
Class.—A class is a subdivision of a kind or species and consists 
of a group of animals which differ from animals in other similar 
groups in certain essential physiological respects. In the attached 
schedule class is, as a rule, based on sex condition. Hence in cattle 
there are five classes: Steers, heifers, cows, bulls, and stags. Each 
class represents a natural and easily distinguished group. All ani- 
mals in a given class differ from animals in other classes in certain 
broad, general, but nevertheless important respects. 
Although meat animals are separated into classes generally on the 
basis of sex condition, the real reason for such segregation lies deeper. 
If it were merely a question of the animal being male or female, cas- 
trated or uncastrated, neither the butcher nor the consumer would 
have any real interest in the matter. The fact that slaughterers and 
consumers usually do differentiate and discriminate sharply between 
animals of different sex conditions therefore indicates that there is 
some basic and fundamental reason for so doing. 
This discrimination is really due to the fact that sex condition has 
an important bearing on the three characteristics—conformation, 
finish, and quality—and on the way in which the three are combined 
in the animal. In each class these three fundamental characteristics 
exist in a ratio peculiar to that class. For example, one class may be 
superior in conformation but relatively deficient in finish, whereas 
another may stand fairly high in quality but be somewhat lacking 
in conformation. This is true, despite the fact that a very close re- 
lationship exists between the three characteristics and that it is im- 
possible materially to raise or lower one without seriously affecting 
the other two. 
The real reason, therefore, that steers, cows, and bulls sell at differ- 
ent prices is the fact that these different classes possess conformation, 
finish, and quality combined in different proportions. Generally 
speaking, grade for grade, the class possessing the highest relative 
degree of quality is preferred and brings the highest price. 
This importance of the ratio in which the three fundamental 
characteristics occur as opposed to mere sex condition, which is in 
