32 BULLETIN 1360, U. S. DEPARTMENT OF AGRICULTURE 
There are several reasons for this. Swine husbandry has developed 
to such a point that there is much greater uniformity in hogs than 
in either cattle or sheep. Furthermore, practically all market hogs 
are slaughtered at a comparatively early age, consequently the 
various factors which in aged animals bring about important changes 
in the tissues and body structure do not have time to function as 
they do in the case of ‘cattle. 
In view of this narrow age limit within which hogs are slaugh- 
tered, weight becomes virtually an all-important factor in determin- 
ing relative desirability. This is demonstrated by the fact that 
when a packer places an order for hogs to be purchased at some 
distant market, in many instances the only specifications laid down 
pertain to weight and price, for experience has shown the packer that 
he can be pr actically certain to get the kind of hogs he wants pro- 
vided they fall within certain weight limitations. It will be noted 
that the limits of the various weight groups vary somewhat between 
ise selections. Packing hogs are usually heavier than butcher and 
bacon hogs. 
GRADES OF HOGS 
Grades of hogs are based on the same three fundamental character- 
istics—con formation, finish, and quality—already described under 
cattle. Different animals possess these characteristics in varying 
degrees and the result obtained by combining these characteristics 
determines the grade into which the animal falls. As was true of 
cattle, the number of grades varies with the weight selection, use 
selection, subclass and class considered. To illustr: ate, it is almost im- 
possible for a hog weighing under 160 pounds to possess sufficient 
finish to be graded prime. Such a hog usually lacks maturity and 
has been too busy growing to put on much finish. 
Following the same line of reasoning, cull, and in some instances 
common orades, are omitted from certain eroups, because it is 
practically impossible to produce a hog that meets the other re- 
quirements of the group which is, at the same time, so deficient in 
conformation, finish, and quality that it would be oraded as cull or 
common. 
To illustrate: A barrow or gilt suitable for slaughter, of such type 
as to make it acceptable as either a butcher or bacon hog, and weigh- 
ing from 200 to 250 pounds, which would put it in ‘the medium- 
weight selection, could not be so deficient in conformation, finish, 
and quality that it would grade below common. Im the case of 
boars, no grades have been listed, because this class is numerically 
unimportant and trade in such animals is extremely limited. Com- 
petition usually is slight and they are generally sold at a flat price 
per pound without gr -ading. 
PIGS 
A pig is a member of the swine family which has not attained 
sufficient age or maturity to make reproduction possible. 
Pigs in reality constitute an age or weight selection, age and 
weight i in pigs being, as a rule, so closely related that specifyii ng the 
weight of an animal usually indicates its approximate age and vice 
versa. However, as with vealers and lambs so in swine, these 
