EESULTS OF SOFT-POKK INVESTIGATIONS, n 47 
The products from typical soft hogs are inconvenient to handle and 
unattractive to many people. The producer marketing hogs sus- 
pected of being soft usually must accept a lower price than if the 
hogs are thought to be firm, or sell subject to grading after chilling. 
Until recent years the problem was regarded as of importance 
only in peanut-producing sections of the country. Later develop- 
ments, however, including a remarkable expansion in the use of soy 
beans in hog production, have enlarged it to one of nation-wide 
scope. 
Cooperative investigations were inaugurated by a number of the 
State stations and the Bureau of Animal Industry on July 1, 
1919. The work has been continued as a cooperative enterprise 
from the beginning without interruption. The experiments were 
conducted in accordance with a program formulated each year by 
the conference of cooperators. With few exceptions the hogs used 
in the work were slaughtered and graded for firmness at the Animal 
Husbandry Experiment Farm at Beltsville, Md. Back fat and leaf 
fat samples were taken from each hog carcass for laboratory exami- 
nation. The refractive index was adopted as the standard laboratory 
measure of firmness of the fats. 
The annual conference of cooperators also studied results in detail, 
made deductions from these results, recommended publications, and 
approved or disapproved material prepared for publication. 
The soft-pork problem, fundamentally, is a fat problem. When 
the fat of feeds is stored by the hog there is no essential change in its 
character with respect to firmness or softness. The fat of most of 
the common feeds is soft and in some cases fluid at ordinary tempera- 
tures. There is enough fat in some feeds to account for all of that 
stored. In such cases the body fat closely resembles the feed fat. 
With feeds low in fat and high in carbohydrates there is little simi- 
larity between the fat consumed by the hog and that found in the 
body when the animal has been fed at least to a moderate weight and 
degree of finish. This is attributable to the admixture of a firm fat 
synthesized from the carbohydrates. When fed in excess of the 
body's needs for growth and maintenance, protein may enter also 
into fat formation and there is no evidence to indicate that it 
produces soft fat. 
In brief, the character of fat stored seems to a great extent to be 
governed, primarily, by the amount and character of fat and, sec- 
ondarily, by the amounts of carbohydrates and protein, particularly 
the former, in the feed consumed in relation to the rate of fat 
deposition. 
When a hog grows and fattens normally the rate of fat deposition 
gradually increases. Thus, while a low-iat feed may contain prac- 
tically fat enough to fulfill the fat-storage requirements of the 
younger hog it probably will not contain enough for the older hog 
fattening at a more rapid rate. The other nutrients, particularly the 
carbohydrates, must enter into fat formation to an increasing extent 
under these conditions. This results in the hog becoming firmer as 
it acquires weight and finish. 
