RESULTS OF SOFT-PORK INVESTIGATION'S, II 5 
its character so far as firmness or softness is concerned. It is an 
interesting fact that the fat of most of the common feeds is soft 
and in some cases oily or fluid at ordinary temperatures. ^ The per- 
centage of fat in the more or less common hog feeds varies widely, 
from less than 1 per cent to approximately 50 per cent. 3 With some 
of the high-fat feeds the hog consumes fat enough to account for all 
of that stored, and in these cases the body fat bears remarkable 
resemblance to the fat of the feed. On the other hand, with feeds 
containing a low percentage of soft or oily fat, the body fat pro- 
duced shows little similarity to the fat of the feed. In the latter 
case the body fat, as a rule, is decidedly firm when the hog has been 
fed to a reasonable degree of finish. 
With the fat of most of the common feeds exerting a softening 
influence the question arises : What feed constituents are responsible 
for the firm hogs which are produced in many cases? The animal 
body uses carbohydrates first to supply its need for energy. Any 
surplus above this need goes to build up a store of fat. Under 
the usual conditions of hog feeding in this country this is the chief 
source of synthesized body fat. Protein also may be used to form 
body fat under certain conditions, as when fed in excess of the body's 
needs for growth and maintenance. Under usual feeding practices 
this seldom happens. There is much evidence to show that carbo- 
hydrates and protein normally produce firm fat in the body of the 
hog and no evidence to indicate that they produce soft fat. Common 
feeds and feed combinations containing high percentages of carbohy- 
drates and low percentages of fat are now recognized as producers of 
hard hogs, when the animals are fed to at least a moderate degree of 
finish. To summarize : The character of fat stored seems to a great 
extent to be governed, primarily, by the amount and character of 
fat, and, secondarily, by the amounts of the other nutrients, particu- 
larly the carbohydrates, in the feed consumed in relation to the rate 
of fat deposition. 
In the normal process of growing and fattening, the rate of fat 
deposition in a hog gradually increases. While the 50-pound pig 
stores fat at a low rate, the percentage of fat in the gain of a 150- 
pound animal is relatively high. This is a significant fact when 
considered in connection with the character of fat stored from any 
certain feed or feed combination, particularly one moderately low in 
fat. Such a feed may contain practically enough fat to satisfy the 
fat-storage requirements of the younger animal, resulting in the 
deposition of a soft body fat. With the increasing rate of storage 
as the animal matures, however, there is a corresponding decrease in 
the feed fat available for deposition. Under these conditions the 
other nutrients, usually the carbohydrates, must furnish an increas- 
ing supply of material for transformation into body fat. Thus a hog 
fed to maturity on a ration moderately low in softening fat gradually 
becomes firmer as it acquires weight and finish. 
BROADENED SCOPE OF THE WORK 
At the beginning of these investigations the peanut was the feed 
which stood forth, demanding the first consideration. In conse- 
quence most of the early experiments were planned to study the 
3 See Department Bulletin 1407 (p. 13, Table 2) for fat composition of common hog 
feeds. 
