RESULTS OF SOFT-PORK INVESTIGATIONS, II 
Table 1. — Refractive index and iodine number limits for grades of carcasses- 
Continued 
IODINE NUMBER 
Ration Group A 
Ration Group B 
Ration Group C 
Ration Group D 
Number of hogs... 
Carcass grade: 
Hard 
Medium hard- 
Medium soft.. 
Soft 
Oily 
465 
66.4 and under 
67 to 70.4 
70.5 to 72.9 
73 to 83.4 
83.5 and above 
216 
60.9 and under. 
61 to 64.9 
65 to 68.9 
69 and above. . 
Occasional oily 
139. 
Limits ill denned 
for all grades. 
Soft hogs run 
from 69 to 78. 
^ Limits not deter- 
mined. 
Except for the cases in which corn followed a softening period 
on soy beans alone or supplemented with corn, the rations listed in 
Group A were fed throughout the experimental period. 
The rations listed under Group B represent the feeding of rice 
polish and rice bran and these feeds followed by corn and brewers' 
rice. The grade limits of both the fat constants are decidedly lower 
throughout than those of the previous group. The low limits for 
hard and medium-hard hogs are especially noteworthy. Thus, for 
a refractive index of 1.4595, hogs fed rice bran or p'olish and hard- 
ened on corn or brewers' rice were graded medium hard, while if 
fattened on corn throughout they were graded strictly hard. This 
discrepancy must necessarily lie in a difference in the composition or 
structure of the fat which is not shown in the fat constants. Unpub- 
lished data on the fatty-acid composition of lards from hogs fed 
the various combinations of rice by-products and corn show the 
usual fluctuation of linolic acid with refractive index and iodine 
number. The saturated-acid content appears to be the better cri- 
terion of firmness although changes in the ratio of linolic acid may 
modify this relationship in some cases. As applied to the case 
cited for fats of the same refractive index but of different grades, 
the medium-hard hogs fed rice bran or rice polish showed a lower 
saturated-acid content in the lard than the hard hogs raised on 
corn. 
The combination of peanuts followed by corn (Ration Group C) 
necessitated a different scale. In the latter case the large quantity 
of unsaturated glycerides formed during the feeding of peanuts had 
caused the retention of the soft condition beyond the usual points 
indicated by fat constants according to the scale of Ration Group A. 
In addition, the saturated-acid content of these peanut-corn lards 
tends to be comparatively low. Most of the 139 hogs included in 
this group were graded soft. The most striking point of the refrac- 
tive-index grade limits is the very narrow range of the two medium 
grades. Possibly greater numbers of hard and medium-hard hogs 
would change the dividing point for these grades. From this 
situation it would appear to be rather difficult at times to determine 
satisfactorily the physical grade of the carcass, particularly those 
of moderate firmness. The limits of grades for iodine numbers in 
this group were so ill defined that it was concluded that this constant 
was of little value. In the case of the Group A rations, the iodine 
number was as reliable as the refractive index. In other words, 
the percentages of values for the two constants which were within 
the respective grade limits were very close, namely about 75 per cent. 
