24 
BULLETIN 1440, U. S. DEPARTMENT OF AGRICULTURE 
more corn to 10 pounds of gain on a hog weighing 300 pounds than on 
one weighing 200 pounds. For this reason most farmer will not feed 
their hogs to quite such weights when corn is high as they will when 
corn is cheap. Just how heavy it pays to feed a hog for a given rela- 
tion of corn prices to hog prices depends upon the skill of the feeder 
and the quality of the hog, but it always pays to feed to the heaviest 
weight when corn is cheapest, and to a lighter weight when corn is 
dearest (22, pp. 11-14, 49-52, 55-58). 
Figure 19 shows how this affects the weight at which hogs are 
marketed. This figure shows moving averages for the corn-hog dif- 
ferential and for the weight of the hogs. A change in the corn-hog 
differential was usually followed by a change in the weight of the 
hogs in a shorter time than it was by a change in the number of hogs 
marketed. This is of course caused by the fact that the weight of 
the hogs was largely influenced by the relation of hog prices to corn 
prices during the months they were being fattened, just before mar- 
CORN-HGG DIFFERENTIAL AND AVERAGE WEIGHT OF HOGS 
245 
240 
235 
2 30 
225 
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Fig. 19.— Average weight of hogs at Chicago in pounds, and the corn-hog differential in dollars, 
both with the seasonal variation smoothed out (by a moving average) . Since 1902 a high corn- 
hog differential has been followed by heavier hogs in a very few months 
keting, while the number marketed was due to changes in the corn- 
hog price relation in the period before the sows were bred; that is, a 
year or more earlier. 
The change in the average weight of market hogs ordinarily tends 
to cause some change in the relative price for hogs of different weights. 
At periods when corn is very cheap relative to hogs, most hogs are 
fattened to fairly good weight. As a result, there tends to be an 
oversupply of heavy hogs and an undersupply of medium or light- 
weight hogs, and the heavy hogs sell at a discount. Similarly, at 
periods when corn is very expensive relative to hogs and most hogs 
are sold rather light, there is frequently an oversupply of light hogs 
and a shortage of heavy hogs, and heavy hogs top the market. The 
strength of demand for lard and for pork cuts of various weights also 
affects the prices for hogs of different weights. Then, too, there are 
seasonal differences in the receipts of hogs of different weights, which 
cause seasonal differences in the prices. But, as is shown in Figure 
20, this was usually not a very significant factor, even with the seasonal 
change eliminated. 
