CORN. AND HOG CORRELATIONS 43 
relatively low correlation between corn crop and slaughter of the 
second winter ( + 0.21) strengthens the conclusion that the early 
marketing of hogs bred with knowledge of the preceding corn crop 
is an appreciable factor in determining the summer slaughter. The 
main influence of corn crop on the following summer's slaughter 
must, however, be through an effect on the time of slaughter of 
hogs, already bred when the size of the crop became known. The 
prevailing high prices of summer hogs would furnish a motive for 
withholding hogs from slaughter in the preceding winter as well as 
advancing the time of marketing from the following winter, if the 
supply of corn permits. 
Heavy breeding made with knowledge of the corn crop would 
increase the next summer slaughter through the sows slaughtered 
after weaning their spring pigs. In harmony with this condition, 
heavy breeding during the given summer should tend to reduce 
slaughter. Indications of such an effect were seen in negative corre- 
lations between summer slaughter and corn crop and price of the 
same year. 
The factors discussed so far go back no farther than one year. 
The correlations with live weight, slaughter, and price in preceding 
years indicate, however, that heavy breeding for several years past 
tends to increase summer slaughter. Although relatively few hogs 
produced by breeding more than a year and a half before would enter 
into the summer slaughter, heavy breeding before this could have an 
effect by causing such a surplus in preceding years that hogs would 
be held to a greater age, thus shoving the surplus into the next season 
with a continuation of. the high age of slaughter. 
Summing up, summer slaughter is determined primarily by various 
effects of the preceding corn crop, including slaughter held back from 
the previous winter and advanced from the following winter to avoid 
low winter prices and made possible only by abundance of corn, heavy 
breeding in the preceding fall resulting in an excess of sows, and 
some early marketed spring pigs. Heavy breeding even as far back 
as the third preceding year results in a surplus of hogs, shoved on 
from year to year by delayed marketing, thus increasing slaughter in 
the summer in question. A big corn crop in the same summer has 
some tendency to reduce slaughter probably both from sows with- 
held for breeding and from pigs withheld for fattening with the 
new corn. 
The preceding corn crop by itself determines 37 per cent of the 
variation in summer slaughter. The three preceding corn crops or 
corn prices determine 57 per cent. The highest percentage deter- 
mination by three factors was that by preceding corn crop and the 
two preceding summer weights (59 per cent). 
WINTER SLAUGHTER 
The winter slaughter is largely composed of the preceding spring- 
pig crop and hence is determined largely by the amount of breeding 
m the second preceding fall. The outstanding correlation is that 
with summer live weight a year and a half before ( + 0.78), which, as 
we have seen, is an indicator of the amount of breeding. The exist- 
ence of some correlation with the summer weight two and a half 
years before ( + 0.19) indicates that heavy breeding 2 or even 3 years 
