PRICES OF FARM PRODUCTS. 
9 
derision is made before there is a decrease in the number of colts, 
and four years before there is a decrease in 3-year-old colts. For 
several years the decrease in number of colts raised increases the 
apparent surplus of horses, for a mare can do more work when she 
does not raise a colt. By the time the supply of mature horses is so 
short as to be reflected in prices, there is a shortage in several crops 
of colts. If colt raising is again begun, it still further increases the 
apparent shortage of horses, becauses large numbers of mares are 
bred and they can not then do a full year's work. In 1878 the pur- 
chasing power of horses began to rise and continued for 10 years. 
It then fell for 10 years, rose for 14 years, fell for 9 years, and has now 
risen 1 year. Apparently the tide has turned. The value per head 
in dollars still fell in 1921, but the dollars have acquired so much 
more purchasing power that horses have risen in exchange value. 
INDEX NUMBERS OF PURCHASING POWER OF HOGS a HORSES 
HOGS, VALUE PER HEAD !9!0-!4-= 100 
HORSES, VALUE PER HEAD I9I0-I4-I00 
Fig. 4. — Purchasing power of hogs and horses in the United States. Periods of relatively high and low 
prices for hogs come at frequent intervals. Horses have longer and more violent periods of over and 
under production. 
The primary reason for the decline in the price of horses was over- 
production. The decline would undoubtedly have occurred in any 
event, but trucks, autos, and tractors increased the depression, so 
that the purchasing power of a horse in January, 1920, was the lowest 
ever reported. Judging by past experiences, the expectation is that 
horses will gradually rise in purchasing power; that is, if other 
prices remain stationary horses will increase in price, or if other 
prices fall horses will fall less rapidly. Before many years a decided 
shortage of horses is to be expected. 
Hogs multiply very rapidly, so that errors in estimating the supply 
that can be absorbed are more quickly corrected. Hogs usually fall 
in price for one to three years and then rise one to three years. The 
complete cycle from low to low with hogs is about one-fourth as long 
as with horses. The weights at which hogs are sold can be changed 
59143°— 21— Bull. 999 2 
