x 
12 BULLETIN 637, U. S. DEPARTMENT OF AGRICULTURE. 
that when corn is 60 cents per bushel the carbohydrates and propor- 
tional protein in a ton of peanut cake are worth $10.21. The excess 
protein in a ton of cake thus costs $30 — $10.21 =$19.79. Since 
there are 790 pounds of this excess protein, a single pound costs 
$19.79 + 790 = $0.025, or 2.5 cents. 
A few additional problems will show the facility with which com- 
putations may be made by use of this table. 
1. Corn is available at 60 cents a bushel. Choice cottonseed meal 
ean be bought at $32 a ton and high-grade gluten feed at $24. 
Which of the latter is the cheaper source of protein ? 
Solution: 
Cottonseed meal. Gluten feed. 
$32.00 $24. 00 
171.49 116.48 
2666) 20.51 2326) 7.56 
0.0308 0. 0232 
Hence, gluten feed, under the conditions named, is the cheaper 
source of protein. It furnishes this element at 2.32 cents per pound, 
as against 3.08 cents for cottonseed meal. 
In case the price of corn is not given exactly in the table, use the 
nearest price given. In this case the result will not be exact, but the 
inaccuracy will be of such nature that the result is never misleading. 
2. With corn at 80 cents a bushel, choice cottonseed meal $45 per 
ton, and tankage (45-55 per cent) $50 per ton, which of the latter 
furnishes protein more cheaply ? 
Solution: 
Cottonseed meal. Tankage. 
$45. 00 $50. 00 
15. 30 11. 44 
666) 29.70 907) 38.56 
0. 0446 0. 0425 
The $15.30 and $11.44 in the above solution are taken from Table 
TV, column headed ‘‘$0.80’’; the 666 and 907 are taken from the last 
column. Tankage is seen to be the cheaper source of protein at the 
prices given. 
HOW TO USE TABLE IV. 
Given a certain number of protein feeds with the local selling 
prices per ton, to determine the relative cost of protein per pound, 
proceed as follows: 
1. In columns headed ‘‘Value of corn per bushel” select the one 
corresponding most nearly to the local market price of that grain. 
2. In that column take the amount found opposite the name of the 
feed in question and subtract it from the local selling price of that 
feed. The difference represents the value of the excess carbohydrate. 
1 From column headed $0.60in TableIlV. This figure is the valueof thecarbohydrates and proportional 
protein in a ton of the feed in question. 
2 From last column of TableITV. Pounds of excess protein in a ton of this feed. 
