8 CIRCULAR 905, U. S. DEPARTMENT OF AGRICULTURE 
smaller quantity of grain than does the preceding increase in forage. 
In producing 100 pounds of pork, the first 5 pounds of forage reduce 
the grain required from 327.5 to 325.1 pounds—a saving of 2.4 pounds 
of grain. When the amount of forage is increased from 45 to 50 
pounds, the amount of grain saved is only 0.6 pound. Note that in 
column 8 the average amount of grain replaced by each additional 
pound of forage is 0.48 pound when the first 5 pounds of forage are 
added. This declines to only 0.12 pound of grain saved per pound 
of hay added when the amount of forage is increased from 45 to 50 
pounds. 
Taste 3.—lorage and grain feed combinations and substitution rates 
in increasing the weight of a hog from 60 to 225 pounds * 
Average quan- 
tity of forage 
required to 
Teplace a 
Feed combinations per 100 pounds of gainin |Average ete 
weight of grain replaced 
per pound of 
Forage as per- 
centage of total 
forage added feed (percent 
Hay Grain (pounds) (poumids) a Meter <) 2 
Pounds: a 
Oo patios: BE pate 0. 48 2.08 O28 
he Lae sees 325. 1 The 
\ _ 46 2.17 { 
iOskol kei daw 322. 8 3.0 
\ 40 2. 50 { 
1k 4 (PO Bi Mi 320. 8 4.5 
\ 36 2.78 { 
Na.caghithe whi 319.0 5.9 
\ 32 3,12 { 
Dia tt. ae ee 317. 4 7.3 
\ 28 3.57 { 
80 v. Lesh snes 316. 0 8.7 
\ 24 4.17 |} 
TED, Gans 314, 8 10.0 
\ 20 5. 00 { 
10: eRe 313. 8 11.3 
\ eile 7.15 { 
Abies son tries caigia 1 313.1 12.6 
a 
BOL te ee ed 312.5 2 p88 13. 8 
1 Based on the following regression equation: X,=327.5—0.5113X1+0.00423 
X,;*, where X, refers to pounds of grain and X; refers to pounds of forage per 100 
pounds of gain in weight. 
FORAGE-GRAIN SUBSTITUTION RATES IN BEEF PRODUCTION 
Production of beef is represented by many cattle-feeding systems. 
Production systems vary all the way from a beef herd which utilizes 
only forage to dry-lot feeding operations which include three times 
as much grain as forage. Also, a great deal of variation exists in 
grades of cattle fed. It is not possible here to consider the feed-sub- 
stitution relationships for all of these situations. The forage-grain 
substitution rates given in table 4 are based on an Jowa pasture ex- 
periment which involved choice yearling feeder steers (7). The ex- 
periment was repeated in each of 5 years and included four production 
systems, each of which involved different combinations of forage and 
