Dec. 15, 1924 
Feed Cost of Milk Production 
601 
centage of the milk, t , as: Nl=Kl 
(2.66+Q. The nutrients required for 
maintenance per pound of milk, N M) 
(because of the nature of the relation 
existing between fat percentage and 
size of cow and between fat percentage 
and milk yield) may also be expressed 
as a function of fat percentage, as: 
N m ~Km (2.66 + 0- Consequently the 
total nutrients required for milk pro¬ 
duction per pound of milk, Nt, may 
be expressed as: N?=K T (2.66 + 0- 
The cost in dollars per pound of 
nutrients is practically unaffected by 
fat percentage and consequently the 
feed cost ($) per pound of milk, FC, 
may be expressed, as: FC=K (2.66+0- 
In these relations Kl, Km, K t , and K 
are constants so far as affected by fat 
percentage. 
The price differential for fat test 
as judged by the whole-milk markets 
of 101 cities seems to be tending to 
distribute about a mean which is 
approximately the same as the cost 
of production differential. The price 
of milk may be adjusted in proportion 
to the cost of production by the equa- 
. tion p== 2 ^ bj rb + in whi °h P& 
is the base price, b is the fat per¬ 
centage to which the base price applies, 
and P is the price to be paid according 
to the fat test, t , of the milk delivered. 
This assumes that the cost of produc¬ 
tion is proportional to the feed cost 
of milk production, so far as affected 
by fat percentage. 
LITERATURE CITED 
(1) Brody, S., Ragsdale, A. C., and Turner, 
C. W. 
1923. THE RATE OF GROWTH OF THE DAIRY COW, 
m. Jour. Gen. Physiol. 6: 21-40, illus. 
(2) Eckles, C. H. 
1923. DAIRY CATTLE AND MILK PRODUCTION. Rev. 
ed., 591 p., illus. New York and London. 
(3) Gaines, W. L., and Davidson, F. A. 
1923. relation between percentage fat con¬ 
tent and yield of milk—correction of milk 
yield for fat content. Ill. Agr. Exp. Sta. 
Bui. 245, p. 575-621, illus. 
(4) Haecker, T. L. 
1914. investigations in milk-production. Minn. 
Agr. Exp. Sta. Bui. 140, 79 p. 
(5) Henry, W. A., and Morrison, F. B. 
1922. feeds and feeding. Ed. 18, 770 p., illus. 
Madison, Wis. 
(6) Pearson, F. A. 
1919. THE COST OF MILK PRODUCTION COMPUTED 
ON THE YEAR BASIS. Ill. Agr. Exp. Sta. Bul. 216, 
p. 343-364, illus. 
(7) Ross, H. A., Hall, H. F., and Rhode, C. S. 
1923. THE FEED COST OF MILK AND FAT PRODUC¬ 
TION AS RELATED TO YIELDS. Ill. Agr. Exp. 
Sta. Bul. 244, p. 551-573, illus. 
