ANIMAL FEEDS 207 
Skim milk is used extensively for feeding calves and pigs, and, 
properly “reinforced,” makes an excellent substitute for whole 
milk in feeding these animals. It is also often fed to poultry. It 
is now, as a rule, obtained by the centrifugal method, which fur- 
nishes a by-product containing, on the average, 9.5 per cent solids, 
composed of about 0.10 to 0.15 per cent fat, 5 per cent sugar, 3.5 
per cent casein and albumen, and 0.9 per cent ash. It is, therefore, 
essentially a protein feed, with a nutritive ratio of 1:2; hence is 
preferably supplemented in feeding animals with starchy or medium- 
protein feeds, like cereals, wheat middlings or shorts, etc. Creamer- 
ies furnish their patrons enormous quantities of skim milk in the 
aggregate, viz., as a rule, 80 per cent of the milk delivered. The 
whole milk is nt run through a separator on many dairy farms 
where cream is shipped or delivered to the creamery; the skim 
milk thus obtained is warm and in the best possible condinen for 
feeding young stock. 
The value of separator skim milk for feeding purposes is vari- 
ously estimated at 15 to 25 cents per hundred pounds; according 
to the feed-unit system, six pounds of skim milk are of the same 
value as one pound of grain; at one cent a pound for this ($20 per 
ton), 100 pounds of skim milk would, therefore, be worth 16 cents, 
and at 114 cents for grain it would be worth 25 cents per hundred. 
Experiments conducted at the Wisconsin station showed that 
the best results in feeding skim milk and corn meal to pigs will 
be reached by feeding these in the ratio of 3 to 1. Assuming that 
five pounds of corn meal fed alone would produce a pound of gain, 
the value of 100 pounds of skim milk would be 31 cents, with corn 
at $20 per ton; 46 cents with corn at $30 per ton. The rule given 
by Gurler as to the value of the skim milk is that 100 pounds when 
‘fed with corn to fattening pigs are worth one-half the market price 
of a bushel of corn (56 pounds). 
Unless fed perfectly sweet and under sanitary conditions, skim 
milk will be likely to cause scouring in calves; pasteurized skim 
milk is less apt to give trouble in this respect, and it is important, 
therefore, that creameries adopt the method of pasteurizing the 
skim milk before it is returned to the patrons. This will also 
improve the keeping quality of the milk and will serve the still 
more important object of removing the danger of spreading tubercu- 
losis through the skim milk, as the tubercle bacillus is readily 
killed on heating to pasteurizing temperatures of 160° F. or over 
(Fig. 39). 
