458 IOWA DEPARTMENT OF AGRICULTURE 



MILK BY-PRODUCTS DO THEIR BIT IN PORK MAKING. 



By John M. ;Ewabd, Animal Husbandry Section, Iowa Experiment 



Station. 



Hundreds of letters are received annually inquiring as to the value of 

 skim milk or buttermilk for pig purposes. 



Now skim milk and buttermilk are of about equal value, both being of 

 practically the same composition and both giving approximately the 

 same results in feeding experiments. The whole milk is skimmed once 

 to get the skim milk, but buttermilk is really what is left from the 

 second skimming. The cream is taken from the whole milk and then 

 the butter is taken from the cream, in reality the practical equivalent 

 of skim milk is left as buttermilk in the churn. In truth, we now 

 make practically all of our culture buttermilks which we buy at soda 

 fountains through the use of skim milk, one of which is particularly 

 named, namely: — the Bulgarian buttermilk, a skim milk bacteriological 

 product. 



The old rules proposed years ago in order to find out the value of a 

 hundred pounds of skim milk hardly cover the issue nowadays, al- 

 though they have proven useful in their time. Two of these rules are 

 particularly interesting, the one by Hoard given by Henry and Morri- 

 son is as follows: "To find the value of 100 pounds of skim milk when 

 fed alone, multiply the market price of live hogs in cents per pound 

 by five; if fed in combination with corn or barley, multiply by six." On 

 this basis the money value of 100 pounds of skim milk with $10 hogs 

 is fifty cents; $20.00 hogs, $1.00. In reality though this relationship is 

 based between pounds of skim milk and price of hogs per hundred 

 pounds there is very little relationship between the price of hogs and 

 the value of skim milk; this will be shown shortly. 



The Gurler rule runs as follows: "The value of 100 pounds of skim 

 milk when fed alone with corn to fattening hogs is half the market price 

 of corn per bushel." On this basis, therefore, the value of 100 pounds 

 of milk is fifty cents with $1 corn, and $1 with $2 corn. This relation- 

 ship, therefore, is on the basis of the price of corn rather than the 

 price of hogs. 



In order to determine the value of skim or buttermilk we have done 

 considerable work with buttermilk, and the figures secured are appli- 

 cable to skim milk. 



In an average of four trials in which buttermilk was fed in limited 

 quantity, from two to ten pounds per head daily, to young growing and 

 fattening shoats this section has found that a hudred pounds of butter- 

 milk replaces six pounds of corn and six pounds of meat meal tankage. 

 The tests were run in this way: One group of pigs was self-fed on 

 corn and tankage "Free-Choice" style; another similar group out of the 

 same dams and sire was fed exactly the same ration with the excep- 

 tion that they were given some buttermilk daily. Naturally when they 

 got the buttermilk they would hold up on the corn and tankage. 



Physiologically their demands were different with the buttermilk in 

 their stomachs and alimentary tract than where it was not present. By 



