RELATION OF BACTERIA TO DAIRY PRODUCTS 563 



easily cleaned and freed from the sour milk odor which is so 

 difficult to remove when raw skim-milk is allowed to sour in 

 them, as is often the case. 

 Feeding value of pasteurized skim-milk. 



Experiments have been made at several agricultural colleges 

 to show the effect of pasteurization on the feeding value of 

 skim-milk. Dean, of the Guelph Agricultural College, reports 

 that " the total gain in four weeks of four calves fed pasteurized 

 skim-milk as part of their ration was 110 lb., and of four calves 

 fed raw skim-milk was 105 lb." 



Otis, at Kansas, compared the feeding value of hand-separator 

 skim-milk with "sterilized" creamery skim-milk and obtained 

 the following results : Six calves were fed " sterilized " creamery 

 skim-milk for 142 days and made an average gain a head of 250 

 lb. Seven calves fed the same length of time on hand-separa- 

 tor skim-milk made an average gain a head of 251 lb. Otis 

 states that "at first the calves showed a dislike to the odor of 

 the 'sterilized' skim-milk but they soon became accustomed 

 to it and drank it readily." . . . "The hand-separator skim- 

 milk was fed immediately after separation." . . . "Observa- 

 tions show that the calves receiving sterilized skim-milk were 

 less subject to scours." 



In feeding skim-milk to calves it is important that they be 

 fed the same kind of milk all the time. It is the changing from 

 sweet to sour or from raw to pasteurized skim-milk that is 

 often the cause of sickness in calves. 

 Amount of water added to skim-milk by pasteurizing with steam. 



The extent to which skim-milk is diluted by heating it with 

 both high- and low-pressure steam (boiler and exhaust steam) 

 was determined at our Dairy School creamery by heating a 

 weighed quantity of skim-milk as it comes from the separator 

 to various temperatures by forcing steam into it and weighing 

 the hot skim-milk. The following table gives the results of 

 these observations. 



