15 Oct., 1919.] Silage in Relation to Acidity in Milk. 



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SILAGE IN RELATION TO ACIDITY IN MILK. 



{L. M. McNah, B. Ag. Sc.) 



Whether silage has an effect in causing milk to " sour " quickly has been 

 a debatable point amongst dairy farmers for some time, and in many cases 

 silage is blamed when the increased acidity reported by the factory is 

 perhaps due to improper care and handling of the milk. 



With the idea of clearing up any misconception, the following tests were 

 carried out at Werribee Research Farm on eight Friesian cows. 



For the first week they were fed on rations containing 9 lbs. of silage per 

 day ; the second week this was increased to 18 lbs. ; and during the third 

 week the rations contained no silage at all. 



The acidity tests were carried out within a quarter of an hour of milking, 

 and, therefore, before any development of lactic organisms could affect the 

 acidity figure. 



The following results were compiled from over 100 exjiminations of 

 morning and evening milk and are reckoned in terms of the number of cubic 

 centimeters of decinormal ( -^ ) caustic soda solution necessary to neutralize 

 the acidity of 100 cubic centimeters of milk, using phenol-pthalein as an 

 indicator. 



The tests were carried out during the last three weeks in August, 1919 : — 



Cow No. 7 received no silage during the second week, and 18 lbs. during 

 the third week, to act as a check on the rest of the herd. 



It will be noticed that when the cows were fed on silage, the average 

 for the herd was "4 c.cs. lower than when fed without silage, instead of 

 showing the increased acidity expected. The difference is so slight that it 

 need not be taken into account, since individual cows varied 3 * 4 c.cs. between 

 the highest acidity and lowest acidity cows. 



In addition, samples were collected at the same time, and after being 

 kept at similar temperatures were examined 8, 15, 48, and 72 hours after. 

 No increased acidity was shown in the case of milk from silage- fed cows over 

 that of cows fed without. 



The conclusion to be derived is that silage does not cause milk to " sour " 

 more rapidly. 



