ANNUAL REPORT, 1939 19 



here, have been published in Bulletin 362. Results secured since the bulletin 

 was issued deal chiefly with the use of phosphoric acid as a preservative for grass 

 silage. While it would be unfair to draw final conclusions from one season's 

 work, feeding trials with 28 cows conducted in the winter of 1938-39 indicated 

 that: 



1. The phosphoric acid silage was not as palatable to the cows and did not 

 produce quite as much milk as either corn silage or molasses silage. Gains in 

 weight also were less than on either of the other kinds. 



2. Phosphoric acid seems to do a better job of preservation than molasses, 

 as the carotene content of silage made with it was somewhat higher than that for 

 a similar lot of molasses silage. 



3. Flavor of the milk from cows receiving phosphoric acid silage was pro- 

 nounced, by impartial flavor experts, superior to the flavor of milk from the 

 same cows when they received either corn or molasses silage. 



Approximately 125 tons of phosphoric acid silage has been stored this year, 

 and is now being compared with corn silage in an extensive feeding trial to see 

 whether the results of last year will be confirmed. Approximately 63 tons of 

 molasses silage stored this year will be fed to growing dairy heifers in comparative 

 trials with corn silage. 



DEPARTMENT OF BACTERIOLOGY 

 Leon A. Bradley in Charge 



Iodine in the Ration with Reference to the Coli-acidophilus Ratio in the Stools 

 of White Rats. (James E. Fuller and W. B. Esselen, Jr.) It is recognized that 

 an adequate amount of iodine in food is necessary for the proper nutrition of man 

 and animals. Food materials produced in many localities are deficient in iodine, 

 and this fact has encouraged research workers to investigate methods for in- 

 creasing the iodine content of food substances. This research suggested the study 

 of the possible effect of increased iodine in food on the intestinal flora of white 

 rats, with special reference to the relative numbers of Escherichia {Bacillus) coli 

 and Lactobacillus acidophilus. This is of interest because L. acidophilus is con- 

 sidered by many to be desirable in the intestine, and E. coli relatively undesirable. 



One group of young white rats was given hamburg steak for a month to increase 

 the coli content of the stools, and another group of an equal number of rats was 

 given a cereal diet to increase the acidophilus content. Then each group was 

 divided into four sub-groups and fed as follows: 1, raw milk; 2, raw milk with 

 added iodine; 3, pasteurized milk; and 4, pasteurized milk with added iodine. 

 For several weeks the different milk rations were added to the hamburg and 

 cereal diets respectively, and then for the final several weeks milk alone was 

 given. The amount of iodine used daily for each rat represented what would be a 

 high-iodine ration for humans if it were fed to them in the same proportion in 

 relation to body weight as to the rats. Bacteriological tests made frequently 

 during the course of the experiment showed that total bacteria counts were quite 

 erratic both in individual rats from time to time, and in rats of the same sub- 

 group at any given examination time. There was no evidence that the iodine 

 in the ration either increased or decreased the coli or acidophilus counts, and these 

 counts were quite as erratic as were the total counts. The experiment indicated 

 that iodine in a quantity desirable from a nutritional or a physiological standpoint 

 would not influence intestinal bacteria significantly. 



Indol Production by Escherichia Coli. (James E. Fuller.) The theory of auto- 

 intoxication is based upon the production, by bacteria in the intestine, of sub- 



