ANNUAL REPORT, 1944-45 15 



from the production records of these cows in the first part of their lactations. 

 At the end of the fortieth week of lactation, after twenty-one weeks of hormone 

 feeding, average weekly production was 227 pounds per cow in comparison with 

 an expected weekly production, based on previous performance, of 162 pounds 

 per cow. 



Four cows fed the hormone in alternate four-week periods for twenty-four 

 weeks showed a definite response in the first two alternate periods, but it was 

 unlike that of cows fed the hormone continuously in that it took the form of sharp 

 increases in yield while the hormone was fed, followed by just as sharp decreases 

 when it was discontinued. By the time the third and last alternate period of 

 hormone feeding had been reached this sharp upward trend was no longer mani- 

 fest and actual production dropped nearly to the level of expected production. 



Of four cows fed the hormone in alternate two-week periods for twelve weeks, 

 only one showed a marked response in milk yield. 



Increases in milk production were usually accompanied by some loss in body 

 weight, especially in the group that received this hormone continuously. These 

 losses varied considerably in individual cows; over a period of five months they 

 averaged approximately 50 pounds per cow in the continuous group, 30 pounds 

 per cow in the 4-week group, and 20 pounds per cow in the 2-week group. No 

 adjustment of the rations of these cows was made, but more recent work in the 

 State College herd indicates that such losses can be made good by increasing the 

 grain allowance in proportion to the increased milk yield. 



There were no significant changes in the general condition, appearance, or 

 behavior of these cows, neither was the composition of the milk significantly 

 affected. There was some apparent disturbance of the reproductive function 

 in the continuous group, these cows requiring on the average twice as many ser- 

 vices for conception as they had required the previous year. 



Because of labor conditions at the Medfield State Hospital, work on this pro- 

 ject was transferred to the State College herd in the autumn of 1944. In the 

 work in progress here, emphasis is being placed on the effect of the hormone on 

 milk composition. Nineteen cows (seven Ayrshires, six Holsteins, and six Jerseys) 

 were included in the trials conducted during the past winter. All that can be 

 said at this time is that there have been rather marked differences in response to 

 the hormone by the different breeds and also by different individuals within a 

 breed. The project is being conducted in cooperation with Cerophyl Laboratories, 

 Inc., of Kansas City, Missouri, which is furnishing the necessary thyroprotein. 



DEPARTMENT OF BACTERIOLOGY 

 Leon A. Bradley in Charge 



Bacteriological Studies of Rural Water Supplies. (James E. Fuller.) This is a 

 study of the growth and behavior of coliform bacteria at incubating temperatures 

 up to 46° C, in the effort to evaluate the many atj^pical cultures encountered in 

 testing rural water supplies. The cultures employed in the study were obtained 

 from water samples sent to the laboratory for routine testing. Only typical 

 Escherichia coli of sewage type was able to produce gas from lactose at 46° C. 

 Most of the cultures studied proved, on this basis, to be soil-type coliform bacteria 

 of questionable sanitary significance. Good results were obtained from the use 

 of the methyl-red test at 44° C. This procedure seemed able to separate typical 

 E. coli (positive at 44° C.) from atypical coliform cultures (positive at 37° C, 

 but negative at 44° C). 



