BUEEAU OF ANIMAL INDUSTRY. 337 



RESEARCH LABORATORIES. 



The research laboratories of the Dairy Division, in charge of Mr. 

 L. A. Rogers, have been engaged as heretofore upon various chemical 

 and bacteriological problems in connection with milk, butter, and 

 cheese. 



MILK INVESTIGATIONS. 



The milk investigations have been a continuation of the work car- 

 ried on in the preceding year, which is a study of the bacteria of milk 

 and the products resulting from the presence of certain bacteria. 

 This is an unlimited field, and it is hoped to continue this study until 

 the specific characteristics of the common bacteria found in milk are 

 all fully understood. 



A new medium for the estimation of the number of bacteria of the 

 colon group has been perfected. Ap])aratus has been devised and 

 some work done on the effect of ultraviolet rays on bacteria in milk. 

 Special work is in progress on the group of bacteria producing an 

 alkaline reaction and causing decomposition of milk. Work on 

 chemical changes due to pasteurization has been completed, and the 

 results have been prepared for publication. 



A study of bacteria found in commercial ice cream is in progress. 

 A study of gas-forming bacteria has been carried on to such iin 

 extent that the results are prepared for publication. This study 

 includes the exact analysis of gases from over 100 different culture^^, 

 and also a determination of the ability of each to ferment certain 

 carbohydrates and alcohols. A method for preparation of calciiuu 

 lactate of high purity from whey has been worked out, but has not 

 yet been proven commercially profitable. This method makes pos- 

 sible the utilization of all sugar in the whey. 



The investigations in milk secretion have been continued at Co- 

 lumbia, Mo., in cooperation with the University of Missouri Agricul- 

 tural Experiment Station. One of the principal problems studied is 

 the influence of the plane of nutrition on the composition of the 

 milk, with special reference to the fat constants. The work in which 

 the plane of nutrition has been varied by changing all the food con- 

 stituents in the same direction has given consistent results and will 

 be followed by experiments in which the variation will be confined 

 to one constituent. The work on the effect of cotton seed, cottonseed 

 meal, and cottonseed hulls on the composition of the milk fat has 

 included an attempt to explain certain inconsistencies in the results 

 by a study of the variations in the composition of cotton seed from 

 various sources and of the relation of other feeds to the influence of 

 cotton seed. Some progress has been made in isolating from butter 

 fat some of the typical fats of cotton seed. The pigment of the milk 

 serum has been identified and found to be distinct from that of the 

 fat. The identification of the pigment of butter fat has been made 

 and its relation to certain pigments of the animal body and of phmts 

 established. Considerable work has been done on methods of pre- 

 serving milk samples. 



BUTTEB INVESTIGATIONS. 



"Butter investigations have been continued along the same general 

 lines as those reported last year. Valuable data have been secured 



70481°— AGB 1912 22 



