BUREAU OF ANIMAL INDUSTRY. 85 



fundamental nature, promises to be of practical value in dairy-cattle 

 feeding problems. Results so far obtained point to a satisfactory 

 explanation of the method by which pliospliorus and calcium are 

 transferred from the blood to the milk. 



FACTORS IN PRODUCING CLEAN MILK. 



Extensive and careful experiments showed the following four 

 factors to be of major importance in the production of milk con- 

 taining small numbers of bacteria: (1) Thorough sterilization of milk 

 utensils; (2) cleanliness of cows, especially of udders and teats; (3) 

 the use of the small-top milk pail; (4) prompt and proper refrigera- 

 tion. All those factors, as well as the health of the cows and of the 

 attendants and the personal cleanliness of those who handle the prod- 

 uct, are essential in the production of milk suitable for human food. 



SWISS CHEESE. 



Though for many years cheese of the Swiss type has been made in 

 the United States, this domestic cheese sells for much less than the 

 imported, largely because of the imperfect formation of the holes, 

 or " eyes." The investigations to discover the organism that causes 

 the eye formation have been continued with the expectation that it 

 will be possible to develop a pure culture that will bring the com- 

 mercial manufacture of Swiss cheese under absolute control. At 

 E resent cheese closely resembling the imported is made with certainty 

 y the use of mixed cultures. 



SOFT CHEESE. 



Simple methods for making cream cheese and Neufchatel cheese 

 have been developed and already have been put into successful 

 operation. The Neufchatel group, particularly because they require 

 no ripening and but little equipment, are well adapted for manufac- 

 ture on a small scale and frequently furnish a profitable market for 

 milk. 



BY-PRODUCTS. 



The creamery at Grove City, Pa., because it is operated by the 

 Dairy Division, furnishes equipment and makes possible studies in 

 the economical utilization of by-products on a large scale. One of 

 the most important results accomplished was the working out of a 

 method for making high-grade cottage cheese from a mixture of 

 skim milk and buttermilk. 



Because of the failure of imports, casein, an essential in the mak- 

 ing of paper, has been in great demand. While the best grade of 

 casein is made from skim milk, it has been possible by the use of 

 improved methods and equipment to make from buttermilk a quality 

 that is but slightly inferior to the best grades of skim-milk casein. 

 In fact buttermilk casein made at Grove City readily sold at only a 

 cent or two below the highest grade of the domestic skim-niilk 

 product, and the manufacturers of paper prefer it to the poorer 

 grades made from skim milk. 



A study was also made of the economical utilization of skim milk 

 by condensing. Bulk-evaporated, bulk-sweetened, and case-sweet- 



