BUREAU OF ANIMAL INDUSTRY. 217 



(1) The influence of the plane of nutrition on the composition and 

 properties of milk. The plan followed was to keep certain cows on 

 maintenance rations for a period, then to feed them on a ration that 

 supplied less nutriment than the amount necessary to maintain the 

 body and support the milk production. The animals were then 

 gradually brought back to the maintenance ration, and finally fed an 

 excessive amount of feed, causing a deposition of fat on the body. 

 These variations in the plane of nutrition were tried several times on 

 the same animals. The experimental part of this investigation is 

 completed, but the data have not been prepared for pubhcation. 

 The results secured are beheved to be of considerable importance and 

 bring to light new factors that will have to be taken into account in 

 the future as causes of variation in the composition of milk. 



(2) The effect of cotton seed, cottonseed meal, and cottonseed 

 hulls on the composition and properties of milk. Three phases of the 

 problem have received special consideration, namely, (a) the effect 

 of the amount fed; (b) the efl'ect of the kind of supplementary feeds 

 used with the cottonseed meal ; (c) the effect of adding lime to the 

 ration. Considerable data have been obtained, but the investigation 

 has not been completed. 



(3) A study of the coloring matter of butter. Further work has 

 been done on the isolation and identification of the lipochrome, or 

 natural coloring matter of butter, but the work is not yet completed. 



(4) The preservation of milk samples for analysis. A thorough 

 study of the efficiency of certain chemicals as milk preservatives, and 

 the best conditions, such as the temperature and the container, etc., 

 for preserving milk, has been in progress all the year. This work is 

 nearly completed. 



The investigations that are still incomplete will receive first con- 

 sideration, and wTill be finished during the coming year, if possible. 

 It is also planned to study the effect of cotton seed, cottonseed meal, 

 and cottonseed hulls on the market value of butter. 



CHEESE INVESTIGATIONS. 



Swiss cheese. — The work on the Swiss type of cheese has been 

 considerably handicapped by the moving of the laboratory from 

 Albert Lea, Minn. It has been found, however, that cheese without 

 gas holes other than the usual "eyes" can be made from very gassy 

 milk by the use of the so-called Bacillus hulgaricus starter of excep- 

 tional activity, ordinary cultures of this organism failing to produce 

 the same results. A study of the bacterial flora of imported and 

 domestic S\\ass cheese showed that after the initial period the bacteria 

 consisted almost exclusively of two varieties of the B. hulgaricus type. 

 This fact has an important bearing on these investigations. 



The chemical work in connection \\ith S\nss cheese has established 

 the fact that the first proteolytic change in ripening Swiss cheese is 

 the formatiim of substances soluble in salt solution. A method for 

 collecting the gases from the eyes of Swiss cheese has been worked 

 out, ancf the apparatus for this determination constructed. The 

 study of pasteurization of milk for Swiss cheese making is being 

 continued. 



Cheddar cheese. — The work relating to the Cheddar type of cheese 

 has continued about as in the past. The use of hydrochloric acid in 



