86 EXPERIMENT STATION. [Jan. 



STUDIES IN MILK SECRETION. 



BY J. B. LINDSEY. 



The Effect of Protein upon the Production and Com- 

 position OF Milk. 



Investigations and observations indicate that milk is not a 

 simple fluid secreted directly by the blood, bnt a complex sub- 

 stance resulting from the activity of the milk cells. The cells 

 and milk glands take from the blood and lymph vessels sub- 

 stances suited to their purposes, and by chemical and physiologi- 

 cal processes convert them into a different substance, namely, 

 milk. Milk, therefore, consists for the most part of recon- 

 structed cell substance, and it is not possible, by any system of 

 feeding, to produce very great modification in its composi- 

 tion. The composition of milk depends principally upon the 

 breed and individuality of the cow, stage of lactation and de- 

 velopment of the milk cells. 



G. Kuhn,^ M. Fleischer ^ and E. Wolff,- during the years 

 1868 to 1876, studied the additions to the different basal 

 rations of increasing amounts of protein upon the composition 

 of the milk, and noted only very slight variations. They 

 observed that of all the milk components the percentage of fat 

 was the most influenced by the food supply. N. J. Fjord and 

 F. Friis,^ as a result of experiments by the group method with 

 1,152 cows, concluded that the protein was practically with- 

 out influence in varying the proportions of the several milk 

 ingredients. ^Y. II. Jordan '^ has conducted a number of trials, 

 and failed to note any specific influence of the protein in 



■ Landw. Versuchsstationen 12 Bd., 1869; Journal fiir Landw., 1874. 



2 Die Versuchsstationen Hohenheim, Berlin, 1870; R6sum6 in Die Ernahrung der Landw. 

 NiUzthiere, E. Wolff, 1876. 



' Beretning fra den Klg. VeterinEer. og LandViohoiskole Lab. for landokonomiske Forsog. 

 Kopenhagen, 1892; R63um6 in Centralblatt f. Agricultur Chemie, 22 Jahrg., 1893. s. 604. 



< Maine Experiment Station, reports for 1885-86, 1886-87; New York Experiment Station, 

 Bulletin 197, 1906. 



