1018 EXPERIMENT STATION RECORD. 



or the residue from the manufacture of starch from corn were fed, it 

 was found, as a rule, that food rich in oil did not give, as was expected, 

 a milk fat with a low melting j)oint, but instead one with an uncom- 

 monly high melting point. In other words, such food did not give a 

 soft butter, as is generally stated, but a hard butter instead. 



The fat of the food does not go directly iuto the milk, but forces into 

 the milk bodj' fiit, i. c, tallow, and thus indirectly increases the quan- 

 tity of milk fat. I^ormal butter fat is certainly a product of the 

 activity of the lacteal glands. Its amount can therefore not be mate- 

 rially increased by the manner of feeding without increasing the secre- 

 tion of milk as a whole. Unlike the carbohydrates and protein, the fat 

 of the food can materially increase the fat content of the milk, but only 

 by the body fat, produced from the carbohydrates, being transported 

 to the milk, whereby the fat of the food is probaldy consumed to keej) 

 up the oxidation in jilace of the body fat. 



From the results obtained the author believes that in purchasing- 

 concentrated feeding stuffs for cows special weight should be laid upon 

 high fat content. While at present the protein is rated at about 

 one and a lialf times the money value of fat, in future the fat of con- 

 centrated feeding stuffs will be considered of at least equal value to 

 protein, and probably of higher value. In concentrated feeding stuff's 

 the fat should be guarantied separately. The oil factories should be 

 induced to furnish oil cakes with a higher fat content, as was formerly 

 the case before tlie methods of extraction were perfected. 



These facts, the author believes, throw a new light upon the secretion 

 of milk, furnishing a further ground for the belief that the constituents 

 of milk result from the breaking down of organized tissue. On a ration 

 poor in fat the milk fat is newly formed fat of a special kind, distin- 

 guished from other animal and plant fats by its higher content of vola- 

 tile fatty acids. On a fat-free ration only this "normal" fat (/. c, that 

 resulting from the breaking down of milk-producing tissue) can api)ear 

 in the milk, and its amount can not be increased by adding fat-producing 

 nutrients (carbohydrates) or protein to the food. Fat-free food can 

 increase the production of milk fat only by increasing the tissue which 

 yields milkby decomi)ositiou,in which case the other milk constituents 

 are increased in the same jiroportion as the fat. The feeding of large 

 amounts of carbohydrates can increase the body fat, but not the milk 

 fat, since they do not contribute to the formation of milk-producing 

 tissue; when fed in large (juantities with a ration which is not rich in 

 protein, as hay, they decrease the fat content of the milk, because they 

 diminish the proportion of protein in the ration, that is, the tissue- 

 forming material (glandular tissue and white blood corpuscles). The 

 fat of the food alone is capable of bringing about a one-sided increase 

 in the fat content of the milk; it causes a transmission of the body fat 

 to the milk without itself going into the milk. The greater the fat con- 

 tent of the food, the larger the proportion of milk fat which is derived 



