DAIRY FARMING DAIRYING. 1085 



Among the author's conclusions are the following: 



" (1) A cow fed during 95 days ou a ration from which the fats had heen nearly all 

 extracted continued to secrete milk similar to that produced when fed on the same 

 kinds of bay and grain in their normal condition. 



"(2) The yield of milk fat during the 95 days was 62.9 lbs. The food fat eaten 

 during this time was 11.6 lbs., 5.7 lbs. only of which was digested; consequently at 

 least 57.2 lbs. of the milk fat must have had some source other than the food fat. 



"(3) The milk fat could not have come from previously stored body fat. This 

 assertion is supported by three considerations: (1) The cow's body could have con- 

 tained scarcely more than 60 lbs. of fat at the beginning of the experiment; (2) she 

 gained 47 lbs. in body weight during this period of time with no increase of body 

 nitrogen, and was judged to be a much fatter cow at the end ; (3j the formation of 

 this quantity of milk fat from the body fat would have caused a marked condition 

 of emaciation, which, because of an increase in the body weight, would have 

 required the improbable increase in the body of 104 lbs. of water and intestinal 

 contents. 



"(4) During 59 consecutive days 38.8 lbs. of milk fat was secreted and the urine 

 nitrogen was equivalent to 33.3 lbs. of protein. According to any accepted method 

 of interpretation, not over 17 lbs. of fat could have been produced from this amount 

 of metabolized protein." 



As to the source of milk fat, the conclusion is reached that in these 

 experiments the milk fat " was produced, in part at least, from carbohy- 

 drates, as previous experiments have demonstrated to be the case with 

 body fat." 



It is pointed out that, while the German standard calls for 2.5 lbs. of 

 protein per day, an average yield of 30 lbs. of milk would not contain 

 over 1 lb. of protein, leaving 1.5 lbs. of protein unused, so far as known, 

 for necessary constructive purposes. It is shown that — 



"The quantity of milk solids secreted bore a definite relation neither to the digest- 

 ible protein eaten nor to the extent of the protein metabolism. . . . The extent 

 of protein metabolism seems to be influenced mainly by the protein supply rather 

 than by the quantity of milk solids secreted. . . . 



"We desire to propose as a rational explanation of the notable influence upon 

 milk secretion of an abundant supply of digestible protein in the ration that it is 

 due to the influence of protein upon metabolic activity rather than because so much 

 was needed from which to form milk solids. This view would not minimize our esti- 

 mate of the importance of the nitrogenous constituents of cattle foods, but simply 

 emphasizes more fully one reason, and perhaps the main one, why they should be 

 supplied in such generous proportions. 



"[As to the composition of the milk], this bore no definite relation to the amount 

 anrl kind of food. 



"Neither a deficiency in the protein of the ration nor a depression of the digest- 

 ible nutrients to about 5 5 lbs. per day caused the cow to produce poorer milk. The 

 only apparent effect was in changing the quantity of product. . . . 



"The changes in the proportion of milk solids were due almost wholly to changes 

 in the percentage of [milk] fat." 



Investigations on the composition of colostrum and the change 

 to normal milk, F. G. Deissmann (Inaug. Diss., Heidelberg, 1897, pp. 

 98). — The author introduces the account of his investigations with a 

 quite thorough review of work previously published on the subject. His 

 investigations were made on ."> cows and 2 sheep. Complete analyses 

 were made of the milk immediately after calving and at short intervals, 



