CHAP. IV. 



VARIATIONS IN MILK OF SAME COW. 



289 



The morning milk usually contains from | to 1 per cent, more water 

 than the evening milk, but on the other hand there is generally more 

 of it. This is attributed to the fall of temperature during the night, 

 which would necessitate the oxidation of more carbonaceous material 

 to keep up the body warmth, and to the lessened activity of the animal. 

 But Fleischmann and Vieth 1 experimenting on Count von Schieffen's 

 Mecklenburg herd of 119 cows, found not only that the proportion of 

 fat in the evening oscillated within wider limits than in the morning, 

 but they also observed that from March to July, the period of greatest 

 activity of the mammary gland, the morning milk was richer in 

 fats than that of the evening, the cows being pastured on common 

 land at the time. It is interesting to note, too, that the annual 

 yield of milk of this herd was, for each cow, 5*69 times its own 

 live weight. That the fat, though represented by a smaller per- 

 centage in the morning milk, may yet be present in greater abso- 

 lute quantity is shown by the following average results obtained 

 by the same experimenters 2 after a, year's examination of the milk 

 of several cows : \ 



Specific gravity 

 Percentage of fat 

 Yield per cow in pounds 

 Yield of fat in ounces 



\Morning milk. 

 1-0316 

 3-374 

 7-814 

 4-224 



Evening milk. 



1-0318 



3-420 



7-566 



. 4-083 



The differences in the milk drawn at the beginning and at the end of 

 milking have been studied by Schmidt, 3 who employed a middle-aged 

 Dutch cow giving twenty-one imperial pints daily. A measured quan- 

 tity (seven-eighths of a pint) was taken from the two hinder teats at 

 the commencement of the morning milking, and an equal quantity at 

 the end of the same milking. One hundred parts by weight of the 

 milk contained : 



Total solids . 



i Casein . 

 Albumin 

 Peptone 

 Fat 



Sugar . . 

 Ash 



First milk. 

 9-20 

 2-24 

 0-31 

 0-10 

 0-76 

 5-08 

 0-69 



Last milk. 

 13-64 

 2-11 

 0-29 

 0-12 

 5-60 

 4-92 

 0-66 



Thus, the difference in the quantity of the total solids is almost 

 entirely in the fat, which is between seven and eight times more abun- 

 dant in the last than in the first milk. The explanation offered is, 

 that the fat at first lodges in or adheres to the lactiferous ducts, and 

 that a separation of cream begins in the udder, and this would, as fat- 

 as circumstances permitted, seek to float on the denser fluid aggregated 

 at the base of the teats. The udder of a cow killed immediately after 

 milking showed, on examination, that the ducts contained a residue of 

 rich milk. Excepting the fat, the great bulk of the milk secreted by a 



1 " Landwirthschaftliche Versuchs-Stationen, " vol. xxiv. 



2 "Bieder. Centr.," 1880. 



3 Ibid., 1883. 



U 



