Southern Wisconsin Cheesemakers' and Dairymen's Association / Proceedings of the tenth annual meeting of the Southern Wisconsin Cheesemakers' and Dairymen's Association held at Monroe, Wisconsin, Thurs. and Fri., January 27 and 28, 1910
Hart, T. B.
Variations in the amount of casein in cows' milk and the operation of the casein test, pp. 44-53 PDF (1.9 MB)
SOUTHERN WIS. CHRESEMAKERS' & DAIRYMEN'S ASS'N. 47 cultural Chemist's method. The samples were from a mix- ture of night's and morning's milk. Fats were run by the Babcock test from composite samples selected over a period of one week in the usual way. The collection of the samples for casein determination was made in the middle of the week during which the fat sample was being taken. The analyses cover a period from July 26 to August 7. The animals are arranged in the table according to breed. The table contains, besides the percentages of fat and ca- sein, a column showing the amount of casein calculated bv Van Slyke's rule from the fat content. Besides these data, two seperate columns show the relations of fat to casein and casein to fat. The table shows that in a large number of instances the application of the rule gives data agreeing closely with actual determination. There are, however, as Van Slyke has already emphasized, high fat milks where the agree- ment is not very close, and actual determinations would alone disclose their true casein contents. Dorine, with a fat content in her milk practically identical with that of Molly, nevertheless shows a casein content .65 per cent lower than the latter animal. The table further shows that there is considerable relative variation of fat and casein not only among animals of different breeds, but between animals o the same breed. Percentage variation of casein ranges from 1.88 in Holsteins to 3 65 in Jerseys. Among Holsteins themselves the range of percentage is from 1.88 to 2.50, while among Jerseys it is from 2 45 to 3.65. Reduced to a ratio of pounds of casein, we have among. different breeds, for instance, at the time these analyses were made, Jewel, a Jersey, showing 2.06 pounds of fat for every pound of casein, while Maggie a Holstein, shows 1.37 pounds of fat for one pound of casein. Floradora, a Guernsey, shows 2.16 pounds of fat for every pound of casein, while Adelaide, an Ayrshire, shows 1.4 pounds of fat for one pound of casein. These are the extreme cases among the number of animals investigated.
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