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The Riboflavin Value of Milk¹

Department of Some Economics

W. H. Riddell

Department of Dairy Husbandry, Kansas Agricultural Experiment Station

ABSTRACT

Biological assays of samples of milk secured in September, 1936, following an abnormally dry summer with no green pasture available, showed riboflavin values of about 2 micrograms per gram of milk. Later, after the cows had been on pasture, values approximately 25 per cent higher were secured. However, data obtained the following spring did not show the expected increase as a result of pasture feeding when compared with values on the winter ration. When all values representing before and after pasture feeding were submitted to statistical analysis no significant difference was found. It is concluded, therefore, that under the conditions of this study the rations did not have any very significant effect on the riboflavin content of milk. It is suggested that climatic and seasonal factors may be of more importance. In further support of this is the fact that the milk from the experimental herd maintained without green feed for over two years yielded milk at least as rich as the milk from the station herd, presumably fed a more desirable ration.

The average riboflavin value for all samples of milk tested was 2.1 micro-grams per gram of milk. On this basis a quart of milk would furnish approximately 542 Bourquin-Sherman units.

The riboflavin determinations of the milks by a fluorimetric method gave results valuable as checks and comparable to biological assay findings. The maximum difference between the biological findings and the Fluoray lamp readings was 25 per cent in a limited number of determinations with an average difference of ± 10 per cent. While consistently lower the fluorimetric results showed the same general trend.

¹ Contribution No. 73, Department of Home Economics, and Contribution No. 118, Department of Dairy Husbandry, Kansas Agricultural Experiment Station, Kansas State College, Manhattan.

² Faculty of Marymount College, Salina, Kansas.