Citric acid content of milk in Manitoba

Abstract

The citric acid content of 440 samples of milk has been determined. The average citric acid content of bulk milk of an estimated 10,000 cows was 0·172%. The average citric acid content of the mixed milk of a Holstein herd of 35 cows was 0·168%, and the average citric acid content of the milk of individual cows was 0·171–0·189%. The coefficients of variation of the citric acid content were: in bulk milk 3·49, in mixed herd milk 7·74 and in the milk of individual cows 10·6–13·5. The citric acid content of the milk of individual cows may differ significantly. The citric acid content of milk in the grazing season was slightly lower and more variable than in the housing season. The stage of lactation had no significant effect on the citric acid content of milk. The time of day of the milking had no influence on the citric acid content of milk. Marked differences may occur in the citric acid content of milk from two successive milkings of an individual cow, and in this study differences up to 0·034% or 23·6% of the lowest value have been found.