Interrelationships of Milk Constituents

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Abstract
The interrelationships of the milk constituents in 258 milk samples were analyzed for statistical significance. Correlation and regression coefficients and regression equations between 23 milk constituents were calculated and tabulated. Most constituents of milk change positively and highly significantly with changes in total solids. However all of the constituents do not change at the same rate and consequently do not always make up the same proportion of the total solids. Five constitutents[long dash]nonprotein N, organic and inorganic soluble, P, citric acid, and Mg are exceptions and do not change significantly in relation to changes in total solids. Since the fat is so closely correlated to total solids, it shows relationships to the other milk constituents similar to those of the total solids. The casein, whey proteins, and proteose-peptone increase at respectively slower rates as the total solids content of the milk increases. Ca and P show highly significant correlations to casein. Both Mg and citric acid tend to decrease with increasing casein content. The mineral constituents show considerable variability in their distributions. Both citric acid and Mg are extremely independent of changes in most other milk constituents. Changes in citric acid correlate most closely to changes in soluble inorganic P. Mg correlates inversely to the Ca content. The possibility of Ca salts in the proteose-peptone fraction is suggested by the high correlation between these 2 constituents.