Variability and Interrelationships of Composition and Yield of Daily Milk Samples

Analysis of data from 2,052 milk samples, taken from randomly selected Jerseys, Holsteins, and Guernseys during six consecutive days, resulted in dayto-das" repeatability estimates of 0.46 to 0.62 for fat content, and 0.75 to 0.95 for milk yield and contents of SNF, protein, chloride, acidity, and pH. In most investigations involving these variables, a gain in accuracy, from taking two samples rather than one, of 19 to 27% could be expected for fat content, and 2 to 20% for the renmining variables. Zero-order correlations between all combinations of variables were presented for each breed on a total basis and on the basis of the within cow-test-period wriation. Variation in SNF was moderately related to fat, protein, and chloride contents, but was essentially unrelated to milk yield, pH, and acidity.