Date of Award:

5-1977

Document Type:

Thesis

Degree Name:

Master of Science (MS)

Department:

Nutrition, Dietetics, and Food Sciences

Department name when degree awarded

Nutrition and Food Sciences

Committee Chair(s)

Gary H. Richardson

Committee

Gary H. Richardson

Committee

Paul B. Larsen

Committee

C. A. Ernstrom

Abstract

Milk samples from three Jersey and three Holstein herds were used to determine if the degree of churning correlated with the initial milkfat assay, and also to determine if the churned milkfat could be measured as accurately as the initial milkfat using the Milko-Tester.

Regression lines for the initial milkfat test versus churned milk- fat test fit polynomial curves. The degree of churning was greater for Jerseys than Holsteins and correlated with the initial milkfat test.

The repeatability of initial milkfat tests vas 0.98 for Jerseys and 0.99 for Holsteins. However, the repeatability of churned milkfat tests was lower for both breeds, especially for Jerseys. This indicated that the churned sample could not be measured for its milkfat content as accurately as the nonchurned sample. Churned milkfat samples all tested lower than initial milkfat samples, thus the Milko-Tester Mark III was unable to provide an initial fat test estimate following sample churning.

Cows were different from each other in the difference between initia1 and churned milk fat tests. This suggested that cows which produce milk with a higher tendency for churning are apt to receive less reliable milkfat tests from central laboratories than other cows, when all milk samples are subjected to churning conditions.

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