Genetic and non-genetic determination of repeatability of blood and milk indices in black-and-white cows.

A herd of cows of the same age, kept in a stable system under controlled environmental conditions, was used to estimate the repeatability of diagnostic blood and milk indices in several stages of the I, II and III lactation. Attention was paid to genetic and non-genetic sources of phenotypic variation. Statistically significant values of the regression coefficient were found for the following milk parameters: fat and protein content, milk density, calcium, potassium and lysozyme levels, as well as the following blood parameters: leucocytes' number, lymphocytes and neutrophils number, uric acid content, leucocytes acid phosphatase activity, lysozyme and blood serum alkaline phosphatase activity. Examined indices were analysed which proved to be suitable for prognostic and breeding application.