STUDY ON THE INFLUENCE OF SOME FACTORS ON THE NUMBER OF SOMATIC CELLS IN MILK IN BULGARIAN BLACK AND WHITE COWS

Tatyana Ivanova, Milen Boichev

Abstract: The purpose of the current study was to determine the influence of different factors on the somatic cells in milk. The study comprised 1354 individual samples from Bulgarian Black and White cows from January 2009 to January 2010. Milk productivity was expressed as mean daily yield of the recording day (kg). The animals were divided in four groups with an interval of 10kg for the first, second, third and more lactations, selected in winter (December - February), spring (March - May), summer (June - August) and autumn (September - November) according to the mean daily yield. In order to examine the influence of the lactation period the animals were grouped in five weight classes according to the date of calving: to the 60th, 150th, 240th, 330th and up to 330th day. A linear model was used to determine the level of influence of the
different factors (Harvey, 1990). The factor order of lactation exercised a high authentic influence on the number of the somatic cells in milk with a test value 21.89*** was followed by the factor level of milk production with a test value 2.85*. There was no influence on the phenotypic appearance of the trait by the factors lactation period and season.

Keywords: cows; factors; milk yield; somatic cell

Date published: 2023-02-28