Genetic and environmental factors influencing the casein / fat ratio in raw cows milk

Galina Dicheva, Teodora Angelova, Daniela Yordanova, Jivko Krastanov

Abstract: The aim of the present study was to investigate the influence of genetic and environmental factors
on the casein / fat ratio in raw cow’s milk. In order to monitor the dynamics of the casein / fat ratio
in cow’s milk, 480 pooled milk samples taken during morning milking were analyzed. The subject
of the study were two breeds (Black and White cattle and Brown cattle), bred in 3 cattle farms. From
each breed of the respective farm, 120 pooled milk samples were analyzed – 30 samples during the
4 seasons of the year. The determination of casein was performed by the method of formal titration.
The determination of the fat content in the milk was performed using an ultrasonic milk analyzer
Lactoscan. The obtained phenotypes were adjusted for the main factors influencing milk yield in a
separate control day, using a mixed linear model. Environmental and genetic factors have a highly significant
effect on the casein / fat ratio (p > 0.001). The breed factor has a highly reliable influence, as
the milk produced by the Black-colored breed is characterized by a higher ratio of casein / fat – 0.715,
and in the Brown breed it is 0.688.

Keywords: Black and White cattle and Brown cattle; milk; phenotypes; ratio casein / fat

Date published: 2021-04-26