Influence of genotypes of CSN1S1 of signs characterized the qualitative composition and coagulation ability of milk in Bulgarian Black and White Cattle

Daniela Yordanova, Teodora Angelova, Jivko Krastanov

Abstract: The aim of the present study was to determine the influence of the different genotypes of CSN1S1
on the traits characterizing the coagulation ability of milk and those assessing its quality in cows
of the Bulgarian Black and White Cattle. To establish the coagulation ability and the qualitative
composition of the milk, 129 individual milk samples from 129 cows of the Bulgarian Black and
White Cattle, bred in 4 farms. Milk samples were taken during morning milking without the addition
of a preservative. The animals included in the study were from the 1st to the 4th lactation, regardless of
the lactation period. The analysis of the individual coagulation ability of milk was performed in the
laboratory of the Agricultural Institute – Stara Zagora, using Computerized Renneting Metter – Polo
Trade, Italy. The milk was tested within 3 hours of sampling. Genetic polymorphism of milk proteins
was determined in 129 tissue samples using PCR-RFLP analysis in a laboratory of the University of
Padua – Italy. Heterozygous animals carrying the BC genotype of CSN1S1 are characterized by the
highest average milk yield – 33.90 kg and the highest percentage of fat in milk – 3.43%. Animals with
CC genotype CSN1S1 were found to produce milk with the fastest coagulation time – 14.09 min and
with the hardest coagulum – 34 mm. A highly reliable influence of all environmental and genetic
factors the trait of milk yield was found (p < 0.001).

Keywords: CSN1S1; individual coagulation ability of cows milk.; polymorphism milk protein; qualitative composition

Date published: 2021-02-26