Correlation between phenotypic characteristics of chemical composition and rennet coagulation of sheep milk

Abstract

The aim of the present study was to establish a correlation between phenotypic characteristics of chemical composition, somatic cell count and rennet coagulation of sheep milk during different stages of lactation. The experimental milk samples were taken from Bulgarian autochthonous sheep breed-Local Stara Zagora sheep, newly developed breed-Bulgarian dairy synthetic population (BDSP), and Lacaune sheep breed. From the data obtained about the chemical composition of sheep milk, it was established that Bulgarian dairy synthetic population sheep breed had the highest fat value - 9.50%, whereas for the other breeds the fat value was approximately 8.30%. A slight variation in values for protein, lactose, solids-non-fat (SNF) and density was observed in the individual milk samples. The determined somatic cell count in the experimental samples ranged from 11 400 to 9 560 866 cells/ml, as the average value for the whole lactation period was 643 259 cells/ml. Strong negative correlation between somatic cell count value and parameters of milk coagulation ability was also established - SSC:RCT (-0.170); SCC:K20 (-0.142) and SCC:A30 (-0.254). The collected data showed undeniably that in order to improve rennet coagulation of sheep milk, conduction of thorough research, analysis and evaluation of milk productivity was needed, as well as application of selective breeding approaches and reduction of somatic cell count in milk.