IDENTIFICATION OF MILK COMPOSITION AND PROTEINS POLYMORPHISM CORRELATED WITH CHEESE QUALITY, TO SELECT THE BEST CARPATINA GOATS

Cristina Lazăr, Rodica Pelmus, Elena Ghiţă, M.C. Rotar

Abstract
    The purpose of this study was to identify the proteins polymorphism in Carpatina goat in order to select the best individuals which exhibit the most increased polymorphism for αs1-caseins. Milk composition was analysed for fat (5.08%) and protein (4.14%). Protein percentage didn’t display high variability and ranged between 4.82% and 3.22%. SDS-PAGE analysis revealed, after electrophoresis, five protein fractions in milk samples: αs1, β, k-CN, and β-LG, and α-LA. Different expressions of the same type of protein fraction were discovered by densitometry analysis for each investigated goat. The casein group, composed by three fractions α s1-, β- and k-casein (17.5%, 48.8%, 10.9%), shows in fact that they are 77.2% of the total milk protein and 22.8% are albumins, similar with other studies for goats. Three levels of expression were recorded for each milk protein in every milk sample: 19.04% of the goats manifested strong expression for α s1-CN and medium and low expression for 57.15% and 23.81% of it. In case of the β-LG, strong expression level was found for 38.09% of the goats and medium and low expression level for 47.62% and 14.09%, respectively. Further investigations will be necessary to confirm the results by PCR-RFLP analysis to identify Carpatina goat caseins polymorphism with the genetic variants for each protein locus. This will allow keeping for reproduction the most suitable animals with strong genetic expression and high content in caseins very well correlated with milk quality and quantity.

Key words: Carpatina, dairy goats, milk composition, milk proteins polymorphism