Phenotypic Correlations among Milk Yield and Chemical Composition per Normal Lactation in Romanian Black and White Breed

In this study we have established phenotypic correlations between quantitative and qualitative indices of normal lactation milk production in Romanian Black and White breed for 125 lactations. The correlation coefficients and their statistical significance were calculated with STATISTICA program. Between the amount of milk and chemical components from milk there were values of correlation coefficient over 0.900. Also, between these characters was a very significant positive correlation (p<0.001). The correlation between the quantity of milk and the indices of milk quality (fat percentage, protein percentage, lactose percentage, percentage of dry defatted matter and percentage of total solids) varies between r = -0.046 percentage of fat and r =0.126 between amount of milk and percentage of dry defatted milk. Those values are statistically insignificant (p>0.05). Between the percentage values of fat, protein, lactose, fat dry matter and total dry matter were obtained highly significant correlations (p <0.001), ranging from r=0.510 between fat percentage and the percentage of lactose and r=0.883 between the percentage of defatted dry matter and total solids.