Relationships Between Dye Reduction Test Scores and Somatic Cell Count in Bovine Raw Milk

Abstract

The aim of this study was to reveal the relationships between dye reduction test scores and somatic cell count (SCC) in bovine raw milk. The SCC, methyelene blue reduction scores (MTS) and resazurin reduction test scores (RTS) were determined at biweekly intervals in four test days (TD) between March and April 2017 in a total of 89 raw milk samples sold in Samsun province as unpacked. While SCC values were recorded by an automatic counter, all SCC values were transformed to log10 base before statistical analysis. In MTS method, the time for the change of the color of milk from blue to white was noted and milk quality was assessed using a 1 to 4 point scale (1=>5h-good/excellent; 2=2-5h-medium; 3=0.5-2h-bad and 4=<0.5h-very bad). The change of milk color caused by resazurin solution after one-hour incubation at 37°C was evaluated by a 1 to 3 point scale (1=blue-very well; 2=mauve/deep pink-medium and 3=light blue/uncolored-poor). While significant differences were determined among logSCC means by TD groups after one-way analysis of variance (One-way ANOVA), effects of TD on MTS or RTS were insignificant. Besides, when the samples were examined by lower or higher than 500×103 cells/ml that assumed as the threshold for SCC in this study, no significant effect of SCC on the MTS or RTS. In this study, correlation and determination coefficients of SCC with MTS and RTS were calculated to be r=0.279; R2=0.149 and r=0.18; R2=0.097 and, it was concluded that dye reduction tests are not suitable to reliably determine the quality of bovine raw milk.