Beta-lactoglobulin polymorphism does not affect physico-chemical characteristics and milk stability

The objective of this study was to evaluate the effect of beta-lactoglobulin polymorphism, breed and seasonality on physico-chemical characteristics and stability of bovine milk. Six Holstein-Zebu (H-Z) and five Holstein dairy herds were selected, of which 660 Holstein and 293 crossbred Holstein-Zebu milk and blood samples were collected, adding up 953 samples, distributed in two collecting periods at rainy and two at dry seasons. Each milk sample was analyzed for titratable acidity, pH, freezing point and milk ethanol stability, at the following ethanol concentrations: 70, 76, 80 and 84 degrees GL. Individual blood samples were submitted to polymerase chain reaction (PCR) for the determination of beta-lactoglobulin polyrnorphism. No effect of beta-lactoglobulin polymorphism was observed in physico-chemical characteristics of milk, in both studied breed. Breed effect for Holstein and H-Z, respectively, was observed on titratable acidity (16.16 and 17.07 degrees D, while effect of seasonality (for rainy and dry seasons, respectively) was also observed on freezing point (45411 and -0.5376 degrees H). Effects of breed and seasonality on milk stability were observed (Holstein-Zebu milk was less stable on dry season), however, no effect of beta-lactoglobulin on milk stability was observed.