Milk is a complex colloidal system, the quality of which besides the chemical constituents depends on its physical parameters. These quality parameters are influenced by various factors, among which, the stage of lactation has an important role. A study was carried out to determine the effect of stage of lactation on titratable and active acidity, density and freezing point of cross bred Sharri sheep milk. Individual milk samples collected from 25 sheep at monthly intervals during March- August 2007 were taken and analyzed. Results were statistically analyzed using JMP-IN 5.1.2 statistical package. The results showed a linear increase of titratable acidity during stage of lactation, reaching the highest value (12.34 oSH) at its end, but differences between months were not statistically significant (P=0.1256). However, the stage of lactation had higher effects (P<0.05) on pH, density and freezing point value. From these results, most pronounced values of density and freezing point are observed in last month of lactation. In conclusion, results of this study confirm that the stage of lactation has high influence on all analyzed physical parameters of cross bred Sharri sheep milk.
The effect of stage of lactation on physical parameters of cross breed sharri sheep milk