Hygienic quality, milk yield and basic composition of sheep milk depending on the stage of lactation

The aim of the study was to determine the influence of the stage of lactation on the yield and quality of sheep milk. The material for the investigation was milk from morning milking of 30 East Friesian sheep in their third to fifth lactation. Milking began after the lambs were weaned and continued for about 120 days. Milk samples were collected individually from the sheep in three stages of lactation: at its peak, during the stabilized stage and at the end (late) lactation. Daily milk yield, total bacterial count, somatic cell count and the basic composition of the milk were determined. The microbiological quality of the milk was very high and the somatic cell count was favourable. As lactation progressed the somatic cell count increased while microbiological quality remained stable. At the end of lactation a significant increase was noted in the concentration of dry matter, protein and fat, accompanied by a decrease in lactose concentration, in comparison with the peak of lactation. Yield was shown to be negatively correlated with fat (–0.63; p≤0.01) and dry matter (–0.53; p≤0.01) and positively correlated with lactose (0.61; p≤0.01).