Quality and safety assessment of sheep milk and colostrum

Abstract

Sheep’s milk contains a significant amount of protein, iron, calcium, vitamins A, B and E, as well as phosphorus and magnesium, compared to cow’s milk. The purpose of research was to identify changes in physicochemical parameters, concentrations of immunoglobulins in sheep’s milk and colostrum depending on the day of lactation. The material of the study was 73 samples of ewes milk and colostrum of the Merinolandschaf breed sheep at the private enterprise «Ukrsilgosprom» in Dnipropetrovsk region. It was found that, in terms of organoleptic parameters, the samples of sheep colostrum of the first days after lambing differed significantly from the milk of the subsequent days of lactation. The color of colostrum in the first days was creamy yellow, in all other samples it varied from white to yellowish; smell – pleasant, specific to sheep’s milk, without foreign odors. The taste of colostrum was salty. The consistency of colostrum for the first three days was viscous, especially on the first day, on the following days, it was homogeneous, without mucus, not viscous. It was found that the acidity of sheep colostrum (1–7 days of lactation) ranged from 13.8°T to 34.0°T, density – from 23.2 °A to 94.1 °A. On the second day of ewes lactation, the number of somatic cells (706 ± 221×103 cells / ml) and immunoglobulins (18.72 ± 5.19 mg/ml) decreased by almost half compared with the first day (1 293 ± 231×103 cells / ml and 37.79 ± 7.45 mg/ml, respectively). Electrical conductivity was the only indicator that increased 1.5 times on the second day of lactation (4.23 ± 0.29 mS/m). On the fifth day of lactation, fat indicators (7.13 ± 0.83 %), density (34.90 ± 1.82 °A), acidity (16.7 ± 0.8 °T) almost halved in comparison with characteristics of the first-day colostrum. On the first day after lambing, the highest acidity was observed (33.9 ± 5.8 °T), which was caused by the maximum amount of immunoglobulins (37.79 ± 7.45 mg/ml) in colostrum. After lambing the number of immunoglobulins significantly decreased, on the 6th day – 4.92 ± 1.88 mg/ml (P < 0.001 compared with the first day). The obtained results allow producers of sheep’s milk and cheese to reduce the withstand of the colostrum period and to mix a secret with collected ewe’s milk on the 5th day of lactation.