Effects of somatic cell count on the gross composition, protein fractions and mineral content of individual ewe’s milk

Abstract

The aim of the research was to evaluate the effect of two somatic cell content (SCC) levels (<265,000 and >265,000 cells/ml) on ewe milk composition, protein fractions and mineral content. Samples were collected during two years, from three different ewe herds. Each herd was surveyed four times per year, one per season. For each survey more than 10 individual milk samples were collected during morning milking and analysed for SCC. On the basis of the results, two individual milk samples were selected: one from a sheep with low milk SCC (up to 265.000 cells/mL; LCC) and one from a sheep with high milk SCC (over 265,000 and less than 1,000,000 cells/mL; HCC). In one herd, it was not possible to collect the milk samples in summer. So, a total of 44 ewe milk samples (22 comparative pairs) were collected. On each milk sample, crude protein, crude whey protein, casein, casein number, non protein nitrogen x 6.38, true protein, true whey protein, fat, lactose, dry matter, ash, phosphorus, calcium, magnesium and chloride were determined. Average SCC in LCC was 170,000 and 466,000 cells/ml in HCC milk. HCC milk had lower lactose (4.05 vs. 4.60 g/100 g), casein (3.91 vs. 4.28 g/100 g), phosphorus (131.31 vs. 138.81 mg/100 g), calcium (157.28 vs. 170.48 mg/100 g) and magnesium (14.59 vs. 15.30 mg/100 g) contents than LCC milk. Additionally, HCC milk had lower casein number (76.53 vs. 79.03%) and higher contents of true whey protein (1.00 vs. 0.92 g/100 g), ash (0.90 vs. 0.87 g/100 g) and chloride (103.57 vs. 93.17 mg/100 g) than LCC milk. Somatic cell content significantly affected ewe milk quality. As a result of the higher lactose, casein, phosphorus, calcium and magnesium contents, LCC milk was more suitable for cheese making than HCC milk.

Key words: Ewe milk, milk quality, chemical composition, somatic cell content.