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The evaluation of the effect of somatic cells count on ewe's milk composition, its properties and on the quality of rennet curd was carried using milk samples obtained from a total 10 ewes F₁₁₂ crossbreeds of Lacaune (L), East Friesian (EF) and Improved Wallachian (IW), reared on a ecological sheep farm in Valašská Bystřice. All ewes were on the 1^st lactation, in good nutritive condition and clinically healthy. The sampling was carried on 47^th, 81^st, 123^rd, 152^nd and 189^th day of lactation. The analysis involved a total of 50 milk samples, which were categorized into 5 different SCC groups: 1^st group (≤ 10 000 SC/ml), 2^nd group (11 000-50 000 SC/ml), 3^rd group (51 000-100 000 SC/ml), 4^th group (101 000-200 000 SC/ml), 5^th group (≥ 201 000 SC/ml). Milk composition and milk properties were determined by standard methods. For the evaluation of the quality of rennet curd (class quality) was used following scale: 1^st class - very good and hard curd, 2^nd class - good curd, 3^rd class - bad curd, 4^th class - very bad curd, 5^th class - no or invisible flocculation of casein. Recorded data were statistically analyzed using the classical least squares method (SAS; PROC GLM variant ss4). The SCC had a significant effect on all components of milk under study. The lowest contents of total solids (TS), fat (F), solids non-fat (SNF), protein (P) and casein (CN) were found in the group with the highest SCC (5^th group). On the other hand, the highest contents of all above-mentioned milk components were found in the group with the lowest SCC. The significantly lowest content of lactose (4.42 %) was found in the group with the lowest SCC. The SCC had also significant effect on pH and titrable acidity. However on the other hand SCC had not a significant effect on rennetability and rennet curd quality (RCQ). The highest value of pH was found in the 5^th group (the highest SCC). Titrable acidity has decreased from 10.10 °SH to 8.66 °SH depending on growth of SCC. The longest rennetability (257 s) was found in the group with the highest SCC. The best RCQ (class: 1.90) was found in the group where SCC per1 ml of milk ranged from 51 000 to 100 000. On the other hand the worst RCQ (class: 2.28) was found in the group with the lowest SCC.

The aim of this thesis was to evaluate the changes of the microbiological quality of milk during storage. Fresh pasteurized milk was used for the laboratory experimentations. Cooling chain of the samples was broken for 8 and for 12 hours at different temperatures (22-30 °C). In these samples, total count of psychrotrophic microorganisms was assessed.
Technological indiscipline, i. e. higher storage temperature (24 °C and more), was associated with higher increase of total count of microorganisms and psychrotrophic microorganisms. Microbiological results proved that the samples stored under standard conditions were of very good quality. However, in fresh pasteurized milk the representation of total count of microorganisms and psychrotrophic microorganisms meets fully the norm requirements. It is necessary respect a sustentation of a lower temperature of fresh pasteurized milk during storage, especially in summer months.