Comparison of the Quality of Mountain Sheep Milk Obtained from Animals Kept on a Natural and Organic Mountain Pasture

Abstract

Abstract The purpose of this study was to evaluate the quality of mountain sheep milk obtained from animals kept on mountain pastures: natural and organic. The experimental procedure was conducted under production conditions, during annual grazing of mountain sheep on two mountain pastures in the region of the Polish Carpathians: on organic pasture certified for organic farming and natural mountain pasture belonging to the National Park. This study showed greater plant species diversity in the organic mountain pasture, but its yielding was lower than that of the natural pasture. The sward of the natural pasture was characterised by lower dry matter and fibre content but contained more total protein. The type of pasture did not affect the basic composition of the milk of mountain sheep, while differences were found in terms of acidity, alcohol number, fatty acid profile of fat and milk protein fractions. Milk obtained from sheep grazed on organic pasture was characterised by a higher proportion of medium chain fatty acids, as well as polyunsaturated fatty acids, and also essential unsaturated fatty acids, both linoleic acid, α-linolenic acid, γ-linolenic acid and arachidonic acid. In milk originating from the natural mountain pasture, a higher proportion of monounsaturated fatty acids, docosahexaenoic acid and the CLA c9-t11 isomer was found. The composition of milk protein fractions varied according to the location of grazing: milk from sheep grazing on natural pasture had a higher content of whey fractions, important for consumer health, milk from organic pasture had a higher content of κ-casein, of greatest importance in dairy processing technology. The floral composition of the pasture had an influence on the quality of sheep milk in relation to the fatty acid profile of fat and protein fractions of milk, which is important in terms of both the health-promoting and technological aspects of the raw material and may affect the quality of products made from it.