Milk fatty acid composition of goats grazing on alpine pasture

Interest in goat keeping in Slovenia has been growing recently, particularly in areas of higher altitudes, and on remote mountain and highland pastures. No literature data was found on the chemical composition of goat's milk produced on Alpine pasture. Therefore, the aim of our study was to determine the chemical milk composition of two dairy goat flocks kept at different altitudes, with the emphasis on milk fatty acid profile. The highland flock consisted of goats of the Saanen breed grazing at an altitude of 615–630 m, while the mountain flock consisted of goats of Alpine breed grazing at an altitude of 1060–1075 m. Goat keepers in Slovenia do not like keep more than one breed of goats together.The composition, free fatty acids (FFAs) and fatty acid (FA) profile of goat's milk collected from these two flocks grazing on Alpine pasture were determined. FA composition was determined by in situ transesterification and capillary column gas–liquid chromatography. Significant differences between the flocks were found for all components analysed (P = 0.0019 for protein, P = 0.0001 for lactose, P = 0.0020 for total solids and P = 0.0010 for FFAs), except in fat content. The relationship between the FFA content and total fat was well described by the equation: FFA (mmol/l) = −0.1127 (%) + 0.4588 fat (%) − 0.0359 fat (%)2, with R2 = 0.73 and a S.D. of the error of 0.097 mmol/l, n = 40, for both flocks. The most abundant FAs in the milk of both flocks were C16:0, C18:1, n−9, C14:0 and C10:0. The average content of saturated FAs was 74.52 and 73.05% in milk from the higland and mountain flocks, respectively. Three saturated fatty acids (caprylic (C8:0), capric (C10:0) and lauric acid (C12:0)), were present at significantly higher amounts in milk from the highland flock than in milk from the mountain flock. Monounsaturated FAs represented 20.49 and 22.32% and polyunsaturated FAs 3.73 and 3.24% of the milk from the highland and mountain flocks, respectively. Among the monounsaturated FAs, palmitoleic + palmitelaidic acid (16:1, n − 7) showed a significantly higher concentration in milk from mountain flock than in milk from the highland flock. The content of linolelaidic acid (18:2, n − 6) was significantly higher in comparison to milk from the highland flock.The average quantity (32 mg 100 g−1 milk) of essential α-linolenic acid (18:3, n − 3) was slightly higher in milk of the highland flock than in milk from the mountain flock (26 mg 100 g−1 milk).