1Department of Animal Science,Biotechnical Faculty,University of Ljubljana,Jamnikarjeva 101,SI-1000 Ljubljana,Slovenia.
2Department of Environmental Science,Jožef Stefan Institute,Jamova 39,SI-1000 Ljubljana,Slovenia.
Animal. 2019 May;13(5):1111-1118. doi: 10.1017/S1751731118002598. Epub 2018 Oct 12.
Sheep rearing on mountain pastures is an ancestral tradition in northwestern Slovenia. The indigenous Bovec sheep are widespread there and are well adapted to the rough Alpine rearing conditions. Every year, after weaning, the sheep start grazing in the lowlands (L) and then gradually move to mountain pastures, and finally, to the highland (H) pastures of the Alps. Grazing positively affects the fatty acid (FA) composition in sheep milk fat with increased availability of polyunsaturated FA (PUFA) in grass, and subsequently, in milk. Consequently, the objective of this work was to study the FA profile in sheep milk during grazing in four geographical areas in the Alps. A total of 15 ewes of the Bovec sheep breed were randomly selected and milk samples from these ewes were taken at four different pasture locations that differed with regard to altitude: the L pasture location at an altitude of 480 m, the mountain pastures (M1 and M2) at altitudes of 1100 to 1300 m and 1600 to 1900 m, respectively, and the H pastures at altitudes of 2100 to 2200 m. Milk samples from the ewes were taken during the grazing season from April to September. The chemical and FA composition of the milk samples from each pasture location were determined. There were significant differences in the concentrations of FA among the L, M1, M2 and H milk samples. We observed decreases of the concentrations of saturated FA (SFA) in milk from L to H pastures. The concentration of α-linolenic FA, monounsaturated FA (MUFA), PUFA and n-3 PUFA in milk were increased significantly with pasture altitude. The n-6/n-3 PUFA ratio was reduced by the change of pasture altitude with the lowest value at the M1 pasture (1.5). The concentrations of total SFA decreased significantly and was lowest at the L pasture. Our results underline the importance of the effect of grazing in the Alpine region associated with pasture altitude on the FA profile of sheep milk. The first variation in FA concentration in sheep milk occurred between L and M1, although it was more evident on H pastures in the Alpine mountains. Changes of the FA profile in sheep milk due to pasture altitude were related to variation in FA concentration in the pasture and the botanical composition of the pasture location.
在斯洛文尼亚西北部山区，牧羊是一项传统的产业。当地的波维茨羊（Bovec sheep）分布广泛，适应高山放牧的艰苦条件。每年，在断奶后，羊群开始在低地（L）放牧，然后逐渐转移到高山牧场，最后到达阿尔卑斯山的高地（H）牧场。放牧会影响羊奶脂肪中的脂肪酸（FA）组成，因为牧草中多不饱和脂肪酸（PUFA）的含量增加，羊奶中的脂肪酸也会增加。因此，本研究的目的是在阿尔卑斯山的四个地理区域研究放牧期间羊奶中的 FA 分布。随机选择了 15 只波维茨羊，在四个不同的牧场采集羊奶样本，这些牧场的海拔不同：低地（L）牧场海拔 480 米，山地牧场（M1 和 M2）海拔分别为 1100-1300 米和 1600-1900 米，高山牧场（H）海拔为 2100-2200 米。从四月到九月的放牧季节采集了母羊的奶样。对每个牧场的奶样的化学和 FA 组成进行了测定。L、M1、M2 和 H 奶样的 FA 浓度有显著差异。我们观察到从 L 牧场到 H 牧场，羊奶中的饱和脂肪酸（SFA）浓度降低。α-亚麻酸、单不饱和脂肪酸（MUFA）、多不饱和脂肪酸（PUFA）和 n-3 多不饱和脂肪酸（n-3 PUFA）的浓度随着牧场海拔的升高而显著增加。n-6/n-3 PUFA 比例随着牧场海拔的变化而降低，在 M1 牧场的比例最低（1.5）。总 SFA 的浓度显著降低，在 L 牧场最低。我们的研究结果强调了高山放牧地区放牧对羊奶 FA 分布的影响的重要性。羊奶 FA 浓度的第一个变化发生在 L 和 M1 之间，尽管在阿尔卑斯山的高山牧场更为明显。由于牧场海拔的变化导致羊奶中 FA 分布的变化与牧场中 FA 浓度的变化以及牧场位置的植物学组成有关。
