Through the analysis of blood and hair samples, this study evaluated the effects of grazing in alpine areas on welfare indices and indicators of stress in dairy cows. Twenty-one Holstein dairy cows (body weight: 637 ± 21.5 kg; days in milk: 133 ± 17.7, and second parity) were randomly assigned to 3 groups: control (nongrazing), 12 h of alpine grazing (12 hG), and 24 h of alpine grazing (24 hG). Blood samples for plasma collection were taken for 3 consecutive days at the end of the experiment. Hair samples were collected at the beginning and end of the experiment. Hormone measurements included cortisol, serotonin, and dehydroepiandrosterone (DHEA) in both plasma and hair samples. Plasma cortisol and DHEA levels did not differ among the 3 groups, whereas the plasma serotonin level was higher in the 24 hG group than that in the other groups. The plasma cortisol to DHEA ratio was lower in the 24 hG group than that in the control and 12 hG group. The hair samples taken at the end of the experiment showed that the cortisol level was significantly higher in the control group than that in both of the grazing groups and also higher in the 12 hG than that in the 24 hG group. Hair DHEA and serotonin levels were highest in the 24 hG group. The hair cortisol to DHEA ratio was significantly higher in the control group than that in the 12 hG and 24 hG groups and in the 12 hG group than that in the 24 hG group. Our study showed that grazing dairy cows in alpine areas for 24 h improved their welfare, as indicated by increased serotonin levels in hair and plasma, increased hair DHEA level, and decreased stress indicators, including the hair cortisol level and cortisol to DHEA ratio. Farm facilities should allocate optimal grazing time for optimal welfare of dairy cows.

通过对血液和毛发样本的分析，本研究评估了高山地区放牧对奶牛福利指数和压力指标的影响。将 21 头荷斯坦奶牛（体重：637 ± 21.5 kg；产奶天数：133 ± 17.7，第二胎）随机分为 3 组：对照组（非放牧）、12 小时高山放牧（12 hG）和24 小时高山放牧 (24 hG)。在实验结束时连续3天采集用于血浆采集的血样。在实验开始和结束时收集头发样本。激素测量包括血浆和头发样本中的皮质醇、血清素和脱氢表雄酮 (DHEA)。3组间血浆皮质醇和DHEA水平无差异，而24 hG组血浆5-羟色胺水平高于其他组。24 hG 组血浆皮质醇与 DHEA 的比率低于对照组和 12 hG 组。实验结束时采集的毛发样本显示，对照组的皮质醇水平显着高于两个放牧组，12 hG 的皮质醇水平也高于 24 hG 组。头发 DHEA 和血清素水平在 24 hG 组中最高。对照组头发皮质醇与DHEA的比值显着高于12 hG和24 hG组，12 hG组高于24 hG组。我们的研究表明，在高山地区放牧奶牛 24 小时改善了它们的福利，表现为毛发和血浆中血清素水平增加、毛发 DHEA 水平增加以及压力指标（包括毛发皮质醇水平和皮质醇与 DHEA 比率）降低。