Mitigation of exercise-induced stress is of key interest in determining ways to optimize performance horse health. To test the hypothesis that dietary supplementation of a Saccharomyces cerevisiae fermentation product would decrease markers of exercise-induced stress and inflammation in young horses, Quarter Horse yearlings (mean ± SD; 9 ± 1 mo) were randomly assigned to receive either no supplementation (CON; n = 8) or 21 g/d S. cerevisiae fermentation product (10.5 g/feeding twice daily; SCFP; n = 10) top-dressed on a basal diet of custom-formulated grain as well as ad libitum Coastal bermudagrass hay. After 8 wk of dietary treatments, horses underwent a 2-h submaximal exercise test (SET) on a free-stall mechanical exerciser. Serum was collected before dietary treatment supplementation (week 0), at week 8 pre-SET, and 0, 1, and 6 h post-SET and analyzed for concentrations of cortisol and serum amyloid A (SAA) by commercial enzyme-linked immunosorbent assay (ELISA) and for cytokine concentrations by commercial bead-based ELISA. Data were analyzed using linear models with repeated measures in SAS v9.4. From week 0 to 8 (pre-SET), serum cortisol decreased (P = 0.01) and SAA did not change, but neither were affected by diet. Serum concentrations of all cytokines decreased from week 0 to 8 (P ≤ 0.008), but granulocyte colony-stimulating factor (G-CSF), granulocyte-macrophage colony-stimulating factor, and interleukin-8 (IL-8) decreased to a greater extent in CON than in SCFP horses (P ≤0.003). In response to the week 8 SET, serum cortisol increased in all horses (P < 0.0001) but returned to pre-SET levels by 1 h post-SET in horses receiving SCFP. At 6 h post-SET, cortisol concentrations in CON horses returned to pre-SET concentrations, whereas cortisol declined further in SCFP horses to below pre-SET levels (P = 0.0002) and lower than CON (P = 0.003) at that time point. SAA increased at 6 h post-SET in CON (P < 0.0001) but was unchanged through 6 h in SCFP horses. All cytokines except G-CSF increased in response to the SET (P < 0.0001) but showed differing response patterns. Concentrations of IL-1β, IL-6, and tumor necrosis factor-alpha were lesser (P ≤ 0.05), and concentrations of G-CSF and IL-18 tended to be lesser (P ≤ 0.09) in SCFP compared with CON horses throughout recovery from the SET. In summary, 8 wk of dietary supplementation with 21 g/d of SCFP may mitigate cellular stress following a single, prolonged submaximal exercise bout in young horses.

中文翻译：

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酿酒酵母发酵产物的膳食补充剂可减轻幼马运动引起的压力标志物

减轻运动引起的压力是确定优化表现马健康的方法的关键。为了验证酿酒酵母发酵产物的膳食补充剂会降低年轻马运动引起的压力和炎症标志物的假设，季马一岁马（平均值 ± SD；9 ± 1 个月）被随机分配接受不补充（CON ; n = 8) 或 21 g/d S. cerevisiae 发酵产物（10.5 g/每天喂食两次；SCFP；n = 10）在定制配方谷物的基础日粮以及随意的沿海狗牙根干草上进行追肥。经过 8 周的饮食治疗后，马在自由失速的机械锻炼器上进行了 2 小时的次最大运动测试 (SET)。在饮食治疗补充之前（第 0 周）、在第 8 周 pre-SET 和第 0、1、和 SET 后 6 小时，通过商业酶联免疫吸附试验 (ELISA) 分析皮质醇和血清淀粉样蛋白 A (SAA) 的浓度，并通过商业基于珠的 ELISA 分析细胞因子浓度。在 SAS v9.4 中使用具有重复测量的线性模型分析数据。从第 0 周到第 8 周（pre-SET），血清皮质醇下降（P = 0.01），SAA 没有变化，但两者都不受饮食影响。所有细胞因子的血清浓度从第 0 周到第 8 周下降（P ≤ 0.008），但粒细胞集落刺激因子（G-CSF）、粒细胞巨噬细胞集落刺激因子和白细胞介素 8（IL-8）下降到更大CON 的程度高于 SCFP 马 (P ≤0.003)。响应于第 8 周的 SET，所有马的血清皮质醇增加（P < 0.0001），但在接受 SCFP 的马中，在 SET 后 1 小时恢复到 SET 前的水平。在 SET 后 6 小时，CON马的皮质醇浓度恢复到SET前的浓度，而SCFP马的皮质醇进一步下降至低于SET前的水平（P = 0.0002）并在那个时间点低于CON（P = 0.003）。SAA 在 CON 中 SET 后 6 小时增加（P < 0.0001），但在 SCFP 马中到 6 小时没有变化。除 G-CSF 外，所有细胞因子均响应 SET 增加（P < 0.0001），但显示出不同的响应模式。与 CON 马相比，SCFP 中 IL-1β、IL-6 和肿瘤坏死因子-α 的浓度较低 (P ≤ 0.05)，G-CSF 和 IL-18 的浓度往往较低 (P ≤ 0.09)从 SET 中恢复。总之，8 周的膳食补充剂和 21 克/天的 SCFP 可以减轻幼马单次、长时间的次极量运动后的细胞压力。