Abstract
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 Saccharomyces 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 (wk 0), and at wk 8 pre-SET, and 0, 1, and 6 h post-SET, and analyzed for concentrations of cortisol and serum amyloid A (SAA) by commercial ELISA, and for cytokine concentrations by commercial bead-based ELISA. Data were analyzed using linear models with repeated measures in SAS v9.4. From wk 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 wk 0 to 8 (P ≤ 0.008), but granulocyte colony-stimulating factor (G-CSF), granulocyte-macrophage colony-stimulating factor (GM-CSF), and interleukin-8 (IL-8) decreased to a greater extent in CON than in SCFP horses (P ≤ 0.003). In response to the wk 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, while 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. Serum amyloid A 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 (TNFα) were lesser (P ≤ 0.05), and concentrations of G-CSF and IL-18 tended to be lesser (P ≤ 0.09) in SCFP compared to 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.
The Effects of Dietary Supplementation of Saccharomyces cerevisiae Fermentation Product During Late Pregnancy and Lactation on Sow Productivity, Colostrum and Milk Composition, and Antioxidant Status of Sows in a Subtropical Climate
