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.

Calcium nitrate supplementation has recently been suggested to provide potential benefits to sows and, in particular, their offspring when administered at a level of 1,200 ppm in feed shortly before farrowing through lactation. More specifically, nitrate supplementation has been suggested as one opportunity for improved placental and/or fetal blood flow and has been hypothesized in previous work to be important to the swine industry in light of the global trend toward larger litter sizes. The benefit is likely manifested through exposure to the nitrate moiety, but interestingly, nitrate has historically been considered a compound of concern for swine. High levels of nitrate once metabolized to nitrite can interfere with the oxygen-carrying capacity of hemoglobin, resulting in increased methemoglobin and, subsequently, methemoglobinemia (MetHb) if the animal is deprived of significant amounts of oxygen; however, the level of nitrate exposure necessary to induce MetHb in sows is not clearly defined. This work was undertaken to examine methemoglobin levels in sows and piglets exposed to the potentially beneficial levels of 1,200 and 6,000 ppm nitrate added to their diets over the course of the periparturient period. Other oxygen capacity blood variables were evaluated (e.g., hemoglobin, hematocrit, and various measures of hemoglobin and red blood cell volumes and concentrations), as well as performance endpoints (weight changes and feed intake) and general observations over the 27-day period. No evidence of treatment-related toxicity manifestation was observed at these supplemental levels. Nearly all oxygen-related variables were affected by time (independent of treatment), indicating adaptive general effects of farrowing. These findings support the hypothesis that MetHb is not a concern up to at least 6,000 ppm supplemental nitrate exposure, even in combination with additional nitrate in the sow’s daily diet. This work is important to help swine producers understand that consideration of nitrate benefit should outweigh concern for risk of nitrate-induced toxicity.

IntroductionNutritional and environmental stressors can disturb the gut microbiome of horses which may ultimately decrease their health and performance. We hypothesized that supplementation with a yeast-derived postbiotic (Saccharomyces cerevisiae fermentation product-SCFP) would benefit horses undergoing an established model of stress due to prolonged transportation.MethodsQuarter horses (n = 20) were blocked based on sex, age (22 ± 3 mo) and body weight (439 ± 3 kg) and randomized to receive either a basal diet of 60% hay and 40% concentrate (CON) or the basal diet supplemented with 21 g/d Diamond V TruEquine C (SCFP; Diamond V, Cedar Rapids, IA) for 60 days. On day 57, horses were tethered with their heads elevated 35cm above wither height for 12 h to induce mild upper respiratory tract inflammation. Fecal samples were collected at days 0, 28, and 56 before induction of stress, and at 0, 12, 24, and 72 h post-stress and subjected to DNA extraction and Nanopore shotgun metagenomics. Within sample (alpha) diversity was evaluated by fitting a linear model and between sample (beta) diversity was tested with permutational ANOVA.ResultsThe SCFP stabilized alpha diversity across all time points, whereas CON horses had more fluctuation (P < 0.05) at 12, 24, and 72 h post-challenge compared to d 56. A significant difference between CON and SCFP was observed at 0 and 12 h. There was no difference in beta-diversity between SCFP and CON on d 56.DiscussionTaken together, these observations led us to conclude that treatment with SCFP resulted in more robust and stable microbial profiles in horses after stress challenge.

Dietary intervention may be a valuable strategy to optimize the intra-articular environment in young horses to prolong their performance career. To test the hypothesis that dietary supplementation of a Saccharomyces cerevisiae fermentation product would reduce markers of joint inflammation and increase markers of cartilage metabolism following a single inflammatory insult, Quarter Horse yearlings (mean ± SD; 9 ± 1.0 mo) were balanced by age, sex, body weight (BW), and farm of origin and randomly assigned to: 1.25% BW/d (dry matter basis) custom-formulated concentrate only (CON; n = 9) or concentrate top dressed with 21 g/d Saccharomyces cerevisiae fermentation product (SCFP; n = 10) for 98 d. Horses had ad libitum access to Coastal bermudagrass hay. On d 84, one randomly selected radial carpal joint from each horse was injected with 0.5 ng lipopolysaccharide solution (LPS). The remaining carpal joint was injected with sterile lactated Ringer’s solution as a contralateral control. Synovial fluid obtained before supplementation (d 0) and on d 84 at pre-injection h 0, and 6, 12, 24, 168, and 336 h post-injection was analyzed for prostaglandin E2 (PGE2), carboxypeptide of type II collagen (CPII), and collagenase cleavage neopeptide (C2C) by commercial assays. Rectal temperature, heart rate, respiration rate, carpal surface temperature, and carpal circumference (CC) were recorded prior to each sample collection and for 24 h post-injection. Data were analyzed using linear models with repeated measures. From d 0 to 84, synovial C2C declined (P ≤ 0.01) and the CPII:C2C ratio increased (P ≤ 0.01) in all horses with no effect of diet. In response to intra-articular LPS, synovial PGE2 increased by h 6 (P ≤ 0.01) and returned to baseline by h 336, CPII increased by h 12, remained elevated through h 168 (P ≤ 0.01), and returned to baseline by h 336, and C2C increased by h 6 (P ≤ 0.01) but did not return to baseline through h 336 (P ≤ 0.01). Post-intra-articular injection, PGE2 levels were lower in SCFP than CON horses (P = 0.01) regardless of injection type. Synovial CPII and the CPII:C2C ratio demonstrated stability during the LPS challenge in SCFP compared to CON horses (P ≤ 0.01). Clinical parameters were not influenced by diet but increased in response to repeated arthrocentesis (P ≤ 0.01). Dietary SCFP may favorably modulate intra-articular inflammation following an acute stressor and influence cartilage turnover in young horses.

Saccharomyces cerevisiae fermentation product (SCFP) is a dietary postbiotic compound shown to support digestive health and immune function in several species. Two studies were performed to evaluate the effects of SCFP (Diamond V Mills, Inc.; Cedar Rapids, IA) in canines exposed to exercise and transport stress. In both studies, 36 Labrador Retrievers (18 males/18 females) >5y were used. Study 1 consisted of a 3-wk adaptation period followed by a 14-wk series of distance-defined running exercise regimens (DDER) with subjects randomly allocated to three groups of 0 mg/d SCFP, 250 mg/d SCFP, or 500 mg/d SCFP. Study 2 consisted of a 3-wk adaptation period followed by an 8 wk phase of DDER and a final, single transport stress event. Subjects were randomly allocated to two treatments of 0 mg/d SCFP and 250 mg/d SCFP. Parameters examined over the two studies included body composition, body weight, feed intake, activity, running speed, stool quality. The following serum biomarkers were also measured: saliva cortisol (CORT), total antioxidant capacity (TAC), thiobarbituric acid reactive substances (TBARS), c-reactive protein (CRP), creatine kinase (CK), haptoglobin (HAP), serum amyloid A (SAA), TNF-α, immunoglobulin E (IgE), and immunoglobulin G (IgG). Subjects fed SCFP exhibited numeric net increases in lean mass (Table 1), numeric increases in stool quality, and significantly higher activity during exercise (P < 0.05) vs CON (Table 2). The 500 mg/d SCFP group exhibited lower CK (P < 0.03), increased HAP (P < 0.001), increased SAA (P < 0.05), increased TNF-α (P < 0.007), increased CORT, improved TAC (P < 0.001), reduced TBARS (P < 0.01), IgE (P < 0.001) and IgG (P < 0.001), and increased CRP during transport (P < 0.001) (Table 3). These results demonstrate that Labrador Retrievers supplemented with SCFP may exhibit improved vitality, utilization of nutrients, immune function, and reduced cellular damage when subjected to exercise and transport stress.