Mature Horses Research Articles

Management of bladder rupture in mature horses

SummaryRupture of the urinary bladder of adult horses is rare with both reports of surgical repair and conservative management in the literature. The case report by Gosling et al. in this issue describes the successful treatment of an iatrogenic bladder tear in an adult gelding. The aim of this commentary is to review the described treatment options.

Recovery heart rates as a predictor of race position in race-fit National Hunt racehorses

Prediction of race-fitness using the principles of excess post-exercise oxygen consumption is a potentially valuable applied exercise physiology tool. We hypothesised that horses with a faster heart rate recovery (HRR) after a field test would perform better in their subsequent race. Twenty mature (17 experienced, 3 unraced) National Hunt horses (15 geldings, 5 mares; 6.5±1.1 years; 489±33.5 kg), underwent 34 pre-race 3-interval field exercise tests using telemetric heart rate (HR) and global positioning satellite (GPS) monitoring on a 1,400 m track inclined 32 m. Horses were classified into 3 groups based on post-exercise HRR values obtained 1 minute after peak HR during interval 3 (>140 bpm; unfit; 120-140 bpm; fit-to-race; <120 bpm; fully fit). All horses were from the same yard, under the same management and in their final stage of training (race-ready). Horses were excluded if they were lame or clinically unwell. The outcome measure of finishing in the top third of the field was compared to classification using 2×2 tables (Statcalc, EpiInfo). Peak HR, peak speed and 1 min HRR were 213.4±5.1 bpm, 49.3±1.8 kph and 125.3±15.8 for interval 3. Horses classified as unfit (n=8) did not race. Fully fit and fit-to-race horses competed in 26 jump races (23 hurdles, 3 bumper; 3,200-5,000 m). Fully fit (n=16) horses were more likely to finish in the top 3rd of the field than fit-to-race (n=10) (odds ratio 12.0; 95% confidence interval 1.8-81.7; P=0.01). We conclude that HRR following interval exercise can be used as a predictor of race position in National Hunt racehorses and a useful guide for trainers.

PSI-36 Effect of short-chain fructooligosaccharides on Trolox equivalent antioxidant capacity and thiobarbituric acid reactive substances in mature and senior stock-type horses

Abstract Oxidative stress (OS) causes health complications through the destruction of cellular components as individuals age. Reactive oxygen species are used to measure OS through Trolox equivalent antioxidant capacity (TEAC) and thiobarbituric acid reactive substances (TBARS). Other prebiotics have been used to reduce OS markers in numerous species; however, the effect of short-chain fructooligosaccharides (scFOS) on OS has not been studied in the horse. Ten healthy stock-type horses were blocked by age into 2 groups: mature (MA; n = 5; 7.0 ± 0.87 yr) and senior (SR; n = 5; 22.6 ± 1.1 yr) to analyze effects of scFOS on TEAC and TBARS. Horses were randomly assigned to 1 of 3 diets for 25 d before transition to another diet. Diets were bermudagrass hay offered at 1.5% BW/d hay as-fed, hay with a ration balancer (CON), or hay with a ration balancer and scFOS added at a rate of 2.5 g/kg (PRE). Prior to a total fecal collection for an alternate study, horses were fasted overnight for 8 h with blood samples taken immediately prior to feeding (0), 30, and 60 min postprandial. Oxidative stress markers were analyzed for the 2 ration balancer diets. Statistical analysis was performed with SAS using the MIXED procedure with horse within diet as a random effect with significance of P ≤ 0.05. Trolox equivalent antioxidant capacity was unaffected by diet (P = 0.827) or age (P = 0.347). Time (P = 0.006) was significant for TBARS which increased postprandial regardless of treatment or age. Consistent with other species, higher levels of OS was found in SR compared to MA regardless of time or diet (P = 0.037; 4.491 µM vs. 3.412 µM TBARS, respectively). These results indicate that scFOS do not seem to be effective in reducing OS in SR and MA horses.

Effect of Different Blanket Weights on Surface Temperature of Horses in Cold Climates

The objective of this study was to examine changes in surface temperature of blanketed horses during cold weather. Four mature stock-type horses were used in a 4 × 4 Latin square design. Treatments included 3 different blanket weights (based on g of fiberfill): light weight (LW; 0 g), medium weight (MW; 200 g), heavy weight (HW; 400 g), and a nonblanketed control (CON). Thermographic images were obtained from a standardized lumbar location before blanketing and immediately after cold exposure. During cold exposure, horses were outside with ad libitum access to grass hay and water for 1 hour. Mean temperature was −23°C with a wind chill of −32°C. After 1 hour, horses were brought inside (15°C) and lumbar images immediately recorded. A 30-minute equilibration period was allowed between each sampling period. Analysis of variance was computed using the general linear model procedure of SAS with statistical significance declared at P values ≤ 0.05. There was an overall treatment effect (P = .02) for lumbar temperatures after horses were outside for 1 hour with temperatures measuring 22.3°C, 26.8°C, 30.3°C, and 31.5°C for CON, LW, MW, and HW, respectively. Lumbar temperature was warmer (P ≤ .009) for HW and MW compared with CON and tended to be warmer (P = .10) in LW compared with CON. Change in lumbar temperature decreased significantly (P ≤ .01) in CON compared with all other treatments. In conclusion, wearing a blanket can increase lumbar surface temperature during cold weather with the degree of warmth influenced by blanket weight.

Relationships Between Measurements of Body Fat in Thoroughbred Horses

Equine obesity is increasing in prevalence, and weight loss diets are frequently recommended for these horses. However, there are also management situations in which horses are deemed to be too thin. To monitor the efficacy of weight change programs, estimates of body fat are often made. There are several systems available to estimate body fat, and there are benefits and challenges to using each method. The objective of this study was to compare four different methods of estimating body fat in Thoroughbred horses. In 14 mature Thoroughbred horses, relationships among body condition score (BCS), morphometric measurements, ultrasonic measures of subcutaneous fat depots, and estimation of total body fat (BFD) via measurement of total body water through deuterium oxide dilution were evaluated. Body condition scores ranged from 4.5 to 6.5 on a 9-point scale. Body condition score, heart girth-to-body weight ratio, and BFD were all positively correlated with each other (P < .05). Subcutaneous fat depth at the tailhead tended to be positively related to BFD when only horses with BCS ≥ 5 were included (P = .0680). These data suggest that BCS remains a simple means of monitoring adiposity in mature horses in moderate condition. Tailhead fat depots may become useful for monitoring changes in body fat in Thoroughbreds with a BCS above 5, although more work with animals of higher adiposity is required and at different times of year.

Evaluation of allogeneic freeze-dried platelet lysate in cartilage exposed to interleukin 1-\u03b2 in vitro

BackgroundPlatelet-rich plasma (PRP) as well as other platelet-derived products have been used as a potential disease-modifying treatment for musculoskeletal diseases, such as osteoarthritis (OA). The restorative properties of such products rely mainly on the high concentrations of growth factors, demonstrating encouraging results experimentally and clinically. Yet, the autologous blood-derived nature of the PRP product lead to limitations that precludes it’s widespread use. The main limitations for PRP use are; product variability, the need for minimum laboratory settings in most cases, and the need for storage at low temperatures to preserve its properties. Based on these limitations, the objective of this study was to investigate an allogeneic off-the-shelf platelet lysate (PL) in cartilage exposed to interleukin 1β (IL-1β). For this purpose, blood and cartilage were harvested from eight skeletally mature and healthy horses. Blood was processed into PL aliquots and divided into three groups (Frozen, Freeze-dried and Filtered freeze-dried), used in autologous and allogeneic conditions and in three different concentrations (1.5, 3 and 6-fold). Different PL preparations were then applied in cartilage culture with interleukin-1 beta and cultured for 10 days. Cartilage and media samples were collected and analyzed for total GAG and 35SO4-labeled GAG content.ResultsNo significant differences between the controls and PL groups in cartilage and media were demonstrated. The effects of PL on cartilage matrix were concentration dependent and intermediate concentrations (3-fold) in PL showed increased 35SO4-labelled GAG in cartilage.ConclusionIn conclusion, the allogeneic freeze-dried PL presented equivalent effects compared to frozen autologous PL. Intermediate platelet concentration on average demonstrated improved results, demonstrating less GAG loss compared to other concentrations.

Short-term stall housing of horses results in changes of markers of bone metabolism

In previous research, stall-housing growing horses resulted in decreased bone mineral content (BMC) of the third metacarpal (MCIII) compared to pasture-housing. To determine whether stall confinement negatively impacts bone, regardless of age, and whether the effects could be reversed upon return to pasture, 12 mature horses (5-15 years) and 12 yearlings were pair-matched by age and gender and randomly assigned to one of two treatment groups: pasture (PT) or stall (ST). Horses on PT remained there for the 84-d study, while horses on ST spent the first 28 d in stalls and the remaining 56 d on pasture. Radiographs and blood samples were taken on d 0 for baseline determinants. Radiographs and blood were taken every 7 d for radiographic photodensitometry estimates of BMC and analysis of osteocalcin (OC) and C-telopeptide (CTX-1)-markers of bone formation and degradation. There were no differences in BMC between treatments at the medial cortex of MCIII in mature horses. There were treatment (P=0.05) and day (P&lt;0.01) differences in BMC at the lateral cortex of MCIII. In yearling horses, the BMC of the medial cortex of MCIII had a day difference with the lowest overall average at d 21 and highest at d 70 (P=0.04). There were day by treatment differences (P&lt;0.05) for both OC and CTX-1 with the mature and yearling horses on ST having lower OC on d 14 than PT horses (P&lt;0.05) indicative of reduced bone formation. In mature and yearling ST horses, CTX-1 was greater on d 14 and 28 compared to horses on PT (P≤0.05) suggesting greater bone resorption. Results from serum markers of bone formation and deformation confirm that stalling negatively impacts bone formation in horses regardless of age.

Influence of diet fortification on body composition and apparent digestion in mature horses consuming a low-quality forage.

Stock-type mares (498 ± 9 kg BW; 12 ± 7 yr) were used in a completely randomized design for 56 d to test the hypothesis that concentrate fortification improves apparent digestion and enhances lean mass over the topline. Horses were stratified by age, BW, and BCS and randomly assigned to either a custom pelleted concentrate (CON; n = 13), or an iso-caloric, iso-nitrogenous pellet that included amino acid fortification, complexed trace minerals, and fermentation metabolites (FORT; n = 10). Concentrate was offered at a total 0.75% BW/d (as-fed) twice daily, and diets were designed to meet or exceed maintenance requirements for mature horses. Horses had ad libitum access to Coastal bermudagrass hay (7.4% CP, 67% NDF, and 40% ADF). Every 14 d BW and BCS were recorded, and ultrasound images were captured every 28 d. longissimus dorsi area (LDA) and subcutaneous fat thickness (FT) were measured between the 12th and 13th ribs (12th/13th) and 17th and 18th ribs (17th/18th). Intramuscular fat at the 17th/18th ribs and rump fat-thickness were also obtained. Horses were dosed with 10 g/d of titanium dioxide (TiO2) for 14 d to estimate forage dry matter intake (DMI). To account for diurnal variation, fecal samples were collected twice daily at 12-h intervals during the last 4 days, advancing by 3 h each day to represent a 24-h period. Fecal samples were composited by horse and analyzed for TiO2 to estimate fecal output and acid detergent insoluble ash was used to calculate forage DMI. To evaluate body composition, horses were infused with a 0.12 g/kg BW deuterium oxide (D2O) on d 0 and 56. Body fat percentage (BF) was determined by quantifying D2O in plasma samples collected at pre- and 4-h postinfusion via mass spectrometry. All data were analyzed using PROC MIXED (SAS v9.4). The model contained a fixed effect of diet; horse (diet) was a random effect. Horses receiving FORT gained 17th/18th FT (P < 0.01) and increased 17th/18th LDA from d 0 to 56 (P < 0.01) while 17th/18th FT and LDA were unchanged in CON. Regardless of diet, BF estimated by D2O infusion increased in all horses from d 0 to 56 (P < 0.01). Average hay DMI was 2.1% BW, but did not differ between diets. In this study, concentrate fortification did not significantly (P ≥ 0.27) affect apparent digestion. In conclusion, concentrate fortification may promote greater muscle development along the posterior topline.

Managing anthelmintic resistance in cyathostomin parasites: Investigating the benefits of refugia-based strategies

Selective anthelmintic therapy has been recommended as a sustainable strategy for cyathostomin control in horse populations for several decades. The traditional approach has been to determine strongyle fecal egg counts (FEC) for all horses, with treatment only recommended for those exceeding a predetermined threshold. The aims are to achieve a reduction of overall egg shedding, while leaving a proportion of the herd untreated, which lowers anthelmintic treatment intensity and reduces selection pressure for development of anthelmintic resistance. This study made use of the cyathostomin model to evaluate the influence of treatment strategies with between 1 and 8 yearly treatment occasions, where either 1) all horses were treated, 2) a predetermined proportion of the herd remained untreated, or 3) horses were treated if their FEC exceeded thresholds between 100 and 600 strongyle eggs per gram. Weather data representing four different climatic zones was used and three different herd age structures were compared; 1) all yearlings, 2) all mature horses 10–20 years old, and 3) a mixed age structure of 1–20 years of age. Results indicated a consistent effect of age structure, with anthelmintic resistance developing quickest in the yearling group and slowest among the mature horses. Development of anthelmintic resistance was affected by treatment intensity and selective therapy generally delayed resistance. Importantly, the results suggest that the effects of selective therapy on resistance development are likely to vary between climatic zones and herd age structures. Overall, a substantial delaying of resistance development requires that the average number of treatments administered annually across a herd of horses needs to be about two or less. However, results also indicate that an age-structured prioritisation of treatment to younger horses should still be effective. It appears that a ‘one-size-fits-all’ approach to the management of anthelmintic resistance in cyathostomins is unlikely to be optimal.

92 Digestawell® fiber improves in-vitro digestibility of alfalfa and coastal bermudagrass hay fed to horses

Abstract Enhanced microbial activity in the equine hindgut increases nutrient availability, reduces fecal waste, and adds value to low quality forages. The dietary supplement DigestaWell® Fiber (DF; fibrolytic cofactors: methionine and B vitamins), designed to increase microbial efficiency, has been shown to improve in-vitro digestibility of alfalfa and tall fescue forages after 48h incubation. The objective of this study was to determine if DF would improve in-vitro dry matter digestibility (DMD) and ADF digestibility (ADFD) of alfalfa and coastal bermudagrass hays incubated for 48h or 72h. Utilizing a crossover design, four mature Quarter Horse mares were fed 2% BW daily of alfalfa (AF; 32.8% NDF, 27.1% ADF) or coastal bermudagrass (CB; 63.2% NDF, 35.4% ADF) hay for 19d periods. DMD and ADFD were determined after 48h or 72h incubation with or without treatment (320mg/L DF) at 37.5°C in an ANKOM Daisy II incubator inoculated with 200g fresh feces. Forage samples were run in triplicate. Data were transformed to approximate normality, then analyzed using a repeated measures mixed model in SAS with main effects of forage, treatment, incubation time, and feeding period, and statistically significant interactions. Across incubation times, DMD was higher for AF than CB (P &lt; 0.01; 49.4% vs 42.1%). Across forages, DMD was higher at 72h than at 48h incubation (P &lt; 0.01; 47.5% vs 43.9%). DF improved DMD across forages at 48h (P = 0.03), but not at 72h (P = 0.47). Across incubation times, DF improved DMD of CB (P &lt; 0.01), but not AF (P = 0.79). Additionally, across both forages and both incubation times, DF improved ADFD (P &lt; 0.01). In conclusion, DF may improve microbial fermentation in the equine hindgut. Future research should investigate in-vivo effects of oral supplementation of DF on forage digestibility measures.

16 Digestawell® fiber improves in-vitro digestibility of alfalfa and coastal bermudagrass hay fed to horses

Abstract Enhanced microbial activity in the equine hindgut increases nutrient availability, reduces fecal waste, and adds value to low quality forages. The dietary supplement DigestaWell® Fiber (DF; fibrolytic cofactors: methionine and B vitamins), designed to increase microbial efficiency, has been shown to improve in-vitro digestibility of alfalfa and tall fescue forages after 48-h incubation. The objective of this study was to determine if DF would improve in-vitro dry matter digestibility (DMD) and ADF digestibility (ADFD) of alfalfa and coastal bermudagrass hays incubated for 48h or 72h. Utilizing a crossover design, four mature Quarter Horse mares were fed 2% BW daily of alfalfa (AF; 32.8% NDF, 27.1% ADF) or coastal bermudagrass (CB; 63.2% NDF, 35.4% ADF) hay for 19-d periods. DMD and ADFD were determined after 48-h or 72-h incubation with or without treatment (320mg/L DF) at 37.5°C in an ANKOM Daisy II incubator inoculated with 200g fresh feces. Forage samples were run in triplicate. Data were transformed to approximate normality, then analyzed using a repeated measures mixed model in SAS with main effects of forage, treatment, incubation time, and feeding period, and statistically significant interactions. Across incubation times, DMD was higher for AF than CB (P &lt; 0.01; 49.4% vs 42.1%). Across forages, DMD was higher at 72h than at 48h incubation (P &lt; 0.01; 47.5% vs 43.9%). DF improved DMD across forages at 48h (P = 0.03), but not at 72h (P = 0.47). Across incubation times, DF improved DMD of CB (P &lt; 0.01), but not AF (P = 0.79). Additionally, across both forages and both incubation times, DF improved ADFD (P &lt; 0.01). In conclusion, DF may improve microbial fermentation in the equine hindgut. Future research should investigate in-vivo effects of oral supplementation of DF on forage digestibility measures.

90 Evaluation of transport duration on immune response and blood parameters in sedentary horses

Abstract Transport has cogent effects on the physiological and immunological welfare of horses, resulting in inevitable stressors regardless of adaptation or conditioning. We hypothesized transporting sedentary horses would yield allied results to studies using transport-conditioned horses. Mature stock-type horses (n = 4) were subjected to three transport durations (0.25, 3 and 6 hours) with 7–8 days between transport. All subjects were transported simultaneously for all durations of transport. Blood samples were collected before, post-transport and 24 hours post-transport and analyzed for complete blood count (CBC). Body weight (BW), rectal temperature (RT), blood glucose (GLU) and blood lactate (BLA) were recorded before and post-transport. All data (p&lt;0.05) were analyzed using PROC MIXED (SAS © 9.4). Transport duration did not influence CBC, BLA or other physical measurements. Resulting GLU increased after 3 (158.5±8.5 mg/ dL) and 6 (147.50±8.5 mg/dL) hours of transport compared to 0.25 hour of transport (117.8±7.2 mg/dL). Weights decreased after transport; however, this was likely due to eliminative behavior during transport. Total WBC tended (P = 0.06) to increase before transport (7.71±0.6 K/µL) than post (5.64±0.59 K/µL) and 24 hours post-transport (6.14±0.06 K/µL). Percent neutrophils (N) increased post-transport (66.8±2.5%) compared to before transport (55.7±2.6%) and 24 hours post-transport (57.2±2.5%). Neutrophil to lymphocyte ratio (N:L) tended (p= 0.07) to increase post-transport (66.7±2.7%) than before (55.7±2.7%) and 24 hours post-transport (57.3±2.6%) regardless of duration. Increases in N are consistent with previous research indicating a short-term stress response. Previous research measuring adrenocortical response reported elevated N:L ratios indicating stress; our results suggests transport, even minimal, may stimulate a stress response in rarely-transported horses. Elevated GLU after transport may further support an adrenocortical response as cortisol can influence blood glucose concentrations. Findings indicate even short-term transport elicits an immunological stress response and may be intensified in rarely transported horses compared to seasoned travelers.

A high protein meal affects plasma insulin concentrations and amino acid metabolism in horses with equine metabolic syndrome

Equine metabolic syndrome (EMS) is characterized by an abnormal insulin response to a glycemic challenge but despite the known insulinotropic effects of certain amino acids, there is a paucity of data evaluating the impact of dietary protein on insulin dynamics in these horses. The objective was therefore to assess insulin and amino acid responses following intake of a high protein meal in healthy horses and those with EMS. Six mature horses diagnosed with EMS and six age-matched control horses without EMS were used. Horses were fed 2g/kg body mass (BM) of a high protein pellet (31% crude protein) at time 0 and 30min, for a total of 4g/kg BM, following an overnight fast. Blood samples collected during a 4h period were analysed for plasma glucose, insulin, amino acids and urea concentrations.Glucose concentrations were not different between groups (P=0.2). Horses with EMS had a 9-fold greater insulinemic response to the consumption of a high protein meal compared with controls (P=0.046). Post-prandial levels of histidine, citrulline, tyrosine, valine, methionine, isoleucine, leucine and ornithine were higher in horses with EMS (P<0.05). Baseline urea nitrogen concentrations were not significantly different between groups (P=0.1). Knowing that certain amino acids are insulin secretagogues, these results illustrate that consumption of a high protein meal caused a hyperinsulinemic response and affected amino acid dynamics in horses with EMS. These findings suggest that dietary protein content should be taken into consideration in the management of horses with insulin dysregulation.

Effects of exercise on voluntary intake, morphometric measurements, and oral sugar test response in horses on ad libitum forage

In a previous study, exercise resulted in weight loss and improvements in insulin and glucose metabolism, but horses on free-choice forage may increase feed intake in response to exercise, potentially negating the benefits. This study aimed to determine if light exercise increases intake in mature horses, and if horses on ad libitum forage achieve the benefits previously observed. Eight mature, stock-type geldings (594.3±50.5 kg; 12.0±1.7 yr) were adapted to a diet of ad libitum grass hay. Baseline dry matter intake (DMI) was measured for 7 d. Horses then remained idle (CON, n=4) or entered an exercise program (EX, n=4) for 3 weeks. Voluntary DMI was quantified daily. Body weight (BW), heart girth (HG), girth to height ratio (G:H), neck circumference (NC), neck circumference to height ratio (NC:H), rump fat thickness (RF), percent body fat (BF), serum insulin, plasma ghrelin, and plasma leptin were quantified weekly. An oral sugar test was conducted on day 0 and 21, and insulin to glucose ratio (Ins:glc) and 60-min insulin sensitivity index (ISI60) were calculated. Statistical analysis was performed using repeated measures. Insulin, ghrelin, Ins:glc, and ISI60 were not normally distributed, so they were log-transformed for analysis. P≤0.05 was considered significant. The EX group showed no difference in DMI or (log) ghrelin compared to the CON group. The CON group showed increases in BW, RF, and BF, while the EX group showed decreases in HG, G:H, NC, NC:H, (log) insulin, and leptin. EX showed lower (log) Ins:glc than CON after treatment. Overall, light exercise did not alter DMI in mature horses on ad libitum forage, but resulted in improvements in morphometric measurements, (log) Ins:glc, and plasma leptin concentrations, and avoided gains in BW and rump fat.

Increased leishmanicidal activity of alveolar macrophages from mature horses with mild equine asthma

ABSTRACT Alveolar macrophages (AMs) are an essential part of defense mechanisms within the lungs and their phagocytic activity is important for organ homeostasis. The phagocytic ability of AMs obtained from bronchoalveolar lavage from 17 mature mixed-breed pleasure horses (8 healthy and 9 diagnosed with mild equine asthma) was studied through assays with Leishmania (Viannia) braziliensis promastigotes, which enabled the calculation of a phagocytic index (PI) and a survival index (SI). Results indicate that phagocytic activity of AMs in asthma affected horses is similar to healthy horses, while leishmanicidal activity is significantly increased in horses with asthma.

Effect of crude protein on fiber digestibility of a warm-season forage-based diet in mature horses

Effect of crude protein on fiber digestibility of a warm-season forage-based diet in mature horses

Effect of vortex wave circulation stimulation on muscle thickness in mature horses on stall rest

Effect of vortex wave circulation stimulation on muscle thickness in mature horses on stall rest

Influence of trimming and shoeing on hoof temperature and digital cushion thickness in mature horses

Influence of trimming and shoeing on hoof temperature and digital cushion thickness in mature horses

Bioavailable silicon supplementation may influence biomarkers, but not lameness, in mature horses

Bioavailable silicon supplementation may influence biomarkers, but not lameness, in mature horses

Are prebiotics beneficial for digestion in mature and senior horses?

Fructooligosaccharides (FOS) and inulin may modulate hindgut fermentation. It was tested if digesta batch cultures taken from horses adapted to FOS and inulin show different fermentation compared with such taken from nonsupplemented horses. Six horses received 0.15 g FOS and inulin/kg body weight/d via Jerusalem artichoke meal (JAM) upon a hay-based diet; six horses received corncob meal without grains (CMG) as placebo. The horses were euthanized after 20 days. Digesta samples were taken from stomach, cecum, ventral colon ascendens (VCA), and colon transversum (CT). Digesta batch cultures were incubated 48 hours to measure in vitro gas production as well as pre- and post-incubation pH and oxidation-reduction potential (ORP). A distinct fermentation of the surplus of fructans present in the inoculum was found with JAM-adapted batch cultures. Gas production was accelerated in inoculated gastric contents of horses adapted to JAM compared with CMG adapted ones (7.8 vs. 16.4 hours to achieve half of the 48 hours gas quantity, respectively; P > .05). Although buffered, pH decreased during fermentation. Postincubation pH was lower with JAM than CMG-adapted batch cultures (P > .05). Preinoculation ORP was lower with stomach batch cultures adapted to CMG than with such adapted to JAM. The ORP increased twofold from pre- to post-incubation with the latter. Asymptotic maximal gas production decreased gradually using cecum, VCA, or CT digesta. Parts of FOS and inulin of digesta are fermented in the stomach, which reduce possible effects on hindgut fermentation. Elevated fermentation may considerably impact stomach health.