Modification of the equine gastrointestinal microbiota by Jerusalem artichoke meal supplementation.

The objective of this study was to investigate the impact of natural prebiotic active compounds on the microbial composition in different regions of the equine gastrointestinal tract. Twelve adult horses (body weight [bwt] 534 ± 64.5 kg; age 14 ± 7.5 years) were randomly divided into two feeding groups. Six horses received a basal diet consisting of 1.5 kg hay/100 kg bwt x d-1 and oat grains equal to 1.19 g starch/kg bwt x d-1, supplemented with Jerusalem artichoke meal providing prebiotic fructooligosaccharides + inulin in a quantity of 0.15 g/kg bwt x d-1. The remaining horses received a placebo added to the basal diet. The horses were fed for 21 d and euthanized at the end of the feeding period. Digesta samples from different parts of the gastrointestinal tract were taken, DNA extracted and the V1-V2 region of the 16S rRNA gene amplified. Supplementation with the prebiotic increased the relative abundance of Lactobacillus (P < 0.05), with a concurrent reduction of the relative abundance of Streptococcus mainly in the stomach (P < 0.05). In the hindgut, the supplemental prebiotic also increased the relative abundance of Lactobacillus but further reduced the relative abundance of fibrolytic bacteria, specifically the unclassified members of the families Lachnospiraceae (P < 0.05) and Ruminococcaceae. The relative abundance of the genus Ruminococcus increased solely in the caecum and colon transversum. Overall, the addition of the prebiotic significantly increased the diversity in nearly all parts of the gastrointestinal tract (P < 0.05). The feeding of this natural prebiotic compound to horses had an impact on the microbial community in the entire gastrointestinal tract. Furthermore, the effect on the bacterial community in the foregut (especially the stomach) was more pronounced in comparison to the effect in the hindgut. Therefore, the impact on stomach health should be carefully considered.

Glycaemic and insulinaemic responses of adult healthy warm-blooded mares following feeding with Jerusalem artichoke meal.

This study aimed to investigate the impact of the supplementation of a pre-biotic compound [Jerusalem artichoke meal (JAM)] on the glycaemic and insulinaemic response in healthy, non-obese warm-blooded horses. Six adult mares [mean body weight (bwt) 529 ± 38.7 kg; body condition score 5.1 ± 0.49/9] were used. In two equal meals per day, the horses received crushed oat grains (1 g starch/kg bwt per day) and meadow hay (2 kg/100 kg bwt per day) which together were likely to meet the energy recommendation for light work (GfE, ). Additionally, they received either 0.15 g fructo-oligosaccharides and inulin (FOS+INU)/kg bwt per day via commercial JAM or maize cob meal without grains as control (CON) in 2 × 3-week periods according to a crossover design. Blood was collected on d21 of the feeding period at different ante- and postprandial (PP) time points (-60, 0, 30, 60, 90, 120, 180, 240 and 300 min), and the plasma glucose and serum insulin levels were determined. Feeding JAM vs. CON did not change the PP peak of glucose or insulin (glucose: 6.3 ± 0.40 vs. 7.0 ± 0.87 mmol/l; insulin: 0.508 ± 0.087 vs. 0.476 ± 0.082 nmol/l) nor did it cause different AUCs until 120 and 300 min PP for glucose and insulin, respectively (AUC120 , glucose: 997 ± 41.6 vs. 1015 ± 41.63 mmol/l per minute, insulin: 49 ± 6.3 vs. 42 ± 6.3 nmol/l per minute; AUC300 , glucose: 1943 ± 142.3 vs. 2115 ± 142.3 mmol/l per minute, insulin: 94 ± 14.8 vs. 106 ± 14.8 nmol/l per minute; p > 0.05). Following JAM vs. CON feeding, glucose and insulin levels declined more rapidly until 240 min PP and tended to be lower (p = 0.053 and p = 0.056, respectively) at this time point. This result might be promising and should further be studied more detailed.

Effects of isoenergetic quantities of a low-starch muesli feed high in fat and fibre vs. oat grains on the glycemic and insulinemic responses and feed intake patterns in sport ponies.

Aim of this study was to compare glycemic and insulinemic responses and feed intake patterns in sport ponies after feeding isoenergetic quantities of low-starch muesli feed high in fat and fibre (FF) or oat grains (OG). Six sport ponies were randomly assigned to one of these two treatment groups for 2 × 3 weeks according to a crossover-design. Ponies received two equal meals/day of either semi-crushed OG (1 g starch/kg bwt*meal-1 ) or an isoenergetic quantity of FF. Hay was also given in two equal meals/day and provided the remaining metabolisable energy up to 1.3-fold maintenance level. On day 21, blood was sampled 1 h after each pony received 0.5 kg hay (0 min). Then, the concentrate was provided and blood sampled 30, 60, 90, 120, 180, 240 and 300 min thereafter. Plasma glucose and serum insulin were analysed, and the areas under the curve (AUC) was calculated 120 and 300 min postprandial (PP). Feed intake patterns were measured in 4 ponies/group via a modified halter. OG was ingested faster than FF (feed intake time; FITDM in min/kg DM: 8.8 ± 1.6 vs. 15.9 ± 1.62, p < 0.05) combined with a higher chewing frequency (p < 0.05). The AUCsgluc120/300, ins120/300 were statistically higher with OG than FF (mmol/L*min-1 : AUCgluc120 : 776 ± 128 vs. 676 ± 80.4; AUCgluc300 : 1811 ± 295.3 vs. 1569 ± 126.3; nmol/L*min-1 : AUCins120 : 38 ± 18 vs. 22 ± 8.1; AUCins300 : 83 ± 39 vs. 35 ± 12; p < 0.05). Plasma glucose tended to decline following the intake of FF, which might be beneficial for equines with reduced glucose tolerance. This, however, requires further investigation. In this study, the ponies consumed OG unexpectedly rapidly. The rate of feed intake was similar to the results previously reported in the literature for warmblood horses.

Hypoglycin A Content in Blood and Urine Discriminates Horses with Atypical Myopathy from Clinically Normal Horses Grazing on the Same Pasture.

Hypoglycin A (HGA) in seeds of Acer spp. is suspected to cause seasonal pasture myopathy in North America and equine atypical myopathy (AM) in Europe, fatal diseases in horses on pasture. In previous studies, this suspicion was substantiated by the correlation of seed HGA content with the concentrations of toxic metabolites in urine and serum (MCPA-conjugates) of affected horses. However, seed sampling was conducted after rather than during an outbreak of the disease. The aim of this study was to further confirm the causality between HGA occurrence and disease outbreak by seed sampling during an outbreak and the determination of i) HGA in seeds and of ii) HGA and MCPA-conjugates in urine and serum of diseased horses. Furthermore, cograzing healthy horses, which were present on AM affected pastures, were also investigated. AM-pastures in Germany were visited to identify seeds of Acer pseudoplatanus and serum (n = 8) as well as urine (n = 6) from a total of 16 diseased horses were analyzed for amino acid composition by LC-ESI-MS/MS, with a special focus on the content of HGA. Additionally, the content of its toxic metabolite was measured in its conjugated form in body fluids (UPLC-MS/MS). The seeds contained 1.7-319.8 µg HGA/g seed. The content of HGA in serum of affected horses ranged from 387.8-8493.8 µg/L (controls < 10 µg/L), and in urine from 143.8-926.4 µg/L (controls < 10 µg/L), respectively. Healthy cograzing horses on AM-pastures showed higher serum (108.8 ± 83.76 µg/L) and urine concentrations (26.9 ± 7.39 µg/L) compared to control horses, but lower concentrations compared to diseased horses. The range of MCPA-carnitine and creatinine concentrations found in diseased horses in serum and urine were 0.17-0.65 mmol/L (controls < 0.01), and 0.34-2.05 µmol/mmoL (controls < 0.001), respectively. MCPA-glycine levels in urine of cograzing horses were higher compared to controls. Thus, the causal link between HGA intoxication and disease outbreak could be further substantiated, and the early detection of HGA in cograzing horses, which are clinically normal, might be a promising step in prophylaxis.