Metabolic response to dietary fibre composition in horses

Abstract

The hypothesis for this study was that a higher dietary proportion of soluble fibre would result in stable and constant plasma metabolite and regulatory hormone concentrations. The study was a 4 × 4 Latin Square design with a sequence of 17 days adaptation to the ration followed by 8 sampling days. The feed rations consisted of only timothy hay (H), hay plus molassed sugar beet pulp combined with either whole oats (OB) or barley (BB) and hay plus a loose chaff-based concentrate (M). Four horses were fitted with permanent caecal cannulas and liquid caecal content was withdrawn manually and blood was drawn from the jugular vein at 0, 3 and 9 h postprandial. The horses were exercised daily at medium level for about 1 h. Samples were analysed for shortchain fatty acids (SCFA) and metabolic traits. Caecal SCFA and propionic acid concentrations increased with increased dietary starch and soluble fibre. The diet highest in soluble fibre (M) resulted in the highest plasma glucose and insulin concentrations in the morning, which then remained stable and constant throughout the day. A strong interaction (P < 0.01) between time and diet was measured for plasma urea, glucose, insulin and leptin. The greatest variations in plasma glycaemic and insulinaemic responses were associated with the cereal grain diets (OB and BB). There were indications of a negative energy balance, which was reflected in a significantly higher plasma β-hydroxybutyrate concentration and a numerically higher non-esterified fatty acid concentration. In conclusion, this study found that inclusion of soluble fibre resulted in increased total caecal SCFA and propionic acid concentrations. This consequently resulted in stable and constant plasma glycaemic and insulinaemic responses. Diets with a high content of soluble fibre provided enough energy for horses at medium work level.

Early colonisation and temporal dynamics of the gut microbial ecosystem in Standardbred foals

“…In particular, the major end‐products of the gut microbiota catabolism of dietary fibre, i.e. the short‐chain fatty acids acetate, propionate and butyrate, represent a key energy source for the horse, accounting for more than 50% of the total daily animal requirement . The relevance of the gut microbial ecosystem in horse physiology is also highlighted by the deleterious impact of several gut microbiota‐compromising factors on the horse health, such as antimicrobial administration, dietary changes or gastrointestinal infections .…”

Comparison of the microbiome, metabolome, and lipidome of obese and non-obese horses

“…For example, production of short-chain fatty acids (SCFA) from the microbial digestion of cellulose provides a substantial portion of the daily energy requirements of a horse. While SCFAs are well-recognized for their effects on host mucosal health and maintenance of mucosal homeostasis, they represent a small fraction of the thousands of metabolites produced by the microbiota each day, many of which also have important impact on host health [24]. Despite the importance of the intestinal microbiota for equine health and availability of molecular techniques for assessing this complex microbial community, information regarding the quantification, characterization, and metabolic activity of the equine gastrointestinal microbiota is limited.…”

Associative Effects between Forages and Concentrates on In Vitro Fermentation of Working Equine Diets

“…Through fermentation, the fibrous components are degraded to monosaccharides. The anaerobic environment of the hindgut prevents the complete oxidation of monosaccharides and instead produces VFA, acetate, propionate, and butyrate [ 45 ]. The results from previous studies indicated that changing the energy source from starch-rich feeds to high-fiber feeds in training horses changes the muscle energy supply from glucose to acetic acid due to increased fermentation in the hindgut [ 46 ] and the acetate/propionate ratio increases when the forage/concentrate ratio increases [ 47 ].…”