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Topic:Digestive Tract
The digestive tract in horses is a complex system responsible for the breakdown and absorption of nutrients essential for maintaining equine health. It includes several key components: the mouth, esophagus, stomach, small intestine, cecum, large colon, small colon, and rectum. Each segment of the digestive tract performs specific functions, from the mechanical breakdown of feed to the enzymatic digestion and absorption of nutrients. The horse's digestive system is uniquely adapted to process fibrous plant material, relying heavily on microbial fermentation, particularly in the hindgut. This page compiles peer-reviewed research studies and scholarly articles that explore the anatomy, physiology, and function of the equine digestive tract, as well as common disorders and their management.
Water intake, faecal output and intestinal motility in horses moved from pasture to a stabled management regime with controlled exercise. A change in management from pasture to stabling is a risk factor for equine colic. Objective: To investigate the effect of a management change from pasture with no controlled exercise to stabling with light exercise on aspects of gastrointestinal function related to large colon impaction. The hypothesis was that drinking water intake, faecal output, faecal water content and large intestinal motility would be altered by a transition from a pastured to a stabled regime. Methods: Within-subject management intervention trial involving changes in feeding and exercise using noninvasive techniques. M...
Proteinase-activated receptor 2 expression in the intestinal tract of the horse. Proteinase-activated receptor 2 (PAR2) is a G-protein-coupled receptor for trypsin and mast cell tryptase; it is highly expressed at the intestinal level with multiple functions, such as epithelial permeability and intestinal motility. Many proteases activate PAR2 during tissue damage, suggesting a role of the inflammatory response receptors. The aim of the study was to evaluate the distribution and expression of PAR2 in the jejunum, the ileum and the pelvic flexure, using samples collected from healthy adult horses after slaughter. Proteinase-activated receptor 2 immunoreactivity (PAR2-IR) wa...
Temporal feeding pattern may influence reproduction efficiency, the example of breeding mares. Discomfort in farm animals may be induced by inappropriate types or timing of food supplies. Thus, time restriction of meals and lack of roughage have been shown to be one source of emergence of oral stereotypies and abnormal behaviour in horses which have evolved to eat high-fibre diets in small amounts over long periods of time. This feeding pattern is often altered in domestic environment where horses are often fed low fibre meals that can be rapidly consumed. This study aimed at determining the effect of the temporal pattern of feeding on reproductive efficiency of breeding mares, One hund...
In vitro studies on intestinal peptide transport in horses. Published data on the physiology of nutrient transport across the equine intestine are limited, and the existence and relevance of peptide transporters are still unknown in the horse. In the present study, the equine intestinal peptide transport was investigated by Ussing chamber experiments using the radioisotope tracer technique and by uptake studies into brush border membrane vesicles (BBMV). Jejunal mucosae of 16 healthy adult horses were used. Tissue samples were mounted in Ussing chambers, and electrophysiological parameters as well as unidirectional flux rates of the radiolabelled dipep...
Reduction in absorption of gallium maltolate in adult horses following oral administration with food: chemistry and pharmacokinetics. Gallium (Ga) is under study for the treatment of osteolytic disorders in equines. Previous studies indicate that oral gallium maltolate (GaM) would provide a higher bioavailability than oral Ga salts. However, oral administration to adult horses of 2 mg/kg of GaM, in the form of a solution mixed with food, did not lead to detectable Ga levels in plasma. Therefore, a study was performed to model the chemical behaviour of GaM in the digestive tract. The equilibrium formation constants for Ga(III) and maltol were calculated by means of UV–visible measurements and validated by 1H-NMR measurement...
Influence of laxatives on gastric emptying in healthy Warmblood horses evaluated with the D-xylose absorption test. The use of laxatives is crucial in the treatment of horses with large colon impaction. To reach the impacted mass, the laxative must leave the stomach and pass through the small intestine. The aim of this study was to determine whether the most frequently used saline and lubricant laxatives influence gastric emptying. Six fasted normal adult Warmblood horses were used in a randomized study design with five laxative trials (1.8% sodium sulfate [1.8% Na2SO4], 4.2% magnesium sulfate [4.2% MgSO4], mineral oil [MOil], 25% sodium sulfate [25% Na2SO4], 25% magnesium sulfate [25% MgSO4]) and two trial...
Effects of Saccharomyces cerevisiae supplementation on apparent total tract digestibility of nutrients and fermentation profile in healthy horses. Supplementation with Saccharomyces cerevisiae (SC) in horses may have some potential to modify microbial populations and thereby improve fibre digestibility. The aim of this study was to investigate the effects of SC on apparent total tract digestibility (ATTD) of nutrients, with a special focus on fibre digestion in healthy horses. The fermentation profile of microbial populations was another focus of interest. Twelve geldings were randomly assigned to three groups. The basal diet consisted of cracked corn (2 g starch/kg body weight [BW]) and hay (1.2 kg/100 kg BW). During adaptation (3 weeks...
Systemic, renal, and colonic effects of intravenous and enteral rehydration in horses. Intravenous (IV) and intragastric (IG) administration of fluid therapy are commonly used in equine practice, but there are limited data on the systemic, renal, and enteric effects. Objective: IV fluid administration will increase intestinal and fecal hydration in a rate-dependent manner after hypertonic dehydration, but will be associated with significant urinary water and electrolyte loss. Equivalent volumes of IG plain water will result in comparatively greater intestinal hydration with less renal loss. Methods: Six Thoroughbred geldings. Methods: Experimental study. 6 by 6 Latin square desi...
Comparison of microbial populations in the small intestine, large intestine and feces of healthy horses using terminal restriction fragment length polymorphism. The composition of the microbiota of the equine intestinal tract is complex. Determining whether the microbial composition of fecal samples is representative of proximal compartments of the digestive tract could greatly simplify future studies. The objectives of this study were to compare the microbial populations of the duodenum, ileum, cecum, colon and rectum (feces) within and between healthy horses, and to determine whether rectal (fecal) samples are representative of proximal segments of the gastrointestinal tract. Intestinal samples were collected from ten euthanized horses. 16S rRNA gen...
Digestive capacity in weanling and mature horses. The ability of young and mature horses to digest DM, OM, and NDF was compared using 6 weanling colts and 6 mature (13.2 ± 3.0 yr) geldings. Each colt was paired with a gelding, and the pair was adapted to a diet containing 67% alfalfa cubes and 33% concentrate for 21 d. During the adaptation period, horses were accustomed to housing and all handling procedures. The adaptation period was also used to adjust the amount of feed offered to minimize orts and to maintain similar rates of intake within a pair. After the adaptation period, a 5-d fecal collection period using fecal collection harnesse...
The effect of very low food intake on digestive physiology and forage digestibility in horses. Equid digestion is often conceptualized as a high-throughput/low-efficiency system, in particular compared with ruminants. It is commonly assumed that ruminants have an advantage when resources are limited; the effect of low food intake on digestive physiology of horses has, however, not been explored to our knowledge. We used four adult ponies [initial body mass (BM) 288 ± 65 kg] in two subsequent trials with grass hay-only diets [in dry matter (DM): hay1, mid-early cut, crude protein (CP) 10.5%, neutral detergent fibre (NDF) 67.6%; hay2, late cut, CP 5.8%, NDF 69.5%], each fed subsequent...
Bacterial carbohydrate-degrading capacity in foal faeces: changes from birth to pre-weaning and the impact of maternal supplementation with fermented feed products. The present study aimed at (1) describing age-related changes in faecal bacterial functional groups involved in carbohydrate degradation and in their activities in foals (n 10) from birth (day (d) 0) to 6 months (d180) and (2) investigating the effect of maternal supplementation (five mares per treatment) from d - 45 to d60 with fermented feed products on response trends over time of the foal bacterial carbohydratedegrading capacity. Maternal supplementation with fermented feed products stimulated foal growth from d0 to d60 and had an impact on the establishment of some digestive bacterial gro...
Saccharomyces boulardii viability and efficacy in horses with antimicrobial-induced diarrhoea. Saccharomyces boulardii has been successfully used in the prevention and treatment of antimicrobial-associated diarrhoea in humans. We hypothesised that a viable, dried lyophilised preparation of S boulardii would survive in the gastrointestinal tract of horses with antimicrobial-associated enterocolitis, and significantly decrease the duration of diarrhoea. Twenty-one horses, over one year of age, with antimicrobial-associated diarrhoea of up to 72 hours duration, were consecutively randomised in a controlled prospective study. The treatment group received S boulardii (25 g, orally, every 12 ...
The influence of casein and urea as nitrogen sources on in vitro equine caecal fermentation. To access the fermentative response of equine caecal microbial population to nitrogen availability, an in vitro study was conducted using caecal contents provided with adequate energy sources and nitrogen as limiting nutrient. Two nitrogen (N) sources were provided, protein (casein) and non-protein (urea). Caecal fluid, taken from three cannulated horses receiving a hay-concentrate diet, was mixed with a N-free buffer-mineral solution. The influence of four N levels (3.7, 6.3, 12.5 or 25 mg of N in casein or urea) was studied using the gas production technique. Total volatile fatty acids (VFA)...
Expression of sweet receptor components in equine small intestine: relevance to intestinal glucose transport. The heteromeric sweet taste receptor T1R2-T1R3 is expressed on the luminal membrane of certain populations of enteroendocrine cells. Sensing of sugars and other sweet compounds by this receptor activates a pathway in enteroendocrine cells, resulting in secretion of a number of gut hormones, including glucagon-like peptide 2 (GLP-2). This subsequently leads to upregulation in the expression of intestinal Na(+)/glucose cotransporter, SGLT1, and increased intestinal glucose absorption. On the basis of the current information available on the horse genome sequence, it has been proposed that the ge...
Apparent digestibility of wheat bran and extruded flax in horses determined from the total collection of feces and acid-insoluble ash as an internal marker. Several studies have reported data on comparisons between two methods: the total collection of feces and the internal markers method. The aim of this study was to assess the apparent digestibility of two concentrates and to compare the apparent digestion coefficients using the total collection of feces and acid-insoluble ash (AIA) as the internal marker method. In 2009, six adult geldings aged between 3 and 11 years, with an average weight per trial of 543, 540 and 542 kg, respectively, were used to determine the apparent digestibility by means of three in vivo digestibility trials on hay, hay...
In vitro studies on intestinal calcium and phosphate transport in horses. Transepithelial transport mechanisms play a key role in regulating the absorption and secretion of calcium (Ca(2+)) and inorganic phosphate (P(i)) in the gastrointestinal tract. Although intestinal disorders with imbalances in macromineral homeostasis are frequently observed in horses, available data on intestinal Ca(2+) and P(i) transport are limited. The aim of the present study was to characterize the intestinal Ca(2+) and P(i) transport functionally by using the in vitro radioisotope tracer technique with Ussing chambers and to identify components involved in Ca(2+) transport at both mRNA ...
Characterization of L-lysine transport across equine and porcine jejunal and colonic brush border membrane. In nonruminant herbivores, microbially derived AA could contribute to whole-body AA homeostasis and thus decrease predicted AA requirements. However, postileal capacity of AA uptake is currently unknown. Therefore, to test the hypothesis that Lys is transported across the large colon mucosal apical membrane with capacity similar to that of the small intestinal mucosa in the pony and pig, we examined Lys transport in vitro using brush border membrane vesicles (BBMV). Mucosa was collected from the distal jejunum (DJ) and proximal large colon (PLC) of growing pigs (n = 3) and ponies (n = 4), flas...
Voluntary ingestion of wood shavings by obese horses under dietary restriction. Dietary restriction for the weight-loss management of obese horses limits the natural trickle-feeding behaviour. During feed restriction, wood shavings are often advised as bedding to prevent dietary supplementation from non-feed sources. Data from twelve overweight/obese horses and ponies of mixed breed and sex, bedded on wood shavings during 16 weeks of feed restriction, were retrospectively evaluated. DM intake (DMI) was restricted to 1.25 % of body mass (BM) daily. Animals were randomly assigned to one of two diets (hay/chaff, n 6; hay/balancer meal, n 6). BM was recorded weekly. Feeding b...
Expression patterns of intestinal calcium transport factors and ex-vivo absorption of calcium in horses. In many species, the small intestine is the major site of calcium (Ca(2+)) absorption. The horse differs considerably from most other species with regard to the physiology of its Ca(2+) metabolism and digestion. Thus, this study was performed to get more information about the transcellular Ca(2+) absorption in the horse.Two mechanisms of intestinal Ca(2+) absorption are described: the passive paracellular pathway and the active, vitamin D-dependent transcellular pathway. The latter involves the following elements: vitamin D receptors (VDR), transient receptor potential vanilloid channel member...
Effect of dental correction on voluntary hay intake, apparent digestibility of feed and faecal particle size in horse. In nine adult Warmblood horses with mild to moderate dental findings (no signs of discomfort during chewing), voluntary hay intake before and after dental correction was examined. In a second experiment, digestibility of feed and faecal particle size were determined (3 days of total faecal collection) before and after dental correction. During both digestion trials including a 3-day adaptation period, the amount of hay and concentrate (mixture of oats, barley and maize) was kept constant in each individual horse before and after dental correction. Voluntary hay intake in individual horses ra...
Investigation of the effect of pasture and stable management on large intestinal motility in the horse, measured using transcutaneous ultrasonography. Management regimes have been identified as risk factors for equine intestinal motility disorders. However, it is not known how management factors affect gastrointestinal motility. Objective: Large intestinal motility was similar in horses on a stabled and a pastured management regime. Objective: To investigate the effect of 2 different management regimes on large intestinal motility assessed with ultrasonography. Methods: A within-subjects crossover design was used to compare large intestinal motility between a stabled and a pastured regime in 16 working horses. Group A was managed under a sta...
In vitro validation of the lactose 13C-ureide breath test for equine orocaecal transit time measurement. Validation of a reliable, noninvasive clinical test for quantification of equine orocaecal transit time (OCTT) is required. This would facilitate an evidence-based approach to investigation and treatment of equine small intestinal disorders. Objective: 1) Comparison of the lactose (13) C-ureide breath test (LUBT) with the hydrogen breath test (H(2) BT) for OCTT measurement. 2) Identification of the characteristics of gastrointestinal microbial glycosylureide hydrolase activity in vitro. 3) Production of an optimised protocol for the LUBT for in vivo measurement of equine OCTT. Objective: Signi...
Understanding the equine cecum-colon ecosystem: current knowledge and future perspectives. Having evolved as a grazing animal, a horse's digestive physiology is characterized by rapid gastric transit, a rapid but intense enzymatic digestion along the small intestine, and a long and intense microbial fermentation in the large intestine. The process of understanding and describing feed degradation mechanisms in the equine digestive system in general, and in the hindgut ecosystem in particular, is essential. Regardless of its importance for the nutritional status of the host, the significance of the cecum-colon ecosystem has not yet been fully understood, and few reports have focused d...
Motivation for hay: effects of a pelleted diet on behavior and physiology of horses. The natural diet of free-ranging horses is grass, which is typically high in fiber and calorically dilute, however diets for high performance domestic horses are often low in fiber and calorically dense. The aim of the study was to determine the motivation of horses for hay when fed a low roughage diet. Their motivation could be used to determine if low roughage diets compromise the welfare of horses. Eight mares were fed two different diets in counterbalanced order: ad libitum orchard grass hay; a complete pelleted feed (pellets). Each trial lasted three weeks, with a one-week transition peri...
Comparison of in vitro digestibility estimates using the DaisyII incubator with in vivo digestibility estimates in horses. The objective of this study was to determine if in vitro methodologies developed for the Ankom Daisy(II) incubator could produce accurate estimates of in vivo equine DM digestibility (DMD) and NDF digestibility (NDFD) when equine feces were used as the inoculum source. Four mature geldings were utilized in a 4 × 4 Latin square design experiment with a 2 × 2 factorial arrangement of dietary treatments (timothy hay, alfalfa hay, timothy hay plus oats, and alfalfa hay plus oats), in which the geldings were individually housed and fed. During each 5-d total fecal collection period, feces were co...
Meckel’s diverticulum as a cause of colic: 2 cases with different morphological features. Persistent Meckel's diverticulum is an uncommon embryonic developmental anomaly of the distal small intestine created by a portion of the vitelline duct adjacent to intestine that remains patent. This portion can form a diverticulum (Meckel's diverticulum) or a fibrous band, called vitelloumbilical band, and can be associated with colic after local impaction or strangulation of the small intestine around the remnant. This report describes two cases of Meckel's diverticulum with different morphological features in older horses. This congenital disorder should be considered as a reason for abdom...
The interstitial cells of Cajal of the equine gastrointestinal tract: what we know so far. Gastrointestinal motility disorders are a serious problem in both veterinary and human medicine and may represent a dysfunction of the neural, muscular or pacemaker components (interstitial cells of Cajal) of bowel control. The interstitial cells of Cajal are considered to be the pacemakers and mediators of certain forms of neurotransmission in the gastrointestinal tract. These cells have been implicated, either primarily or secondarily, in the pathogenesis of gastrointestinal disease processes in which there is a prominent element of disturbance to intestinal motility. In the horse, their inv...
A comparison between the 2N and 4N HCl acid-insoluble ash methods for digestibility trials in horses. The digestibility of horse feeds and rations can be determined using different techniques such as calculations based on the chemical composition, in vivo or in vitro methods. The marker methods overcome difficulties like discomfort for the animals and longer experimental times encountered using the ingesta/egesta method. In field conditions, a natural indigestible marker like acid-insoluble ash (AIA), with no changes in the normal ration, could be a very useful tool for digestibility trials. A group of six standardbred horses was used in a set of seven apparent digestibility trials. The diets ...
Cationic and neutral amino acid transporter transcript abundances are differentially expressed in the equine intestinal tract. To test the hypothesis that AA transporter transcripts are present in the large intestine and similarly expressed along the intestinal tract, mRNA abundance of candidate AA transporter genes solute carrier (SLC) family 7, member 9 (SLC7A9), SLC7A1, SLC7A8, and SLC43A1 encoding for b(0,+)-type AA transporter (b(0,+)AT), cationic AA transporter-1 (CAT-1), L-type AA transporter-2 (LAT-2), and L-type AA transporter-3 (LAT-3), respectively, was determined in small and large intestinal segments of the horse. Mucosa was collected from the equine small (jejunum and ileum) and large intestine (cecum, l...
