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.
Liu G, Bou G, Su S, Xing J, Qu H, Zhang X, Wang X, Zhao Y, Dugarjaviin M.Gastrointestinal microbiota has significant impact on the nutrition and health of monogastric herbivores animals including donkey. However, so far the microbiota in different gastrointestinal compartments of healthy donkey has not been described. Therefore, we investigated the abundance and function of microbiota at different sites of the gastrointestinal tract (GIT) (foregut: stomach, duodenum, jejunum and ileum; hindgut: cecum, ventral colon, dorsal colon, and rectum) of healthy adult donkeys mainly based on 16S rRNA gene sequencing and phylogenetic investigation of communities by reconstruc...
Fowler AL, Pyles MB, Hayes SH, Crum AD, Lawrence LM.Across the equine literature, estimates of true P digestibility range from -23% to 79%. This large range cannot be explained by differences in P intake or phytate-P intake alone. However, differences in endogenous P secretion into the GI tract may explain the variation. In horses, excess absorbed P is not excreted in the urine but is re-secreted into the GI tract, increasing faecal P and leading to estimates of low P digestibility. Thus, accurate estimates of P digestibility can only be obtained if absorbed P is retained in the horse. The objective of this study was to examine P digestibility ...
Reed L, MacNicol JL, Charchoglyan A, Brewer D, Murrant C, Pearson W.The objective of this study was to evaluate the effect of a botanical-based equine nutraceutical on contractility of gastric smooth muscle in vitro. Gastric ulcers are prevalent in performance horses and negatively impact horse welfare. Gastric hypermotility has been positively associated with the development of gastric ulceration in nonequine species, and reduction of hypermotility may be protective against their development. Stomachs from 12 pigs processed for food at a provincially inspected abattoir were collected within 1 hour of slaughter. Explants of nonglandular gastric tissue were p...
Grimm P, Combes S, Pascal G, Cauquil L, Julliand V.Starchy diets can induce hindgut dysbiosis in horses. The present study evaluated the impact of a yeast (Saccharomyces cerevisiae) and microalgae (Aurantiochytrium limacinum) supplementation on caecal, colonic and faecal microbial ecosystem and on blood inflammatory parameters of horses fed high-fibre or high-starch diets. Six fistulated geldings in a 2 × 2 Latin-square design were alternatively supplemented and received during each period 100 % hay (4 weeks) followed by a 56/44 hay/barley diet (3 weeks). Caecal, colonic and faecal samples were collected 4 h after the morning meal three times...
Cappelli K, Gialletti R, Tesei B, Bassotti G, Fettucciari K, Capomaccio S, Bonfili L, Cuccioloni M, Eleuteri AM, Spaterna A, Laus F.Guanylate cyclase-C (GC-C) is a multifunctional receptor encoded by the gene, representing an attractive target for therapy in several gastrointestinal diseases in humans. Little is known about this system in horses. We investigated for the first time the gene expression of guanylin, uroguanylin and GC-C receptors in different horse's gastrointestinal tracts. Tissue samples from stomach, duodenum, jejunum, ileum, head and body of cecum, left and right dorsal colon, left and right ventral colon, pelvic flexure, transverse colon, descending colon and rectum were collected from adult horses with...
Glatter M, Borewicz K, van den Bogert B, Wensch-Dorendorf M, Bochnia M, Greef JM, Bachmann M, Smidt H, Breves G, Zeyner A.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 p...
Wolford AN, Coverdale JA, Leatherwood JL, Pinchak WE, Anderson RC, Wickersham TA.Eight previously cecally cannulated Quarter Horse geldings were utilized in a crossover design with two 28-d periods with a 21-d washout period between to evaluate the influence of housing on the cecal environment and dry matter intake (DMI). Horses were adapted to diet and housing from day 1 to 19, DMI was determined from day 20 to 24, and cecal fluid was collected on day 28. Horses were paired by age and body weight (BW) and randomly assigned to treatment. Treatments consisted of housing horses individually in stalls or group housed in a pen. Regardless of treatment, all horses were individu...
Salem SE, Hough R, Probert C, Maddox TW, Antczak P, Ketley JM, Williams NJ, Stoneham SJ, Archer DC.Periparturient mares are at increased risk of colic including large colon volvulus, which has a high mortality rate. Alterations in colonic microbiota related to either physiological or management changes, or both, that occur at this time have been suggested as potential causes for increased colic risk in this population of horses. Although the effect of management changes on the horse faecal microbiota has been investigated, limited work has been conducted to investigate changes in faecal microbiota structure and function in the periparturient period. The objectives of the current study were ...
Fehlberg LK, Lattimer JM, Drouillard JS, Douthit TL.Effects of Co on fiber digestibility in horses are largely unknown. Our objective was to evaluate effects of Co chloride on in vitro gas production, VFA production, and dry matter (DM) disappearance (IVDMD) using cecal fluid from 4 cannulated Quarter Horses. Five grams DM of alfalfa or smooth bromegrass hay were provided as substrate with Co added at 0.0, 0.5, 5.0, 25.0, or 50.0 mg/kg substrate DM. Ten milliliters cecal fluid and 140 mL McDougall's buffer were incubated in duplicate, and pH, VFA concentrations, and IVDMD were measured after 48 hours. Gas production, used as an indicator of...
Mura E, Edwards J, Kittelmann S, Kaerger K, Voigt K, Mrázek J, Moniello G, Fliegerova K.Anaerobic fungi are potent fibre degrading microbes in the equine hindgut, yet our understanding of their diversity and community structure is limited to date. In this preliminary work, using a clone library approach we studied the diversity of anaerobic fungi along six segments of the horse hindgut: caecum, right ventral colon (RVC), left ventral colon (LVC), left dorsal colon (LDC), right dorsal colon (RDC) and rectum. Of the 647 ITS1 clones, 61.7 % were assigned to genus level groups that are so far without any cultured representatives, and 38.0 % were assigned to the cultivated genera Ne...
Pyles MB, Fowler AL, Bill VT, Harlow BE, Crum AD, Hayes SH, Flythe MD, Lawrence LM.Adult horses depend on the microbial community in the hindgut to digest fiber and produce short-chain fatty acids that are use for energy. Colonization of the foal gastrointestinal tract is essential to develop this symbiosis. However, factors affecting colonization are not well understood. The objectives of this study were to evaluate the age-related changes and effects of maternal diet on select fecal bacterial groups in foals from 1 to 28 d of age. Thoroughbred foals ( = 18) were from dams fed forage and one of two concentrates: an oat-based (OB) or corn and wheat middlings-based (CWB) pell...
Leandro RM, Filho RPPF, De Silvio MM, Quilici AP, Sattin MM, Paretsis BF, Souza VA.Anatomy is traditionally regarded as a difficult, non-motivating course involving a large body of theoretical and practical content, and it is often associated with high levels of dropout and failure. Given the relevance of the topic, we propose an alternative active multisensory teaching tool consisting of the construction of a low-fidelity anatomical model assembled into an articulated equine skeleton. Model construction and assembly assists students in the recognition of the topography and anatomical boundaries of the equine abdominal digestive system. Digestive system organs (liver, pancre...
Crotch-Harvey L, Thomas LA, Worgan HJ, Douglas JL, Gilby DE, McEwan NR.Anthelmintics are used as anti-worming agents. Although known to affect their target organisms, nothing has been published regarding their effect on other digestive tract organisms or on metabolites produced by them. The current work investigated effects of fenbendazole, a benzimidazole anthelmintic, on bacteria and ciliates in the equine digestive tract and on and their major metabolites. Animals receiving anthelmintic treatment had high faecal egg counts relative to controls. Analysis was performed over two weeks, with temporal differences detected in bacterial populations but with no other ...
Gerstner K, Liesegang A.Free faecal water (fluid excreted separate from normal faeces) is a common problem of unknown origin in horses. Multifactorial causes are assumed. This study assessed the effect of a commercial product (EMP) sold to help support intestinal health of horses, particularly regarding the occurrence of free faecal water. The hypothesis was that water-binding capacity and microbial activity are improved in the large intestine of horses fed EMP. EMP contained montmorillonite-bentonite, whey and extracts from hop and absinthium. Eight adult and healthy horses kept on the same diet and bedding were add...
Nakamae Y, Ishihara A, Itoh M, Yanagawa M, Sasaki N, Yamada K.Computed tomography (CT) was performed for an 18-year-old female pony with enterolithiasis in the prone and supine positions. CT images from the prone position revealed displacement of the large dorsal colon, which contained an enterolith to the ventral side of the abdomen, and those from the supine position revealed displacement to the dorsal side. A high-density material suggestive of a metallic foreign body was also observed in the enterolith core. An enterolith (422 g, 104 mm) was surgically removed from the large dorsal colon. This caused no complications after surgery and increased the h...
Williams TL, Mochal-King C, Rude BJ, Weed BC, Nicodemus MC.Cecal and ileal cannulations have previously been used to determine equine digestibility and define gastrointestinal physiology. However, research has been limited to specific portions of the equine digestive tract lacking utilization of dual cannulations. The purpose of this study was to develop and implement surgical and preoperative and postoperative procedures for cannulation of dual sections, ileum and cecum, of the equine digestive tract including development of recommendations for addressing postsurgery complications. A total of 8 ponies went through surgical procedures for the placemen...
Stegelmeier BL, Davis TZ.Because most poisonings occur by toxin ingestion, the gastrointestinal system is the first exposed and, in most cases, it is exposed to the highest toxin concentrations. Consequently, enterocyte damage is common. However, because many toxins produce organ-specific damage, and enterocyte necrosis is easily confused with autolysis, many gastrointestinal lesions are overlooked or overshadowed by other clinical and pathologic changes. The objective of this work is to review several common toxins and poisonous plants that produce primarily gastrointestinal disease.
Montgomery JB, Bracamonte JL, Alam MW, Khan AH, Mohammed SK, Wahid KA.This pilot study assessed wireless capsule endoscopy in horses. Image transmission was achieved with good image quality. Time to exit the stomach was variable and identified as one limitation, together with gaps in image transmission, capsule tumbling, and inability to accurately locate the capsule. Findings demonstrate usefulness and current limitations. Cette étude pilote a évalué l’endoscopie par capsule chez les chevaux. La transmission d’images a permis d’obtenir une bonne qualité d’image. Le temps jusqu’à la sortie de l’estomac était variable et identifié comme une li...
Hummel J, Scheurich F, Ortmann S, Crompton LA, Gerken M, Clauss M.There is a discrepancy in the literature on potential digesta separation mechanisms in horses, with both a selective retention of fine and of large particles postulated in different publications. To assess the net effect of such mechanisms, we fed ponies on a hay-only diet a pulse dose of whole (unchopped) marked hay together with a solute marker, collected faeces on a regular basis, measured marker concentrations in whole faeces and in their large (2.0-16 mm), medium (0.5-1.0 mm) and small (0.063-0.25 mm) particle fraction, and calculated the corresponding mean retention times (MRTs). For ...
Harlow BE, Lawrence LM, Harris PA, Aiken GE, Flythe MD.Cereal grains are often included in equine diets. When starch intake exceeds foregut digestion starch will reach the hindgut, impacting microbial ecology. Probiotics (e.g., lactobacilli) are reported to mitigate GI dysbioses in other species. This study was conducted to determine the effect of exogenous lactobacilli on pH and the growth of amylolytic and lactate-utilizing bacteria. Feces were collected from 3 mature geldings fed grass hay with access to pasture. Fecal microbes were harvested by differential centrifugation, washed, and re-suspended in anaerobic media containing ground corn, whe...
Muscher-Banse AS, Marholt L, Eigendorf N, Wilkens MR, Schröder B, Breves G, Cehak A.For horses, distinct differences in intestinal phosphate transport have been postulated to account for the unique features of hind gut fermentation compared to other monogastric animals and ruminants. So far published data on mechanisms and underlying transport proteins involved in intestinal phosphate transport in the horse are still missing. Therefore we investigated intestinal phosphate transport in horses at both functional and molecular levels. Segmental diversity of intestinal phosphate transport along the intestinal axis was documented using the Ussing chamber technique. A transcellular...
Sadet-Bourgeteau S, Philippeau C, Julliand V.Feeding a diet with a small amount of hay and a high proportion of concentrate given in large meals entails a risk of colic to horses as this can impact the hindgut microbial ecosystem. To counteract this potential negative effect, one feeding strategy is to modify the distribution sequence of concentrate and hay. The purpose of the present study was to assess the impact of feeding the concentrate meal before or with the hay meal on fermentative parameters postprandial variations in caecum and right ventral colon contents and faeces. We focused on the comparison of pH value and volatile fatty ...
Ericsson AC, Johnson PJ, Lopes MA, Perry SC, Lanter HR.Horses are exquisitely sensitive to non-specific gastrointestinal disturbances as well as systemic and extraintestinal conditions related to gut health, yet minimal data are available regarding the composition of the microbiota present in the equine stomach, small intestine, and cecum and their relation to fecal microbiota. Moreover, there is minimal information regarding the concordance of the luminal and mucosal microbial communities throughout the equine gut. Illumina-based 16S rRNA gene amplicon sequencing of the luminal and mucosal microbiota present in seven regions of the gastrointestin...
Yamada K, Sato F, Horiuchi N, Higuchi T, Kobayashi Y, Sasaki N, Nambo Y.Autopsy imaging (Ai), postmortem imaging before necropsy, is used in human forensic medicine. Ai was performed using computed tomography (CT) for a 1-month-old Thoroughbred foal cadaver found in a pasture. CT revealed pericardial effusion, collapse of the aorta, bleeding in the lung lobe, gas in the ventricles and liver parenchyma, and distension of the digestive tract. Rupture in the left auricle was confirmed by necropsy; however, it was not depicted on CT. Therefore, Ai and conventional necropsy are considered to complement each other. The cause of death was determined to be traumatic cardi...
Coverdale JA.Intensive management practices in the horse industry present a unique challenge to the microbiome of the large intestine. Common management practices such as high-concentrate diets, low forage quality, meal feeding, and confinement housing have an impact on intestinal function, specifically large intestinal fermentation. The microbiome of the equine large intestine is a complex and diverse ecosystem, and disruption of microbiota and their environment can lead to increased incidence of gastrointestinal disorder. Digestion in the horse can be improved through a variety of approaches such as feed...
Brøkner C, Austbø D, Næsset JA, Blache D, Bach Knudsen KE, Tauson AH.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...
Bełżecki G, Miltko R, Michałowski T, McEwan NR.This paper describes cultivation methods for ciliates from the digestive tract of horses. Members of three different genera were successfully grown in vitro for short periods of time. However, only cells belonging to the genus Blepharocorys, which resides in the horse's large intestine, were maintained for longer periods. This Blepharocorys culture was successfully grown in vitro after inoculation of freshly excreted horse faeces in culture medium containing a population of bacteria. The ciliates survived for over six months, and the density of their population varied between 1.7 × 10(3) and ...
Schaafstra FJ, van Doorn DA, Schonewille JT, Wartena FC, Zoon MV, Blok MC, Hendriks WH.Methodological aspects of digestibility measurements of feedstuffs for equines were studied in four Welsh pony geldings consuming four grass-hay diets in a 4 × 4 Latin square design. Diets contained either a low (L), medium (M), high (H), or very high (VH) ADF content (264, 314, 375, or 396 g·kg DM, respectively). Diets were supplemented with minerals, vitamins, and TiO (3.9 g Ti·d). Daily feces excreted were collected quantitatively over 10 consecutive days and analyzed for moisture, ash, ADL, AIA, and titanium (Ti). Minimum duration of total fecal collection (TFC) required for an accurate...
Miller MA, Moore GE, Bertin FR, Kritchevsky JE.Postmortem findings in 241 equids admitted to a teaching hospital that were at least 15 years old at autopsy were reviewed (1) to determine disease prevalence, (2) to compare the cause of death (or euthanasia) in equids 15 to 19 years of age (n = 116) with that in equids ≥20 years of age (n = 125), and (3) to catalog coexisting lesions in equids with pituitary pars intermedia dysfunction (PPID). Breed and sex were evenly distributed between the age groups. Death or euthanasia was attributed to disease of the digestive system (41.5%), pituitary gland (12.9%), locomotor system (10.0%), nervous...
Philippeau C, Sadet-Bourgeteau S, Varloud M, Julliand V.This study aimed at assessing the impact of four barley forms on total tract apparent digestibility of dietary fibre in horses fed a large amount of starch in the morning meal (0.27% BW). Processed barley forms had a greater pre-caecal starch digestibility than the whole form. Based on this result, we hypothesised that using barley-processing methods would limit the potential dumping of undegraded starch in the hindgut of horses and, consequently, the potential negative effect on fibre degradation in the hindgut. In a 4×4 latin square design, four mature geldings fitted with a right ventral c...
Garber A, Hastie P, McGuinness D, Malarange P, Murray JA.Abrupt dietary changes, as can be common when managing horses, may lead to compositional changes in gut microbiota, which may result in digestive or metabolic disturbances. The aim of this study was to describe and compare the faecal microbiota of ponies abruptly changed from pasture grazing ad libitum to a restricted hay-only diet and vice versa. The experiment consisted of two, 14-day periods. Faecal samples were collected on day 0 and days 1-3,7,14 after abrupt dietary change from grass to hay and from hay to grass. Microbial populations were characterised by sequencing the V3-V4 region of ...
Edouard N, Fleurance G, Martin-Rosset W, Duncan P, Dulphy JP, Grange S, Baumont R, Dubroeucq H, Pérez-Barbería FJ, Gordon IJ.Food intake is a key biological process in animals, as it determines the energy and nutrients available for the physiological and behavioural processes. In herbivores, the abundance, structure and quality of plant resources are known to influence intake strongly. In ruminants, as the forage quality declines, digestibility and total intake decline. Equids are believed to be adapted to consume high-fibre low-quality forages. As hindgut fermenters, it has been suggested that their response to a reduction in food quality is to increase intake to maintain rates of energy and nutrient absorption. Al...
Clauss M, Loehlein W, Kienzle E, Wiesner H.In order to test the suitability of the horse as a nutritional model for elephants, digestibility studies were performed with six captive Asian elephants on six different dietary regimes, using the double marker method with acid detergent lignin as an internal and chromium oxide as an external digestibility marker. Elephants resembled horses in the way dietary supplements and dietary crude fibre content influenced digestibility, in calcium absorption parameters and in faecal volatile fatty acid composition. However, the absolute digestibility coefficients achieved for all nutrients are distinc...
Hintz HF, Hogue DE, Walker EF, Lowe JE, Schryver HF.Eleven ponies were fed diets containing 1:0, 3:2 or 1:4 forage-grain ratios for 30 days. Animals were killed 4 hr. after feeding and the entire digestive tracts were removed and segments isolated. Digestion coefficients were calculated for dry matter, protein, available carbohydrate (ACHO) and neutral detergent fiber (NDF) by Cr2O3-nutrient ratio for seven segments of the gut.
The major site of ACHO and protein digestion was prececal; whereas, the major sites of NDF digestion were the colon and cecum regardless of the hay:grain ratio. Therefore the relative importance of digestion in the lo...
Salem SE, Hough R, Probert C, Maddox TW, Antczak P, Ketley JM, Williams NJ, Stoneham SJ, Archer DC.Periparturient mares are at increased risk of colic including large colon volvulus, which has a high mortality rate. Alterations in colonic microbiota related to either physiological or management changes, or both, that occur at this time have been suggested as potential causes for increased colic risk in this population of horses. Although the effect of management changes on the horse faecal microbiota has been investigated, limited work has been conducted to investigate changes in faecal microbiota structure and function in the periparturient period. The objectives of the current study were ...
Wambacq WA, van Doorn DA, Rovers-Paap PM, Ducatelle R, Vlaminck L, Lourenço M, Hesta M.As colic and intestinal disorders are a major concern in horses, the aim of the present study was to investigate the effect of dietary supplementation of butyrate, known to have a diverse array of beneficial effects on intestinal health. The effect of micro-encapsulated sodium butyrate supplementation on gut histology and immunohistochemistry parameters was studied in 14 healthy warmblood horses destined for slaughter in two separate periods. Horses were fed a low fiber - high starch diet, designed to induce subsequent starch overflow in the large intestine, aiming to create a mild challenge f...
Principato M.Listed and described herein are the main macroscopic lesions produced along the whole digestive tract of free-ranging horses by larvae of the five Gasterophilus spp., occurring in Umbria, a region of central Italy: Gasterophilus intestinalis, Gasterophilus nasalis, Gasterophilus pecorum, Gasterophilus inermis, Gasterophilus haemorrhoidalis. Lesions are classified on the basis of their sizes and shapes and the host's anatomic sites infested, and they are examined in relation to the developmental stages of larvae causing them. The examination of the lesions shows that it is very difficult to dif...
Chiocchetti R, Giancola F, Mazzoni M, Sorteni C, Romagnoli N, Pietra M.The lower esophageal sphincter (LES) is a specialized, thickened muscle region with a high resting tone mediated by myogenic and neurogenic mechanisms. During swallowing or belching, the LES undergoes strong inhibitory innervation. In the horse, the LES seems to be organized as a "one-way" structure, enabling only the oral-anal progression of food. We characterized the esophageal and gastric pericardial inhibitory and excitatory intramural neurons immunoreactive (IR) for the enzymes neuronal nitric oxide synthase (nNOS) and choline acetyltransferase. Large percentages of myenteric plexus (MP) ...
de Fombelle A, Veiga L, Drogoul C, Julliand V.This trial was conducted to determine the extent of prececal starch digestibility depending on the botanical origin of starch and on diet characteristics (i.e., composition and feeding pattern). The prececal disappearance of six substrates (oats, barley, corn, horse bean, potato, and wheat) was measured in four cannulated horses fed (as-fed basis) 11.8 g/kg BW of a high-fiber (HF) or high-starch (HS) pelleted feed and 10.0 g/kg BW of meadow hay using the mobile bag technique (MBT). The daily feeding pattern was either three meals (two meals of pellets and one meal of hay) or five meals (three ...
Muhonen S, Sadet-Bourgeteau S, Julliand V.Fibrous feeds are essential for horses. When developing feeding regimens promoting health and performance, we need to understand the digestion of plant cell walls and the functioning of the hindgut microbial ecosystem. Our objective was to investigate the effect of grass fibre maturity and legume forage on the hindgut microbiota and its activity. Six caecum and colon fistulated geldings were fed three diets differing in fibre composition: concentrate and late harvested grass haylage (35:65 energy ratio) (C); early and late harvested grass haylage (80:20) (G); lucerne and late harvested grass h...
Bełżecki G, Miltko R, Michałowski T, McEwan NR.This paper describes cultivation methods for ciliates from the digestive tract of horses. Members of three different genera were successfully grown in vitro for short periods of time. However, only cells belonging to the genus Blepharocorys, which resides in the horse's large intestine, were maintained for longer periods. This Blepharocorys culture was successfully grown in vitro after inoculation of freshly excreted horse faeces in culture medium containing a population of bacteria. The ciliates survived for over six months, and the density of their population varied between 1.7 × 10(3) and ...
Lester GD, Merritt AM, Kuck HV, Burrow JA.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...
Pilo C, Altea A, Scala A.Gasterophilus larvae are common obligate parasites of the digestive tract of the equids. Horses become infected with this parasite by ingesting the larvae hatched from eggs laid by the female flies. In this study carried out monthly, we (i) counted the Gasterophilus eggs deposited by female flies on the coat of 30 grazing horses, (ii) counted and identified the Gasterophilus larvae retrieved from the digestive tract of 128 slaughtered horses, and (iii) compared these results to meteorological data. Eggs were deposited on all monitored horses, and were present from October to January and from M...
Sadet-Bourgeteau S, Philippeau C, Julliand V.Feeding a diet with a small amount of hay and a high proportion of concentrate given in large meals entails a risk of colic to horses as this can impact the hindgut microbial ecosystem. To counteract this potential negative effect, one feeding strategy is to modify the distribution sequence of concentrate and hay. The purpose of the present study was to assess the impact of feeding the concentrate meal before or with the hay meal on fermentative parameters postprandial variations in caecum and right ventral colon contents and faeces. We focused on the comparison of pH value and volatile fatty ...
Zeyner A, Geissler C, Dittrich A.To investigate effects of hay intake and feeding sequence on indicators of the microbial activity within the hindgut, six horses were fed 1.00 kg oats plus 0.50, 0.67, 0.83 or 1.00 kg hay/100 kg body weight (BW) x day, each for 14 days. Oats was offered either 30 min prior to hay (OA) or in the reversed sequence (HA) in a 2 x 8-week crossover design. Because typically exercised horses should be subjected to the study, faeces was used as substrate. Faecal dry matter (DM), the faecal waters' short-chain fatty acids (SCFA, in mmol/1) and molar percentages (mol%) of propionate and iso-butyrate wer...
De Marco M, Miraglia N, Peiretti PG, Bergero D.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...
Argenzio RA, Stevens CE.Effects of diet and time after feeding on osmolality and inorganic ion content of gastrointestinal digesta were studied in 24 ponies. Animals, fed either a conventional or a low-protein, high-cellulose diet, were sacrificed 2, 4, 8, or 12 h after a meal. Animals fed the conventional diet showed cyclic variations in the ionic composition and osmolality of digesta with time after feeding. The most marked variations were seen in the contents of the stomach and small colon. However, results also indicated a cyclic appearance and disappearance of Na in large intestinal contents that correlated with...
Zannoni A, Bombardi C, Dondi F, Morini M, Forni M, Chiocchetti R, Spadari A, Romagnoli N.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...
Crotch-Harvey L, Thomas LA, Worgan HJ, Douglas JL, Gilby DE, McEwan NR.Anthelmintics are used as anti-worming agents. Although known to affect their target organisms, nothing has been published regarding their effect on other digestive tract organisms or on metabolites produced by them. The current work investigated effects of fenbendazole, a benzimidazole anthelmintic, on bacteria and ciliates in the equine digestive tract and on and their major metabolites. Animals receiving anthelmintic treatment had high faecal egg counts relative to controls. Analysis was performed over two weeks, with temporal differences detected in bacterial populations but with no other ...
Orton RK, Hume ID, Leng RA.Rates of passage of fluid and particulate digesta markers and apparent digestibility estimated by three methods were compared in yearling horses fed high (14 per cent) or low (8 per cent) crude protein diets with one of two levels of exercise (0 or 12 km trotting per day at 12 km/h). Mean retention times (MRT) of the fluid marker (51Cr-EDTA) were shorter than those of the particulate marker (ruthenium-phenanthroline). There were no significant effects of dietary protein level on passage of either marker or on apparent digestibility of dry matter. Exercise increased voluntary feed intake and ap...
Jensen RB, Austbø D, Bach Knudsen KE, Tauson AH.A total of four diets with different carbohydrate composition were investigated in a 4×4 Latin square design experiment with four Norwegian Coldblooded trotter horses. The objective of the present study was to increase the fermentable fibre content and reduce the starch intake of the total ration obtained by partly substituting mature hay and barley with sugar beet pulp (SBP), a soluble fibre source. The diets investigated were hay only (HAY), hay (85% of dry matter intake (DMI)) and molassed SBP (15% of DMI) (SBP), hay (68% of DMI) and barley (32% of DMI) (BAR), and hay (68% of DMI), barley ...
Plummer AE.Impactions of the small and large intestines are frequently diagnosed as the cause of colic in horses. An impaction is an accumulation of dehydrated ingesta in a portion of the digestive tract, typically at sites where the intestinal diameter decreases. The specific pathogenesis for impactions is not fully understood, although risk factors have been identified for several types of impactions. Treatment for impactions includes withholding feed until the impaction passes, rehydrating the ingesta, and, if necessary, administering analgesic agents. In severe cases, surgery may be necessary to reli...
Rodrigues MN, Carvalho RC, Franciolli AL, Rodrigues RF, Rigoglio NN, Jacob JC, Gastal EL, Miglino MA.Since the horse has a highly precocial reproductive strategy, most organs are functionally well developed at birth and thus, embryonic and fetal life is interesting. Data on the development of important organs are very limited. Here, we detailed macroscopically and histologically the equine digestive system, focusing on the first third of gestation. At 21 days, the oral cavity was an empty space, and the liver contained proliferating endodermal cells. At 25 days, a fusiform stomach and the pancreatic bud were present. At 28 days, a small tongue and the esophagus occurred. At 30 days, primary a...
Hoffman RM, Wilson JA, Kronfeld DS, Cooper WL, Lawrence LA, Sklan D, Harris PA.Carbohydrates may be hydrolyzed or fermented in the digestive tract, and this distinction is important for the evaluation of the diet of herbivores. Both hydrolyzable and fermentable carbohydrates are included in the nonstructural carbohydrate (NSC) fraction as estimated by difference using proximate analysis. Our objectives were to measure hydrolyzable carbohydrates in forages and concentrates, to compare these values with nonstructural carbohydrate, to test for prediction of hydrolyzable carbohydrate concentration in forages from its near-infrared spectrum, and to examine seasonal variation ...
Mackenthun E, Coenen M, Vervuert I.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...
Liu N, Yu W, Guo X, Chen J, Xia D, Yu J, Li D.Lytic polysaccharide monooxygenases (LPMOs) belonging to the auxiliary activity 9 family (AA9) are widely found in aerobic fungi. These enzymes are O-dependent copper oxidoreductases that catalyze the oxidative cleavage of cellulose. However, studies that have investigated AA9 LPMOs of aerobic fungi in the herbivore gut are scare. To date, whether oxidative cleavage of cellulose occurs in the herbivore gut is unknown. Results: We report for the first time experimental evidence that AA9 LPMOs from aerobic thermophilic fungi catalyze the oxidative cleavage of cellulose present in the horse gut t...
Coverdale JA, Moore JA, Tyler HD, Miller-Auwerda PA.Soybean hulls have been successfully fed to ruminant animals as an economical substitute for hay. This feedstuff is a source of highly digestible fiber that does not contain starch. The purpose of this trial was to evaluate soybean hulls as a replacement fiber in horse diets. Four cecally cannulated Quarter Horse geldings, aged 6 to 10 yr and averaging 502 kg, were used in a 4 x 4 Latin square design with 21-d periods. Diets consisted of alfalfa/bromegrass hay (14.4% CP, 58.1% NDF, 39.1% ADF; DM basis) with the replacement of either 0, 25, 50, or 75% (as-fed basis) unpelleted soybean hulls (13...
