The pH level in horses is a measure of the acidity or alkalinity of various bodily fluids and tissues, which can influence numerous physiological processes. In horses, pH balance is essential for maintaining metabolic functions and overall health. The pH of blood, for example, is maintained within a narrow range through various buffering systems to ensure optimal cellular activity and enzyme function. Deviations from the normal pH range can indicate underlying health issues, such as metabolic disorders or respiratory problems. This topic encompasses peer-reviewed research studies and scholarly articles that explore the regulation, measurement, and implications of pH levels in equine biology, including their impact on performance, digestion, and disease states.
Franzan BC, Coelho IDS, de Souza MT, Santos MMM, de Almeida FQ, Silva VP.Sudden changes in horses' diet have been previously associated with gastrointestinal disease. This study evaluated the effects of a sudden change of diet composed exclusively of Coastcross hay (CHD) to a complete extruded diet (CED) on the fecal microbiome of horses. A completely randomized design with repeated measurements was used. The study started with eight adult horses randomly split into group A, fed with CHD, and group B, fed with CED. After 34 days of diet adaptation, the diets were abruptly changed between the groups. Fecal samples were collected at 0, 24, and 96 hours after the diet...
Simonenko ES, Begunova AV.Since ancient times, mare's milk has been widely used by many peoples. Thanks to its unique composition, it is now used in the nutrition of people with allergies to cow's milk, in the technologies of foods for special dietary uses, etc. To expand the range of products with useful properties, it is advisable to develop fermented milk products based on mare's milk. Numerous studies indicate that the use of fermented milk products provides various health benefits. And the use of probiotic cultures in the composition of starter cultures for fermented milk products allows you to add a number of fun...
Kalantari RK, Rouzbehan Y, Fazaeli H, Direkvandi E, Salem AZM.The aim of this study was to investigate, the effect of different levels of concentrates and grain processing on feeding behavior, nutrient digestibility, fecal pH and blood metabolites in the horse. Sixteen 5 to 11 years old Turkmen horses with an initial body weight 433±50 kg were used in this experiment based on completely randomized design. Four treatments were studied, in three treatments were used 20, 25 and 30% of concentrate containing processed grains (A20, A25 and A30, respectively), and in one treatment was used 25% of concentrate containing whole grain (B25). The amount of feed in...
Berreta A, Kopper JJ, Alexander TL, Kogan CJ, Burbick CR.Probiotics, by definition, are live micro-organisms and should remain viable when they reach the intended site of action which is typically the cecum and/or colon. In humans, probiotics often need enteric protection to survive transit through the proximal gastrointestinal (GI) tract. Typically, equine probiotics do not advertise enteric protection and to the author's knowledge the viability of equine probiotics after exposure to the proximal GI tract has not been evaluated. The objective of this study was to evaluate the effect of an in vitro simulation of the equine proximal GI tract on probi...
Beldarrain LR, Morán L, Sentandreu MÁ, Insausti K, R Barron LJ, Aldai N.A full-randomized block design was used for the study of the FA composition and meat quality parameters, considering ageing time as a split-plot factor. Chemical and fatty acid composition of steaks (longissimus thoracis and lumborum muscle) from 15 month old semiextensively reared Hispano-Bretón horses were characterized (day 0), and the effect of vacuum ageing (0, 7, 14 and 21 days) on several meat quality parameters (pH, instrumental color and texture and cook loss) was determined. The average fat content of horse loin was 3.31%, and the n-3 polyunsaturated fatty acid content, although hig...
Rahman AZA, Adzahan NM, Zakaria Z, Mayaki AM.Horse wounds can be easily infected with bacteria depending on the nature of its cause such as laceration, abrasion, or puncture as well as the nature of its environment. Various treatments are available in managing open wounds, including the usage of topical antibiotics and antiseptics. However, antibiotic resistance has been a major concern attributed with chronic wound infection. The aim of this study was to test the efficacy of ionized water at different pH against the growth of common bacteria from horse wounds. Methods: Ten swab samples from equine infected wounds were collected and bact...
Collinet A, Grimm P, Julliand S, Julliand V.In horses, abrupt changes from high-fiber (HF) to high-starch (HS) diets can affect the cecal and colonic microbiota. This study investigated modifications and recovery of fecal microbiota after two consecutive abrupt dietary changes. Twelve horses fed HF for 2 weeks were changed to HS for 5 days then returned to HF for 7 weeks. Six received lactic acid bacteria supplementation. Bacterial population diversity, structure, and activity, especially fibrolysis, were assessed to obtain an overview of alteration in hindgut microbiota. Two days after the abrupt change from HF to HS, the findings in f...
Magalhaes HB, Canuto LEF, Canisso IF.The objectives of this study were to determine (i) the usefulness of serial assessment of mammary gland electrolytes concentrations and correspondent pH to detect impending parturition in jennies; and (ii2) the associations between mammary gland secretions, and gestation length, foal sex, maternal, placental, and foal birth weights. Multiparous jennies (n = 37) were monitored daily from 350 to 355 days of gestation until parturition. The pH of mammary gland secretions was assessed daily with a hand-held device. Aliquots of mammary secretions were frozen daily and then retrospectively assesse...
Dorneles TEA, Costa Junior JD, Almeida RM, Teixeira Neto AR.Anaerobic cellular metabolism causes a series of structural and physiologic changes during storage that could compromise post-transfusion viability, reducing the safety of using blood stored for an extended period. Objective: We aimed to follow the biochemical and hematologic alterations of equine blood stored in plastic bags containing citrate-phosphate-dextrose-adenine (CPDA-1) for up to 28 days. Methods: Whole blood samples (450 mL) were collected from 20 Brazilian Saddle horses into CPDA-1 pouches and stored between 2°C and 6°C in a blood bank. On days 0, 7, 14, 21, and 28 of storage, ...
Wellard L, Medyk K, Pearson W.Feed additives that accelerate gastrointestinal transit time may help support normal gastrointestinal function in horses at risk for impaction colic. Previous research has demonstrated significant stimulatory effect of a hemp-based nutraceutical product (Gs Formula; GF) on contractility of gastric smooth muscle and gastrin production in vitro. Objective: To quantify effects of GF on indicators of GIT transit time and tight junction proteins. Methods: Randomized placebo-controlled cross-over study. Methods: Eight Standardbreds were administered 200 plastic beads by nasogastric tube before (base...
Saeidi E, Mansoori Yarahmadi H, Fakhraei J, Mojahedi S.The objectives of this study were to determine the effects of dietary prebiotic fructooligosaccharides (FOS) from inulin and Enterococcus faecium on nutrient digestibility, fecal pH, and some blood parameters. In this experiment, twelve adult Kurdish horses with average bogy weight of 416 ± 43.3 kg and age averaging 6 ± 1.8 year were used in a replicated 4 × 4 Latin Square experiment with a 2 × 2 factorial design during 4 periods of 28 days, including 21 days for dietary adaptation and 7 days for sampling. Horses were offered 1 of 4 treatments: (1) no FOS or 2.5 × 10 colony forming ...
Sorensen RJ, Drouillard JS, Douthit TL, Ran Q, Marthaler DG, Kang Q, Vahl CI, Lattimer JM.The effect of hay type on the microbiome of the equine gastrointestinal tract is relatively unexplored. Our objective was to characterize the cecal and fecal microbiome of mature horses consuming alfalfa or Smooth Bromegrass (brome) hay. Six cecally cannulated horses were used in a split-plot design run as a crossover in two periods. The whole plot treatment was ad libitum access to brome or alfalfa hay fed over two 21-d acclimation periods with subplots of sampling location (cecum and rectum) and sampling hour. Each acclimation period was followed by a 24-h collection period where cecal and f...
Tuniyazi M, He J, Guo J, Li S, Zhang N, Hu X, Fu Y.Laminitis is a common and serve disease which caused by inflammation and pathological changes of the laminar junction. However, the pathologic mechanism remains unclear. In this study we aimed to investigate changes of the gut microbiota and metabolomics in oligofructose-induced laminitis of horses. Results: Animals submitted to treatment with oligofructose had lower fecal pH but higher lactic acid, histamine, and Lipopolysaccharide (LPS) in serum. Meanwhile, oligofructose altered composition of the hindgut bacterial community, demonstrated by increasing relative abundance of Lactobacillus and...
Ochonski P, Drouillard JS, Douthit TL, Vahl C, Lattimer JM.Commercial horse feeds use cereal grains and by-products; however, their effects on the caecal environment remain poorly characterised. Objective: Characterise the effect of commonly used feed ingredients on caecal pH and volatile fatty acid (VFA) concentration. Methods: 6 × 6 Latin square. Methods: Two days prior to the start of the study, 6 caecally cannulated Quarter horses were moved into individual stalls where Smooth bromegrass hay (brome) was offered at 2.0% BW/d split between 2 feedings (0600 and 1800). On day 0, caecal digesta was collected every 2 h for 12 h relative to the 0600...
Pei L, Yang H, Qin S, Yan Z, Zhang H, Lan Y, Li A, Iqbal M, Shen Y.The objective of the present study was to evaluate the probiotic properties, security and antibacterial ability in vivo of isolated strains from healthy equine. In the present study, two Pediococcus acidilactici (P1 and P2) and two Lactobacillus equi (L1 and L2) were isolated. All isolates were died when exposed to pH 2.0 for 3 hours but survived at pH 3.0 and pH 4.0 with differential survival rate, and there is a higher survival rate at pH 4.0. Similarly, the isolates showed different tolerance to bile. The viable bacteria count was sustained at high levels in a tolerance test with artificia...
Cerri S, Taminiau B, de Lusancay AH, Lecoq L, Amory H, Daube G, Cesarini C.Omeprazole administration is associated with changes in gastric and fecal microbiota and increased incidence of Clostridioides difficile enterocolitis in humans and dogs. Objective: Study purpose was to assess the effect of omeprazole on gastric glandular and fecal microbiota in healthy adult horses. Methods: Eight healthy horses stabled on straw and fed 100% haylage. Methods: Prospective controlled study. Transendoscopic gastric glandular biopsies, gastric fluid, and fecal samples were obtained from each horse twice at a 7-day interval before the administration of omeprazole. Samples were tak...
Jacobs RD, Gordon MBE, Vineyard KR, Keowen ML, Garza F, Andrews FM.Low gastric pH for extended periods of time can increase the risk of gastric ulceration in horses. Therefore, nutritional interventions that buffer stomach acid may be helpful to decrease ulcer risk. The objective of this trial was to evaluate whether the incorporation of calcified Lithothamnion corallioides and Phymatolithon calcareum (Calmin; Celtic Sea Minerals, Cork, Ireland) into an equine ration would buffer equine gastric juice. Nine mature, Thoroughbred-cross horses, including 6 geldings and 3 mares (524 ± 49 kg) were housed in stalls and fed 2 kg/day of a texturized concentrate (Pu...
Arfuso F, Giannetto C, Giudice E, Fazio F, Panzera F, Piccione G.The aim of this study was to assess whether acid-base profile exhibits changes in regularly trained show jumping horses undergoing increasing exercise workloads. Seven female Italian saddle horses were subjected to three different physical exercise trials of increasing workload identified as three exercise phases (EPs). During EPI horses were subjected to a standardized exercise test consisting of 15 minutes of treadmill, during EPII horses were subjected to a show jumping test (height, 0.9-1.1 m; course length, 300 m), during EPIII horses underwent two jumping sessions carried out over two...
Sgorbini M, Freccero F, Castagnetti C, Mariella J, Lanci A, Marmorini P, Camillo F.Induction of parturition in horses is still not well accepted due to the potential peripartum complications for mares and newborn foals. We assessed differences after spontaneous and induced parturition with low doses of oxytocin (OX) in 1) incidence of peripartum complications in mares; 2) viability, behavioral, physical, and venous blood gas analyses in foals. In this study 61 mares were included; 45/61 were enrolled in the spontaneous foaling group (SF) and 16/61 in the induced foaling group (IF). In the IF group, when the calcium in mammary secretion reached concentrations of ≥250 ppm, ...
Moore-Colyer M, Tuthill P, Bannister I, Daniels S.Traditions and the economic advantage when producing big athletic Thoroughbred (TB) yearlings for sale encourage owners to feed high levels of cereals. Such diets can predispose gastric ulceration and developmental orthopedic diseases, impacting negatively on future careers. This study aimed to (1) determine if an all-fiber creep feed (total mixed fiber ration [TMFR] would sustain equal growth rates in TB foals versus a cereal-based stud cube (SC) and (2) compare pH and lactate produced by SC and TMFR in in vitro foregut and hindgut conditions. Eight TB foals in matched-pairs were fed SC or T...
Garber A, Hastie PM, Farci V, Bulmer L, Alzahal O, Murray JMD.Fibre is essential to maintain healthy gut; however, energy demands of performance horses can be too high to be met by forages alone. Yeast may support the function of cellulolytic bacteria to digest fibre. The aim of this work was to determine the effect of an oral supplement (VistaEQ) containing 4% live yeast on the in vitro and in vivo digestibility of high-starch (HS) and high-fibre diets (HF). Eight ponies were used in a 4 × 4 Latin square design consisting of 4- × 19-day periods and four diets: HF, HF + yeast (HFY), HS and HS + yeast (HSY). In vivo apparent digestibility (AD) was estim...
Lundström T, Lingström P, Wattle O, Carlén A, Birkhed D.The role of saliva composition and dietary sugar in development of infundibular caries in equine cheek teeth is not fully understood. This study analysed electrolyte and urea concentrations in saliva in relation to different forage and measured pH changes after sucrose application in vivo in sound and carious cheek teeth. Results: Forage type had no effect on the equine saliva electrolyte concentrations, which varied considerably both intra- and inter-individually. Chewing resulted in increased values for all electrolytes except bicarbonate. Compared with stimulated human saliva, horse saliva ...
Halpin MY, Drouillard JS, Fehlberg LK, Douthit TL, Lattimer JM.To assess the impact of protein on fermentation by equine cecal microorganisms, cecal fluid from 4 cecally cannulated horses was used to inoculate fermentation bottles containing buffer, forage, and supplemental protein. In experiment 1, sodium caseinate (SC) provided 0, 0.5%, 1%, 2%, or 4% additional crude protein (CP) to bottles containing alfalfa or native warm-season prairie grass hay. Bottles were equipped with continuous gas pressure monitors and placed into a shaking incubator for 48 hours at 39°C. Cultures with alfalfa had greater (P < .0001) in vitro dry matter disappearance (IVDMD...
Morrison PK, Newbold CJ, Jones E, Worgan HJ, Grove-White DH, Dugdale AH, Barfoot C, Harris PA, Argo CM.Bacteria residing in the gastrointestinal tract of mammals are crucial for the digestion of dietary nutrients. Bacterial community composition is modified by age and diet in other species. Although horses are adapted to consuming fibre-based diets, high-energy, often high-starch containing feeds are increasingly used. The current study assessed the impact of age on the faecal bacteriome of ponies transitioning from a hay-based diet to a high-starch diet. Over two years, 23 Welsh Section A pony mares were evaluated (Controls, 5-15 years, n = 6/year, 12 in total; Aged, ≥19 years, n = 6 Year 1;...
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...
Linhares Boakari Y, El-Sheikh Ali H, Dini P, Loux S, Barbosa Fernandes C, Esteller-Vico A, Scoggin K, Lawrence L, Ball B.An intravenous large dose of protein led to an increased blood urea nitrogen (BUN), resulting in a lesser uterine pH and altered uterine gene expression in mares. The objective of the present study was to evaluate effects of a more physiological methodology to increase BUN on the endometrium of mares. Mares were fed hay and a treatment or control diet (n = 11 mares/treatment) in a crossover design starting at time of ovulation detection (D0) and continuing until D7. Mares of the treated group were fed urea (0.4 g/kg BW) with sweet feed and molasses, and those of the control group were fe...
Bachmann M, Glatter M, Bochnia M, Wensch-Dorendorf M, Greef JM, Breves G, Zeyner A.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 we...
Pezzanite L, Chow L, Soontararak S, Phillips J, Goodrich L, Dow S.Equine veterinarians frequently inject aminoglycoside antibiotics intra-articularly, either to treat septic arthritis or for prophylaxis with other medications when injecting joints for osteoarthritis. Although aminoglycosides have been demonstrated to be toxic to equine mesenchymal stem cells (MSC), their effects on resident joint cells have not been previously investigated. Moreover, safe and effective intra-articular doses have not been defined. Objective: To determine effects of concentration, duration of exposure, pH and the presence of synovial fluid on the cytotoxic effects of amikacin ...
Padalino B, Davis GL, Raidal SL.Transportation has been suggested as a risk factor for gastric ulceration in horses, but limited evidence supports this assumption. Methods: Twenty-six Standardbred, Thoroughbred, and Warmblood mares from a university teaching herd. Methods: Twelve mares were confined for 12 hours, overnight, in reproductive stocks with indwelling nasogastric tubes (NGTs) to assess pH of gastric fluid (GF). Gastric ulceration was assessed endoscopically before and after confinement. Subsequently, 26 horses were transported for 12 hours, overnight, in 2 consignments. During transportation, GF was aspirated ...
Kirsch K, Sandersen C.Early recognition and management of acid-base, fluid, and electrolyte disorders are crucial for the maintenance of health and performance in equine athletes. Objective: To analyze changes in acid-base and electrolyte status associated with exercise during cross-country competitions at different levels using traditional and quantitative approaches. Methods: Thirty-eight eventing horses. Methods: Prospective observational study. Jugular venous blood samples were collected before and after the cross-country test of 25 international eventing competitions ranging from 2-star (formerly 1-star) to 5-...
Padalino B, Davis GL, Raidal SL.Transportation has been suggested as a risk factor for gastric ulceration in horses, but limited evidence supports this assumption. Methods: Twenty-six Standardbred, Thoroughbred, and Warmblood mares from a university teaching herd. Methods: Twelve mares were confined for 12 hours, overnight, in reproductive stocks with indwelling nasogastric tubes (NGTs) to assess pH of gastric fluid (GF). Gastric ulceration was assessed endoscopically before and after confinement. Subsequently, 26 horses were transported for 12 hours, overnight, in 2 consignments. During transportation, GF was aspirated ...
Hildebrand DP, Burk DL, Maurus R, Ferrer JC, Brayer GD, Mauk AG.The spectroscopic and structural properties of the His93Tyr variant of horse heart myoglobin have been studied to assess the effects of replacing the proximal His residue of this protein with a tyrosyl residue as occurs in catalases from various sources. The variant in the ferric form exhibits electronic spectra that are independent of pH between pH 7 and 10, and it exhibits changes in absorption maxima and intensity that are consistent with a five-coordinate heme iron center at the active site. The EPR spectrum of the variant is that of a high-spin, rhombic system similar to that reported for...
Tuniyazi M, He J, Guo J, Li S, Zhang N, Hu X, Fu Y.Laminitis is a common and serve disease which caused by inflammation and pathological changes of the laminar junction. However, the pathologic mechanism remains unclear. In this study we aimed to investigate changes of the gut microbiota and metabolomics in oligofructose-induced laminitis of horses. Results: Animals submitted to treatment with oligofructose had lower fecal pH but higher lactic acid, histamine, and Lipopolysaccharide (LPS) in serum. Meanwhile, oligofructose altered composition of the hindgut bacterial community, demonstrated by increasing relative abundance of Lactobacillus and...
Sorensen RJ, Drouillard JS, Douthit TL, Ran Q, Marthaler DG, Kang Q, Vahl CI, Lattimer JM.The effect of hay type on the microbiome of the equine gastrointestinal tract is relatively unexplored. Our objective was to characterize the cecal and fecal microbiome of mature horses consuming alfalfa or Smooth Bromegrass (brome) hay. Six cecally cannulated horses were used in a split-plot design run as a crossover in two periods. The whole plot treatment was ad libitum access to brome or alfalfa hay fed over two 21-d acclimation periods with subplots of sampling location (cecum and rectum) and sampling hour. Each acclimation period was followed by a 24-h collection period where cecal and f...
Kang CH, Ferguson-Miller S, Margoliash E.1. The steady state kinetics for the oxidation of ferrocytochrome c by yeast cytochrome c peroxidase are biphasic under most conditions. The same biphasic kinetics were observed for yeast iso-1, yeast iso-2, horse, tuna, and cicada cytochromes c. On changing ionic strength, buffer anions, and pH, the apparent Km values for the initial phase (Km1) varied relatively little while the corresponding apparent maximal velocities varied over a much larger range. 2. The highest apparent Vmax1 for horse cytochrome c is attained at relatively low pH (congruent to 6.0) and low ionic strength (congruent to...
Gomez DE, Arroyo LG, Stämpfli HR, Cruz LE, Oliver OJ.The quantitative effect of strong electrolytes, pCO2 , and plasma protein concentration in determining plasma pH and bicarbonate concentrations can be demonstrated with the physicochemical approach. Plasma anion gap (AG) and strong ion gap (SIG) are used to assess the presence or absence of unmeasured anions. Objective: The physicochemical approach is useful for detection and explanation of acid-base disorders in horses with colitis. AG and SIG accurately predict hyperlactatemia in horses with colitis. Methods: Fifty-four horses with acute colitis and diarrhea. Methods: Retrospective study. Ph...
Merritt AM, Sanchez LC, Burrow JA, Church M, Ludzia S.Ulceration of the squamous gastric mucosa is commonly associated with intensive training programmes in horses, but only one compound ('Gastrogard') has been subjected to controlled scrutiny as to therapeutic efficacy. Objective: To compare the gastric acid inhibitory efficacy of one manufactured ('GastroGard') and 3 generic pharmacy-compounded preparations of the proton pump inhibitor omeprazole (OME) in the mature horse. Objective: All OME preparations tested would induce a clinically acceptable effect. Methods: Six healthy mature gastrically cannulated horses of various breeds, 3 mares and 3...
Siess W, Lapetina EG.Phospholipase C has been studied in homogenates, total particulate and soluble fractions of horse and human platelets. This enzyme, assayed with exogenous L-3-phosphatidyl[14C]inositol, is predominantly localized in the soluble fraction and its distribution parallels that of lactate dehydrogenase. A small percentage of activity present in the particulate fraction seems to be due to contamination with soluble enzyme. Enzyme from horse and human platelets appears identical, having a Km of 0.10-0.15 mM, acid pH optimum (pH 5.5) and showing Ca2+-dependency and weak inhibition by deoxycholate. Anal...
Clerbaux T, Gustin P, Detry B, Cao ML, Frans A.1. The entire oxygen dissociation curve (ODC) and the effects of temperature, pH and 2,3-diphosphoglycerate (DPG) on this curve, have been compared in four mammalians: man, dog, horse and cattle. 2. If the oxyphoric capacities are similar between these species (around 1.39 ml O2/gHb), their P50, measured in standard conditions, i.e. at pH 7.4; pCO2 40 mmHg and T 37 degrees C, varies between 23.8 (+/- 0.8) mmHg for the horse, 25.0 (+/- 1.4) mmHg for cattle, 26.6 (+/- 1.2) for man and 28.8 (+/- 2.6) mmHg for the dog. 3. The higher dispersion of the dog's P 50 is due to difference between breeds;...
Regis WC, Fattori J, Santoro MM, Jamin M, Ramos CH.The work in the literature on apomyoglobin is almost equally divided between horse and sperm whale myoglobins. The two proteins share high homology, show similar folding behavior, and it is often assumed that all folding phenomena found with one protein will also be found with the other. We report data at equilibrium showing that horse myoglobin was 2.1 kcal/mol less stable than sperm whale myoglobin at pH 5.0, and aggregated at high concentrations as measured by gel filtration and analytical ultracentrifugation experiments. The higher stability of sperm whale myoglobin was identified for both...
Pead S, Durrant E, Webb B, Larsen C, Heaton D, Johnson J, Watt GD.The binding of Cd2+, Zn2+, Cu2+, Ni2+, Co2+, Mn2+, and Mg2+ to apo, holo, reconstituted horse spleen ferritin (HoSF), and native holo HoSF with phosphate removed was measured by gel-exclusion chromatography. Three classes of strong binding interactions (Kd < 10(-7) M) with apo HoSF at pH 7.5 were found for the various M2+ studied: high stoichiometric binding (30-54 M2+/HoSF) for Cd2+, Zn2+, Cu2+, with two protons released per metal bound; intermediate binding (16 M2+/HoSF) for Ni2+ and Co2+, with one proton released per metal bound; and low levels of binding (2-12 M2+/HoSF) for Mn2+, Mg2+, and...
Peiró JR, Borges AS, Gonçalves RC, Mendes LC.To compare results reported for blood gas partial pressures, electrolyte concentrations, and Hct in venous blood samples collected from cattle, horses, and sheep and analyzed by use of a portable clinical analyzer (PCA) and reference analyzer (RA). Methods: Clinically normal animals (24 cattle, 22 horses, and 22 sheep). Methods: pH; Pco(2); Po(2); total carbon dioxide concentration; oxygen saturation; base excess; concentrations of HCO(3)(-), Na(+), K(+), and ionized calcium; Hct; and hemoglobin concentration were determined with a PCA. Results were compared with those obtained for the same bl...
Bailey SR, Rycroft A, Elliott J.Acute laminitis can be induced experimentally in horses by the administration of carbohydrate, resulting in fermentation within the cecum and ischemia-reperfusion of the digits. The products of fermentation that trigger acute laminitis are as yet unknown; however, compounds such as amines might play a role due to their potential vasoactive properties. The objectives of this study were to quantify the amines present in equine cecal contents and to use a model of carbohydrate overload in vitro to test the hypothesis that carbohydrate fermentation is associated with increased amine production. Ce...
Martin DH, Dietz WH, Alvaerez O, Johnson KM.One hundred and fifty-eight strains of Venezuelan equine encephalomyelitis virus were typed antigenically and classified epidemiologically as either epizootic or enzootic. Plaque sizes for 148 of these strains were determined, and the pH requirements for hemagglutination (HA) of goose erythrocytes of 131 were studied. Only antigenic variant group IABC strains could be classified epidemiologically as epizootic. In vitro these strains were characterized by the formation of small plaques in Vero cells and a relatively narrow pH range for optimum HA reactivity. Experimental studies in horses confi...
Bismuto E, Colonna G, Irace G.The free energy of unfolding of horse myoglobin has been calculated from the denaturation pattern induced by guanidine hydrochloride as well as by acid. The delta GH2O, i.e., the value in the absence of denaturant obtained by using the two-state transition model, was found to be 25% lower than that determined from the acid denaturation pattern, i.e., 12.0 kcal/mol, although the extent of protein denaturation produced by acid was much lower. The amount of helical structure surviving the acid-induced conformational change was estimated to be 50% of that present in the native protein, and it coul...
Svistunenko DA, Sharpe MA, Nicholls P, Blenkinsop C, Davies NA, Dunne J, Wilson MT, Cooper CE.The paramagnetic species in human metHb and horse metmyoglobin (metMb) have been studied at low temperature using EPR spectroscopy. The high-spin (HS) haem signal in aquometMb has a greater rhombic distortion than the HS metHb signal. Nevertheless, the individual line width (g=6) is smaller in metMb than in metHb, consistent with non-identical signals from the alpha and beta Hb subunits. Three low-spin (LS) haem forms are present in metHb, while metMb has only two. The major LS form in both proteins is the alkaline species (with OH(-) at the sixth co-ordination position). The minor LS forms ar...
Klebanoff SJ, Agosti JM, Jörg A, Waltersdorph AM.Stimulated eosinophils release cytotoxic granule constituents, including eosinophil peroxidase (EPO) and a group of granule basic proteins (GBP). EPO reacts with H2O2 formed by the respiratory burst and a halide to form cytotoxic oxidants. The relative potency of the EPO-H2O2-halide system and the GBP is considered here. Horse eosinophils were induced to degranulate, the degranulation products were separated by chromatography on Sephadex G-50 and comparable volumes of the column fractions were tested for toxicity to Escherichia coli and the schistosomula of Schistosoma mansoni in the presence ...
Beldarrain LR, Morán L, Sentandreu MÁ, Insausti K, R Barron LJ, Aldai N.A full-randomized block design was used for the study of the FA composition and meat quality parameters, considering ageing time as a split-plot factor. Chemical and fatty acid composition of steaks (longissimus thoracis and lumborum muscle) from 15 month old semiextensively reared Hispano-Bretón horses were characterized (day 0), and the effect of vacuum ageing (0, 7, 14 and 21 days) on several meat quality parameters (pH, instrumental color and texture and cook loss) was determined. The average fat content of horse loin was 3.31%, and the n-3 polyunsaturated fatty acid content, although hig...
Murray MJ, Schusser GF.A glass combined pH-reference electrode was placed in the stomachs of 5 adult horses and pH was recorded every 6 mins for 24 h while (1) feed and all bedding materials were withheld for 24 h (unfed), (2) horses had free access to Timothy grass hay for 24 h (fed), and (3) horses had free access to Timothy grass hay and were treated with ranitidine, 6.6 mg/kg body weight, orally, every 8 h for 48 h (fed + ranitidine). There was a significant (P = 0.007) difference in median 24-h gastric pH amongst the 3 protocols, the value being 3.1 in fed horses and 1.55 in unfed horses (P = 0.05) and 4.6 in f...
Husted L, Sanchez LC, Olsen SN, Baptiste KE, Merritt AM.Stall housing has been suggested as a risk factor for ulcer development in the equine stomach; however, the exact pathogenesis for this has not been established. Objective: To investigate the effect of 3 environmental situations (grass paddock, stall alone or stall with adjacent companion) on pH in the proximal and the ventral stomach. Methods: Six horses with permanently implanted gastric cannulae were used in a randomised, cross-over, block design. Each horse rotated through each of three 24 h environmental situations. Horses remained on their normal diet (grass hay ad libitum and grain b.i....
Day TK, Gaynor JS, Muir WW, Bednarski RM, Mason DE.One hundred sixty horses were anesthetized with xylazine, guaifenesin, thiamylal, and halothane for elective soft tissue and orthopedic procedures. Horses were randomly assigned to one of four groups. Group 1 (n = 40): Horses positioned in lateral (LRG1; n = 20) or dorsal (DRG1; n = 20) recumbency breathed spontaneously throughout anesthesia. Group 2 (n = 40): Intermittent positive pressure ventilation (IPPV) was instituted throughout anesthesia in horses positioned in lateral (LRG2; n = 20) or dorsal (DRG2; n = 20) recumbency. Group 3 (n = 40): Horses positioned in lateral (LRG3; n = 20) or d...
Gollnick PD, Bertocci LA, Kelso TB, Witt EH, Hodgson DR.The effect of high-intensity exercise on the respiratory capacity of skeletal muscle was studied in horses which ran five 600-m bouts on a track with 2 min of rest between exercise bouts, or once to fatigue on a treadmill at an intensity that elicited the maximal oxygen uptake. Venous blood and biopsy samples of the middle gluteal muscle were collected at rest, after each exercise bout, and 30 and 60 min post-exercise. Blood samples were analyzed for lactate concentration and pH and muscle samples for metabolites, pH, and respiratory capacity. Venous blood and muscle pH declined to 6.91 +/- 0....
Hamada D, Kuroda Y, Kataoka M, Aimoto S, Yoshimura T, Goto Y.One unique aspect of cytochrome c folding concerns the involvement of the covalently attached heme group and its axial ligands. To elucidate the role of the ligands in stabilizing the native and molten globule states, we studied the conformational and thermodynamic features of the iron-free derivative of horse cyctochrome c (porphyrin-cytochrome c). At neutral pH, far-UV circular dichroism suggested that porphyrin-cytochrome c has native-like alpha-helices, whereas near-UV CD suggested that the side-chains are flexible. Its stability against heat or denaturants was much less than that of the i...
Muhonen S, Connysson M, Lindberg JE, Julliand V, Bertilsson J, Jansson A.The objective of this study was to investigate the effect of CP intake from 2 grass silage-only diets, differing in CP concentration, fed at similar DMI on the equine colon ecosystem after an abrupt feed change between the diets. Four adult right ventral colon-fistulated geldings were fed one silage-only diet high in CP (HP, 873 g of CP/d) and one diet providing recommended intakes (RP, 615 g of CP/d). An adaptation period of 15 d on either the HP or the RP diet was followed by 2 experimental periods when the diets were fed for 22 d each in a crossover design. Colon samples were taken before a...
Van Dael H, Haezebrouck P, Morozova L, Arico-Muendel C, Dobson CM.Despite their homologous structure, c-type lysozymes and alpha-lactalbumins have been found to differ profoundly in their unfolding behavior, in that the alpha-lactalbumins readily enter a partially unfolded collapsed state (the "molten globule"), whereas lysozymes unfold cooperatively to a highly unfolded state. The calcium-binding property of lysozyme from equine milk provides an evolutionary link between the two families of proteins. We demonstrate here that equine lysozyme undergoes a two-stage unfolding transition upon heating or in the presence of guanidine hydrochloride that is highly d...
Nadeau JA, Andrews FM, Patton CS, Argenzio RA, Mathew AG, Saxton AM.To identify the pathogenesis of gastric ulcers by comparing injury to the nonglandular gastric mucosa of horses caused by hydrochloric acid (HCl) or volatile fatty acids (VFAs). Methods: Gastric tissues from 30 horses. Methods: Nonglandular gastric mucosa was studied by use of Ussing chambers. Short-circuit current (Isc) and potential difference were measured and electrical resistance calculated for tissues after addition of HCl and VFAs to normal Ringer's solution (NRS). Tissues were examined histologically. Results: Mucosa exposed to HCl in NRS (pH, 1.5) had a significant decrease in Isc, co...
Tulamo RM, Bramlage LR, Gabel AA.Infectious arthritis was induced experimentally in one tarsocrural joint of six horses by intra-articular injection of 1 ml Staphylococcus-saline suspension containing 9 x 10(4) to 3 x 10(6) organisms. The corresponding contralateral joint was injected with 1 ml of saline and served as a control. The progression of the induced infectious arthritis was assessed over a nine-day period by clinical examination and sequential synovial fluid analysis with pH and lactate measurements. Changes in synovial fluid were present before clinical signs of infectious arthritis were manifested. The diagnostic ...
Rogers HJ.Under a variety of conditions of concentration, Eh, and pH, horse anti- serum and normal horse serum exerted similar bacteriostatic effects against Type A. Ferric iron abolished the bacteriostatic effect when added during the first 2 hours of incubation at Eh+60 mV. Ferrous iron abolished the bacteriostatic effect when added after 3 hours. Ferric iron abolished the bacteriostatic effect at—140 mV. A mixture consisting of horse β- and γ-globulins together with human transferrin exerted a bacteriostatic effect similar to that of whole serum. This system responded in the same way as whole se...
Moczygemba C, Guidry J, Wittung-Stafshede P.Native myoglobin (Mb) consists of two populations which differ in the orientation of the heme by 180 degrees rotation (as verified by nuclear magnetic resonance) but have identical absorption spectra and equilibrium-thermodynamic stability. Here, we report that these two fractions of native oxidized Mb (from horse) both unfold and refold (chemical denaturant, pH 7, 20 degrees C) in two parallel kinetic reactions with rate constants differing 10-fold. In accord, the oxidized heme remains coordinated to unfolded horse Mb in up to 4 M guanidine hydrochloride (pH 7, 20 degrees C).
Bauminger ER, Harrison PM, Nowik I, Treffry A.Ferritin stores iron within a hollow protein shell as a polynuclear Fe(III) hydrous oxide core. Although iron uptake into ferritin has been studied previously, the early stages in the creation of the core need to be clarified. These are dealt with in this paper by using Mössbauer spectroscopy, a technique that enables several types of Fe(II) and Fe(III) to be distinguished. Systematic Mössbauer studies were performed on samples prepared by adding 57Fe(II) atoms to apoferritin as a function of pH (5.6-7.0), n [the number of Fe/molecule (4-480)], and tf (the time the samples were held at room ...
