Equine metabolism encompasses the biochemical processes that occur within horses to maintain life, including the conversion of food into energy, the synthesis of necessary compounds, and the elimination of waste products. These processes are essential for supporting various physiological functions such as growth, reproduction, and physical performance. Key components of equine metabolism include carbohydrate, fat, and protein metabolism, each of which contributes to the overall energy balance and health of the horse. Factors influencing metabolic rate and efficiency in horses include age, breed, diet, exercise, and health status. This page compiles peer-reviewed research studies and scholarly articles that explore the mechanisms, regulation, and implications of metabolic processes in equine physiology.
Rings LM, Swink JM, Dunbar LK, Burns TA, Toribio RE.The enteroinsular axis (EIA) comprises intestinal factors (incretins) that stimulate insulin release after PO ingestion of nutrients. Glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) are the main incretins. The EIA has not been investigated in healthy neonatal foals but should be important because energy demands are high in healthy foals and dysregulation is frequent in sick foals. Objective: To evaluate the EIA response to carbohydrates or fasting in newborn foals. We hypothesized that incretin secretion would be higher after PO versus IV carbohydrate adm...
Haffner JC, Neal DL, Hoffman RM, Grubbs ST.We investigated the stability of adrenocorticotropic hormone (ACTH) in plasma after freezing for different lengths of time. The plasma ACTH concentrations of 12 horses were measured on day 0 (baseline) and over time, after stimulation with thyrotropin-releasing hormone. Samples were stored at -80°C for 3, 7, 30, 60, and 90 d, or at -20°C for 3, 7, 30, and 60 d, or between ice packs at -20°C for 3 and 7 d prior to determination of ACTH concentration. ACTH concentrations were compared to baseline (non-frozen day 0 plasma) for each storage method using a mixed model with repeated measure...
Elzinga SE, Betancourt A, Stewart JC, Altman MH, Barker VD, Muholland M, Bailey S, Brennan KM, Adams AA.Much of the equine population is obese and therefore predisposed to the development of additional health concerns such as equine metabolic syndrome (EMS). However, pharmacologic treatments for EMS are limited. Omega-3 fatty acid supplementation is a therapeutic strategy in humans with metabolic dysfunction that improves insulin sensitivity and reduces inflammation, but the effects of omega-3 fatty acid supplementation in horses with EMS are unclear. Therefore, in this pilot study, 10 mixed-sex and mixed-breed horses with EMS were fed a docosahexaenoic acid (DHA)-rich microalgae containing 16Â ...
Gonzalez ML, Jacobs RD, Ely KM, Johnson SE.Postexercise skeletal muscle repair is dependent on the actions of satellite cells (SCs). The signal(s) responsible for activation of these normally quiescent cells in the horse remain unknown. The objective of the experiment was to determine whether submaximal exercise or tributyrin (TB) supplementation is sufficient to stimulate SC activation. Adult geldings were fed a control diet (n = 6) or a diet containing 0.45% TB (n = 6). After 30 d, the geldings performed a single bout of submaximal exercise. Middle gluteal muscle biopsies and blood were collected on days -1, 1, 3, and 5 relative to e...
Marycz K, Szłapka-Kosarzewska J, Geburek F, Kornicka-Garbowska K.Equine metabolic syndrome (EMS) is characterized by adiposity, insulin dysregulation and increased risk for laminitis. Increased levels of specific liver enzymes in the peripheral blood are typical findings in horses diagnosed with EMS. Current management of EMS is based on caloric restriction and increased physical activity. However, new potential treatment options are arising such as the transplantation of autologous adipose stem cells (ASC). However, cytophysiological properties of ASC derived from EMS horses are impaired which strongly limits their therapeutic potential. We hypothesized, t...
Fitzgerald DM, Pollitt CC, Walsh DM, Sillence MN, de Laat MA.The oral glucose test (OGT) is a useful tool for diagnosing insulin dysregulation (ID) and is somewhat repeatable in ponies under consistent management. This study aimed to determine whether the insulin and incretin responses to an OGT in ponies differed after short-term access to fertilised pasture, compared to unfertilised pasture, by using a randomised, repeated measures study design. Sixteen mixed-breed ponies were classified as severely insulin-dysregulated (SD; post-prandial insulin ≥80 μIU/mL) or not severely insulin-dysregulated (NSD; post-prandial insulin < 80 μIU/mL) using an O...
Ellerbrock RE, Curcio BR, Zhong L, Honoroto J, Wilkins P, Lima FS, Giguere S, Canisso IF.Enrofloxacin may be an alternative antimicrobial for unresponsive cases of severe bacterial infections in pregnant mares. As pregnancy may affect drug bioavailability, distribution, metabolism and excretion, dose adjustment might be necessary. Objective: To determine the disposition of orally and intravenously administered enrofloxacin in pregnant and non-pregnant mares. Methods: Randomised cross-over experiment. Methods: Six light-breed, healthy pregnant mares (260Â days gestation) were given a single dose of either intravenous (5Â mg/kg bwt) or oral compounded (7.5Â mg/kg bwt) enrofloxacin, ...
Mendoza FJ, Perez-Ecija A, Toribio RE.Donkeys and mules show several pharmacodynamic and pharmacokinetic idiosyncrasies that have to be fully considered by any clinician dealing with these species. Because they possess an increased metabolic rate and cellular water content compared with horses, higher doses (or shorter dosing intervals) are usually recommended for those drugs where pharmacologic studies have been performed. Nonetheless, owing to the lack of species-specific information, this assumption cannot be arbitrarily applied. Thus, when a drug protocol published for horses is extrapolated to a donkey or a mule, a close moni...
Pritchard A, Spooner H, Hoffman R.Furosemide is used to reduce the incidence of exercise-induced pulmonary hemorrhage in racehorses. Previous research suggests furosemide negatively impacts calcium balance, which may have long-term implications for bone health. Eleven healthy horses, either control (CON, n = 5) or treatment (FUR, n = 6), were used to test furosemide's effects on bone mineral content (BMC), bone metabolism biomarkers, and weight loss after administration. Treatment horses received IV furosemide at 1 mg⋅kg BW once weekly for seven weeks, and blood was collected before and at 24 hours after administration f...
Skiöldebrand E, Ley C, Björklund U, Lindahl A, Hansson E.Osteoarthritis is a pain-associated progressive disease and pain mediators, such as opioid receptors, expressed in articular cartilage could represent novel therapeutic targets. Acute and chronic stages of OA indicate different metabolic abilities of the chondrocytes depending on inflammatory state. This study aimed to investigate the response of healthy and osteoarthritic chondrocytes and their expression and release of pain mediators in response to acute inflammation. Interleukin-1 beta (IL-1β) and lipopolysaccharide (LPS) were used to induce an acute inflammatory response in cultured equin...
Kemper AM, Drnevich J, McCue ME, McCoy AM.Skeletogenesis is complex and incompletely understood. Derangement of this process likely underlies developmental skeletal pathologies. Examination of tissue-specific gene expression may help elucidate novel skeletal developmental pathways that could contribute to disease risk. Our aim was to identify and functionally annotate differentially expressed genes in equine neonatal and adult articular cartilage (AC) and subchondral bone (SCB). RNA was sequenced from healthy AC and SCB from the fetlock, hock, and stifle joints of 6 foals (≤4 weeks of age) and six adults (8-12 years of age). There w...
Meier AD, de Laat MA, Reiche DB, Sillence MN.Endocrinopathic laminitis, related to equine metabolic syndrome and insulin dysregulation, causes marked pain and suffering in horses and represents a substantial cost to the horse industry. This study investigated the effect of feeding a diet high in nonstructural carbohydrates on concentrations of active glucagon-like peptide-1 (aGLP-1), total insulin-like growth factor-1 (IGF-1), and high-molecular-weight (HMW) adiponectin, in insulin-dysregulated ponies. Thirty-seven ponies were challenged with this diet for up to 18Â d to induce hyperinsulinemia. Hormone concentrations were measured in se...
Nelson EA, Sanchez LC, Mallicote MF, Warren LK, Robelen AM, Reuss SM. To compare urine urinary pH, blood pH and concentration of electrolytes in blood of healthy horses fed an anionic salt supplement to achieve diets with a dietary cation-anion difference (DCAD) of -40 or 0 mEq/kg DM, with horses a fed a diet with a DCAD of 85 mEq/kg DM. Eight healthy horses received each of three diets in a randomised crossover design. Diets consisted of grass hay and concentrate feed, with a varying amount of an anionic supplement to achieve a DCAD of 85 (control), 0 or -40 mEq/kg DM. They were fed for 14 days each with a washout period of 7 days between. Urine pH was m...
Breuhaus BA.Certain breeds of horses may be genetically predisposed to developing insulin dysregulation, which is a risk factor for development of endocrinopathic laminitis in horses. This study was performed to test the hypotheses that Paso Fino horses exhibit evidence of insulin dysregulation compared with Thoroughbred horses and that obesity exaggerates the insulin dysregulation. Intravenous glucose tolerance tests were performed in 14 moderate-weight Thoroughbreds, 12 moderate-weight Paso Finos, and 12 overweight Paso Finos. Moderate Paso Finos had greater baseline serum insulin concentrations, area u...
Júnior WHF, Garcia de Carvalho JR, Mendes de Almeida ML, Macedo Lemos EG, Brioschi Soares OA, Ribeiro G, de Queiroz-Neto A, de Camargo Ferraz G.We compare the expression levels of the lactate transporter complex consisting of the lactate transporter, monocarboxylate transporter 1 (MCT1), and its ancillary protein, cluster of differentiation 147 (CD147), in the membranes of red blood cells (RBCs) from two breeds of jumping horses and associate the expression levels of these proteins with their jumping ability. The expression levels of MCT1 and CD147 proteins on the membranes of RBCs collected from 30 show jumping horses of two different breeds were quantified: the Brazilian Sport Horses (n = 17) and the European Warmbloods (n = 13). ...
Rosser J, Bachmann B, Jordan C, Ribitsch I, Haltmayer E, Gueltekin S, Junttila S, Galik B, Gyenesei A, Haddadi B, Harasek M, Egerbacher M, Ertl P....In this work, we describe a microfluidic three-dimensional (3D) chondrocyte culture mimicking in vivo articular chondrocyte morphology, cell distribution, metabolism, and gene expression. This has been accomplished by establishing a physiologic nutrient diffusion gradient across the simulated matrix, while geometric design constraints of the microchambers drive native-like cellular behavior. Primary equine chondrocytes remained viable for the extended culture time of 3 weeks and maintained the low metabolic activity and high Sox9, aggrecan, and Col2 expression typical of articular chondrocytes...
Owens TG, Barnes M, Gargano VM, Julien L, Mansilla WD, Devries TJ, Mcbride BW, Merkies K, Shoveller AK.Soaking hay and steaming hay are strategies that are used to reduce respirable dust particles for horses but may result in variable nutrient losses, including nonstructural carbohydrates (NSC) and minerals. Since these losses have not been quantified in Canadian hay yet, the first aim of this study was to identify nutrient losses from first-cut timothy-alfalfa hay grown in southern Ontario, Canada, after soaking for 30 min or steaming for 60 min. It is uncertain whether horses prefer hay when it is dry, soaked, or steamed. To address this, 13 Standardbred racehorses were offered 2 of these hay...
Li Y, Zhang K, Liu Y, Li K, Hu D, Wronski T.Large and complex intestinal microbiota communities in hosts have profound effects on digestion and metabolism. To better understand the community structure of intestinal microbiota in Przewalski's horse () under different feeding regimes, we compared bacterial diversity and composition between captive and reintroduced Przewalski's horses, using high-throughput 16S-rRNA gene sequencing for identification. Reintroduced Przewalski's horses were sampled in two Chinese nature reserves, i.e., Dunhuang Xihu Nature Reserve (DXNR; = 8) in Gansu Province and Kalamaili Nature Reserve (KNR; = 12) in Xi...
Dunkel B, Knowles EJ, Chang YM, Menzies-Gow NJ.Blood l-lactate and glucose concentrations were higher in ponies with gastrointestinal disease than in horses, possibly because of differences in body condition (BC). Objective: To investigate whether l-lactate and glucose concentrations correlate with BC and differ between healthy horses and ponies. Methods: Systemically healthy client-owned ponies (n = 101) and horses (n = 51). Methods: Prospective observational study. Breed, weight, height, and subjective and objective measures of BC were recorded and l-lactate and glucose concentrations were measured. Correlations between l-lactate and glu...
Peachey LE, Castro C, Molena RA, Jenkins TP, Griffin JL, Cantacessi C.A plethora of data points towards a role of the gastrointestinal (GI) microbiota of neonatal and young vertebrates in supporting the development and regulation of the host immune system. However, knowledge of the impact that infections by GI helminths exert on the developing microbiota of juvenile hosts is, thus far, limited. This study investigates, for the first time, the associations between acute infections by GI helminths and the faecal microbial and metabolic profiles of a cohort of equine youngstock, prior to and following treatment with parasiticides (ivermectin). We observed that high...
Loos CMM, Dorsch SC, Elzinga SE, Brewster-Barnes T, Vanzant ES, Adams AA, Urschel KL.Equine metabolic syndrome (EMS) is characterized by an abnormal insulin response to a glycemic challenge but despite the known insulinotropic effects of certain amino acids, there is a paucity of data evaluating the impact of dietary protein on insulin dynamics in these horses. The objective was therefore to assess insulin and amino acid responses following intake of a high protein meal in healthy horses and those with EMS. Six mature horses diagnosed with EMS and six age-matched control horses without EMS were used. Horses were fed 2g/kg body mass (BM) of a high protein pellet (31% crude prot...
Luethy D, Johnson AL, Stefanovski D, Boston RC, Orsini JA.Equine metabolic syndrome (EMS) is prevalent in the equine population, and somatostatin analogs might be useful for diagnosis and/or treatment of EMS in horses. The purpose of this study was to evaluate the glucose and insulin responses to subcutaneous and intravenous administration of somatostatin. Six healthy research horses were included in this prospective study. An initial pilot study was performed to assess several different doses (10-22 µg/kg [4.5-10 µg/lb]) in two horses, then a final dosage of 22 µg/kg (10 µg/lb) was administered to six horses IV and SQ in a two-period random...
Banse HE, Getachew F, Levy M, Smits J.Hair cortisol has been demonstrated to reflect hypothalamic-pituitary-adrenal axis activity (including Cushing's disease and stress) in several species. We hypothesized that hair cortisol concentrations are increased in horses with pituitary pars intermedia dysfunction (PPID) compared with healthy adult horses and that this difference is magnified in the fall, when circulating adrenocorticotropin (ACTH) is generally the highest. Cortisol from hair collected using clippers with a #40 blade from the neck was compared between PPID horses and control horses over several months in the fall (August-...
Knych HK, Baden RW, Gretler SR, McKemie DS.Despite their widespread popularity as sport and companion animals and published and anecdotal reports of vast difference in drug disposition and pharmacokinetics between individuals, studies describing equine drug metabolism are limited. It has been theorized that similar to humans, members of the CYP2D family in horses may be polymorphic in nature leading to differences in metabolism of substrates. This study aims to build on the limited current knowledge regarding P450 mediated metabolism in horses by describing the metabolism of the polymorphic CYP2D6 probe drug codeine in vitro. Codeine, ...
Gulmez C, Atakisi O.It was aimed to investigate the effects of kumiss a fermented mare horse beverage on the sirtuin deacetylases in the oxidative stress which had been induced by 1,2-dimethyl hydrazine (DMH). Forty BALB/C male mice were divided into four groups as control, kumiss (2 × 10 cfu/mL), DMH (20 mg/kg), and kumiss + DMH (2 × 10 cfu/mL + 20 mg/kg). At the end of 20-week regimen, SIRT2, SIRT3 protein expressions by western blotting, immunolocalizations, and inhibitory anti-oxidant activity analysis in liver, colon, and kidney tissues were performed. SIRT2 and SIRT3 expressions in DMH g...
Ortiz-Rodriguez JM, Balao da Silva C, Masot J, Redondo E, Gazquez A, Tapia JA, Gil C, Ortega-Ferrusola C, Peña FJ.The population of stallion spermatozoa that survive thawing experience compromised mitochondrial functionality and accelerated senescence, among other changes. It is known that stallion spermatozoa show very active oxidative phosphorylation that may accelerate sperm senescence through increased production of reactive oxygen species. Rosiglitazone has been proven to enhance the glycolytic capability of stallion spermatozoa maintained at ambient temperature. Thus, we hypothesized that thawed sperm may also benefit from rosiglitazone supplementation. Thawed sperm were washed and resuspended in Ty...
Della Malva A, De Palo P, Lorenzo JM, Maggiolino A, Albenzio M, Marino R.The aim of this study was to evaluate the effect of post-mortem aging on tenderness development and proteolysis of myofibrillar proteins in 3 different horse muscles. Warner-Bratzler shear force decreased during aging in all muscles, showing the lowest values in longissimus lumborum (LL) in all sampling points. Myofibril fragmentation index significantly increased in LL and semimembranosus (SM) muscles throughout aging time whereas in semitendinosus (ST) it increased after 14 days of aging. Proteomics analysis revealed the major content of intact myofibrillar proteins with high molecular wei...
The Journal of physiologyFebruary 15, 1995
Volume 483 ( Pt 1), Issue Pt 1 201-209 doi: 10.1113/jphysiol.1995.sp020578
Hartmann J, Scepek S, Lindau M.1. We have investigated the granule size distributions in human and horse eosinophils by time-resolved patch-clamp capacitance measurements. 2. During exocytosis of single granules the electrical capacitance of the plasma membrane increases in discrete steps. The steps in horse cells are about six times larger than those in human cells in accordance with the difference in granule size. 3. In both species a multimodal capacitance step size distribution is observed with a first peak at 6-7 fF corresponding to granules with a diameter of about 450-500 nm and a surface area of about 0.7 microns2, ...
Taylor PM.Information on equine stress responses to anaesthesia and surgery is sparse. Six ponies were anaesthetized for 2 h with halothane and no surgery was performed. Plasma concentrations of glucose, lactate, non-esterified fatty acids, cortisol, insulin, catecholamines and adrenocorticotropic hormone (ACTH) were measured. The results were compared with those obtained in the same group of ponies over the same time period on a different day with the animals conscious. Anaesthesia induced an increase in plasma concentrations of glucose, lactate, cortisol and ACTH and a decrease in plasma concentration...
Blaue D, Schedlbauer C, Starzonek J, Gittel C, Brehm W, Einspanier A, Vervuert I.The objective of this study was to illuminate the changes in serum NEFA concentrations during a combined glucose-insulin test (CGIT) and basal serum triacylglycerides (TGs) with increasing BW in Shetland ponies and warmblood horses. Therefore, basal blood samples were taken during fasting and a CGIT was performed in 19 healthy equines (10 Shetland ponies, 9 warmblood horses) (t0). After one (t1) and two (t2) year(s) of receiving 200% of their maintenance metabolizable energy requirement, procedures were repeated in the same equines. Sixteen of 19 equines had no signs of insulin dysregulation c...
Kristoffersen C, Jensen RB, Avershina E, Austbø D, Tauson AH, Rudi K.Knowledge on dynamic interactions in microbiota is pivotal for understanding the role of bacteria in the gut. We herein present comprehensive dynamic models of the horse cecal microbiota, which include short-chained fatty acids, carbohydrate metabolic networks, and taxonomy. Dynamic models were derived from time-series data in a crossover experiment in which four cecum-cannulated horses were fed a starch-rich diet of hay supplemented with barley (starch intake 2 g kg body weight per day) and a fiber-rich diet of only hay. Cecal contents were sampled via the cannula each h for 24 h for both die...
Peugnet P, Wimel L, Duchamp G, Sandersen C, Camous S, Guillaume D, Dahirel M, Dubois C, Jouneau L, Reigner F, Berthelot V, Chaffaux S, Tarrade A....In equids, placentation is diffuse and nutrient supply to the fetus is determined by uterine size. This correlates with maternal size and affects intra-uterine development and subsequent post-natal growth, as well as insulin sensitivity in the newborn. Long-term effects remain to be described. In this study, fetal growth was enhanced or restricted through ET using pony (P), saddlebred (S) and draft (D) horses. Control P-P (n = 21) and S-S (n = 28) pregnancies were obtained by AI. Enhanced and restricted pregnancies were obtained by transferring P or S embryos into D mares (P-D, n =â€...
Bailey SR, Menzies-Gow NJ, Marr CM, Elliott J.Disturbances of digital blood flow are thought to be fundamental to the pathophysiology of acute laminitis. However, factors linking the initiating events in the equine hindgut with these disturbances in the foot remain to be determined. Objective: Amine compounds, formed by bacteria in the equine hindgut, have digital vasoconstrictor effects in vivo. Methods: Tryptamine (1.6 microg/kg/min) and phenylethylamine (2.13 microg/kg/min) were infused i.v. into standing nonsedated horses. Digital blood flow was measured by Doppler ultrasound and foot surface temperature was monitored. Plasma 5-hydrox...
Tyler CM, Golland LC, Evans DL, Hodgson DR, Rose RJ.Thirteen standardbred horses were trained as follows: phase 1 (endurance training, 7 wk), phase 2 (high-intensity training, 9 wk), phase 3 (overload training, 18 wk), and phase 4 (detraining, 12 wk). In phase 3, the horses were divided into two groups: overload training (OLT) and control (C). The OLT group exercised at greater intensities, frequencies, and durations than group C. Overtraining occurred after 31 wk of training and was defined as a significant decrease in treadmill run time in response to a standardized exercise test. In the OLT group, there was a significant decrease in body wei...
Cappelli K, Mecocci S, Capomaccio S, Beccati F, Palumbo AR, Tognoloni A, Pepe M, Chiaradia E.Physical exercise has been associated with the modulation of micro RNAs (miRNAs), actively released in body fluids and recognized as accurate biomarkers. The aim of this study was to measure serum miRNA profiles in 18 horses taking part in endurance competitions, which represents a good model to test metabolic responses to moderate intensity prolonged efforts. Serum levels of miRNAs of eight horses that were eliminated due to metabolic unbalance (Non Performer-NP) were compared to those of 10 horses that finished an endurance competition in excellent metabolic condition (Performer-P). Circulat...
Pösö AR, Soveri T, Oksanen HE.Serum enzyme activities, albumin, protein, urea, cholesterol, triglyceride, free fatty acid, glucose and lactate concentrations as well as hematocrit values were measured in standardbred and Finnish-bred horses at rest and after (i) a short controlled exercise and (ii) a trotting competition. There were no breed differences in the enzyme activities at rest and the 2 breeds responded in the same manner to the exercise. Only after the race proper significant increases in the enzyme activities were found. The activities rose more in the standardbred horses than in the Finnish-bred horses. Urea an...
Quist EE, Hokin LE.A potent inhibitor of (Na+ + K+)-ATPase activity was purified from Sigma equine muscle ATP by cation- and anion-exchange chromatography. The isolated inhibitor was identified by atomic absorption spectroscopy and proton resonance spectroscopy to be an inorganic vanadate. The isolated vanadate and a solution of V2O5 inhibit sarcolemma (Na+ + K+)-ATPase with an I50 of 1 micrometer in the presence of 1 mM ethyleneglycol-bis-(beta-aminoethylether)-N,N'-tetraacetic acid (EGTA), 145 mM NaCl, 6mM MgCl2, 15 mM KCl and 2 mM synthetic ATP. The potency of the isolated vanadate is increased by free Mg2+. ...
Wilson G, Pritchard PP, Papageorgiou C, Phillips S, Kumar P, Langan-Evans C, Routledge H, Owens DJ, Morton JP, Close GL.The present study assessed the effects of a diet and exercise intervention in jockeys on body composition, metabolism, bone and mental health. 10 jockeys followed an individually prescribed 6-wk diet (Carbohydrate=2.5-3.5 g/kg, Protein=2.5 g/kg, Fat=1.0 g/kg). Body mass (59.2±4.6 vs. 57.6±4.5 kg), fat mass (7.5±3.5 vs. 6.2±2.6) and body fat (13.1±5.9 vs. 11.5±4.9%) all decreased (P<0.05) from pre to post-intervention whilst lean mass (47.1±5.3 vs. 47.0±5.5 kg) was maintained (P=0.80). RMR (1703±329 vs. 1975±313 kcal.d(-1)), VO2max (3.8±0.8 vs. 4.1±0.7 L/min(- 1))...
Thorn B, Dunstan RH, Macdonald MM, Borges N, Roberts TK.Erythrocytes have a well-defined role in the gaseous exchange of oxygen and carbon dioxide in the mammalian body. The erythrocytes can contain more than half of the free amino acids present in whole blood. Based on measures showing that venous erythrocyte levels of amino acids are much less than arterial erythrocyte levels, it has previously been proposed that erythrocytes also play a role in the delivery of amino acids to tissues in the body. This role has been dismissed because it has been assumed that to act as an amino acid transport vehicle, the erythrocytes should release their entire a...
Mukai K, Hiraga A, Eto D, Takahashi T, Hada T, Tsubone H, Jones JH.To determine whether warm-up exercise at different intensities alters kinetics and total contribution of aerobic power to total metabolic power in subsequent supramaximal exercise in horses. Methods: 11 horses. Methods: Horses ran at a sprint until fatigued at 115% of maximal oxygen consumption rate (VO(2max)), beginning at 10 minutes following each of 3 warm-up protocols: no warmup (NoWU), 1 minute at 70% VO(2max) (moderate-intensity warm-up [MoWU]), or 1 minute at 115% VO(2max) (high-intensity warm-up [HiWU]). Cardiopulmonary and blood gas variables were measured during exercise. Results: Th...
White SH, Wohlgemuth S, Li C, Warren LK.Exercise is known to promote mitochondrial biogenesis in skeletal muscle as well as enhance mitochondrial function and efficiency in human and rodent models. These adaptations help to decrease exercise-associated production of reactive oxygen species, which can negatively affect health and performance if antioxidant mechanisms are overwhelmed. Little is known about the adaptations of mitochondria in response to exercise training in the growing horse or if supplementation with a dietary antioxidant can improve mitochondrial function. To evaluate the separate and combined effects of selenium (Se...
Gibson JS, Godart H, Ellory JC, Staines H, Honess NA, Cossins AR.Potassium transport was measured in equine red blood cells, using 86Rb+ influx as a convenient assay. A significant component of volume- and pH-sensitive K(+)-Cl- cotransport to the overall K+ flux was observed in all blood samples studied, although fluxes were variable between animals, and within individuals when measured at intervals over a period of weeks. The aryloxyacetic acid [(dihydroindenyl)oxy]alkanoic acid (DIOA), at a final concentration of 100 microM, inhibited most (> 95%) of the Cl(-)-dependent K+ flux, and DIOA sensitivity was therefore used to define the activity of the K(+)...
Barnes A, Kingston J, Beetson S, Kuiper C.This study investigated the physiology of endurance horses competing in warm weather over technical terrain, a situation where horses may become metabolically compromised. Objective: There will be changes in physiological, haematological and biochemical variables as horses progress through the 160 km ride and horses detected clinically at the veterinary inspections as metabolically compromised will have significant differences in measured laboratory variables compared to horses that complete the ride successfully. Methods: Forty-eight horses competing in the Australian Tom Quilty 160 km endura...
Ringmark S, Lindholm A, Hedenström U, Lindinger M, Dahlborn K, Kvart C, Jansson A.Training of Standardbred race horses aims to improve cardiovascular and metabolic functions but studies on the effects of different training strategies from breaking till racing are lacking. Sixteen horses with the goal to race as 3-year-olds were studied from breaking (1-year-olds) to December as 3-year-olds. Horses were allocated to either a control (C) or reduced (R) training program from 2 years of age. The aim was to evaluate the effect of reducing the distance of high intensity exercise by 30% with respect to velocity at lactate concentration 4 mmol/l (VLa4), blood lactate and cardiovasc...
Shrestha HK, Beg MA, Burnette RR, Ginther OJ.Horses are about five times more sensitive to the luteolytic effect of prostaglandin F2alpha (PGF) than cattle, as indicated by a recommended clinical dose of 5 mg in horses and 25 mg in cattle. Novel evaluations of the PGF plasma disappearance curves were made in mares and in heifers, and the two species were compared. Mares and heifers (n = 5) of similar body weight were injected (Min 0) intravenously with PGF (5 mg per animal). Blood was sampled every 10 sec until Min 3, every 30 sec until Min 5, every 10 min until Min 60, and every 30 min until Min 240. The mean PGF concentration was great...
Yu X, Fang C, Liu L, Zhao X, Liu W, Cao H, Lv S.This study was designed to provide a basis for further understanding of the mechanism of lactation based on mRNA expression differences in milk fat between different milk yields in Kazakh horses. Total RNA was extracted from the milk fat during the peak of lactation period. A total of 310 differentially expressed genes (DEGs) were identified by comparative transcriptome analysis of the high-yield and low-yield group. These DEGs regulate lactation by participated in AMPK signaling pathway, FoxO signaling pathway, ErbB signaling pathway, VEGF signaling pathway. In addition, we performed quantita...
Kaartinen L, Panu S, Pyörälä S.Pharmacokinetic behaviour of enrofloxacin was studied in 6 horses after intravenous (i.v.) or intramuscular (i.m.) administration of enrofloxacin (5 mg/kg bwt). Concentration of enrofloxacin and ciproflaxin were measured by high performance liquid chromatography in serum. Antimicrobial activity of the samples was determined with an agar-diffusion technique. Reactions at the site of i.m. injection were monitored clinically and by determination of serum creatine kinase (CK) activity. After i.v. administration, elimination half-life of enrofloxacin was 4.4 h and volume of distribution was 2.3 1/k...
McCutcheon LJ, Geor RJ, Hinchcliff KW.This study examined changes in skeletal muscle GLUT4 content and glucose transport in isolated muscle membranes (GT) from horses before and 2 min after standardised submaximal exercise tests (SET) prior to and after completion of 6 weeks of training. Seven horses, age 3-9 years, body mass mean +/- s.e. 530 +/- 19 kg, and sedentary for at least 4 months, completed 6 weeks of training on a treadmill. An initial SET (UT) was performed on a 4 degree incline at a speed equivalent to 55% of pretraining VO2max and was repeated post-training at the same absolute workload (ABS). A third SET (REL) was p...
Schneider N, Mouithys-Mickalad A, Lejeune JP, Duyckaerts C, Sluse F, Deby-Dupont G, Serteyn D.We investigated the oxygen (O(2)) uptake of equine articular chondrocytes to assess their reactions to anoxia/re-oxygenation. They were cultured under 5% or 21% gas phase O(2) and at glucose concentrations of 0, 1.0 or 4.5g/L in the culture medium (n=3). Afterwards, the O(2) consumption rate of the chondrocytes was monitored (oxymetry) before and after an anoxia period of 25min. The glucose consumption and lactate release were measured at the end of the re-oxygenation period. The chondrocytes showed a minimal O(2) consumption rate, which was hardly changed by anoxia. Independently from the O(2...
Wickler SJ, Hoyt DF, Cogger EA, Hall KM.Horses have a tendency to utilize a relatively narrow set of speeds near the middle of a much broader range they are capable of using within a particular gait, i.e., a preferred speed. Possible explanations for this behavior include minimizing musculoskeletal stresses and maximizing metabolic economy. If metabolic economy (cost of transport, CT) and preferred speeds are linked, then shifts in CT should produce shifts in preferred speed. To test this hypothesis, preferred speed was measured in trotting horses (n = 7) unloaded on the level and loaded with 19% of their body weight on the level. T...
de Laat MA, Robinson MA, Gruntmeir KJ, Liu Y, Soma LR, Lacombe VA.Equine metabolic syndrome is characterized by obesity and insulin resistance (IR). Currently, there is no effective pharmacological treatment for this insidious disease. Glucose uptake is mediated by a family of glucose transporters (GLUT), and is regulated by insulin-dependent and -independent pathways, including 5-AMP-activated protein kinase (AMPK). Importantly, the activation of AMPK, by 5-aminoimidazole-4-carboxamide-1-D-ribofuranoside (AICAR) stimulates glucose uptake in both healthy and diabetic humans. However, whether AICAR promotes glucose uptake in horses has not been established. I...
Marzano G, Moscatelli N, Di Giacomo M, Martino NA, Lacalandra GM, Dell'Aquila ME, Maruccio G, Primiceri E, Chiriacò MS, Zara V, Ferramosca A.Conventional sperm selection techniques used in ARTs rely on centrifugation steps. To date, the different studies reported on the effects of centrifugation on stallion sperm motility provided contrasting results and do not include effects on mitochondrial functionality and different oxidative parameters. The effects of different centrifugation protocols (300 ×g for 5', 300 ×g for 10', 1500 ×g for 5' and 1500 ×g for 10' vs no centrifugation) on motility and oxidative status in cryopreserved stallion sperm, were analyzed. After centrifugation, almost all motility parameters were significantl...
Flauger B, Krueger K, Gerhards H, Möstl E.Glucocorticoids or their metabolites can be measured in several body fluids or excreta, including plasma, saliva, urine and faeces. In recent years the measurement of glucocorticoid metabolites (GCMs) in faeces has gained increasing attention, because of its suitability for wild populations. In horses, however, the group-specific enzyme immunoassay described so far has a limited practicability due to its complex extraction procedure. Therefore, we tested the applicability of other enzyme immunoassays for glucocorticoid metabolites. The present study clearly proved that an enzyme immunoassay (E...
Redekopp C, Irvine CH, Donald RA, Livesey JH, Sadler W, Nicholls MG, Alexander SL, Evans MJ.Plasma ACTH, arginine vasopressin (AVP), and catecholamines were measured at 5-min intervals in the pituitary venous effluent of the unanesthetized horse. Pulses of ACTH and AVP were found to be surprisingly brief (usually of less than 10-min duration) and frequent (averaging between 15-25 min). A highly significant relationship in the changes in concentration of these two hormones was demonstrated (P less than 0.0002) both at rest and after a mild hypoglycemic stimulus. Although there was also a significant correlation (P less than 0.005) between simultaneous plasma ACTH and AVP values the pu...
