Omneity® Pellets
All-In-One Vitamin & Mineral Pellet
Topic:Metabolism
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.
Early embryonic development and evaluation of equine embryo viability. Tremendous progress has been made in the development of assisted reproductive techniques that may enhance the reproductive efficiency of the horse. However, techniques that involve the manipulation of oocytes and/or embryos may themselves be detrimental to embryo viability and subsequent development. Therefore, an objective method of assessing viability of embryos before and/or after oocyte/embryo manipulation is desirable. At this time, morphologic evaluation is the most widely used method of determining the viability of equine embryos. Although morphologic assessment of embryo quality will n...
The effects of bovine somatotropin (bST) and porcine somatotropin (pST) on growth factor and metabolic variables in horses. Effects of exogenous pST and bST on metabolic and growth factor variables were examined in three studies with lighthorse mares (455 to 545 kg). In Study 1, eight mares received five s.c. injections of bST or pST (30 mg/d). In Studies 2 and 3, five mares received one s.c. injection of a prolonged release formulation designed to deliver 500 mg of bST (Study 2) or pST (Study 3) over 14 d. Blood samples were collected for several days before injection to establish baseline values, at frequent intervals during treatment, and for several days thereafter. In all studies, blood urea nitrogen concentra...
Disposition and excretion of 6-methoxy-2-naphthylacetic acid, the active metabolite of nabumetone in horses. To examine, in horses, the disposition and excretion of the active metabolite 6-methoxy-2-naphthylacetic acid (6MNA) of the nonsteroidal anti-inflammatory prodrug nabumetone. Methods: Pharmacokinetic analysis of 6MNA after oral administration of nabumetone and IV administration of 6MNA. Methods: Using a crossover design, 5 horses were orally administered 3.7 mg of nabumetone/kg of body weight. After a 3-week washout period, 4 horses were administered 2.5 mg of 6MNA/kg, IV. Results: Absorption of nabumetone from the gastrointestinal tract and its metabolism to 6MNA had a median appearance half-...
Biological and imaging characteristics and radiation dose rates associated with the use of technetium-99m-labelled imidodiphosphate in the horse. The biological and imaging characteristics of technetium-99m imidodiphosphate (Tc99m-IDP) were measured in 4 horses once and in 1 horse twice. All computational results are expressed with 95.5% (mean +/- 2 SD) confidence limits. The clearance half-time of the radiopharmaceutical from the blood was 29.6 +/- 2.3 min. The percentage of the administered dose circulating in the whole-blood volume at 4 h was 3.9 +/- 0.8%. The Tc99m-IDP radioactivity confined at the plasma fraction of the whole blood at 4 h was 85.3 +/- 1.6%. At 8 h, approximately 45 +/- 16% of the dose administered had been excreted...
The integrative control of adrenocorticotrophin secretion: a critical role for corticotrophin-releasing hormone. Perifused equine anterior pituitary cells were used to investigate the relationships between the secretion of ACTH and substances known to either stimulate (corticotrophin-releasing hormone (CRH), and arginine vasopressin (AVP)) or inhibit (cortisol) ACTH secretion. The experiments were designed to mimic the hormone milieu present in vivo in the horse, with cortisol (0 or 100 nmol/l) and CRH (0 or 0.02 nmol/l) perifused continuously, and pulses of AVP (10 nmol/l) applied for 5 min at 30-min intervals. In columns perifused with 0.02 nmol CRH/l there was no significant overall effect of 100 nmol...
Effect of a warm-up on energy supply during high intensity exercise in horses. The VO2(max) in racehorses is approximately double that of elite human athletes and the rate of increase in VO2 at the onset of high intensity exercise is much greater than in man. The kinetics of gas exchange are affected by a warm-up prior to exercise in humans, there being a greater aerobic contribution to high intensity exercise after warm-up. Our hypothesis was that a warm-up would increase aerobic energy delivery in racehorses during high intensity exercise. Thirteen fit Standardbred racehorses ran to fatigue at 115% of VO2(max) on a treadmill at 10% slope. Prior to acceleration, horses ...
Effects of sodium bicarbonate and sodium chloride on the elimination of etorphine in equine urine. The combination of large doses of sodium bicarbonate and the potent narcotic, etorphine, has reportedly been given to racehorses in attempts to improve their performance and also to "mask" the presence of etorphine in urine samples. The increased urinary output and pH associated with sodium bicarbonate (approximately 500 g) administration may reduce the urinary concentration of etorphine, making it more difficult to detect. Our experiment was designed to examine the effects of this combination. Six Thoroughbred horses were used in a latin-square design with three horse pairs and three treatmen...
Structural investigation of the complexation properties between horse spleen apoferritin and metalloporphyrins. Crystallographic studies of L-chain horse spleen apoferritin (HSF) co-crystallized with Pt-hematoporphyrin IX and Snprotoporphyrin IX have brought significant new insights into structure-function relationships in ferritins. Interactions of HSF with porphyrins are discussed. Structural results show that the nestling properties into HSF are dependent on the porphyrin moiety. (Only protoporphyrin IX significantly interacts with the protein, whereas hematoporphyrin IX does not.) These studies additionally point out the L-chain HSF ability to demetalate metalloporphyrins, a result which is of impor...
Role of heme axial ligands in the conformational stability of the native and molten globule states of horse cytochrome c. 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...
Plasma, urine, and synovial fluid disposition of methylprednisolone acetate and isoflupredone acetate after intra-articular administration in horses. OBJECTIVE--To document plasma, urine, and synovial fluid disposition of 2 common intra-articularly administered steroid preparations, methylprednisolone acetate (MPA) and isoflupredone acetate (IPA). DESIGN--Descriptive investigation. SAMPLE POPULATION--100 mg of MPA or 4 mg of IPA was administered to 2 groups of 4 healthy sound radiographically normal female horses. PROCEDURE--Blood samples were collected at time 0 (before) and 2, 4, 6, 8, 10, 12, 24, 36, 48, 72, and 96 hours after administration of the designated steroid. Complete urine collection for measurement of designated steroid was ac...
Lipid peroxide levels and superoxide-scavenging abilities of Sera obtained from hotbred (Thoroughbred) horses. Hotbred (Thoroughbred) horses were grouped into three classes according to the levels of constant physical exercise (foals, 6 months old; racing horses, 5 years old; horses for breeding, 6-10 years old), and lipid peroxide levels in their sera were measured as thiobarbituric acid-reactive substances. No significant differences were observed among them. The superoxide-scavenging abilities of sera were measured next; to examine the antioxidative properties of hotbreds, and were found to be highest in the racing horses. The higher scavenging ability of the racing horses might contribute to keep t...
13-cis-Retinoic acid affect sheath-shaft interaction of equine hair follicles in vitro. A major challenge to the study of hair follicle growth is an appropriate assay system. Because equine mane follicles are large and noncurved, enabling easy dissection; are readily accessible from a single defined source; and possess a long anagen growth phase, we initiated a study of them in culture. As in our previous studies of human and sheep follicles (Dev Biol 165:469, 1994), we found in this system that transection level dictates the pattern of follicle growth in vitro: follicles transected below the sebaceous gland show a type 1 growth pattern (the shaft grows out with an adherent sheat...
Pharmacokinetics of cefoperazone in horses. The pharmacokinetics and bioavailability of cefoperazone (CPZ) were studied following intravenous (IV) and intramuscular (IM) administration of single doses (30 mg/kg) to horses. Concentrations in serum, urine and synovial fluid samples were measured following IV administration. CPZ concentrations in serum, synovial fluid and spongy bone samples were measured following IM administration. After IV administration a rapid distribution phase (t1/2 (alpha): 4.22 +/- 2.73 min) was followed by a slower elimination phase (t1/2(beta) 0.77 +/- 0.19 h). The apparent volume of distribution was 0.68 +/- 0....
Phospholipid composition of erythrocyte membranes and plasma of mammalian blood including Australian marsupials; quantitative 31P NMR analysis using detergent. The phospholipid classes of erythrocyte membranes and plasma from several domestic animals and marsupials were quantified by 31P NMR using detergents. Washed erythrocyte samples were thoroughly haemolysed by tip-sonication and dissolved in sodium cholate; plasma samples were dissolved in Triton X-100. The species studied were: common wombat (Vombatus ursinus), black-striped wallaby (Macropus dorsalis), bandicoot (Isoodon macrocarpus), Eastern grey kangaroo (Macropus giganteus), Tammar wallaby (Macropus eugenii), sheep (Ovis aries), goat (Capra hircus), cattle (Bos taurus), horse (Equus caballu...
A review of recent research on nutrition and metabolism in the athletic horse. Although a lot of research has been directed at attempts to improve performance of the equine athlete, many of the studies reviewed herein did not show statistically significant improvements in race times or increased time to fatigue. However, it must be remembered that success in racing performances is not always measured in time, but by comparative lengths or even by a nose. Therefore, improvement in the ability of an individual equine athlete is not always measurable and success is most frequently determined by one animal being better than the others in a particular competition. Therefore, ...
Attempts to find phenotypic markers of the virulence plasmid of Rhodococcus equi. Four isolates of Rhodococcus equi, from pneumonic foals, and containing the 85 kb virulence plasmid, a porcine isolate containing an 80 kb plasmid, and their plasmid cured derivatives, were examined for 239 phenotypic properties in an attempt to find characters other than the virulence-associated protein (VapA) which might be encoded by the virulence plasmid in organisms grown at 37 degrees C. Tests chosen included those which have previously given variable results for R. equi isolates, since such variability might be attributed to plasmid curing, and characteristics which have been described ...
Chiral inversion of fenoprofen in horses and dogs: an in vivo-in vitro study. Fenoprofen (FPF) is a chiral non-steroid antiinflammatory drug, marketed as a racemic mixture of its R(-) and S(+) enantiomers. Its stereoselective disposition in humans and animals is due to a chiral inversion converting R(-)FPF into S(+)FPF. The first step of this reaction, which produces an acyl-CoA thioester, is catalysed by an acyl-CoA ligase. A stereospecific high performance liquid chromatography assay was used to study the disposition of FPF enantiomers in four geldings and three male beagle dogs, following intravenous doses of racemic FPF (1 mg/kg in horses), R(-)FPF (0.5 mg/kg in hor...
Effects of exercise intensity and environmental stress on indices of oxidative stress and iron homeostasis during exercise in the horse. The effects of prolonged variable-intensity and short-term high-intensity exercise on indices of oxidative stress and iron homeostasis were compared in six fit horses under cool [20 degrees C, 40% relative humidity (RH)] or hot/humid (30 degrees C, 80% RH) environmental conditions. The exercise protocols were designed to simulate equine competition, including racing (intense exercise) or the speed and endurance phase of a 3-day event (prolonged exercise). Increased plasma concentrations of lipid hydroperoxides and haemolysate concentrations of oxidised glutathione (GSSG) were measured within 3...
Hyaluronan turnover in the synovial fluid in metacarpophalangeal–and middle carpal joints in standardbred horses. The biological turnover of hyaluronan (sodium hyaluronate) of different molecular weights (0.6 x 10(6) and 2.5 x 10(6) Daltons) was studied in the synovial fluid of the middle carpal and metacarpophalangeal joints of 6 clinically healthy Standardbred horses. The hyaluronan was radioactively labelled with 14C. The biological half-life (t1/2) was calculated from repeated synovial samples after injection of the labelled hyaluronan. The mean t1/2 in the metacarpophalangeal joints was 9.7 h for low molecular weight hyaluronan and 8.9 h for high molecular weight hyaluronan and in the middle carpal j...
Relationship of plasma lactate production to cortisol release following completion of different types of sporting events in horses. Fifty-eight healthy horses were studied during five sporting events of various intensities and durations, namely show-jumping (n = 6), cross-country in a three-day event (n = 30), trotting races (n = 7), galloping races (n = 7) and endurance rides (n = 8). Venous blood samples were collected at rest and immediately after exercise and analysed for plasma cortisol (CORT) and lactate (LA) levels. The experimental procedure was the same throughout the investigation so as to permit a reliable comparison between the five types of exercise. The type of event significantly affected both the resting (p...
Bioavailability of pivampicillin and ampicillin trihydrate administered as an oral paste in horses. Pivampicillin was administered as an oral paste to five healthy adult horses, and an oral paste with ampicillin trihydrate was administered to three horses. Pivampicillin was administered to both starved and fed horses, ampicillin trihydrate was administered to fed horses only. The dose of pivampicillin was 19.9 mg/kg, and the dose of ampicillin trihydrate was 17 mg/kg. Both doses are equivalent on a molecular basis to 15 mg/kg ampicillin. Ampicillin concentrations in plasma were determined up to 24 hours after administration. After administration of pivampicillin to starved and fed horses the...
Metabolic, hormonal, and hemodynamic changes during dopamine infusions in halothane anesthetized horses. Selected metabolites, hormones and cardiovascular variables were measured in halothane anesthetized horses during 1 hour of dopamine infusion at a rate of 5 micrograms/kg/min (low) and 10 micrograms/kg/min (high), and for 1 hour after infusion. Plasma cortisol increased twofold in the low-infusion group but did not change significantly in the high-infusion group. Plasma nonesterified fatty acids, blood glucose, blood lactate, and plasma insulin increased in the high-infusion group. There was little difference in heart rate, systolic, diastolic, and mean arterial blood pressure between the two ...
Measurement of maximal oxygen consumption of thoroughbred horses at an altitude of 1250m using open-circuit flow-through calorimetry. This study determined the maximal O2 uptake (VO2max) of Thoroughbred horses acclimatised to mild hypobaric conditions using a standard exercise test on a treadmill inclined at a 7% slope. The O2 uptake (VO2) versus speed relationship was linear below the exercise intensity required to attain VO2max. The VO2max of individual horses ranged from 143.5 to 172.6 ml/kg/min. The proportion of total variance for the VO2 versus speed relationship was greater than 0.992, and the coefficients of variation in repeated tests in individual horses ranged between 0.07 and 1.54%. The VO2 versus speed relations...
The relationship between plasma insulin-like growth factor-I (IGF-I) level and body weight in the horse. The relationship between plasma insulin-like growth factor-I (IGF-I) level and body weight was studied in six breeds of horse. The correlation coefficients between plasma IGF-I and body weight in males and females of 1 year old heavy horses (Percheron and Breton breeds) were 0.62 and 0.12 respectively. The mean plasma IGF-I of males was higher than that of females (p < 0.01). However, the plasma IGF-I levels of heavy horses did not exceed those of light horses (Thoroughbred) or ponies (Shetland and Falabella). These data suggest that IGF-I is at least related to the difference of body weights ...
The synthesis of 19-norandrostenedione from dehydroepiandrosterone in equine placenta is inhibited by aromatase inhibitors 4-hydroxyandrostenedione and fadrozole. 19-Norandrostenedione was synthesized in vitro from dehydroepiandrosterone by explants of equine full-term placenta. The synthesis of 19-norandrostenedione was inhibited by two specific aromatase inhibitors, 4-hydroxyandrostenedione and fadrozole.
Glucose and oxygen metabolism in the fetal foal during late gestation. With the use of [U-14C]glucose tracer methodology, the rates of umbilical uptake, utilization, oxidation, and production of glucose were determined in nine chronically catheterized fetal foals in the fed state between 268 and 325 days of gestation (term approximately 335 days). At the same time, the rates of umbilical O2 and lactate uptake were measured in all nine fetuses by Fick principle. The mean fetal rates of umbilical glucose uptake, glucose utilization, and CO2 production from glucose carbon were 36.9 +/- 2.5, 36.4 +/- 1.7, and 117.7 +/- 17.4 mumol.min-1.kg fetal body wt-1, respectivel...
The pharmacokinetics or oral and intravenous allopurinol and intravenous oxypurinol in the horse. The pharmacokinetics of oral and intravenous allopurinol was studied in five horses and compared with intravenous oxypurinol. The plasma concentration vs. time curves, following intravenous administration of 5 mg/kg, were best described by the biexponential equations Cp = 106.58e(-25.14t) + 159.93e(-10.96t) for allopurinol and Cp = 321.09e(-9.72t) + 82.39e(-0.44t) for oxypurinol, with an elimination half-life (t1/2 beta) of 0.09 h and an area under the curve (AUC) of 19.8 mumol.h/L after intravenous administration, while the t1/2 beta and AUC of oxypurinol were 1.09 h and 231 mumol.h/L, respec...
The dose-related effects of phenylbutazone and a methylprednisolone acetate formulation (Depo-Medrol) on cultured explants of equine carpal articular cartilage. The dose-related effects of phenylbutazone and Depo-Medrol on chondrocyte viability and chondrocyte-mediated synthesis and depletion of proteoglycans were investigated using cultured explants of equine middle carpal joint articular cartilage. Explants from 12 horses (941 x 3 mm diameter) were cultured for a total of 5 days, which included 3 days' exposure to either phenylbutazone (0, 2, 20, 200 or 2000 micrograms/mL) or Depo-Medrol (0, 20, 200 or 2000 micrograms/mL). For each explant, amino sugar content was used as a measure of proteoglycan content, 35S incorporation as a measure of the rate ...
Feed deprivation of mares: plasma metabolite and hormonal concentrations and responses to exercise. Twelve light horse mares were fed a control diet that provided 100% of their maintenance protein and energy requirements for 7 d and were then either continued on the control diet or totally deprived of feed (with access to water) for 3 d . Plasma samples were drawn twice daily throughout the experiment, at 15-min intervals for 9 h beginning 45 h after feed removal, and at 10-min intervals around an exercise bout beginning 73 h after feed removal. Feed deprivation increased (P < or = .06) whole blood beta-hydroxybutyrate and plasma NEFA, urea N, L-lactate, and glucagon concentrations, decrease...
