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.
Selective brain cooling in the horse during exercise and environmental heat stress. Five horses were exercised on a treadmill [to central blood temperature (Tcore) approximately 42.5 degrees C]. Three of those horses were heated at rest in a climate room (53 degrees C, 90% relative humidity) (to Tcore approximately 41.5 degrees C). Temperatures were measured in the rectum, hypothalamus (Thyp), cerebrum, and cavernous sinus (Tsinus), on the skin of the head and midside, and Tcore. When Tcore increased above 38.5 degrees C, Thyp remained 0.6 +/- 0.1 degree C (SE) lower during heat exposure and 1 +/- 0.2 degrees C lower during exercise. During heat exposure, Tsinus was 2.2 +/- 0...
Influence of formulation on the pharmacokinetics and bioavailability of racemic ketoprofen in horses. The bioavailability of S(+) and R(-) ketoprofen (KTP) in six horses was investigated after oral administration of the racemic (rac) mixture. Two oral formulations were studied, an oil-based paste containing micronised rac-KTP and powder from the same source in hard gelatin capsules, each at a dose rate of 2.2 mg/kg. For the oil-based paste two feeding schedules were used; horses were either allowed free access to food or access to food was restricted for 4 h before and 5 h after dosing. The drug in hard gelatin capsules was administered to horses with restricted access to food. After intraveno...
Estimation of metabolic energy cost and heat production during a 3-day-event. The metabolic power required for sustained exercise in the horse is proportional to running speed. Moderately fast speeds require substantial energy expenditure and result in the generation of a massive metabolic heat load. Quantitative estimates of energy expenditure and heat production of horses at various running speeds were developed using empirically derived data from treadmill studies. Total metabolic power represents the sum of aerobic power indicated by the rate of oxygen consumption and net anaerobic power indicated by the rate of plasma lactate accumulation. These data were applied t...
Heart rate response and plasma lactate concentrations of horses competing in the cross-country phase of combined training events. The exercise intensity of horses (n = 175) competing in the cross-country phase of 4 combined training events at 5 levels of competition [novice (N), training (T), preliminary (P), intermediate (I) and advanced (A)] was investigated. Environmental conditions varied from cool and humid (mean +/- s.d. temperature and humidity = 12.1 degrees C +/- 0.6 and 88.4% +/- 8.9 RH) to moderately hot and humid (27.8 degrees C +/- 2.1 and 62.5% +/- 7.8 RH). Heart rates (beats/min) were recorded continuously at 5 s intervals with a heart monitor. Mean +/- s.d. heart rates (beats/min) for each level of compet...
Heart rate response and plasma lactate concentrations of horses competing in the speed and endurance phase of 3-day combined training events. The exercise intensity of horses competing in 3-day combined training events at 3 different levels of competition (CCI, n = 7; CCI, n = 11; CCI, n = 23) was investigated. Environmental conditions during all events were cool with 100% cloud cover. Heart rates were continuously recorded at 5 s intervals by a heart rate monitor. Mean +/- s.d. heart rate for all horses during each phase were: Phase A = 118 +/- 11 beats/min, Phase B = 179 +/- 22.7 beats/min, Phase C = 129 +/- 13.9 beats/min and Phase D = 174 +/- 19.6 beats/min. Mean +/- s.d. heart rates on Phase A and C were significantly different...
Effects of tumor necrosis factor blockade on interleukin 6, lactate, thromboxane, and prostacyclin responses in miniature horses given endotoxin. A monoclonal antibody (MAB) against equine tumor necrosis factor-alpha (Eq TNF) was used to investigate the role of TNF in cytokine, eicosanoid, and metabolic responses of Miniature Horses given endotoxin. Plasma concentrations of interleukin 6 (IL-6), lactate, thromboxane A2 metabolite, and prostacyclin metabolite (6-keto-PGF1 alpha) were measured in 10 Miniature Horses given 0.25 microgram of lipopolysaccharide (LPS; Escherichia coli O55:B5)/kg of body weight. Five horses were given Eq TNF MAB and 5 were given isotype-matched MAB as control. All horses were given 1.86 mg of antibody/kg by IV...
The effects of tonicity, glucose concentration and temperature of an oral rehydration solution on its absorption and elimination. Effects of different tonicities, glucose concentrations and temperatures of an oral rehydration solution (ORS) on its uptake and elimination in resting horses were studied. Fluid and electrolyte deficits similar to those occurring during prolonged exercise were induced by the administration of 1 mg/kg bwt of frusemide i.m., 3 h prior to the ORS. Fluid was administered via nasogastric tube at a volume equivalent to 4% bodyweight, which approximated diuretic induced losses. The uptake of fluid was evaluated by changes in haematocrit (PCV) and plasma total protein concentration (TP). Changes in e...
Physiological, metabolic and biochemical responses of horses competing in the speed and endurance phase of a CCI*****3-day-event. The present study was undertaken to investigate physiological, metabolic, haematological and biochemical changes in horses competing in the Speed and Endurance test of a Concours Complet International (CCI)*****3-day-event held under FEI rules. A total of 28 horses competing in the Burghley Horse Trials Speed and Endurance test were selected to be monitored: 11 horses in 1993 and 17 horses in 1994. Of the 28 horses selected, 17 completed the Speed and Endurance test and went on to complete the showjumping test. Mean +/- s.d. shade temperature and relative humidity, black globe temperature and ...
The effect of ambient temperature and saline loading on changes in plasma and urine electrolytes (Na+ and K+) following exercise. In this study 4 Standardbred geldings (age 3-8 years, weight 431-531 kg) were used. The horses were fed a hay and oat diet and the total sodium intake was about 32 mg/kg bwt (690 mmol/day). An exercise test (ET) which contained 3 phases was performed. Phase I consisted of 23.5 min of mainly submaximal exercise, Phase 2 of 2 h of box rest and Phase 3 of 26 min of exercise including an intensive trot over 2600 m at 90% of VO2max. The ET was repeated 3 times: the first at 20 degrees C (30-40% RH), the second at 35 degrees C (30-40% RH) and the third at 35 degrees C (30-40% RH) after a nasogastric...
Effects of exercise on plasma concentrations of caffeine and its metabolites in horses. The effects of exercise on the metabolism of caffeine (CA) were studied 3h after administration of the drug to race horses which then underwent exercise sets (1000-m gallop). Analysis was made of pharmacokinetics of CA, changes in its plasma concentrations, its metabolites, i.e., theophylline (TP), theobromine (TB) and paraxanthine (PX), and the molar concentration ratios of CA to these metabolites. After exercise, AUC and t1/2 tended to decrease, and the concentration of CA decreased, while the concentrations of TP and TB significantly increased. The TP/CA ratio and TB/CA ratio significantly ...
Equine sweat composition: effects of adrenaline infusion, exercise and training. Significant alterations in plasma electrolyte concentrations have been reported in horses following prolonged exercise, resulting from loss of hypertonic sweat. Sweat was collected from 10 horses undergoing a 10 week training programme; 5 at moderate intensity, to speeds of 10 m/s and 5 at low intensity, to speeds of 5 m/s. Sweat was collected from 2 sites in response to a submaximal exercise test (30 min at 50% VO2max and during an adrenaline infusion (dose mean +/- s.d.; 0.3 +/- 0.05 g/kg over 30 min). Sweat samples were analysed for sodium, chloride, potassium, protein, magnesium, calcium a...
Preparing for and competing in the heat: the human perspective. This review provides an overview of the challenges that face man and horses when exercising in the heat. Some of the strategies that are used and are being developed for human athletes exercising in the heat are reviewed. There are many similarities between human and equine physiological responses to exercise in the heat; and equine exercise science may gain some useful insights from the training, fluid replacement and heat acclimatisation strategies used by human athletes. There are, however, some important differences that impact on the ability of horses to thermoregulate and to regulate flu...
Causes of differences in respiration rate of hepatocytes from mammals of different body mass. Resting O2 consumption of hepatocytes isolated from mammals ranging in mass from 20-g mice to 200-kg horses decreases with increasing body mass. The substrate oxidation system increases in activity with increasing body mass and mitochondrial proton leak and phosphorylation system decrease in activity, resulting in a higher mitochondrial membrane potential in hepatocytes from larger mammals. The absolute rates of O2 consumption due to nonmitochondrial processes, substrate oxidation, mitochondrial proton leak, and the phosphorylation system decrease with increasing body mass. These decreases are...
Variable-temperature study of the heme-reorientation process in equine myoglobin. The redistribution of the initially-formed myoglobin heme-insertion isomers from the initially formed 50/50 mixture to the equilibrium ratio of 90/10 has long been assumed to occur by one of two mechanisms, both of which require the rupture of the heme iron-protein bond (La Mar, G.N., Toi, H. and Krishnamoorthi, K. (1984) J. Am. Chem. Soc. 106, 6395-6401). In this study we compared the use of nuclear magnetic resonance and optical spectroscopic techniques as methods for studying the reorientation of heme within myoglobin. We found that kinetics determinations of the heme insertion isomer redis...
Metalloproteinase activity has a role in equine chorionic girdle cell invasion. Chorionic girdle cells are a highly invasive subpopulation of trophoblast cells of the equine conceptus. By Day 35 (Day 0 = day of ovulation), cells of the chorionic girdle adhere to the uterine epithelium and begin to invade the endometrial wall. Invasive cells must attach to extracellular matrix proteins, secrete proteinases capable of degrading matrix, and migrate through the degraded matrix; invasion is largely dependent on the proteinase activity of the cells. The objective, therefore, was to develop an in vitro system to examine the mechanisms of equine chorionic girdle cell invasion thr...
Simultaneous analysis of tiaramide metabolites in horse urine and plasma by solid-phase extraction and reversed-phase ion-pair liquid chromatography. A simple method for the simultaneous analysis of tiaramide (TRA) metabolites in the horse is described. The sample preparation method using a Bond-Elut PH cartridge and stepwise elution with ice-cold, 30% aqueous methanol followed by additional methanol is effective for recovering the metabolites with different properties. The extraction method gives good recoveries (greater than 80%) and reproducibility. Each metabolite is well separated by high-performance liquid chromatography using an octadecyl-type column of polymer-based packing with a solvent system of 20 mM phosphate buffer (pH 6.5)-ac...
Beta-thiopropionyl cytochromes c modified at lysyl residues: preparation and characterization of the monosubstituted horse cytochromes c. beta-Thiopropionyl derivatives of horse cytochrome c singly modified at each of 18 different lysine epsilon-amino groups have been prepared using sulfosuccinimidyl-2-(biotinamido)ethyl-1,3-dithiopropionate and purified to homogeneity by high-pressure liquid chromatography. These derivatives were characterized by determination of: (i) the location of the modification; (ii) reduction potentials; (iii) visible and NMR spectra: and by (iv) measurement of electron transfer activity with cytochrome-c oxidase. No significant changes in structure were indicated, except for the ferric forms of the deri...
Effect of glucocorticoids on serum osteocalcin concentration in horses. The effects of dexamethasone (0.2 mg/kg of body weight; IV, IM, and PO) and methylprednisolone acetate (120 mg given intra-articularly) on serum osteocalcin and cortisol concentrations were studied in 6 horses. Serum osteocalcin and cortisol concentrations were serially monitored after each treatment. A significant (P < 0.05) decrease in serum osteocalcin and cortisol concentrations was observed from 12 to 24 and 2 to 48 hours, respectively, after IV and IM administrations of dexamethasone. Serum osteocalcin and cortisol concentrations were significantly decreased from 6 to 48 and 3 to 72 h...
Oxygen cost of ventilation in the resting horse. The purpose of this study was to develop a technique to measure the oxygen cost of ventilation and the values of ventilatory parameters in seven normal horses rebreathing carbon dioxide (CO2). All the horses responded to increased inspiratory levels of CO2 by increasing their tidal volume (VT) and frequency of breathing (Vf). The mean (SE) oxygen cost litre-1 of ventilation, measured at rates of ventilation greater than 200 litres min-1 was 1.7 (0.04) ml litre-1, similar to that of normal human subjects ventilating submaximally. It was concluded that the CO2 rebreathing test is a practical, no...
Modulation of 3 beta-hydroxysteroid dehydrogenase (3 beta-HSD) activity in the equine placenta by pregnenolone and progesterone metabolites. The purpose of this study was to measure 3beta-HSD activity in the equine placenta and to assess the effect of fetal and maternal blood plasma progestagens on 3beta-HSD activity was measured in 8 late gestation (collected by caesarian section at 250 to 320 days) and 7 term (collected by caesarian section at 250 to 320 days) and 7 term (collected at birth) equine placentae using a tritium release assay with [3alpha-3H] pregnenolone as substrate. Mean +/- s.d. Km(app) and Vmax for term placentae were in general higher than for late gestation placentae (0.129 +/- 0.217 micromol/l and 23.85 +/- 9....
In vitro Catabolism of very low density lipoproteins from horse (Equus caballus) by the action of autologous lipoprotein lipase. Incubation of equine very low density lipoproteins with lipoprotein lipase isolated from horse postheparin plasma resulted in the formation of lipoproteins of a higher density. Lipoproteins isolated after incubation and plasma lipoproteins had a different chemical composition and triacylglycerol fatty acid pattern. In vitro-obtained low density lipoproteins contained substantially more phospholipids and triacylglycerols but significantly less cholesteryl esters than native low density lipoproteins. Comparing the triacylglycerol fatty acid pattern of plasma very low density lipoproteins and in ...
Effect of treadmill incline and speed on metabolic rate during exercise in thoroughbred horses. We examined the effect of treadmill speed and incline on O2 uptake (VO2), CO2 production, heart rate (HR), plasma lactate concentration, economy of locomotion, stride frequency, and stride length. A further aim was to examine the relationships between HR and VO2 and lactate and VO2 and whether these relationships vary with alterations in treadmill incline. The experiment was a latin square design, using five horses and five treadmill inclines (0, 2.5, 5.0, 7.5, and 10.0%). Fit Thoroughbred horses exercised for 4 min at 3 m/s at 0% slope, after which the treadmill was set to the allocated incli...
Quinidine administration increases steady state serum digoxin concentration in horses. The aim of this study was to determine if quinidine administration increases steady state serum digoxin concentration in horses. Digoxin (0.01 mg/kg q. 12 h per os) was administered to 6 horses for 7 days. Steady state was confirmed by identifying statistically indistinguishable peak and trough serum digoxin concentrations on Days 4, 5, and 6. On Day 6, serum digoxin concentration was measured at baseline and 0.25, 0.5, 1, 2, 4, 6, 8 and 12 h after digoxin administration. On Day 7, quinidine (20 g at baseline and 10 g at 2, 4 and 6 h) was administered per os and serum digoxin concentration was...
The response of the skeleton to physical training: a biochemical study in horses. In this study we tested the hypothesis that exercise induces an adaptive response in the developing skeleton which may be monitored in vivo by measuring biochemical markers of bone metabolism. The effects of exercise on two biochemical markers of bone formation were determined; the carboxy-terminal propeptide of type I procollagen (PICP), and the bone-specific isoenzyme of alkaline phosphatase (BAP), and one putative marker of resorption, the pyridinoline crosslinked telopeptide domain of type I collagen (ICTP). All three markers were measured for a year in 2-year-old thoroughbred horses exerc...
In vitro maturation of equine oocytes obtained from different age groups of sexually mature mares. Oocytes were harvested from mare ovaries obtained at slaughter and were divided into 3 groups based on the age of the donor. The age groups consisted of young (2 to 7 yr), middle-aged (8 to 14 yr) and aged (>or=15 yr) mares. There were no differences between age groups in the proportions of follicles available for examination or the proportions of normal, abnormal or total oocytes collected. After 24 h of culture, the overall maturation rate to the second metaphase (MII) was 52.7%. Maturation rates for oocytes obtained from young and middle-aged mares were similar, but oocytes from aged mar...
Activities of selected aerobic and anaerobic enzymes in the gluteus medius muscle of endurance horses with different performance records. Biopsies of the gluteus medius muscle were taken at three different depths from 36 endurance horses aged 8.42 +/- 2.85 years and of both sexes. Twenty of the horses were considered to be excellent performers on the basis of the mean speed of their three fastest records in endurance events over the previous two or three years, whereas 16 were moderate performers. The biopsy samples were analysed for the activities of the enzymes citrate synthase (an indicator of citric acid cycle activity), 3-OH-acyl-CoA-dehydrogenase (an indicator of lipid oxidation) and lactate dehydrogenase (an indicator of ...
