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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.
Quantification of 19-nortestosterone sulphate and boldenone sulphate in urine from male horses using liquid chromatography/tandem mass spectrometry. Following administration of the anabolic steroid 19-nortestosterone or its esters to the horse, a major urinary metabolite is 19-nortestosterone-17beta-sulphate. The detection of 19-nortestosterone in urine from untreated animals has led to it being considered a naturally occurring steroid in the male horse. Recently, we have demonstrated that the majority of the 19-nortestosterone found in extracts of 'normal' urine from male horses arises as an artefact through decarboxylation of the 19-carboxylic acid of testosterone. The aim of this investigation was to establish if direct analysis of 19-n...
Effects of clinically relevant concentrations of glucosamine on equine chondrocytes and synoviocytes in vitro. To evaluate the effects of glucosamine on equine articular chondrocytes and synoviocytes at concentrations clinically relevant to serum and synovial fluid concentrations. Methods: Articular cartilage and synovium with normal gross appearance from metacarpophalangeal and metatarsophalangeal joints of 8 horses (1 to 10 years of age). Methods: In vitro chondrocyte and synoviocyte cell cultures from 8 horses were treated with glucosamine (0.1 to 20 microg/mL) with or without interleukin-1 (IL-1; 10 ng/mL) for 48 hours. Negative control cultures received no glucosamine or IL-1, and positive control...
Analysis of major proteins and fat fractions associated with mare’s milk fat globules. Although several studies have aimed to identify mare's milk proteins, only the major whey proteins and some caseins have yet been characterized. Incomplete sequencing of the equine genome and the difficulty of recovering highly hydrophobic proteins mean that little is known to date about the proteins associated with milk fat globules, which have been shown to play an important role in newborns' defense mechanisms. The fat fraction, in particular the distribution of unsaturated fatty acids, has been more extensively studied, but complex lipids are only partially elucidated. This study reports a...
Equine placenta expresses glutamine synthetase. In most mammalian species the developing fetus utilizes large amounts of glutamine derived both from the maternal circulation and synthesized de novo in the placenta. The present study was designed to determine the role of the placenta in glutamine synthesis in the horse. The placentae from eight Standardbred mares were sampled immediately after parturition together with additional tissues obtained at necropsy from three Standbred mares during diestrous. Glutamine synthetase protein was detectable in the non-pregnant horn of the placenta in amounts similar to those seen in gluteus muscle, but ...
The effect of mixing and changing the order of feeding oats and chopped alfalfa to horses on: glycaemic and insulinaemic responses, and breath hydrogen and methane production. The aim of this study was to investigate the effects of feeding oats alone before or after feeding chopped alfalfa or, in admixture with the alfalfa on the glycaemic and insulinaemic responses of horses as well as post-prandial breath hydrogen and methane excretion. Horses were fed in a randomized order, chopped alfalfa as a source of dietary fibre and unprocessed oats as a source of starch. Chopped alfalfa intake was adjusted to a crude fibre intake of 0.5 g/kg bodyweight (BW) per meal and the oats intake was adjusted to a starch intake of 2 g/kg BW per meal. The feeds were offered in three d...
Quantitative intradermal terbutaline sweat test in horses. The aim of the current study was to quantify sweating responses to intradermal terbutaline in normal horses. Seven Thoroughbred horses were used. Terbutaline (10-fold dilutions from 1000-0.001 mg/l) and a saline control were injected intradermally (0.1 ml/site) and sweat collected for 30 min into absorbent pads taped over each injection site. Tests were performed monthly for 11 successive months and temperature, relative humidity and dewpoint were measured at the time of testing. There was no significant effect (P<or=0.05) of environmental variables or time of year on sweat responses at any...
Fat content and fatty acids profile of colostrum and milk of primitive Konik horses ( Equus caballus gmelini Ant.) during six months of lactation. The effect of the stage of lactation, the number of foals and age of the mare on changes in the fat content and fatty acid composition of colostrum and milk of primitive Konik horses was investigated. Colostrum and milk samples from 12 lactating mares were collected at the beginning of lactation, on the days 1 and 2 after foaling and then, starting from the first month of lactation, at 4-week intervals up to the sixth month of lactation. Significant differences were observed in fat content as well as the composition of some analysed fatty acids between colostrum and milk of mares of the Konik ...
Blood glucose concentrations in critically ill neonatal foals. Critical illness is associated with hyperglycemia in humans, and a greater degree and duration of hyperglycemia is associated with nonsurvival. Hypoglycemia is also seen in critically ill humans, and is associated with nonsurvival. This might also be true in the critically ill foal. Objective: To investigate the association of blood glucose concentrations with survival, sepsis, and the systemic inflammatory response syndrome (SIRS). Methods: Blood glucose concentrations at admission (515 foals) and 24 hours (159 foals), 36 hours (95), 48 hours (82), and 60 hours (45) after admission were analy...
Plasma vasopressin concentrations in healthy foals from birth to 3 months of age. Arginine vasopressin (AVP) has received increased attention in equine critical care but there is minimal information of AVP concentration in foals. The clinical usefulness of measuring AVP in ill foals depends on knowledge of age-related changes in AVP concentrations in healthy foals. Objective: Plasma AVP concentrations will be significantly different when measured from birth to 3 months of age in healthy foals. Methods: Thirteen healthy university-owned foals. Methods: Prospective, observational study. Blood was collected from healthy foals at birth and 3, 5, 7, 10, 14, 21, 28, 42, 56, and 8...
Effects of crude protein intake from grass silage-only diets on the equine colon ecosystem after an abrupt feed change. 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...
Complementary DNA cloning, functional expression and characterization of a novel cytochrome P450, CYP2D50, from equine liver. Members of the CYP2D family constitute only about 2-4% of total hepatic CYP450s, however, they are responsible for the metabolism of 20-25% of commonly prescribed therapeutic compounds. CYP2D enzymes have been identified in a number of different species. However, vast differences in the metabolic activity of these enzymes have been well documented. In the horse, the presence of a member of the CYP2D family has been suggested from studies with equine liver microsomes, however its presence has not been definitively proven. In this study a cDNA encoding a novel CYP2D enzyme (CYP2D50) was cloned f...
The prokinetic effect of mosapride citrate on horse gastric emptying rates. The prokinetic effect of the 5-HT4 receptor agonist mosapride was evaluated in seven healthy thoroughbreds. Mosapride was orally administered at doses of 0.5, 1.0 or 1.5 mg/kg. The breath 13CO2/12CO2 rate (Delta13CO2), an indirect indicator for the rate of gastric emptying, was measured at appropriate points for 4 hr after drug administration. There was a significant increase compared with the control value at 15, 20 and 165 min for 0.5 mg/kg, 30 min at 1.0 mg/kg and 165 min for 1.5 mg/kg. The results suggest that mosapride may facilitate the gastric emptying in horses.
Characterization and quantification of fluoxymesterone metabolite in horse urine by gas chromatography/mass spectrometry. Fluoxymesterone, an anabolic steroid with the 17alpha-methyl,17beta-hydroxy group, has been developed as an oral formulation for therapeutic purposes. However, it is also used illegally in racehorses to enhance racing performance. In this study, we detected 9alpha-fluoro-17,17-dimethyl-18-norandrostane-4,13-dien-11beta-ol-3-one by gas chromatography/mass spectrometry (GC/MS), which has not been reported as a fluoxymesterone metabolite so far in horse. It was synthesized for use as a reference standard, and characterized on the basis of (1)H NMR and (13)C NMR spectra, as well as GC/MS EI mass s...
High-intensity exercise induces structural, compositional and metabolic changes in cuboidal bones–findings from an equine athlete model. Fatigue fracture of cuboidal bones occurs in the human foot as well as the equine carpus. The racehorse provides a naturally-occurring model to study the effects of high-intensity exercise on the morphology and metabolism of cuboidal bones. We studied both the mineral and the collagenous matrix of the third (C(3)) and radial (C(r)) carpal bones of raced and non-raced Thoroughbred (TB) horses. We hypothesised that racehorses would show increases in the mineral component of these bones and post-translational modifications of the collagenous matrix alongside changes in markers of collagen remodel...
Effect of feeding increasing quantities of starch on glycaemic and insulinaemic responses in healthy horses. The aim of this study was to investigate the effect of increasing the intake of starch on the glycaemic and insulinaemic responses of horses. A cross-over study design was used in which four horses were fed increasing amounts of a compound feed (0.5-3.5 kg) to provide 0.3, 0.6, 0.8, 1.1, 1.4 and 2 starch/kg bodyweight (BW)/meal. The glycaemic response increased with starch intake (P<0.05), while feeding <1.1 g starch/kg BW resulted in a lowered response, compared to when 1.1-2 g starch/ kg BW was fed (P<0.01). The results suggested that insulin responses may be more appropriate to def...
Insulin sensitivity in Belgian horses with polysaccharide storage myopathy. To determine insulin sensitivity, proportions of muscle fiber types, and activities of glycogenolytic and glycolytic enzymes in Belgians with and without polysaccharide storage myopathy (PSSM). Methods: 10 Quarter Horses (QHs) and 103 Belgians in which PSSM status had been determined. Methods: To determine insulin sensitivity, a hyperinsulinemic euglycemic clamp (HEC) technique was used in 5 Belgians with PSSM and 5 Belgians without PSSM. Insulin was infused i.v. at 3 mU/min/kg for 3 hours, and concentrations of blood glucose and plasma insulin were determined throughout. An i.v. infusion of g...
Estrogenic activity of the equine estrogen metabolite, 4-methoxyequilenin. Oxidative metabolism of estrogens has been associated with genotoxicity. O-methylation of catechol estrogens is considered as a protective mechanism. 4-Methoxyequilenin (4-MeOEN) is the O-methylated product of 4-hydroxyequilenin (4-OHEN). 4-OHEN, the major catechol metabolite of the equine estrogens present in the most widely prescribed hormone replacement therapeutics, causes DNA damage via quinone formation. In this study, estrogen receptor (ERa) binding of 4-MeOEN was compared with estradiol (E2) and equilenin derivatives including 4-BrEN using computer modeling, estrogen response element (...
Exercise induced stress in horses: selection of the most stable reference genes for quantitative RT-PCR normalization. Adequate stress response is a critical factor during athlete horses' training and is central to our capacity to obtain better performances while safeguarding animal welfare. In order to investigate the molecular mechanisms underlying this process, several studies have been conducted that take advantage of microarray and quantitative real-time PCR (qRT-PCR) technologies to analyse the expression of candidate genes involved in the cellular stress response. Appropriate application of qRT-PCR, however, requires the use of reference genes whose level of expression is not affected by the test, by ge...
Spelt, an ancient cereal and first pressure linseed oil as ingredients of compound feedstuffs for modern horse feeding. Spelt is a covered cereal with large glumellas. In experiment 1, it has been compared in terms of chemical composition with barley, oat and maize. Spelt is characterized by rather low protein and ether extract (EE) contents. The neutral detergent fibre (NDF) content of spelt was slightly higher than that of oat but the acid detergent fibre (ADF) content was lower. Two compound feedstuffs were fed along with hay to six horses used in a cross-over design. Both diets were well appreciated by the horses and there were no significant differences in the apparent digestibility coefficients, except fo...
Effects of warm-up intensity on oxygen transport during supramaximal exercise in horses. 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...
Dietary energy source affects glucose kinetics in trained Arabian geldings at rest and during endurance exercise. Advances in modeling and tracer techniques provide new perspective into glucose utilization and potential consequences to health or exercise performance. This study used stable isotope and compartmental modeling to evaluate how adaptation to a feed high in sugar and starch (SS) compared with a feed high in fat and fiber (FF) affects glucose kinetics at rest and during exercise in horses. Six trained Arabians adapted to each feed underwent similar tests at rest and while running approximately 4 m/s on a treadmill. For both tests, horses received 100 micromol/kg body weight [6,6-(2)H]glucose thr...
Acquired multiple Acyl-CoA dehydrogenase deficiency in 10 horses with atypical myopathy. The aim of the current study was to assess lipid metabolism in horses with atypical myopathy. Urine samples from 10 cases were subjected to analysis of organic acids, glycine conjugates, and acylcarnitines revealing increased mean excretion of lactic acid, ethylmalonic acid, 2-methylsuccinic acid, butyrylglycine, (iso)valerylglycine, hexanoylglycine, free carnitine, C2-, C3-, C4-, C5-, C6-, C8-, C8:1-, C10:1-, and C10:2-carnitine as compared with 15 control horses (12 healthy and three with acute myopathy due to other causes). Analysis of plasma revealed similar results for these predominantly...
Serum leptin concentrations in Lipizzan fillies. To determine seasonal changes in circulating leptin concentrations, as well as leptin fluctuations in various patterns of seasonal ovarian activity, blood samples were taken in 107 Lipizzan fillies aged 1-4 years over the whole year from January to December. Serum concentrations were measured in samples obtained once a month (leptin) or twice a month (progesterone), and evaluated with respect to the age of animals (yearlings, 2-, 3- and 4-year olds) and the pattern of ovarian activity (anoestrous, seasonal cycle, prolonged cyclicity, continuous cyclicity). The mean and monthly leptin concentra...
Distribution of glutamine synthetase and an inverse relationship between glutamine synthetase expression and intramuscular glutamine concentration in the horse. Glutamine plays important roles in the interorgan transport of nitrogen, carbon and energy but little is known about glutamine metabolism in the horse. In this study we determined the tissue distribution of glutamine synthetase expression in three Standardbred mares. Expression of glutamine synthetase was highest in kidney and mammary gland, and relatively high in liver and adipose tissue. Expression was lower in gluteus muscle, thymus, colon and lung, and much lower in small intestine, pancreas and uterus. The pattern of glutamine synthetase expression in the horse is similar to that of other...
Plasma concentration of leptin and ghrelin in Standardbred foals as related to the age, sex, exercise and training. The effect of acute exercise was studied in a group of 42 clinically healthy young Standardbred trotters. These trotters had been divided into four groups according to their age. Their ages were from 1.5 to 3 years. Three jugular venous blood samples were collected via venipuncture from each horse. These samples were collected while (1) at rest, (2) after the end of the exercise and (3) 30 min after the end of the exercise. Exercise showed a significant increase in plasma leptin concentration (3.8 ± 0.31 at rest v. 4.3 ± 0.37 just after exercise and 4.4 ± 0.47 ng/ml after a 30-min rest; ANO...
Mineral balance in horses fed two supplemental silicon sources. Numerous studies suggest that silicon (Si) supplementation is beneficial for mineral metabolism and bone health. Mineral balance studies have not been performed in horses to determine how these supplements affect absorption of other minerals. The purpose of these studies was to investigate the effects of two different Si supplements on mineral absorption and retention in horses. Eight geldings were randomly placed in one of two groups: control (CO) or supplemental Si, which was provided by one of two supplements. The first, sodium aluminium silicate (SA), contains a bioavailable form of Si and...
Intake and excretion of disodium monomethylarsonate in horses: a speciation study. Capillary electrophoresis coupled to inductively coupled plasma mass spectrometry was used in a speciation study on disodium monomethylarsonate (DS-MMA(V)) and its metabolites in horses, to which the drug was administered by intramuscular injection on five consecutive days at a single arsenic dosage of 270 mg day(-1). Samples of urine, whole blood, plasma, and mane hair were analyzed before, during, and after drug administration. The data show that blood clearing and urinary excretion of MMA is a fast process following first-order kinetics with biological half-lives of about 38 h and 44 h for ...
