Topic:Energy Metabolism
Energy metabolism in horses refers to the biochemical processes that convert nutrients into energy within the body, supporting various physiological functions. This process involves the breakdown of carbohydrates, fats, and proteins to produce adenosine triphosphate (ATP), the primary energy carrier in cells. Key metabolic pathways include glycolysis, the citric acid cycle, and oxidative phosphorylation. Energy metabolism is essential for maintaining muscle function, thermoregulation, and overall health in horses. Factors such as diet, exercise, and health status can influence these metabolic processes. This page compiles peer-reviewed research studies and scholarly articles that explore the mechanisms, regulation, and implications of energy metabolism in equine physiology.
Methane output of rabbits (Oryctolagus cuniculus) and guinea pigs (Cavia porcellus) fed a hay-only diet: implications for the scaling of methane production with body mass in non-ruminant mammalian herbivores. It is assumed that small herbivores produce negligible amounts of methane, but it is unclear whether this is a physiological peculiarity or simply a scaling effect. A respiratory chamber experiment was conducted with six rabbits (Oryctolagus cuniculus, 1.57±0.31 kg body mass) and six guinea pigs (Cavia porcellus, 0.79±0.07 kg) offered grass hay ad libitum. Daily dry matter (DM) intake and DM digestibility were 50±6 g kg⁻⁰·⁷⁵ d⁻¹ and 55±6% in rabbits and 59±11 g kg⁻⁰·⁷⁵ d⁻¹ and 61±3% in guinea pigs, respectively. Methane production was similar for both species (0.2...
Modulation of circulating purines and pyrimidines by physical exercise in the horse. This study was designed to examine the influence of sub-maximal exercise on purine and pyrimidine catabolism in horses. Ten horses were initially trained for 12 weeks at the end of which they underwent a standardized exercise test (SET); venous blood samples were taken at rest, 5 and 30 min after the SET. Six untrained healthy horses, from which a blood withdrawal was taken at rest, were used as the control group. Samples were analyzed by HPLC for the simultaneous determination of uric acid, uridine, β-pseudouridine and creatinine in plasma. Glucose and lactate were measured in blood. Trained...
The development of a metabolizable energy system for horses. The development of a metabolizable energy (ME) system for horses is described. Predictive equations for gross energy and digestible energy (DE) are revisited. The relationship between feed protein content and renal energy losses and the relationship between feed fibre content and methane energy losses were analysed in a literature review to develop predictive equations for ME. In horses, renal energy losses are much higher than losses by methane energy. Renal energy losses were correlated more strictly to protein intake than to digestible protein intake. The reason probably is that per gram of...
Voluntary intake and digestibility of teff hay fed to horses. The objective of this study was to evaluate nutrient composition, voluntary DMI, and apparent DM digestibility of teff hay cut at 3 different stages of maturity to evaluate its potential as a preserved forage for horses. Six mature Quarter Horse mares (12 +/- 3 yr; 553 +/- 39 kg of BW) were used in a replicated balanced Latin square design with 3 periods and 3 maturities of teff hay. Eragrostis tef ('Tiffany' teff) was planted in May and harvested at the boot, early-heading, or late-heading stage of maturity through the summer. Horses were acclimated to a mixture of maturities of teff hay for ...
Nutritional aspects of post exercise skeletal muscle glycogen synthesis in horses: a comparative review. Carbohydrate (CHO) stored in the form of skeletal muscle glycogen is the main energy source for glycolytic and oxidative ATP production during vigorous exercise in mammals. In man, horse and dog both short-term high intensity and prolonged submaximal exercise deplete muscle glycogen. In horses, however, muscle glycogen synthesis is 2-3-fold slower than in man and rat, even when a diet high in soluble CHO is fed. There appear to be significant differences in CHO and glycogen metabolism between horses and other mammals, and it is becoming increasingly clear that many conclusions drawn from human...
Serum fructosamine concentrations in relation to metabolic changes during late pregnancy and early lactation in mares. The changes in blood serum fructosamine concentrations as indicators of glycaemia during a longer period of time were investigated in mares during late pregnancy and early lactation, as well as their relationship to the changes in the concentration of biochemical indicators of energetic status. The samples were taken from eleven mares on 60 +/- 10 and 20 +/- 10 days before foaling, and 20 +/- 10 and 60 +/- 10 days after foaling. Concentrations of serum fructosamine, non-esterified fatty acids and triglycerides were higher during late pregnancy (from P < 0.05 to P < 0.0005), while the con...
Adaptive evolution of the mitochondrial ND6 gene in the domestic horse. Mitochondria play a crucial role in energy metabolism through oxidative phosphorylation. Organisms living at high altitudes are potentially influenced by oxygen deficits and cold temperatures. The severe environmental conditions can impact on metabolism and direct selection of mitochondrial DNA. As a wide-ranging animal, the domestic horse (Equus caballus) has developed various morphological and physiological characteristics for adapting to different altitudes. Thus, this is a good species for studying adaption to high altitudes at a molecular level. We sequenced the complete NADH dehydrogenas...
Impact of feeding level on digestibility of a haylage-only diet in Icelandic horses. Eight mature Icelandic geldings were used in an experiment arranged as a change-over design to evaluate the effect of feeding level on the digestibility of a high-energy haylage-only diet. The horses were fed a low feeding level 10.7 g dry matter (DM)/kg body weight (BW) (maintenance) and a high feeding level 18.1 g DM/kg BW (1.5 × maintenance) during two 23 days experimental periods. Total collection of faeces was performed for 6 days at the end of each period to determine the coefficient of total tract apparent digestibility (CTTAD). The CTTAD for DM, organic matter, neutral detergent fibre...
Changes in Adenylate Nucleotides Concentration and Na, K-ATPase Activities in Erythrocytes of Horses in Function of Breed and Sex. The aim of this study was to examine the relationships between the concentrations of ATP, ADP, AMP (HPLC methods), total nucleotide pool (TAN), adenylate energy charge (AEC) and Na(+), K(+)-ATPase erythrocytic activities (by Choi's method) of horses as a function of breed and sex. The studies were conducted on 54 horses (stallions and mares) of different constitution types: breathing constitution (Wielkopolska and Hanoverian breed) and digestive constitution (Ardenian breed). Horse erythrocytes, independently of examined breed, present low ATP concentration in comparison to other mammal specie...
Application of fluorogenic derivatization-liquid chromatography-tandem mass spectrometric proteome method to skeletal muscle proteins in fast Thoroughbred horses. To extend the applicability of the fluorogenic derivatization-high performance liquid chromatography-tandem mass spectrometry (FD-LC-MS/MS) method, which consists of fluorogenic derivatization (FD), separation by liquid chromatography (LC), and identification by LC-tandem mass spectrometric (MS/MS) proteomic analysis, we applied it to Thoroughbred horse muscle. With the optimization of the protein extraction and separation procedure, reproducible chromatograms were obtained and the changes in protein expressions during exercise were able to be analyzed. To quantify the changed protein expressi...
Oral acetate supplementation after prolonged moderate intensity exercise enhances early muscle glycogen resynthesis in horses. Oral acetate supplementation enhances glycogen synthesis in some mammals. However, while acetate is a significant energy source for skeletal muscle at rest in horses, its effects on glycogen resynthesis are unknown. We hypothesized that administration of an oral sodium acetate-acetic acid solution with a typical grain and hay meal after glycogen-depleting exercise would result in a rapid appearance of acetate in blood with rapid uptake by skeletal muscle. It was further hypothesized that acetate taken up by muscle would be converted to acetyl CoA (and acetylcarnitine), which would be metaboliz...
Adipokines: a review of biological and analytical principles and an update in dogs, cats, and horses. In addition to its role as an energy storage depot, adipose tissue is now recognized as a complex endocrine organ. Adipose tissue releases a variety of factors, termed adipokines, that regulate energy metabolism, cardiovascular function, reproductive status, and immune function. Some of the better-studied adipokines include leptin, adiponectin, and components of the renin-angiotensin system such as angiotensinogen. The function of more recently discovered adipokines such as resistin are under intense scrutiny. Abnormal production or regulation of adipokines occurs in obese individuals and is i...
Feeding management of elite endurance horses. This article reviews the principles of feeding management for endurance horses. The amount and type of dietary energy (calories) are key considerations in dietary management, because (1) there is evidence that the body condition score, an indicator of overall energy balance, influences endurance exercise performance, and (2) the source of dietary energy (ie, carbohydrate versus fat calories) impacts health, metabolism, and athletic performance. Optimal performance is also dependent on provision of adequate feed, water, and electrolytes on race day.
The effect of weight loss by energy restriction on metabolic profile and glucose tolerance in ponies. In nine initially obese ponies, a weekly weight loss according to 1% of their ideal body weight was evaluated for its impact on insulin sensitivity and metabolic profile. Weight loss was obtained solely through energy restriction, initially at 70% of maintenance energy requirements, but to maintain constant weight loss, feed amount had to be decreased to 50% and 35% of maintenance energy requirement during the course of the trial. An oral glucose tolerance test (OGTT) was performed at weeks 0, 10 and 17. Fasted blood samples were taken on weeks 0, 3, 10, 17 for analysis of triglycerides (TG), ...
Motions of the running horse and cheetah revisited: fundamental mechanics of the transverse and rotary gallop. Mammals use two distinct gallops referred to as the transverse (where landing and take-off are contralateral) and rotary (where landing and take-off are ipsilateral). These two gallops are used by a variety of mammals, but the transverse gallop is epitomized by the horse and the rotary gallop by the cheetah. In this paper, we argue that the fundamental difference between these gaits is determined by which set of limbs, fore or hind, initiates the transition of the centre of mass from a downward-forward to upward-forward trajectory that occurs between the main ballistic (non-contact) portions o...
Voluntary intake and digestibility in horses: effect of forage quality with emphasis on individual variability. Food intake is a key biological process in animals, as it determines the energy and nutrients available for the physiological and behavioural processes. In herbivores, the abundance, structure and quality of plant resources are known to influence intake strongly. In ruminants, as the forage quality declines, digestibility and total intake decline. Equids are believed to be adapted to consume high-fibre low-quality forages. As hindgut fermenters, it has been suggested that their response to a reduction in food quality is to increase intake to maintain rates of energy and nutrient absorption. Al...
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...
The effect of oral sodium acetate administration on plasma acetate concentration and acid-base state in horses. Sodium acetate (NaAcetate) has received some attention as an alkalinizing agent and possible alternative energy source for the horse, however the effects of oral administration remain largely unknown. The present study used the physicochemical approach to characterize the changes in acid-base status occurring after oral NaAcetate/acetic acid (NAA) administration in horses. Methods: Jugular venous blood was sampled from 9 exercise-conditioned horses on 2 separate occasions, at rest and for 24 h following a competition exercise test (CET) designed to simulate the speed and endurance test of 3-da...
Electrolyte distribution and yolk sac morphology in frozen hydrated equine conceptuses during the second week of pregnancy. To investigate how equine conceptuses expand rapidly despite the hypo-osmolality of their yolk sac fluid, 18 conceptuses, aged 8-12 days and 0.8-10.0 mm in diameter, were examined by cryoscanning electron microscopy and energy dispersive X-ray microanalysis to determine the distribution of Na, Cl and K in their fluids. No osmotic gradient was found between central and peripheral yolk sac fluid. In conceptuses > or = 6 mm in diameter, the concentrations of both Na and K in the subtrophectodermal compartments were higher than those determined previously in uterine fluid, supporting the concep...
Short-term effects of energy changes on plasma leptin concentrations and glucose tolerance in healthy ponies. To determine whether plasma leptin concentrations and glucose tolerance are affected by changes in energy balance, nine healthy Shetland ponies were fed at 140% followed by 75% of their maintenance requirements for 13 days in each of the two periods. Bodyweight was recorded every three days. Blood samples were taken every two days and analysed for leptin and cortisol. An oral glucose tolerance test was performed on day 7 of each period. Serial blood samples were analysed for glucose and insulin. Although bodyweight was not affected, plasma leptin concentrations increased (P<0.001) initially...
Equine metabolic myopathies with emphasis on the diagnostic approach. Comparison with human myopathies. A review. This review gives an overview of the presently known human and equine metabolic myopathies with emphasis on the diagnostic approach. Metabolic myopathies are muscle disorders caused by a biochemical defect of the skeletal muscle energy system, which results in inefficient muscle performance. Myopathies can arise in different levels of the metabolic system. In this review the metabolic myopathies are categorized in disorders of the carbohydrate metabolism, lipid metabolism, mitochondrial myopathies (other than those described in lipid metabolism), disorders of purine metabolism, primary disorde...
Influence of cryopreservation on mitochondrial functions in equine spermatozoa. Cryopreservation of spermatozoa is of essential importance for artificial insemination and breeding programs in horses. Besides other factors, spermatozoal motility depends on mitochondrial energy metabolism. Based on changes of single mitochondrial functions it has been suggested that mitochondrial damage during cryopreservation could be a major reason for diminished post thaw semen quality. However, it is still unclear to which extent this influences the whole bioenergetic performance of mitochondria and whether this plays a role during routine cryopreservation procedures. Therefore, it was ...
Posture, gait and the ecological relevance of locomotor costs and energy-saving mechanisms in tetrapods. A reanalysis of locomotor data from functional, energetic, mechanical and ecological perspectives reveals that limb posture has major effects on limb biomechanics, energy-saving mechanisms and the costs of locomotion. Regressions of data coded by posture (crouched vs. erect) reveal nonlinear patterns in metabolic cost, limb muscle mass, effective mechanical advantage, and stride characteristics. In small crouched animals energy savings from spring and pendular mechanisms are inconsequential and thus the metabolic cost of locomotion is driven by muscle activation costs. Stride frequency appears...
Harnessed vs. mounted standardbreds on the track: changes in gait and physiological variables. It has become apparent through analysis of elite races over the past 20 years that mounted races are always slower than harnessed races when performed by the same horses over the same distances on the same tracks. Objective: To investigate and compare physiological and gait variables in mounted and harnessed activities in trotters. Methods: Ten trotters were taken at random in 2 standardised field exercise tests one week apart: a harnessed and a mounted test with standardised weight jockeys and drivers. Speed, heart rate (HR), respiratory frequency (RF), blood lactate concentration (La), strid...
Energetic cost of locomotion on different equine treadmills. Human athletes run faster and experience fewer injuries when running on surfaces with a stiffness 'tuned' to their bodies. We questioned if the same might be true for horses, and if so, would running on surfaces of different stiffness cause a measurable change in the amount of energy required to move at a given speed? Objective: Different brands of commercial treadmills have pans of unequal stiffness, and this difference would result in different metabolic power requirements to locomote at a given speed. Methods: We tested for differences in stiffness between a Mustang 2200 and a Säto I comme...
Oxygen consumption (VO2) during trotting on a 10% decline. Although there have been reports of oxygen consumption measurements of horses running on the level and incline, there are no measurements during decline locomotion. This may be due, in part, to the potential for muscle damage produced by eccentric contractions. In man, running on a 10% decline, VO2 decreased by 35% and stride frequency (SF) decreased by 3% when compared to level locomotion. Objective: The rate of O2 consumption and SF would be decreased in horses on a 10% decline when compared to the level. Methods: Six horses (average 467 +/- 68 kg) were acclimated to trotting on the level an...
Interval exercise alters feed intake as well as leptin and ghrelin concentrations in standardbred mares. Horses in training tend to become inappetant; however, the mechanism responsible for this training-induced inappetance is not known. Objective: Training and/or ulcers alter the feed intake (FI) and hormonal and/or biochemical (active ghrelin, leptin, glucose, insulin and cortisol) responses to acute high intensity exercise. Methods: Eight Standardbred mares underwent 3 interval exercise tests (IET) and 3 parallel control tests (CON) before (IET1) and after 8 weeks of training (IET2) and after treatment for gastric ulcers (IET3). Plasma samples were taken before (0 min), during (last 10 sec of ...
Exercise response, metabolism at rest and digestibility in athletic horses fed high-fat oats. High starch intakes increase the risk for metabolic disorders and therefore alternative feedstuffs are of interest. High-fat oat varieties have a lower starch and higher energy content than regular oats and may therefore be useful in this context. Objective: Feeding high fat oats causes no adverse effects on the response to exercise and that the total amount of oats offered could be reduced compared to feeding with regular oats. Methods: Twelve Standardbred trotters were fed regular oats (diet C), high-fat oats (F), and a mixture (50:50) of C and F (M), together with haylage (30:70), in a Lati...
Influence of training on plasma adrenaline and noradrenaline kinetics in untrained standardbreds. Catecholamines (CAT) play an important role in modulating the response to exercise. But the kinetics of CAT changes during exercise are difficult to study due to their short biological half-life. Objective: Learning about variations in plasma CAT levels during training could furnish new information regarding sweating, redistribution of blood flow and energy metabolism. Methods: Four untrained Standardbreds, adapted to treadmill work, were used to determine the influence of training on plasma adrenaline (A) and noradrenaline (NA) kinetics. Horses underwent a standardised exercise test (SET) on ...
Biogas production with horse dung in solid-phase digestion systems. Experiments on methanogenesis from horse dung were conducted in laboratory-scale batch reactors in order to determine the substrate performance in a solid-phase digestion process, more specifically in terms of potential energy recovery and suitable process technology. Dung from a horse stable with straw bedding was used. The temperature was kept in the mesophilic range. In the percolation process (with process water sprinkled over the stacked biomass) a proportion of 10-20% of solid inoculum (pre-digested horse dung) was found to be suitable. Comparative experiments with both percolation and f...