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.
Effects of fat feeding and energy level on plasma metabolites and hormones in Shetland ponies. The aim of this study was to investigate the influence of a fat-supplemented diet compared with a carbohydrate diet on the lipid metabolism and the enteroinsular axis of Shetland ponies. The 'crossover' experiment was divided into two parts: in the first 10 weeks the diets comprised the correct number of calories according to requirements and in the following 10 weeks they were hypercaloric, in order to check the effect of a different energy content of the diets. Feeding the fat-enriched diet, independently of its energy content, led to a significant decrease in plasma triglycerides, associate...
Dynamics of structure and energy of horse carboxymyoglobin after photodissociation of carbon monoxide. The energetics and structural volume changes after photodissociation of carboxymyoglobin are quantitatively investigated by laser-induced transient grating (TG) and photoacoustic calorimetric techniques. Various origins of the TG signal are distinguished: the phase grating signals due to temperature change, due to absorption spectrum change, and due to volume change. We found a new kinetics of approximately 700 ns (at room temperature), which was not observed by the flash photolysis technique. This kinetics should be attributed to the intermediate between the geminate pair and the fully dissoc...
[Supplemental fat in the diet of horses…is it advantageous?]. Feeding fat-supplemented diets to horses has drawn considerable interest. One of the advantages of such diets is that the energy density is increased, so that less feed is needed to meet energy requirements. In addition, adding fat to the diet enhances the contribution of fat oxidation to energy production, thus sparing muscle glycogen. The 'spared' glycogen is available for energy metabolism when the acutely exercising horse reaches a point of oxygen deficit and must rely on anaerobic metabolism. This appears to be beneficial for both aerobic and anaerobic performance. Fats are readily digest...
The effect of forage quality and level of feeding on digestibility and gastrointestinal transit time of oat straw and alfalfa given to ponies and donkeys. Four donkeys and four ponies were fed molassed dehydrated alfalfa or oat straw, either ad libitum or restricted to about 70% ad libitum intake in a Latin-square design for four periods of 21 d. Measurements of apparent digestibility and gastrointestinal transit time were made on the last 7 d of each period. When the forages were provided ad libitum, all animals ate significantly more of the alfalfa than of the oat straw. Ponies consumed significantly more of both diets per unit live weight than donkeys. Higher apparent digestibilities of dietary DM, energy and fibre fractions were seen in donk...
Dietary fat supplementation effects on in vitro nutrient disappearance and in vivo nutrient intake and total tract digestibility by horses. Addition of fat to the diet of the equine is a popular method of increasing energy density of the diet while reducing feed intake. Reducing feed intake is of interest to race horse trainers because additional feed is seen as additional weight and, therefore, a hindrance to performance. Limited information is available regarding the interactions of fat with other dietary components, particularly fiber, in the equine digestive system. The effect of dietary fat on in vitro nutrient disappearance in equine cecal fluid was studied in Exp. 1 using a split-plot design within a 2 x 2 Latin square. Two...
The interaction of ferrocytochrome c with long-chain fatty acids and their CoA and carnitine esters. Non-covalent modification of cytochrome c may have implications for electron transport and energy metabolism. We examined the interaction of various fatty acids (FAs), their coenzyme A and carnitine esters, and fatty alcohols with horse heart ferrocytochrome c. A comparison of FAs indicated a minimum chain length of 14 carbons was required for significant effect on the ferroheme chromophore and major changes in electronic spectra. Coenzyme A and carnitine esters interacted less strongly than FAs whereas long-chain alcohols did not interact with the protein. We found a single, saturable FA bind...
[Energy and protein supply for event horses during training: comparison between intake and requirements]. In horses that exercise intensively (for example, event horses in training) the intake and energy requirements were compared on the basis of a diet record and estimates of energy required for exercise. Daily net energy intake over a 7 days period was on average 30% (n = 15) higher than the net energy requirement. Since the horses had a constant body weight, and thus were in energy balance, the energy intake was overestimated and/or the energy requirement was underestimated. The intake of digestible protein was 92% higher than the protein requirement. This study illustrates the problems concern...
Energy expenditure of horse riding. Oxygen consumption (VO2), ventilation (VE) and heart rate (HR) were studied in five recreational riders with a portable oxygen analyser (K2 Cosmed, Rome) telemetric system, during two different experimental riding sessions. The first one was a dressage session in which the rider successively rode four different horses at a walk, trot and canter. The second one was a jumping training session. Each rider rode two horses, one known and one unknown. The physiological parameters were measured during warm up at a canter in suspension and when jumping an isolated obstacle at a trot and canter. This s...
Carbohydrate supplementation of horses during endurance exercise: comparison of fructose and glucose. To delay the onset of fatigue, endurance horses are often fed at rest stops during races. The resulting increase in blood insulin may adversely inhibit lipolysis. In humans, ingestion of fructose produces a smaller insulin rise than glucose. This study compared glucose and fructose as carbohydrate supplements for endurance horses. Three Arabian geldings were given 300 g of fructose (F), glucose (G) or 50% glucose: 50% fructose (GF), in 1.5 L water, by stomach tube. In the Resting Test, carbohydrate was administered at rest. Following treatment, blood samples were taken every 30 min for 8 h, an...
Preferred speed and cost of transport: the effect of incline. Preferred speed is the behavioral tendency of animals to utilize a relatively narrow set of speeds near the middle of a much broader range that they are capable of using within a particular gait. Possible explanations for this behavior include minimizing musculoskeletal stresses and maximizing energetic economy. If preferred speed is determined by energetic economy (cost of transport, C(T)), then shifts in preferred speed should produce shifts in C(T). To test this hypothesis, preferred speeds were measured in trotting horses on the level and on an incline. The preferred trotting speed decreas...
The effect of replacing nonstructural carbohydrates with soybean oil on the digestibility of fibre in trotting horses. The hypothesis tested was that the intake of extra fat at the expense of an isoenergetic amount of nonstructural carbohydrates reduces fibre utilisation in horses. In a crossover trial with feeding periods of 42 days each, 6 mature trotting horses (age 4-12 years, bodyweight 340-476 kg) were given either a control or test diet. The test concentrate was formulated to contain 37% of net energy in the form of soybean oil. The control concentrate contained an isoenergetic amount of corn starch plus glucose. The concentrates were fed in combination with the same amount of hay so that the control an...
Digestible energy expenditure in grazing activity of growing horses. Ten Thoroughbred yearlings (5 females and 5 males) were used to examine the effect of time of grazing on pasture forage and digestible energy (DE) intake, bodyweight gain and DE expenditure in grazing activity. Five females were grazed for 17 h/day (LTG), 5 males were grazed for 7 h/day (STG) and they were fed differently. As a result, DE intake from pasture forage of LTG horses and STG horses was 27.3 and 12.7-13.9 Mcal/day, respectively. The average daily gain (ADG) of LTG and STG horses was 0.37 and 0.39-0.61 kg/day, respectively. The regression lines between DE intake and ADG of both group...
A comparison of grain, oil and beet pulp as energy sources for the exercised horse. High-grain diets for the exercising horse were compared with diets which provided 15% of the total caloric intake from either vegetable oil or a highly fermentable fibre source (beet pulp). Six Thoroughbreds age 3 years were fed one of 3 diets or 5 weeks in a replicated 3 x 3 Latin square. The CONTROL diet was 3.65 kg of sweet feed (SF), 0.9 kg of a protein/vitamin/mineral pellet and 5.45 kg of hay cubes. The FAT diet replaced 1.15 kg of SF with 0.45 kg of soybean oil and the FIBRE diet replaced 1.15 kg of SF with 1.36 kg of beet pulp. Horses were exercised 3 times per week on a high-speed tre...
Contributions of equine exercise physiology research to the success of the 1996 Equestrian Olympic Games: a review. Following public concern about the weather conditions for the 1996 Olympic Games in Atlanta an international research programme was initiated. The primary objective of this effort was to identify strategies for ensuring welfare of horses competing in the heat. Field observations of horses during the endurance test of 3-day events in Europe, Canada, and the USA characterised the work effort of this form of competition; laboratory treadmill studies assessed limitations to performance of heat and humidity, explored the relationships of thermoregulatory demands to the phases of the competition and...
Effect of a post exercise fat-supplemented diet on muscle glycogen repletion. Low muscle glycogen at the beginning of exercise may adversely affect performance, increase protein degradation and contribute to the onset of fatigue. As horses are sometimes required to compete on consecutive days both in racing and endurance types of competition, optimal muscle glycogen repletion may improve performance on the day following a race day. The purpose of this experiment was to study the effects of fat supplementation on repletion of muscle glycogen. Twelve Finnhorses performed an exercise test on a treadmill, and 2 and 4 h later they received hay and concentrate (Trial A). Two ...
Hyperbolic relationship between time-to-fatigue and workload. The power:time-to-fatigue relationship for high-intensity exercise in man is useful in determining anaerobic work capacity. The purpose of this study was to determine the nature of this relationship in horses. Eight Standardbred horses performed 5 or 6 run-to-fatigue trials on a treadmill. Exercise intensities were chosen to induce fatigue in 30 to 240 s. The order of trials was randomised for each horse, but balanced overall for the first 4 trials. The data for power (independent variable) and time-to-fatigue (dependent variable) were tested for goodness of fit to hyperbolic, linear and expon...
The effect of diet composition and feeding state on the response to exercise in feed-restricted horses. Eight Thoroughbred horses were used to determine the effects of long-term calorie restriction and diet composition on serum T4 and T3 concentrations and metabolic responses with exercise. Horses were randomly assigned to 2 treatment groups (n = 4): Group 1, horses were fed a calorie-restricted diet designed to have 70% of the calories from the roughage source (RHR); Group 2, horses were fed a calorie-restricted diet designed to have 70% of the calories from the concentrate source (RHC). Horses then completed 2 step-wise exercise tests; one following a 12 h fast and one 2 h after a meal of 2 kg...
Influence of chromium tripicolinate on growth and glucose metabolism in yearling horses. Thoroughbred and Quarter Horse yearlings (n = 24; 335+/-7 d of age) were used in a 112-d feeding trial to determine whether chromium (Cr) supplementation would alter growth, development, and energy metabolism of growing horses on high-concentrate diets. The horses were assigned at random within breed and gender subgroups to one of four treatment groups: A) basal concentrate; B) basal plus 175 microg of Cr/kg concentrate; C) basal plus 350 microg of Cr/kg concentrate; and D) basal plus 700 microg of Cr/kg concentrate. Chromium was provided via Cr tripicolinate (Prince Agri Products, Quincy, IL)...
Effects of prior exercise on muscle metabolism during sprint exercise in horses. The effect of warm-up exercise on energy metabolism and muscle glycogenolysis during sprint exercise (Spr) was examined in six fit Standardbred horses exercised at 115% of maximal O(2) consumption (VO(2 max)) until fatigued, 5 min after each of three protocols: 1) no warm-up (NWU); 2) 10 min at 50% of VO(2 max) [low-intensity warm-up (LWU)]; and 3) 7 min at 50% VO(2 max) followed by 45-s intervals at 80, 90, and 100% VO(2 max) [high-intensity warm-up (HWU)]. Warm-up increased (P < 0.0001) muscle temperature (T(m)) at the onset of Spr in LWU (38.3 +/- 0.2 degrees C) and HWU (40.0 +/- 0. 3 de...
Metabolic functions of L-carnitine and its effects as feed additive in horses. A review. L-carnitine, a betaine derivative of beta-hydroxybutyrate, is found in virtually all cells of higher animals and also in some microorganisms and plants. In animals it is synthesized almost exclusively in the liver. Two essential amino acids, i.e., lysine and methionine serve as primary substrates for its biosynthesis. Also required for its synthesis are sufficient amounts of vitamin B6, nicotinic acids, vitamin C and folate. The first discovered ergogenic function of L-carnitine is the transfer of activated long-chain fatty acids across the inner mitochondrial membrane into the mitochondrial m...
The relationship between mechanical work and energy expenditure of locomotion in horses. Three-dimensional motion capture and metabolic assessment were performed on four standardbred horses while walking, trotting and galloping on a motorized treadmill at different speeds. The mechanical work was partitioned into the internal work (W(INT)), due to the speed changes of body segments with respect to the body centre of mass, and the external work (W(EXT)), due to the position and speed changes of the body centre of mass with respect to the environment. The estimated total mechanical work (W(TOT)=W(INT)+W(EXT)) increased with speed, while metabolic work (C) remained rather constant. A...
[Nutrition of horses: digestion, energy and protein evaluation and nutritional standards]. The diet of horses should cover the energy and nutrient requirements of these animals. The desired composition of the ration depends on its digestion in the equine gastrointestinal tract. Nutritional problems or diseases caused by incorrect composition of the ration or by incorrect feeding should be prevented. The digestion of carbohydrates, fats, and proteins in the different parts of the gastrointestinal tract is described. In addition, the recently introduced net energy and digestible protein evaluation systems for feeds, and the energy and protein requirements of horses are presented.
Suckling behaviour does not measure milk intake in horses, Equus caballus. Studies of parental investment in mammals have frequently used suckling behaviour to estimate energy transfer from mother to offspring, and consequently to measure maternal input. Such studies assume that the more an offspring sucks, the more milk it will receive. This assumption has been questioned, and a review of the literature found little support for it. To test if suckling behaviour provided an accurate index of milk or energy intake we used a radioactive isotope technique to label the milk of thoroughbred mares and to measure milk transfer to foals. We found no significant linear relati...
Effect of an equine-movement therapy program on gait, energy expenditure, and motor function in children with spastic cerebral palsy: a pilot study. The purpose of this study was to evaluate the effects of an 8-week program of hippotherapy on energy expenditure during walking; on the gait dimensions of stride length, velocity, and cadence; and on performance on the Gross Motor Function Measure (GMFM) in five children with spastic cerebral palsy (CP). A repeated-measures within-subjects design was used consisting of two baseline measurements taken 8 weeks apart, followed by an 8-week intervention period, then a posttest. After hippotherapy, all five children showed a significant decrease (X2(r)=7.6, P<0.05) in energy expenditure during walk...
Effect of density and weight of load on the energy cost of carrying loads by donkeys and ponies. Two experiments were designed to compare the energy used in carrying loads by donkeys and ponies. In the first experiment 3 donkeys and 3 ponies were compared on treadmills in the UK. Density of load (lead shot or straw) had no significant effect on the energy cost of carrying loads; however, the energy cost of carrying a load decreased significantly (p < 0.001) as the weight of the load increased (in donkeys 6.44, 4.35 and 3.03 J/kg load/m, in ponies 5.82, 3.75 and 3.68 J/kg load/m, for loads of 13, 20 and 27 kg/100 kg liveweight (M) respectively). Differences between species were not sign...
Functional anatomy of the cartilage of the distal phalanx and digital cushion in the equine foot and a hemodynamic flow hypothesis of energy dissipation. To examine macro- and microscopic characteristics of cartilage of the distal phalanx (ungual cartilage [UC]) and digital cushion in the equine foot and to relate them to the foot's function of energy dissipation. Methods: 85 horses and 5 foals of various breeds and ages. Methods: Feet, obtained at necropsy, were perfused with India ink (n = 30), latex (5), or polymer plastic (10). Select feet were examined histologically for tissue architecture and to identify elastic fibers. Immunochemistry to identify substance P peptides in nerves (feet from foals) and gold chloride impregnation of axons (n...
The energetic feed evaluation in Germany. The paper describes the energetic feed evaluation systems for ruminants, pigs, poultry and horses presently used in Germany. During the last ten years the "Ausschuss für Bedarfsnormen" (AfB; Committee of Nutrient Requirements) of the "Gesellschaft für Ernährungsphysiologie" (GfE, Society of Nutritional Physiology) introduced new recommendations for energy requirements of domestic animals including national and international references. The energetic requirements were factorially deduced (demand for maintenance and various performances) under consideration of partial efficiency of utilized m...
Forelimb joint moments and power during the walking stance phase of horses. To calculate normative joint moments of force and power for the forelimb of walking horses as a benchmark against which to compare these mechanical variables in horses with specific lameness. Methods: 4 Dutch Warmblood horses with no recent history of lameness. Methods: Horses were walked by hand through the test area, and data from 5 walking trials were collected for each horse. Two camera views were combined with vertical and craniocaudal ground reaction forces to calculate net moments of force in the sagittal plane across the carpal, metacarpophalangeal (fetlock), and distal interphalangeal...
Study of the heart rate and energy expenditure of ponies during transport. The energy expenditure and heart rate of five Shetland ponies were measured during transport and compared with the values recorded while they were at rest and walking. Secondary aims of the study were to investigate whether there was any correlation between heart rate and energy expenditure and whether different orientations affected the values to different degrees. The measurements were recorded at one-minute intervals while the ponies were at rest, walking and being transported in four different orientations, on journeys lasting 30 minutes. There were significant increases (P < 0.001) in ...
Effects of various feeding regimens on the energy balance of equine neonates. To determine the effect of diet on energy intake, loss, and metabolism in foals 2 to 7 days old. Methods: 14 pony foals. Methods: Group-A foals suckled their dams, group-B foals were fed milk replacer, and group-C foals were fed by total parenteral nutrition (TPN). Energy balance studies were performed over 8-hour periods on postpartum days 2, 4, and 7. Results: Mean gross energy (GE) intake of group-A foals increased between days 2 and 7. Approximately 3% of GE was excreted in urine and feces, and energy expenditure remained constant. These foals were in positive energy balance, and mean body...