Topic:Body Mass
Body mass in horses refers to the total weight of an individual horse, which is an important parameter in equine health and management. It influences various aspects of a horse's physiology, including metabolism, locomotion, and overall health status. Accurate assessment of body mass is essential for determining appropriate feeding regimens, medication dosages, and for evaluating growth and development in young horses. Body mass can be measured directly using scales or estimated using body condition scoring systems and weight tapes. This page compiles peer-reviewed research studies and scholarly articles that explore the methods for assessing body mass, its impact on equine health and performance, and its role in the management of different horse breeds and disciplines.
Oxygen transport during exercise in large mammals. I. Adaptive variation in oxygen demand. This study investigated mechanisms used by horses and steers to increase O2 uptake and delivery (VO2) from resting to maximal rates and identified the mechanisms that enable horses to achieve higher maximal rates of O2 consumption (VO2max) than steers. VO2 and circulatory variables were measured while Standardbred trotting horses and steers (450-kg body mass) stood quietly and ran on a treadmill at speeds up to those eliciting VO2max. As VO2 increased in both species, heart rate and circulating hemoglobin (Hb) concentration increased, thereby increasing O2 delivery by the circulation, while ca...
Oxygen transport during exercise in large mammals. II. Oxygen uptake by the pulmonary gas exchanger. Because the maximal rate of O2 consumption (VO2max) of the horse is 2.6 times larger than that of steers of equal size, we wondered whether their pulmonary gas exchanger is proportionately larger. Three Standardbred racehorses [body mass (Mb) = 447 kg] and three domestic steers (Mb = 474 kg) whose cardiovascular function at VO2max had been thoroughly studied (Jones et al. J. Appl. Physiol. 67: 862-870, 1989) were used to study their lungs by morphometry. The basic morphometric parameters were similar in both species. The nearly 2 times larger lung volumes of the horses caused the gas exchange ...
Total muscle mitochondrial volume in relation to aerobic capacity of horses and steers. The relationship between maximal oxygen consumption rate (VO2max) and mitochondrial content of skeletal muscles was examined in horses and steers (n = 3 each). Samples of the heart left ventricle, diaphragm, m. vastus medialis, m. semitendinosus, m. cutaneous thoracicus and m. masseter, as well as samples of muscles collected in a whole-body sampling procedure, were analyzed by electron microscopy. VO2max per kilogram body mass was 2.7 x greater in horses than steers. This higher VO2max was in proportion to the higher total volume of mitochondria in horse versus steer muscle when analyzed from...
Resistance of mammalian red blood cells of different size to hypertonic milieu. 1. The resistance of different mammalian red blood cells (RBCs) to hyperosmotic environments was studied. RBCs of six mammalian species were exposed to 10 increasingly hyperosmotic NaCl solutions for 24 hr at 5 degrees C. 2. The osmolality at which the amount of liberated haemoglobin reached a preset level (e.g. 3-4% of the total haemoglobin) showed a linear correlation with negative slope with RBC volume. This indicates that small RBCs are more resistant to hyperosmotic milieu than large ones. 3. A similar relation can be found from literature data when maximal urinary tonicities are plotted ...
The nutritional status of pregnant and non-pregnant mares grazing South East Queensland pastures. It has been reported that the increasing nutritional demands from mid to late pregnancy of grazing mares may not be met when these stages of gestation coincide with pastures being affected by frost. It was established in this study that grass/legume pastures could support the nutritional requirements of brood mares by providing digestible energy intakes of 68.0 and 91.7 MJ/day and digestible nitrogen intake of 91.2 and 138 g/day during mid and late pregnancy, respectively.
Speed, stride frequency and energy cost per stride: how do they change with body size and gait? In this study we investigate how speed and stride frequency change with body size. We use this information to define 'equivalent speeds' for animals of different size and to explore the factors underlying the six-fold difference in mass-specific energy cost of locomotion between mouse- and horse-sized animals at these speeds. Speeds and stride frequencies within a trot and a gallop were measured on a treadmill in 16 species of wild and domestic quadrupeds, ranging in body size from 30 g mice to 200 kg horses. We found that the minimum, preferred and maximum sustained speeds within a trot and a...
Experimentally induced cartilaginous fractures (osteochondritis dissecans) in foals fed low-copper diets. Four Thoroughbred foals were weaned from their dams when they were 1 day old and were fed a liquid milk-replacer diet containing approximately 1.7 micrograms of copper/g from plastic buckets for 4 to 7 months. They were kept in stalls with fiberglass walls and asphalt floors covered with rubber pads. Serum copper and zinc concentrations were determined 3 times/week by atomic absorption spectrophotometry, and liver copper and zinc concentrations were determined similarly after acid digestion of tissues taken at necropsy. The amount of soluble collagen in articular cartilage and aortic tissue wa...
Nutritional management of horses competing in 160 km races. A survey was taken of dietary management and training schedules of 54 horses competing in two 160 km endurance races. A total of 52 owners, representing 54 horses, responded to a questionnaire distributed prior to the races. Diet and training schedules were compared between horses that successfully completed the races and those that were eliminated for metabolic reasons. Horses that completed the races were 11.5 +/- 4 years old, weighed 429 +/- 4.5 kg and were ridden 61 +/- 32 km a week when training. Feed intake was reported as "free choice hay or pasture" by 34 of the respondents. Dry matter...
Effect of meal frequency on fluid balance and behavior of ponies. Twelve ponies were fed their total daily ration either as one large meal or divided into six small meals. Pre- and post-feeding behavior was recorded six times a day. Blood samples were taken for 30 min before and two hr after the meal. Plasma protein increased from 7.0 to a peak of 7.3 g/dl with small meals and from 7.3 to 8.1 g/dl with large meals, and returned to pre-feeding levels by 90 min post-feeding. Hematocrit rose from 33.3 to 34.1% with small meals and from 33.0 to 36.0% with large meals. These rapid and short-lived increases indicate a decrease in plasma volume. Plasma osmolality r...
Growth and calcium metabolism in horses fed varying levels of protein. The effect of level of protein intake on growth and calcium metabolism was studied in 24 foals. Starting at four months old, the foals were fed one of three diets containing all nutrients, with the exception of protein, at levels recommended by the United States National Research Council Subcommittee on Horse Nutrition for a 12 month period. The protein levels in the three diets were 9 per cent (low protein) 14 per cent (NRC recommended level) and 20 per cent (high protein). The foals fed the low protein diet were changed to the high protein diet after 140 days when they were nine months old. ...
The effect of lateral and dorsal recumbency on cardiopulmonary function in the anaesthetised horse. The effect of lateral and dorsal recumbency on cardiopulmonary function in six anaesthetised horses were compared. Cardiac output/kg, stroke volume/kg, alveolar ventilation, venous admixture, pulmonary shunt and blood-gas values were determined. From lateral to dorsal recumbency cardiac output/kg decreased non-significantly. A significant increase in pulmonary shunt occurred. A positive correlation between body mass and pulmonary shunt in dorsal recumbency was found. Alveolar ventilation increased significantly in dorsal recumbency when breathing air compared to oxygen.
Relationships between stride length, stride frequency, velocity, and morphometrics of foals. Velocity-dependent changes in stride length and frequency were studied in 19 male foals, 6 to 8 months of age, and were related to body morphometrics. Eighteen distance and 8 angle measurements were digitized from 16-mm films of standing foals. The total mass and the percentage of total mass acting through the forelimbs were also recorded. Stride length and frequency data were extracted from 16-mm films of 239 strides of the walk, trot, and canter-gallop. Polynomial-regression analysis was used to determine the equation that best described the relationship between data of stride length or freq...
Equine energetics. II. Energy expenditure in horses during submaximal exercise. Energy expenditure was measured in four geldings (433 to 520 kg) during submaximal exercise on a racetrack using a mobile open-circuit indirect respiration calorimeter. A total of 304 5-min measurements of O2 consumed and CO2 produced were taken. Measurements were made with and without riders. The amount of energy expended by the horses was exponentially related to speed and was proportional to the body weight of the riderless horse or the combined weight of the horse plus rider and tack. Total energy expended by the four horses walking, trotting, cantering was best described by the equation: ...
Ground reaction force patterns of Dutch Warmblood horses at normal walk. The ground reaction force patterns from 20 clinically sound Dutch Warmblood horses (Group A) were recorded at the normal walk. The data from four to 10 stance phases of each limb were computer averaged after normalisation to the animal's body mass and to the stance time. This analysis method allowed comparison of data from left and right fore- and hindlimbs within and between horses. The left-to-right symmetry in the reaction force peaks of contralateral limbs of one horse exceeded 90 per cent. The time in the stance phase at which the peaks occur were even more symmetrically distributed. A ch...
Exercise and the height of horses. The heights of 89 horses were measured at the withers before and after half a furlong of trotting exercise. The mean (+/- sd) height increase after exercise was 1.75 +/- 0.86 cm and the horses returned to their resting height within seven minutes. There was no linear relationship between gain in height and pre-exercise height.
Roaring in Clydesdales. An endoscopic survey was performed to assess arytenoid cartilage movement during quiet respiration in 48 Clydesdale horses. Physical characteristics which could influence the length of the recurrent laryngeal nerves were also recorded from these horses and the relationship of these characteristics to the presence of abnormal left arytenoid cartilage movements was assessed statistically. Some degree of abnormal arytenoid movement was observed in 50% of the animals over one year of age. No significant correlation between sex, age, estimated weight, height, or neck length could be found although ...
Effect of altered ambient temperature on breathing in ponies. The objective was to determine the effect of moderate changes in ambient temperature (TA) on breathing and body temperature in ponies chronically exposed to a TA of 21 degrees C in the summer and 5 degrees C in the winter. Normal (n = 6) and chronic carotid body-denervated (n = 6, 1-2 yr) ponies were studied during 1) winter months over 3-4 days at 5 (control TA) and 23 degrees C and 2) summer months over 2-4 days at 21 (control TA), 30, and 12 degrees C. Neither rectal nor arterial temperature changed with any alteration of TA (P greater than 0.10). Skin temperature (Tsk) always changed by 2-...
The effect of artificial rearing on the growth of foals. Fourteen Quarter Horse foals were used to evaluate the effects of artificial rearing on growth. Seven foals were removed from their dams at 3 d of age and fed a reconstituted 26% crude protein (CP) milk replacer free choice for 1 mo, at which time ad libitum solid feeding began. Controls were weaned from their dams at 2 mo of age and fed a 21% CP concentrate ad libitum until the end of the trial. Variables measured during the 26-wk trial were live body weight, height at the withers and length of body from point of shoulder to point of hip. No significant differences were found between the two ...
The starch digestion test in the horse. Variable results were obtained when the starch digestion test was carried out on a suspected case of malassimilation in a horse. In order to re-evaluate this test, 15 starch digestion tests were carried out using 4 horses. Results showed a marked variation in the increase in plasma glucose levels between individual horses and especially between poor and good condition horses when the dose of starch was based on body mass. Results also suggest that a fixed dose of starch may give more consistent results.
Studies on equine prematurity 4: Effect of salt and water loss on the renin-angiotensin-aldosterone system in the newborn foal. Plasma renin substrate concentration was measured in 18, four-day-old pony foals after the administration of the natriuretic agent frusemide. Thirteen foals had been delivered spontaneously; labour had been induced in the remaining five mares. Plasma aldosterone concentration was measured in 12 of the spontaneously delivered foals. Renin substrate concentration had risen sharply within 15 mins (P less than 0.005) and peaked at 1 h. The response was consistently greater in the induced foals. Serum sodium concentration fell rapidly in the induced foals (P less than 0.002 by 60 mins) but was bett...
A “standard horse” for use in physiologically based mathematical modelling. Standard data for the horse which can be used in physiologically based mathematical computer modelling are presented. The data includes figures for tissue mass, density and perfusion, obtained by measurement mainly from horses weighing 200 to 300 kg. Other related parameters such as mean transit times and tissue blood volume have been calculated and included in the actual values listed for a 250 kg horse.
Arterial oxygen and carbon dioxide tensions in conscious laterally recumbent ponies. Six adult ponies were trained calmly to assume and maintain left lateral recumbency without the use of sedative or immobilising agents. During a 30 min recumbent period, pHa, arterial oxygen and carbon dioxide tensions (PaO2 and PaCO2) and heart and respiratory rates were monitored at regular intervals to evaluate ventilatory response. Overall, there were no statistically significant differences found between mean control and recumbent or final standing values. When lightweight ponies were compared to heavyweight ponies, only mean PaO2 at 10 mins recumbency was different. This information supp...
A report on the consumption, composition and nutritional adequacy of a mixture of lush green perennial ryegrass (Lolium perenne) and cocksfoot (Dactylis glomerata) fed ad libitum to Thoroughbred mares. Non-pregnant Thoroughbred mares were stabled and subjected to 2 trials, each 24 h in duration, to establish their total consumption of a mixture of freshly cut, lush green perennial ryegrass (Lolium perenne) and cocksfoot (Dactylis glomerata) in approximately equal proportions; and to compare the total intake of crude protein, calcium, phosphorus and mass of the grass mixture on a dry matter basis with their daily nutritional requirements. The body mass of each mare was calculated at the commencement of each trial. In the first trial 2 lactating mares with foals at foot, 65 days and 8 days of ...