bluuebunny/crossref_metadata_2025_split huggingface dataset:
Mechanical properties of metacarpal bones of foals fed different energy and phosphorous levels
Authors: LEACH D. H. , CYMBALUK NADIA F. , HENDRIX ARLENE , WILLIAMS K. 
Published: June 2010

SummaryThe mechanical and geometric properties of metacarpal bones of 41 Quarter Horse yearlings fed diets with different energy and phosphorus levels were tested and compared. A 2 times 3 factorial experiment was used to compare 2 energy sources and 3 levels of dietary phosphorus. The 2 energy sources were based either on alfalfa (2.65 Mcal digestible energy [DE]/kg dry matter [DM] feed) or on grain (3.09 Mcal DE/kg DM). In each diet type, the 3 phosphorus concentrations included: an unsupplemented, low phosphorus (LP) diet; a normal phosphorus (NP) diet supplemented to meet NRC (1978) requirements for weanling foals; and a high phosphorus (HP) diet supplemented to supply 150% of 1978 NRC phosphorus requirements. At the completion of the feeding trial, the yearling horses were destroyed and the metacarpal bones recovered. The left metacarpus was serially sectioned at 0.5 cm thicknesses with a band saw and a section was sampled for histology and measurement of geometric properties including the rectangular moments of inertia (Ix, Iy), the products of inertia and principal moments of inertia (Ixx, Iyy). The moments of inertia were then recalculated to the change in orientation of the x‐y axes and symbolised Ix1 and Iy1. Energy intakes were similar despite differences in energy content of the forage and grain diets. However, forage‐fed yearlings had lower (p<0.0589) breaking strengths (23.4 kilograms per square inch [ksi] than grain‐fed horses (25.4 ksi). The geometric properties between LP and NP groups did not differ. However, the geometric properties (Ix1, Ixx, Iyy) differed (p<0.05) between the HP groups and the LP and NP groups. Within the NP group, (Iyy) differed (p<0.038) between males and females. The right metacarpus, with both small metacarpal bones removed but with the periosteum intact, was loaded in a 4‐point bending until failure. The metacarpal bones were placed in a specially‐made Instron tester made so that the mid‐diaphyses were loaded. All bones failed in a single plane at right angles to the main axis of the bone. Seventeen of the 41 bones (41.5%) fractured through the nutrient foramen. The mechanical properties of males and females did not differ except in the NP group wherein stiffness of the metacarpal bone of females was lower (p<0.05). In the NP group, males were 14% heavier (p<0.0384) than females. Although most mechanical properties did not differ between the LP and NP groups, the HP group had a higher load at yield point (6397 N) than the LP group (5789 N). Phosphorus intakes, therefore, affect both mechanical strength and geometric properties of growing horses.
The influences of different treadmill constructions on ground reaction forces as determined by the use of a force‐measuring horseshoe
Authors: ROEPSTORFF L. , JOHNSTON C. , DREVEMO S. 
Published: June 2010

SummaryIn the present study, 3 horses trotted at a series of different speeds on a SätoTM treadmill and a coir mat treadmill to determine the differences in ground reaction forces due to the surface of the treadmills. The horses were equipped with a force‐measuring horseshoe to quantify the ground reaction forces which were analysed with spectral analysis. Significant differences between the 2 treadmills were seen in frequency content of the power spectrum for the vertical force at the frequency interval 30–80 Hz and for the fore‐aft force at 30–40 Hz and 70–120 Hz.
An index of the environmental thermal load imposed on exercising horses and riders by hot weather conditions
Authors: SCHROTER R. C. , MARLIN D. J. 
Published: June 2010

SummaryThere is a need to determine objectively the environmental heat load imposed on horses competing to an international standard in 3‐day‐events in environments where there is likely to be a high level of radiation added to high ambient temperatures and relative humidity; the presently used FEI ‘Comfort Index’ is severely limited in its applicability. It is proposed that the Wet Bulb Globe Temperature (WBGT) Index be used. This index was originally established for man exercising strenuously under harsh climatic conditions with high solar radiation levels. It may be defined as:WBGT = 0.7Twb + 0.3Tgwhere Twb is the wet bulb temperature of the ambient air, measured in the shade and Tg is the black globe temperature. Climatic conditions should be monitored continuously at a site representative of the detailed topography and nature of the terrain of the competition course.The upper limit for the index for competitions involving fit, fully acclimatised horses, running on ground of optimal going, is recommended to be 32.5°C. This limit should be reduced, by an as yet undetermined amount, for unacclimatised and unfit horses or when the going is less good.
Estimation of metabolic energy cost and heat production during a 3‐day‐event
Authors: JONES J. H. , CARLSON G. P. 
Published: June 2010

SummaryThe 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 to typical running speeds and distances for each of the 4 phases of the endurance day of an Olympic level (CCI****) 3‐day‐event to provide an estimate of the energy expenditure and heat production during each phase. In a given horse, the rates of energy expenditure and heat production are determined by running speed, while total energy expenditure and heat production are determined by a combination of running speed and duration of exercise at that intensity. The highest calculated rate of energy expenditure and heat production occurred during Phase B, the steeplechase, followed closely by Phase D, the cross‐country course. Interestingly, the highest total energy expenditure and heat production occurred on Phase C, Roads and Tracks, which is usually considered a period for cool down and recovery between the relatively high speed steeplechase and the demanding cross‐country course. Nevertheless, because the rate of energy expenditure is low during this phase, the horses would be expected to lose heat and lower body temperature during this interval. In hot and humid climates, dissipation of the exercise‐induced heat load may be compromised, leading to a narrower range of safety between the rate of heat production and the ability of the horse to dissipate this heat to the environment The results of this study could be used, should environmental conditions dictate, to provide quantitative guidelines as to how specific alterations of speed or distance of the various phases of the event would affect heat production.
Physiological, metabolic and biochemical responses of horses competing in the speed and endurance phase of a CCI**** 3‐day‐event
Authors: MARLIN D. J. , HARRIS PATRICIA A. , SCHROTER R. C. , HARRIS R. C. , ROBERTS C. A. , SCOTT C. M. , ORME C. E. , DUNNETT M. , DYSON SUE J. , BARRELET F. , WILLIAMS B. , MARR CELIA M. , CASAS I. 
Published: June 2010

SummaryThe 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 wind speed were 13 ± 1 and 20 ± 2°C, 54 ± 3 and 55 ± 10%, 17 ± 2 and 29 ± 4°C and 2.7 ± 0.7 and 1.2 ± 0.3 m/s, for 1993 and 1994, respectively. Mean heart rate duringPhases A, BandDwas not significantly different between years, but mean heart rate duringPhases CandXwas significantly higher in 1994. Mean (± s.d.) heart rate onPhases BandDfor all horses in both 1993 and 1994 was 198 ± 8 and 188 ± 11 beats/min, respectively. Mean heart rate duringPhase Dshowed a poor correlation with mean speed (r=0.412). Total mean (± s.d.) weight loss from the start ofPhase Ato the end ofPhase Dwas 15.5 ± 6.1 kg in 1993 and 16.5 ± 5 kg in 1994 and did not differ significantly between years. Following 14–18 h completion ofPhase D, mean bodyweight was not significantly different from that at the start ofPhase Ain either year. Mean rectal temperature at the end ofPhase Dwas 41 ± 0.6°C and 41.1 ± 0.6°C in 1993 and 1994, respectively (P>0.05). Both the lowest (39.7°C) and highest (41.8°C) rectal temperatures were recorded at the end ofPhase Din 1994. Plasma lactate concentrations at the end ofPhase Dwere 8.5–38.5 mmol/1. The highest lactate concentration also coincided with the highest plasma glucose concentration (11.4 mmol/1) as well as the joint fastest time in either year, although overall lactate showed only weak correlations with mean speed onPhase D(r=0.12, 1993; r=0.58, 1994). While the Speed and Endurance test at CCI**** level run in a temperate climate presents a considerable challenge to the fitness and ability of the horses competing, the metabolic and physiological changes are not extreme. The majority of horses that finish the test appear to undergo a rapid and considerable degree of recovery and are able to present sound at the final inspection, take part in the showjumping test and complete the competition.
Heart rate response and plasma lactate concentrations of horses competing in the cross‐country phase of combined training events
Authors: WHITE SUSAN L. , WILLIAMSON LISA H. , MAYKUTH PATRICIA L. , COLE S. P. , ANDREWS E. M. , GEISER D. R. 
Published: June 2010

SummaryThe 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°C ± 0.6 and 88.4% ± 8.9 RH) to moderately hot and humid (27.8°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 competition were: 154.4 ± 19.2 beats/min (n=45) (N), 160.4 ± 28.1 beats/min (n=47) (T), 160.6 ± 33 beats/min (n=53) (P), 181 ± 26.6 beats/min (n=29) (I) and 194.6 ± 4.2 beats/min (n=4) (A). Plasma lactate concentration was determined at rest in a random sampling of horses (n=36) from all competitions and within 60 s of completion of the cross‐country phase in all horses. Mean ± s.d. lactate concentration at rest was 0.98 ± 0.3 mmol/1. Mean ± s.d. lactate concentrations (mmol/1) of horses after exercise were: N=8.1 ± 7, T=11.5 ± 4.7, P=17.6 ± 6.1, I=19 ± 6.7 and A=21.3 ± 7.3. Mean plasma lactate increased significantly (P<0.001) as levels of competition increased, although there were few significant differences in heart rate between levels.Rectal temperatures were taken immediately after completion of the cross‐country phase and 10 min later. Mean ± s.d. rectal temperatures were significantly higher 10 min after completion of the cross‐country than those taken immediately after cross‐country (P<0.001). Rectal temperatures 10 min after completion of exercise were significantly higher as the level of competition increased for N through I (P<0.001). Rectal temperatures 10 min after completion of exercise were correlated with ambient temperatures (r=0.22, P=0.01). There was no significant correlation between either pulse or respiratory rate taken immediately after completion of exercise with heart rate during the course.
Heart rate response and plasma lactate concentrations of horses competing in the speed and endurance phase of 3‐day combined training events
Authors: WHITE SUSAN L. , WILLIAMSON LISA H. , MAYKUTH PATRICIA L. , COLE S. P. , ANDREWS F. M. 
Published: June 2010

SummaryThe 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 andPhase D=174 ± 19.6 beats/min. Mean ± s.d. heart rates onPhases AandCwere significantly different from mean heart rates onPhases BandD.Plasma lactate concentrations were determined at rest, within 60 s and 10 min after the end ofPhase Dor the cross country test. Mean ± s.d. lactate concentrations were highest immediately post exercise (mean=18.4 ± 5 mmol/1 for all horses) and had declined significantly in 10 min (mean=15 ± 6.8 mmol/1 for all horses). Mean ± s.d. heart rates and lactate concentrations were not significantly different among levels of competition at each time period. The intensity of work of fit horses successfully competing in 3‐day combined training events consists of both low intensity aerobic exercise and more intense submaximal work with significant anaerobiosis. The work intensity is remarkably constant throughout different levels of competition, despite the increasing distance, number and difficulty of jumping efforts and faster optimum speeds.
Haematological and biochemical changes in horses competing in a 3 Star horse trial and 3‐day‐event
Authors: ANDREWS F. M. , GEISER D. R. , WHITE SUSAN L. , WILLIAMSON LISA H. , MAYKUTH PATRICIA L. , GREEN ELEANOR M. 
Published: June 2010

SummaryHaematological and biochemical changes in horses competing in the Endurance Test (Phase TandD) of an advanced Horse Trial (HT, n=22) and the Endurance Test (Phases A‐D) of an advanced (CCI***) 3‐day‐event (TD, n=11) over a similar course on the same day were studied. Environmental conditions during the event were cool (5.5–11.1°C). Blood samples were collected from the horses in each group the evening prior to the Endurance Test, within 60 s after, and 10 min after, completion ofPhase D(cross‐country jumping). The following were determined in the blood samples and compared between the 2 groups of horses: packed cell volume (PCV), serum total protein [TP], serum albumin [ALB], plasma lactate [lactate], serum total calcium [TCa], plasma ionised calcium [Ca++], serum inorganic phosphate [PO4], plasma pH, plasma sodium [Na], plasma potassium [K], serum chloride [Cl], serum urea nitrogen [SUN], serum creatinine [Cr] and serum glucose concentrations and aspartate aminotransferase (AST) and creatine kinase (CK) activities. The PCV and [Cr] were higher in the TD group and approached significance (P=0.063 and P=0.057, respectively). The [TP], [ALB], [Na], glucose concentration and CK, and AST were significantly higher and [Cl] and [PO4] were significantly lower in the TD group after exercise when compared to the HT group. It was deduced from these data that the horses competing in the 3‐day‐event experienced greater fluid and electrolyte losses, reduced glomerular filtration, higher glycogenolysis and had greater leakage of enzymes from working muscles during competition than horses competing in the horse trial.
Effects of shortening the steeplechase phase (Phase B) of a 3‐day‐event
Authors: ANDREWS F. M. , WHITE SUSAN L. , WILLIAMSON LISA H. , MAYKUTH PATRICIA L. , GEISER D. R. , GREEN ELEANOR M. , RALSTON SARAH L. , MANNSMAN R. A. 
Published: June 2010

SummaryThirty‐four horses competing in the Endurance Test of a 3‐day‐event were divided into 3 groups: horses inGroup 1(n=15) competing in a 3.5 min steeplechase phase; horses inGroup 2(n=13) in a 3 min steeplechase phase (Phase B) and horses inGroup 3(n=6) in a 2.5 min steeplechase phase. The shortening ofPhase Bwas associated with a lengthening ofPhase Cso that the total distance of the event for all horses was 14,940 m. Bodyweight (BW) was measured and total body water (TBW) and water loss estimated. Blood samples were collected from the horses prior to the Endurance Test, at the end ofPhase B, the 4 km marker onPhase C(C4K), the end ofPhase C, and 20 min after the completion ofPhase Dfor measurement of packed cell volume (PCV), total plasma protein [TPP], lactate, ionised calcium, pH, sodium, potassium, chloride, total calcium and glucose concentrations, and aspartate aminotransferase, creatine kinase and lactate dehydrogenase activities. Mean ± s.d. ambient environmental temperature during the Endurance Test was 25.3 ± 1°C (range 20.3°C‐29.7°C). Mean relative humidity was 43.8 ± 2.4% (range 39%‐48.6%) and the average ‘comfort index’ (CI) was 121. There were no significant differences between the groups competing in the Endurance Test, despite the shorterPhase B.However, there were significant decreases in BW, TBW, net exchangeable cations, chloride, ionised calcium, and pH. The sodium and total calcium concentrations remained at near pre‐event values. The PCV, TPP, lactate, potassium, glucose, aspartate aminotransferase, and lactate dehydrogenase activity increased during the Endurance Test, when compared to pre‐event values. Horses competing in this competition experienced significant fluid and electrolyte losses, reduced glomerular filtration, increased glycogenolysis and had significant leakage of enzymes from working muscles during competition. These changes could not be reduced by shorteningPhase Band lengtheningPhase C.
Clinical observations made in nonheat acclimated horses performing treadmill exercise in cool (20°C/40%RH), hot, dry (30°C/40%RH) or hot, humid (30°C/80%RH) conditions
Authors: HARRIS PATRICIA A. , MARLIN D. J. , MILLS P. C. , ROBERTS C. A. , SCOTT C. M. , HARRIS R. C. , ORME C. E. , SCHROTER R. C. , MARR CELIA M. , BARRELET F. 
Published: June 2010

SummaryFour horses (H, J, N and M) undertook a treadmill competition exercise test (CET), designed to simulate the physiological and metabolic stresses of the Speed and Endurance phase of a 3‐day‐event, under 3 different environmental conditions: 20°C/40% relative humidity (RH) (cool, dry [CD]: 2 sessions); 30°C/40% RH (hot, dry [HD]) and 30°C/80% RH (hot, humid [HH]) (Marlin et al. 1995). A number of subjective clinical observations were made at designated time points throughout the exercise test and initial recovery period including buccal mucous membrane colouration, capillary refill time, neck and point of shoulder skin pinch recovery time, grade of abdominal sounds; anal sphincter tone as well as the presence or absence of fatigue and ataxia. The aim was to investigate their value in predicting performance in the final canter phase of the CET equivalent to the cross‐country or Phase D of a field competition. In addition, the use of a more objective assessment, the cardiac recovery index (CRI), was investigated together with the heart rate, rectal temperature and respiratory frequency at the end of Phase C and at the 8 min point of the 10 Minute Box (8′X). The CRI was calculated according to the formula CRI = P2‐P1 where P2 = the heart rate in beats/min at the 8 min point of the ‘10 Minute Box’ (Phase X) of the CET. P1 = the heart rate (beats/min) at the 7 min point just before the horse was made to trot over a distance of 80 m at a speed of 3.7 m/s (at a 3° incline) before returning to a walk.The study suggested that the subjective tests carried out at the ‘End‐C’ and/or ‘8′X’ time points were not useful in predicting subsequent performance in the final canter phase (Phase D) and neither were heart rate, rectal temperature or respiratory frequency. However, the only horse (Horse H) to complete the full CET under HH conditions was the only animal to show a decrease in respiratory frequency between the End‐C and 8′X time points. All others showed an obvious increase. Under HH conditions, Horse H also had the lowest CRI. For 3 of the horses the highest CRI value was found under the HH conditions, for the fourth horse an equally high CRI value was found with one of the CD sessions. However, under the HH conditions, both P1 and P2 values were >100.The study suggested that it could be beneficial if a suitably modified CRI test, as well as a procedure to monitor the change in respiratory frequency during the 10 Minute Box, were evaluated further on the treadmill and in the field with respect to their potential usefulness as additional aids to the assessment of a horse's suitability to proceed to Phase D.
Thermal and cardiorespiratory responses of horses to submaximal exercise under hot and humid conditions
Authors: GEOR R. J. , McCUTCHEON L. J. , ECKER GAYLE L. , LINDINGER M. I. 
Published: June 2010

SummaryThe objective of this study is to determine the effects of heat, and heat and high relative humidity (RH) on the thermal and cardiorespiratory responses to exercise and recovery. Five Thoroughbred horses (age 3 to 6) completed exercise tests under each of 3 environmental conditions: cool, dry (CD, room temperature (T) = 20°C, RH = 45–55%), hot, dry (HD, T = 32–34°C, RH = 45–55%) and hot, humid (HH, T = 32–34°C, RH = 80–85%). Horses were exercised at a workload equal to 50% of V̇O2maxon a treadmill set at a 10% slope until attainment of a pulmonary artery blood (PA) temperature of 41.5°C followed by a 30 min walking recovery (0% slope), and a further 30 min standing recovery in the same environmental conditions. Blood (PA), rectal, skin (dorsal aspect of the thorax) and muscle (middle gluteal muscle) temperatures and heart rate were measured before, during and after exercise. Respiratory rate was measured before exercise and during the 60 min recovery period. Exercise duration for HD (mean ± s.e. 28 ± 2 min) and HH (16.5 ± 1 min) was significantly (P<0.05) decreased when compared with CD (37 ± 2 min). The rate of increase in PA blood temperature was significantly higher in HH (0.26 ± 0.03°C/min) than in HD (0.17 ± 0.04°C/min) and CD (0.12 ± 0.05°C/min). Temperature in the middle gluteal muscle after 15 min of exercise was significantly higher in HH (41.9 ± 0.3°C) than in HD (40.7 ± 0.25°C) and CD (40.15 ± 0.35°C); whereas rectal temperature at the end of exercise was significantly lower in HH (39.1 ± 0.3°C) than in HD (40.1 ± 0.3°C) and CD (40 ± 0.2°C). The PA blood:skin temperature difference was significantly smaller in HD and HH than in CD. When compared with CD, temperatures at all sites were higher in HD and HH during the 60 min of recovery. Throughout exercise and recovery, heart rate was significantly higher in HH when compared with the other conditions. Post exercise respiratory rate was significantly higher in HD and HH than in CD throughout recovery. It was concluded that the added thermal loads of high temperature and relative humidity increased the rate of heat storage during exercise and delayed dissipation of heat during recovery. The impairment to heat dissipation was probably the result of a reduced capacity for heat transfer from the skin to the environment.