Exercise-induced pulmonary haemorrhage (EIPH) is a serious condition that affects the health and possibly the performance of all racehorses. However, only two treatments, furosemide and the Flair™ equine nasal strip, both of which reduce capillary transmural pressure, have been successful in reducing EIPH. Alternatively, transient impairment of platelet function and coagulation during exercise has been considered an additional contributor to EIPH. Consequently, herbal formulations designed to enhance platelet function, and hence coagulation, are hypothesized to reduce EIPH. To investigate the validity of this hypothesis, five Thoroughbred horses completed three maximal incremental exercise tests on a 10% inclined treadmill in a randomized cross-over design experiment. Treatments included twice daily oral administration (for 3 days) of a placebo (PL; cornstarch) and two herbal formulas, Yunnan Paiyao (YP) or Single Immortal (SI). Blood samples for coagulation profiles, complete blood counts and biochemistry profiles were collected before each exercise test. During each test, pulmonary arterial pressure, oxygen uptake, arterial blood gases, plasma lactate and time-to-fatigue were measured. Severity of EIPH was quantified via bronchoalveolar lavage (BAL) at 30–60 min post-exercise. The herbal formulations were not effective in decreasing EIPH (×106 red blood cells ml−1 BAL fluid: PL, 27.1±11.6; YP, 33.2±23.4; SI, 35.3±15.4, P>0.05) or in changing any of the other variables measured with the exception of time-to-fatigue, which was slightly but significantly prolonged by Single Immortal compared with placebo and Yunnan Paiyao (PL, 670±9.6 s; YP, 665±5.5 s; SI, 685±7.9 s, P<0.05). Thus, these results do not support the use of these herbal formulations in the prevention of EIPH.

The present study characterized the fluid and electrolyte shifts that occur in Standardbred racehorses during recovery from high-intensity exercise. Jugular venous blood was sampled from 13 Standardbreds in racing condition, at rest and for 2 h following a high-intensity training workout. Total body water (TBW), extracellular fluid volume (ECFV) and plasma volume (PV) were measured at rest using indicator dilution techniques (D2O, thiocyanate and Evans Blue, respectively). Changes in TBW were assessed from measures of body mass, and changes in PV and ECFV were calculated from changes in plasma protein concentration. Exercise resulted in a 26.9% decrease in PV. At 10 min of recovery TBW and ECFV were decreased by 2.2% and 16.5% respectively, while intracellular fluid volume was increased by 7.1%. There was a continued loss of fluid due to sweating throughout the recovery period such that TBW was decreased by 3.9% at 90 min of recovery. This decrease in TBW was nearly equally partitioned between the extracellular and intracellular fluid compartments. Plasma Na+ and Cl− contents were decreased at 1 min of recovery, but not different from rest by 40 min of recovery. Plasma K+ content at 1 min post exercise was not different from the pre-exercise value; however, by 5 min of recovery K+ content was significantly decreased and it remained decreased throughout the recovery period. It is concluded that there are very rapid and large fluid and electrolyte shifts between body compartments during and after high-intensity exercise, and that full recovery of these shifts requires 90–120 min.

Warm-up of 267 competitors at British Dressage affiliated competitions was observed, including competitors at novice (N) (n = 104), medium (M) (n = 65), Prix St Georges (PSG) (n = 60) and Grand Prix (GP) (n = 38) levels. Competitions were classified as local (n = 103), regional (n = 57) and national championship (n = 107) events. Overall, the mean warm-up duration for competitors at dressage competitions was 29 min 53 s. Total warm-up duration was 25 min 23 s ± 10 min 2 s (mean ± SD) at N level; 31 min 32 s ± 11 min 32 s at M level; 32 min 53 s ± 11 min 19 s at PSG and 34 min 34 s ± 10 min 10 s at GP. Mean proportion of walk, trot and canter at each level was N: walk = 39.26%, trot = 40.31%, canter = 20.43%; M: walk = 43.77%, trot = 32.54%, canter = 23.69%; PSG: walk = 38.53%, trot = 31.03%, canter = 30.43% and GP: walk = 38.79%, trot = 33.26%, canter = 27.95%. There was no effect of rider experience, but level and type of competition affected the proportion of time spent in different paces and total time of warm-up, which was increased at higher levels and championships. Increased warm-up time and specific warm-up design were positively associated with final score at novice and Prix St Georges levels.

Twelve mature and six 2-year-old Arabian horses were used to determine the effect of dietary long-chain polyunsaturated omega-3 fatty acid supplementation on plasma fatty acids and lameness. Lameness scores and stride lengths were measured on day 0. Horses were striated and pair-matched according to age, gender, stride length and, for mature horses, lameness score, and each horse was fed either a treatment diet containing 5.95 g of stabilized omega-3 fatty acids plus a fat carrier (FA), for a total of 19.4 g fat, or a control diet containing 49 g of corn oil (CO) for 75 days. Horses were exercised 5 d week− 1, and blood samples were drawn and body weights recorded on days 0, 25, 50 and 75. Lameness scores and stride lengths were recorded again on day 75. Total plasma omega-3 fatty acid concentrations were higher on all days in FA horses than in CO horses. Total plasma omega-6 fatty acids increased from days 0 to 25, remained elevated through day 50 and returned to baseline on day 75 in all horses. The ratio of plasma omega-6:omega-3 fatty acids was lower in FA horses. Horses on FA had increased plasma docosahexaenoic acid (DHA) on days 25, 50 and 75. No difference in walk stride length was noted; however, FA horses tended to have a longer trot stride after supplementation when compared with CO horses. No differences were seen in prostaglandin E2 (PGE2) metabolite or tumour necrosis factor-α as measured in blood serum. In summary, supplementing omega-3 fatty acids increases plasma DHA, although there was no overall increase in omega-3 in FA horses. While a trend to increase trot stride length was seen, no differences in lameness scores between treatments were noted.

The aim of this study was to determine the heart rate (HR) and work variables of working cattle dogs during actual mustering exercise using a global positioning satellite (GPS) tracking unit‡ with an integrated HR monitor§. The GPS units allowed tracking of seven different Collie and Kelpie working cattle dogs over a total of ten sessions while employed in their usual role of mustering cattle in three locations in Queensland, Australia. Speed, distance and HR data were collected from the dogs during mustering in a variety of working situations. The working dogs covered distances between 13.3 and 30.2 km during mustering sessions ranging from 1 h 59 min to 4 h 24 min at working speeds of up to 43.7 km h− 1. Working temperatures ranged from 29 to 38°C. HR during working exercise ranged between 120 and 237 bpm and was above 180 bpm for 51–68% of the duration of work sessions. There was a positive linear relationship between speed and HR until HRmax (speed 26.0 km h− 1, 233 ± 4.2 bpm), then HR plateaued (R2 = 97.14%, P < 0.001). This study has documented the type of work done by cattle dogs and has shown that GPS devices and HR monitors can be utilized in field conditions to assess the exercise physiology of dogs.

The aim of this study was to determine which oxidant–antioxidant blood markers are of interest for a field exercise test (ET) performed on a racetrack. Healthy Standardbred horses (S: n = 12) and healthy eventing horses (E: n=12) were investigated. Exercise was monitored by measuring velocity (V), heart rate (HR), and plasma lactate (LA). Whilst maximal LA did not differ (11.8±0.88 mmol l−1), maximal V (S: 12.3±0.17 m s−1versus E: 11.1±0.24 m s−1, P<0.05) and final HR (S: 222±1 versus E: 203±8 beats min−1, P<0.05) were significantly different between groups. Venous blood was collected at rest (R) prior to ET and the following oxidant–antioxidant markers were determined: uric acid (UA), ascorbic acid (AA), α-tocopherol (Vit E), vitamin A (Vit A), superoxide dismutase (SOD), glutathione peroxidase (GPx), glutathione (reduced: GSH and oxidized: GSSG), glutathione redox ratio (GRR), copper (Cu), zinc (Zn) and selenium (Se), oxidized proteins (Protox), lipid peroxides (Pool), antioxidant capacity of water-soluble components (ACW) and antioxidant capacity of lipid-soluble components (ACL). The following markers were further determined 15 min (E15) after the ET: UA, ACW, AA, GSH, Protox, Pool, ACL. Standardbreds had significantly higher concentrations of ACW, GSH, ACL and Protox, whilst Se, Zn and SOD were significantly lower than in eventing horses. Exercise induced a significant increase in ACW and UA. GSH decreased in eventing horses and Pool significantly decreased in both horse groups. This study describes a field ET of high intensity for Standardbred and eventing horses, which could be performed by all animals tested. By sampling blood at rest and at E15, changes of the hydrophilic antioxidant defence were partially assessed, whereas no interpretable changes of the lipophilic antioxidants and of oxidation markers (Protox, Pool) could be detected.

The objective of this study was to apply postural sway analysis to measure balance deficits after intravenous administration of detomidine. Six healthy horses were treated intravenously with detomidine (10 μg kg−1, 20 μgkg−1) and saline in random order, with three days between treatments. Postural sway was measured immediately after administration and at 15 min intervals until 120 min had elapsed. Horses stood squarely with all four hooves on a force platform, while the location of the centre of pressure (COP) was recorded continuously for 10 s at 1000 Hz. Five 10 s recordings were analysed and average values calculated for mediolateral COP range of motion, craniocaudal COP range of motion, mean COP radius, COP area and mean COP velocity. All COP variables increased immediately after sedation, but generally returned to normal limits within 15 and 30 min of detomidine administration at 10 and 20 μg kg−1, respectively. The head was lowered for at least 90 min after administration. Balance is affected by detomidine and normal balance is regained later after a higher dose. Procedures requiring balance should not be performed within 15–30 min of detomidine administration. COP variables are a good indicator of the effect of sedation on postural sway, but head position is not.

The aim of this study was to examine the influence of an experienced rider and a novice rider on the stride kinematics of experienced riding horses. SVHS video recordings (50 Hz) were made of ten experienced riding horses jumping a 1.05 m-high vertical fence. The horses were randomly assigned to jump the fence under two experimental conditions: ridden by an experienced rider and ridden by a novice rider. Three trials for each ridden condition were analysed, and the effects of the rider type on four kinematic variables were examined using a repeated measures ANOVA. No significant differences were found between the riders for velocity and stride length during the approach, or for the take-off and landing distances from the fence. The results suggest that the rider's body position and body movement had no effect on the horse's jumping kinematics as measured in this study, and that each horse jumped the fence in its own manner, regardless of what the rider was doing. This is contrary to the current belief that a horse's jumping technique is strongly influenced by the rider. These findings have relevance for both horses and riders, in that if an experienced horse does not respond to a rider's instructions as expected, then the implications for training of the horse and the rider are considerable.

Five previously untrained yearling sled dogs were evaluated for endurance training-induced changes in maximum oxygen consumption (VO2max) and submaximal blood lactate concentrations. Following 3 weeks of light training followed by 4 weeks of moderate training, VO2max increased by 10%, from 180.2 ± 9.9 to 198.7 ± 19.2 ml kg min− 1 (P = 0.046). Light training was not associated with any increase in VO2max. Blood lactate concentrations at the same absolute intensity decreased by 215%, from 9.2 ± 4.7 to 4.3 ± 2.4 mmol l− 1 (P = 0.022). Speeds associated with oxygen consumptions of 70% VO2max increased by 12%, from 4.8 ± 0.4 to 5.4 ± 0.5 m s− 1 (P = 0.008) and speeds associated with VO2max increased by 21%, from 6.7 ± 0.3 to 8.2 ± 0.7 m s− 1 (P = 0.012).

Impact-related peak decelerations with high loading rates are described as indicators of mechanical stress to the limb. The hoof deceleration pattern in the beginning of the stance phase has recently been described, together with ground reaction force measurements at slow speed; however, no information is available at high speeds. The objective of the present study was to investigate the hoof deceleration pattern following impact at slow speeds, comparable to earlier force plate studies, and at high speeds on a racetrack. Eight Standardbreds equipped with triaxial accelerometers mounted on fore- and hind hooves were driven from a jogcart on a harness-training racetrack with a stone dust surface at the mean speeds of 4.7, 5.7, 10.1 and 12.7ms−1. The accelerometer signals were sampled at 10kHz during 10s of constant speed along one straight of the racetrack. The signal was studied for each speed by the analysis of representative peak decelerations. At slow trot, the deceleration pattern was similar to what was found in earlier studies over the force plate. The peak values of both the vertical and horizontal decelerations increased significantly with a higher speed (P≤0.01). It was shown that a higher speed results in changes of the hoof deceleration pattern with higher peak decelerations. The maximum horizontal deceleration, together with the second vertical peak deceleration, were suggested to be major indicators on the mechanical stress subjected to the limb.

The purpose of this work is to investigate the effects of body mass (BM), velocity (V), and hoof shape on compressive surface strains in the wall of the front hoof at the trot. Toe angle (TA), heel angle (HA), toe length (TL), medial and lateral wall length (MWL, LWL) and BM were measured for nine adult, unshod Standardbreds. Five rosette gauges were glued around the circumference of the left forehoof of each animal which was then trotted on a treadmill at a set range of velocities from 3.5 to 7.5 m s−1. Analysis of variance (ANOVA) of principal compressive strains ɛ2 at midstance identified that all primary variables (BM, V, TA, HA, etc.) had a significant effect as did the interactions of TA×HA and BM×TA. These significant variables explained over 96% of the variation in ɛ2. Multiple regression of ɛ2 on these variables gave equations which accurately predicted ɛ2 within 3%, but the individual coefficients did not accurately describe how each variable affected ɛ2. Further tests using bivariate regression gave equations that enabled ɛ2 data to be standardized for BM and V at the gauge locations used here. Strain ɛ2 increased linearly with mass and curvilinearly with velocity (ɛ2∝V+V2), and both caused redistribution of strain to the dorsum and lateral quarter. Variation in each shape variable caused redistribution rather than simple increase or decrease in strains. The primary conclusion with regard to hoof shape is that the effects of change in any one measurement on strain magnitudes are affected by the values of all other measurements. Resolving the interplay among measurements in their effects on ɛ2 will need a considerably larger sample size than that used here.

In Standardbreds, the main aim of early training (begun during the growth period) is the mechanization of athletes leading to a particular gait called the ‘flying trot’. The present cross-sectional study was undertaken to investigate the biomechanical and physiological factors involved in this gait change, and aimed to analyse the effect of age on gait and energetic variables in a population of Standardbred horses under training. One hundred and forty-three horses aged from two to seven years were tested on a track at three speeds (8.5, 10 and 11.6 m s−1) with a gait-analysis system. Gait variables (temporal and linear variables, symmetry, regularity, two-beat rhythm, dorso-ventral, longitudinal and lateral activities) were compared between four age groups (two-, three-, four-, and five-year-olds and above). After a standardized exercise test, two energetic variables (V4 and V200) were also compared between these groups. Most variables were influenced by age/training status. The results indicated that, from young to mature racehorses, stride length and duration increase; and gait becomes more symmetric and more regular. We also observed a decrease in dorso-ventral, longitudinal and lateral activities, i.e. a decrease of thoracic displacements. These differences could be elucidated at slow speed and were still obvious at high speed. V4 and V200 also increased significantly with age/training status. All of these results indicate an improvement in co-ordination and a decrease in metabolic cost with increasing age/training status. Thus gait acquisition could be related to an improvement in trotting efficiency.

Back dysfunction is an important reason for impaired performance in sport horses. Limb movements influence the movements of the back and factors affecting the limbs may therefore affect the movement of the back. The aim of the study was to investigate the influence of weighted boots on the fore- and hind limbs on the movement of the back. The back kinematics of eight horses was studied at the walk and trot on a treadmill. The ranges of movement (ROM) of the back were compared intra-individually, using Wilcoxon matched pairs test, when the horses moved with and without weighted boots on the fore- and hind limbs, respectively. Differences were considered significant at P<0.05. Weighted boots on the hind limbs increased the ROM for dorsoventral flexion and extension in the lumbar back at the walk and decreased the ROM for lateral bending at the thoracolumbar junction at the trot. Weighted boots on the forelimbs decreased the ROM for lateral bending at the withers at the trot. Knowledge of the effect of weighted boots on the back movement is useful in training and rehabilitation of sport horses. Weighted boots on the hind limbs at the walk may induce strengthening of the flexors of the lumbar back and increase the flexion–extension of the lumbar back under controlled conditions.

Feeding regimens for horses are usually based on perceived workload (PW) together with body condition. This can lead to inappropriate energy intake and, in particular, excess weight. Therefore, a more detailed understanding of the factors influencing individual energy needs under practical field conditions would be valuable. The purpose of this study was to evaluate to what extent the variations in actual versus PW may influence the estimated energy intake required to maintain body weight (BW) in individual animals. Eight mature, experienced riding school horses, chosen at random and maintaining a constant BW, were observed in standard flat work lessons with four different instructors at an equine training college. Heart rate (HR) and the structure of the lessons were recorded. Relative workload (RW) was determined for each horse by dividing its average HR per lesson by its estimated maximum HR (HRmax). PW was estimated by each instructor for each horse using a scale of 1–5. One-way ANOVA and t-test were used to determine the differences and Spearman's and Pearson's correlations were used to determine the correlations. The mean estimated RW was 39.1% of the estimated HRmax ( ± 5.7%) and was not significantly different between instructors (P>0.05). Rider weight as a percentage of BW showed a weak but statistically significant positive correlation with mean HR (r2 = 0.14, P < 0.05). Estimated energy intake was negatively correlated with BCS (r2 = 0.65, P < 0.001) and differed significantly (P < 0.05) between light (BW = 455–532 kg) horses (mean 0.18 ± 0.04 MJ kg− 1 BW) and heavy (BW = 622–660 kg) horses (mean 0.15 ± 0.03 MJ kg− 1 BW). No difference was found in estimated energy intake between different workloads (flat work only or flat work and jumping) (P>0.05). When BW was compared with estimated energy intake, no relation was found either (P>0.05). These results suggest that the amount of energy needed to maintain BW in individual horses cannot necessarily be estimated simply on the basis of the intensity and the duration of structured exercise. Other factors including age, individual digestive and metabolic efficiency, body condition and possibly the energy utilized through non-structured activity (e.g. box walking) may need to be taken into account.

Regular monitoring of the heart rate (HR):speed relationship may help evaluate response to training and aid in the early detection of problems. This relationship is normally determined using a treadmill or via a ridden test conducted outside on a track. Simple practical alternative methods to obtain this relationship without access to a treadmill or a track could be of value in the field. To evaluate whether the HR:speed relationship could be determined via an indoor ridden test or a lunge test, HR was monitored on two occasions at least 3 h apart, in 12 adult horses (mixed breed) in a familiar environment during a 5 or 7 m radius circle lunge (unridden) test (5LT or 7LT) and an incremental (ridden) test (RT) on the same day. The RT comprised two ridden laps of the perimeter of a 60 × 40 m indoor school at walk, three laps at trot, three at medium canter and four at fast canter (all on the right rein). The speed of each lap was recorded. The LT comprised lunging for 2 min on each rein at walk, trot and canter. Speed was determined from the number of laps completed and measurement of the distance travelled. HR and speed were highly correlated in both lunge and ridden tests (both r = 0.99 ± 0.01). V140 on the ridden test (5.2 ± 0.6 m s− 1) was significantly greater than on the pooled lunge test data (4.4 ± 0.6; P < 0.0001). There was a negative correlation between recovery HR at 2 min following either the LT or RT and V140 (P < 0.05). The slope of the HR versus speed relationship and V140 were not different between RT and 7LT, but were significantly different from those of the 5LT (P < 0.05). V140 was always lower on the lunge tests compared with the ridden test. This suggests that, in this study, lunging without a rider increased the metabolic demand above that for being ridden at a similar speed. V140 determined by the 7LT gave the closest approximation to the V140 determined by the RT. The HR:speed relationship can be obtained either from riding an incremental test in an indoor school or from an unridden lunge test.

The objective of this experiment was to compare the physiological changes that occurred in horses competing in the cross-country portion of Training, Preliminary and Intermediate horse trials. The hypothesis was that temperature (T), heart rate (HR), respiratory rate (RR), and on-site acid–base and electrolyte monitoring would allow differentiation between difficulty levels in horse trials. Sixteen client-owned horses competing at the Trojan-Horse Spring Horse Trials in Cave Creek, Arizona, USA, were studied. T, HR, RR and anaerobic lithium-heparinized jugular venous samples were obtained before, and 1–2 min after, cross-country exercise. Samples were analysed for blood gases (body temperature-corrected) and concentrations of sodium ([Na+]), potassium ([K+]), chloride ([Cl−]), ionized calcium ([Ca2+]i), blood urea nitrogen ([BUN]) and glucose ([GLC]) using a point-of-care analyser. Results were compared using analysis of variance with the level of significance set at P<0.05. In all groups, exercise increased T, HR, RR, packed cell volume and haemoglobin concentration, and decreased partial pressure of CO2 (PCO2), [total CO2 concentration], bicarbonate concentration ([HCO3−]) and [Ca2+]i (P<0.05). Post-exercise RR was higher, and pH, PCO2, [tCO2], [HCO3−] and base excess were lower, in Intermediate and sometimes Preliminary horses compared with Training horses (P<0.05). It was concluded that horse trials caused milder, but otherwise similar, physical, blood gas and electrolyte changes to those observed in complete three-day events. Physical and point-of-care plasma acid–base and electrolyte monitoring allowed differentiation between horses competing at various levels of difficulty in a horse trial.

At any level of competition, men run faster than women. Consequently, a male speed advantage is often presumed for other species. This assumption was tested in two animals bred for speed: horses and dogs. Results from Thoroughbred (TB), Standardbred (STB) and Greyhound (GH) races were analysed by ANOVA to compare the speeds of victorious males, neutered males (TB and STB only) and females. Separate analyses were run for shorter (TB: ≤ 1609 m, GH: 503 m) and longer (TB: >1609 m, GH: 603.5 m) TB and GH races. All STB races (trotters and pacers) were 1609 m. In TB races, intact males were 0.7% faster than females at ≤ 1609 m (n = 305; P < 0.01) and 1.4% faster at >1609 m (n = 194; P < 0.01). The speed of neutered males was equivalent to that of females at both distances. Gender accounted for 3.8 and 10.7% of the variance in speed at short and long distances, respectively. In STB pacers, intact males were 1.5% faster than females and gender accounted for 10.1% of the variance in speed (n = 96; P < 0.01). Gender was not a significant predictor of STB trotter (n = 95) or GH speed at 503 m (n = 146) or 603.5 m (n = 23). In conclusion, gender has a significant effect on speed of TBs and STB pacers. Although the effect size is small, it may be significant for racing; in a 7 furlong (1408 m) TB race, the 0.7% difference translates to an advantage of several lengths.

The present study used the physicochemical approach to characterize the changes in acid–base status that occur in Standardbred racehorses during recovery from high-intensity exercise. Jugular venous blood was sampled from nine Standardbreds in racing condition, at rest and for 2 h following a high-intensity training workout. Plasma [H+] increased from 39.1±1.0 neq l−1 at rest to 44.8±2.7 neq l−1 at 1 min of recovery. A decreased strong ion difference ([SID]) was the primary contributor to the increased [H+] immediately at the end of exercise, while increased plasma weak ion concentration ([Atot]) was a minor contributor to the acidosis. A decreased partial pressure of carbon dioxide (PCO2) at 1 min of recovery had a slight alkalinizing effect. The decreased [SID] at 1 min of recovery was a result of a 15.1±3.1 meq l−1 increase in [lactate−], as [Na+] and [K+] were also increased by 6.5±0.7 and 1.14±0.06 meq l−1, respectively, at 1 min of recovery. It is concluded that high-intensity exercise and recovery is associated with significant changes in acid–base balance, and that full recovery of many parameters that determine acid–base status requires 60–120 min.

Slippery surfaces are a continuous concern in equine veterinary practice during both treatment and orthopaedic work-ups, especially when horses have to trot on circles. Sliding of the equine foot on the ground with the potential of injury is prevented if the horizontally acting accelerating or decelerating forces on the foot do not exceed maximal friction. Friction can be calculated and therefore anticipated if the coefficient of friction (μ) between the foot of the horse and the particular ground surface is known. Friction between shod and unshod cadaver equine hooves and different ground surfaces (concrete, tarmac and rubber) was determined by pulling the hooves horizontally in a uniform motion. Horizontal forces (Fh) were measured on a force plate and with a portable digital electronic force meter. The coefficient of friction (μ) was calculated as the quotient between Fh and the gravity force (N) of the object, hence: μ = Fh /N. This study has shown that the coefficient of friction between equine hooves and a specific ground surface can be determined using a portable digital force meter or a force plate. Friction significantly depended not only on the type of surface but also on shoeing of the equine foot. Bare feet showed more friction with the hard surfaces (bricks and tarmac), the shod feet showing more friction with the rubber surfaces. Coefficients of friction could be used to estimate the possibility of injuries occurring in the equine industry during exercise and/or lameness or pre-purchase examinations.

This study tested the hypothesis that exercise training would alter feed intake (FI), body composition (BC) and plasma concentrations of active ghrelin, leptin, cortisol, insulin and glucose. Eight Standardbred mares (12±2 years, 509±36 kg body weight (BW), mean±SD) were trained (EX) in an equine Equi-ciser (initially 3 days per week at 60% maximal heart rate (HRmax) for 20 min and gradually increased to 5 days per week at 70% HRmax for 30 min, with a 10-min warm-up and 10-min cool-down period at the walk). Six mares (12±2 years, 537±45 kg) served as non-exercise controls (CON). All mares were unfit and had not been subjected to conditioning for 3 years before the experiment. Pre- and post-training incremental exercise tests (GXT) were run to determine HRmax and maximal oxygen uptake (VO2max). A total mixed ration (TMR) of hay cubes was fed free choice for 16 h day-1 with the primary experiment following a 6-week diet adaptation period. Mares' FI was measured daily and reported in grams per kilogram BW of feed eaten per week. Changes in BC were assessed using BW (electronic scale) and percentage fat calculated using rump fat thickness and the Westervelt equation. Blood samples were taken every 2 weeks at 15:25, before mares were given their allotment of hay cubes on a day when they did not exercise, to measure plasma hormone and glucose concentrations. Gastroscopy for gastric ulcers was performed before, during and after the trial. VO2max increased by 7.0% (P<0.03) in EX, but did not change (P>0.05) in CON. FI decreased (P<0.001) in both groups, but was only different (P<0.02) between EX and CON at week 3. Digestible energy (DE) intake (Mcal day-1) was initially higher (P<0.001) than calculated DE requirements in EX. However, over time, DE only matched and then fell below (P<0.03) the DE intake required for training. In CON horses, DE intake was higher (P<0.001) than calculated requirements. BW and percentage body fat increased (P<0.001) over time in EX and CON. Plasma leptin concentration increased (P<0.001) over time in both groups, but was 60% higher (P<0.04) in CON compared to EX at weeks 4–8. There were no differences (P>0.05) in active ghrelin, glucose, insulin or cortisol between the groups and over time. Five out of seven EX mares developed gastric ulcers. No CON mares developed gastric ulcers. Training was associated with changes in plasma leptin concentration, an increased incidence of gastric ulcers and a disruption of the balance between required DE and actual intake.