Ann. Anim. Sci., Vol. 16, No. 1 (2016) 87 97 DOI: 10.1515/aoas-2015-0049 Can releasing racehorses to paddocks be beneficial? Heart rate analysis preliminary study* * Iwona Janczarek 1, Witold Kędzierski 2, Anna Stachurska 1, Izabela Wilk 1 1 Department of Horse Breeding and Use, Faculty of Animal Biology and Breeding, 2 Department of Biochemistry, Faculty of Veterinary Medicine, University of Life Sciences in Lublin, Akademicka 13, 20-950 Lublin, Poland Corresponding author: iwona.janczarek@up.lublin.pl Abstract The aim of the study was to assess the effect of allowing racehorses to use paddocks, on the heart rate (HR). HR was used as a measure of horses psychosomatic response to environment effect. The study involved 90 Purebred Arabian horses divided into three groups of equal numbers of stallions and mares. The control group (C) was trained at the racetrack. The other two groups were trained in an off-the-racetrack centre and therefore, they were regularly transported to the races. One of those groups (T) was maintained in the same manner as horses at the racetrack, without access to paddocks. Horses from the other group (TP) were additionally released into a paddock every day. Each horse was examined within five three-week measuring periods, during one training season. HR was registered at rest, during saddling, and while walking with a rider. A multivariate analysis of variance (ANOVA, GLM) was used to compare HR. The significance of differences between means was determined using Tukey s test. HR registered from 2nd to 5th measuring periods during saddling and walking was generally lower in TP than in C. For example, in stallions during saddling, HR amounted to: 54.4±14.7 vs 65.3±12.1, 53.2±13.5 vs 64.4±13.1, 55.4±12.2 vs 65.0±11.0 and 53.4±14.0 vs 66.5±13.8 beats/min, respectively. In T stallions and mares, HR tended to increase when the transportation began which was particularly pronounced at rest. The study revealed that the possibility of turnout into paddocks reduced HR in racehorses, in comparison to horses trained at racetrack. Training for horse racing in an off-the-racetrack centre with the use of paddocks was assessed as beneficial, provided the horses were used to being transported. Key words: heart rate, Purebred Arabian racehorses, training, welfare Horses involved in a race training routine are exposed to many stressful stimuli (Mills et al., 1996; Alexander and Irvine, 1998). New living conditions, transport, disorders of social life, physical effort etc. negatively influence the psycho-physio- *This study was supported by the grant No. 180061.
88 I. Janczarek et al. logical balance of a horse (Mircean et al., 2008; Vatistas et al., 1999; Irvine and Alexander, 1996; Art and Lekeux, 2005). The exercise, however, cannot be eliminated. For this reason, the influence of other negative factors should be controlled (Evans, 2003). Through such an evaluation, at least some of these factors or their effects may be mitigated (Leiner and Fendt, 2011). One of the most common approaches to evaluating the horse psychosomatic response to environment effect, is the measuring of heart rate (HR) (Rietmann et al., 2004; Jansen et al., 2009; Visser et al., 2002). The increase in HR was reported in horses moved to new training centre (Janczarek and Kędzierski, 2011 b). According to Janczarek and Kędzierski (2011 c), even keeping the stallions and mares in the same stable resulted in a marked HR increase. Exposure of horses to novelty and just expectation of novelty also increased their HR (Janczarek and Kędzierski, 2011 a). Moreover, the exposure of racehorses to new objects caused a decrease in the gallop speed (Hada et al., 2003). Thus, racing horses exposed to stressful situations showed lowered performance. In addition, the commercialisation of racecourses contributes to the creation of living conditions for horses which are completely inconsistent with the biology of this species (Chaya et al., 2006; MacTaggart et al., 2010). Keeping a racehorse in a box for most of the day results in restriction of freedom of movement which can trigger stereotypy (Henderson, 2007). An unfamiliar environment, isolation, and short feed intake, can also increase the risk of stereotypies (Waters et al., 2002). Therefore, some researchers (e.g. Evans, 2003) and trainers (Del Castillo and Schwartz, 1997) believe that the welfare of the racehorse could be improved by training horses at offthe-racetrack training centres. In these small training centres, an individual approach to the animals is increasingly appreciated. Training horses in off-the-racetrack centres may prove to be very beneficial, despite the need to transport the horses to the racetrack (Kutte, 2012). The transport seems to be an important factor, directly influencing the physical and mental fitness of horses, including HR increase (Fazio et al., 2008; Schmidt et al., 2010 a, b). A hypothesis has been put forward that releasing the horses into paddocks may cause beneficial results. It is believed this activity may not only reduce the negative consequences of transport, but may also help in alleviating the challenges of training and competing in the races. The positive effects of releasing the horses into paddocks were described by Werhahn et al. (2012). These authors have pointed out that paddocks are currently the only possibility for the horses to practise any social interactions. Social interactions are an essential part of natural animal behaviour and they are of great importance for a horse s positive well-being. The aim of this study was to perform a comparative analysis of HR as a physiological parameter that indicates the psychosomatic response of racehorses maintained at a racetrack or at a training centre with access to paddocks. Material and methods The study was supported by the Polish National Centre for Research and Development (grant number 180061). Animal care and experimental procedures were
Effect of allowing racehorses to use paddocks on heart rate 89 in accordance with European Commission Regulations on the Protection of Experimental Animals and were approved by the Local Ethics Review Committee for Animal Experiments. The study lasted from 1st March to 31st October and it covered one racing season. It was conducted in a racing stable at the racetrack, and in an off-the-track training centre, 200 km away from the racetrack. HR was registered for each of the horses in five three-week measuring periods in March, April, June, August and October (1st to 5th measuring periods, respectively). Training (training-only cycle) took place in the first two periods, and the next three periods included both training and races (the race-training cycle). During the race-training cycle, each horse participated in a race at least once a month. The three-week length of the measurement periods was assumed to standardise the measurements within the training-only and race-training cycles and to omit the periods of races. In the periods of races, T and TP horses could have been influenced by a fatigue after races and transport. The results collected from the three groups in the 1st measuring period were treated as the baseline results. Horses Ninety Purebred Arabian stallions and mares were included in the study. At the start of the study, they were between 31 and 33 months old. The horses were clinically healthy and did not show any stereotypies like crib biting, weaving, aggressive behaviour etc. The animals were divided into three equal groups. The control group (C) was trained in Służewiec Horse Race Track (Warsaw, Poland). The other two groups were trained in an off-the-racetrack centre. Therefore, they were regularly transported to the races. One of those groups (T) was maintained in the same manner as horses at the racetrack. Horses from the other group (TP) were additionally released into a paddock every day. Each group contained an equal number of stallions and mares. In the stables, T and TP horses stayed together, however boxes of TP horses were neighbours of each other. Before and during the experiment, the horses were fed and cared for in accordance with the standards set for racehorses (Landers, 2006). The horses were brought to race stables three months before the study. In this time, the horses were acclimated and then trained to be saddled and ridden. The horses were housed in box stables of similar parameters (dimensions of boxes: 3.5 m 4 m). The training procedure used for all the horses was identical. It was developed and monitored by the same trainer. The training sessions lasted about 30 minutes and were performed in the mornings, six days a week. The training sessions were usually identical and only a few sessions before a race the training intensity was individually matched. After the training session, the horses were directed to an automatic horse walker and walked for 30 minutes. Then, they returned to their boxes. C and T groups stayed in boxes until the next training. The horses from group TP were released into a paddock every afternoon for 60 minutes. The mares were pooled into paddocks of approximately 800 m 2 area in stable groups of five familiar individuals. The stallions were released individually into small yards of about 220 m 2 area. The yards were located near each
90 I. Janczarek et al. other and separated by strips of land with a width of 3 m, so the stallions could only see and hear each other but they were not able to touch. The commercial trailer used for transportation of T and TP horses had six single compartments (six horses per load). It was driven by always the same driver. Feed and water were not available during transportation. The horses were tied in single compartments facing forward to the direction of travel. The 4-hour journey took place in the morning (around 5:00 am), on the day in which the horse participated in a race. Just after races, in the evening, the horses were transported back to their training stable. HR measurement Polar S810 devices with 5 s recording intervals were used for measuring the HR (beats per minute, bpm). An elastic belt with the transmitter was put around the chest of the horse. The data were downloaded from the transmitter to the computer with the use of an interface. PolarProTrainer 5.0 software was used to analyse the HR recordings. HR was registered at rest, during saddling, and while walking with a rider. HR at rest was measured 6 to 10 min after attaching the elastic belt around the chest, when the horse was in its box. Next measurement was taken still in the box, when the horse was tentatively cleaned and saddled, until the girth was attached. HR during the walk was measured as soon as the horse under the rider left the stable. Each measurement lasted 5 min. The saddling and walk prepared the horse to training gallop on the track. Racing performance estimation Two following parameters were used as racing performance indicators: individual success coefficient (ISC) and handicapping weight (HCW). ISC means total amount of money earned by the horse divided by the average amount of money earned by all horses of the same age. When the ISC value is higher than 1.00, it means the horse s racing performance is better than that of the average horse. Similarly, when the ISC value is less than 1.00, the horse performs worse than the average racehorse. HCW was assumed according to the handicapping system announced at the end of the racing season (www.pkwk.pl, 2014). Statistical analysis The data were checked with regard to the normality of distribution at P 0.01 (Tests: Shapiro-Wilk, Kolmogorov-Smirnov, Cramer-von Mises, Anderson-Darling). The tests did not reject the normal distribution hypothesis. A multivariate analysis of variance (ANOVA, GLM) was used to compare HR values as well as the racing performance parameters. In the analysis, the experimental group (C, T and TP), horse sex (stallions and mares), and interactions between the factors were taken into account. Results of consecutive measuring periods, separately for stallions and mares of the same group, were compared using repeated measures analysis of variance (Little et al., 2002). The significance of differences between means was determined using Tukey s test. Statistical significance was accepted at the level of P 0.05.
Effect of allowing racehorses to use paddocks on heart rate 91 Results HR in stallions in C group did not differ significantly in subsequent measuring periods (Figure 1). In T group, a significant increase in HR was reported in the 3rd period and a decrease of this parameter was seen in the 5th period. In TP group, the stallions HR during the 5th period was significantly lower than in the 1st period. After the race-training cycle began (3rd period), the highest HR was found in stallions from T group compared to C and TP. During the 5th period, the lowest HR was found in stallions from TP group. 1, 2, 5 the measuring periods; a, b group means marked with different letters within a measuring period significantly differ at P 0.05; * group means marked with asterisk significantly differ (P 0.05) from respective means in the 1st measuring period. Figure 1. Mean heart rate (HR) at rest during subsequent measuring periods in stallions and mares (beats per minute; HR ± SD) There was a gradual decrease in HR in mares from C group in subsequent measurements (Figure 1). The results of the 1st period were significantly higher than those of the last three periods. In mares from T group, the highest HRs were noticed during the 3rd and 4th periods, and the lowest during the 5th period. In mares from TP group, the results obtained during the 5th period were lower than those during
92 I. Janczarek et al. the 1st period. In comparison to mares from C group, mares from T and TP groups had lower HR at the 1st and 2nd measuring. The beginning of race and transportation period led to a significant increase in HR only in mares from T group (the 3rd and 4th periods). 1, 2, 5 the measuring periods; a, b group means marked with different letters within a measuring period significantly differ at P 0.05; * group means marked with asterisk significantly (P 0.05) differ from respective means in the 1st measuring period. Figure 2. Mean heart rate (HR) at saddling during subsequent measuring periods in stallions and mares (beats per minute; HR ± SD) During saddling, HR in stallions from C group did not significantly differ during successive periods compared to the 1st period (Figure 2). Similarly, no differences were found for T group, except for a significantly lower result at the 5th recording. In TP group, HR was significantly lower in the 2nd, 3rd and 5th periods than in the 1st period. In comparison to the results obtained in stallions from C group, HR in stallions from T was significantly lower at 5th measuring, whereas the results in TP group were lower in the 2nd period compared to the 5th period.
Effect of allowing racehorses to use paddocks on heart rate 93 The period of measuring did not influence the results in groups of mares studied during saddling (Figure 2). The results of HR registration in mares from T group were lower than in C during the 2nd, 4th and 5th periods of the study. Similarly, TP results were generally lower than in C, except for the 1st measuring. 1, 2, 5 the measuring periods; a, b group means marked with different letters within a measuring period significantly differ at P 0.05. Figure 3. Mean heart rate (HR) at walk during subsequent measuring periods in stallions and mares (beats per minute; HR ± SD) There were no significant differences in stallions and in mares, in subsequent periods of HR measuring during walking with a rider compared to the 1st measuring period (Figure 3). The highest HR values when walking were observed during the first two measurements in stallions from C group (Figure 3). For the next three periods, HR in stallions from TP was significantly lower than in C group.
94 I. Janczarek et al. HR values in mares from C group studied during walking were significantly higher than in the other groups (Figure 3). Only during the 4th period, HR of mares from C group, still the highest and significantly different from TP, did not differ from T. During the 5th period, the lowest HR values were found in mares from T and TP groups. Mean number of races that the horses participated amounted to 7.21 ± 0.83 and did not differ significantly between the groups. For all the tested horses, ISC was 2.58 ± 0.68 and HCW amounted to 66.88 ± 9.00. In none of the examined cases differences between the racing performance of the horses were significant. Discussion The results of the analyses of horse HR indicate that the place of training, transportation to the races as well as the releasing of the trained horses into the paddocks are the factors significantly affecting the physiological state of the animals. The comparison of horses kept in the racetrack with the horses kept in an off-the-racetrack centre is particularly interesting. It seems that the resting HR is a parameter that can indicate a physiological reaction of horses kept in different conditions. It turned out that off-the-racetrack training sessions and releasing the horses to paddocks were probably enough to lower this parameter. During the training cycle, the resting HR values in both treatment groups were significantly lower than those obtained in C group. These lowered HRs were especially visible in horses provided with an access to paddocks. The effects of releasing the horses into paddocks were discussed by Werhahn et al. (2012), who claimed that access to a paddock positively affected the horses behaviour in a stable, and also during training. An increase in HR was observed from the time the horses began to be transported to the racetrack (i.e., race-training cycle) in both treatment groups, particularly in T at rest. The increase may be associated with the effects of being transported. Wehnert et al. (2008) and Stull and Rodiek (2000) suggest that transport stress in regularly transported horses may even appear in anticipation of the event. Thus, it was not surprising that we obtained elevated HRs in treatment groups of the horses. Next, we wanted to examine how many measuring periods it took, after systematic transportation of horses had begun, for HR at rest to return to the level from before race-training cycle. According to our outcomes, the negative impact of this factor was clearly noticeable and present for a longer period of time in mares in T group. T stallions were characterised by higher HR than HR recorded prior to the beginning of being systematically transported only in the 3rd measuring. However, the horses which had access to paddocks, had lower HRs during 3rd and 4th measuring periods than horses from T group which were maintained in the off-the-racetrack centre without access to paddocks. It means that TP horses which used paddocks, better accepted the fact of being regularly transported than horses from T group. The horse s ability to adapt to being transported was investigated by Shanahan (2003) and Schmidt et al. (2010 b). They reported lowered response of sympathetic nervous system activity in horses which were used to travelling. Summing up, keeping horses
Effect of allowing racehorses to use paddocks on heart rate 95 in the off-the-track centre is a better solution, provided the negative influence of being regularly transported is overcome. It is also interesting that in TP group, i.e. the horses released into the paddock, HR was lower, and the HR decline in consecutive periods was more and more pronounced. In the 5th measuring period, HR was the lowest in the treatment groups. Based on the analysis of the resting HR, we suggest that access to a paddock may lower the psychosomatic response of horses which were regularly transported. Slightly different results of HR during saddling and walking compared to HR at rest, were probably due to the fact that the horses associated saddling and walking with their daily training routine, and not with being transported to the racetrack in the near future. A similar opinion was expressed by Janczarek and Kędzierski (2011 a), who reported lowered HR in horses when the horses stopped awaiting a task. A positive influence of maintaining horses in an off-the-racetrack centre was also visible in HR during saddling, especially in mares. In stallions, HR during saddling was lowered only in TP group in the 2nd to 4th measuring periods, compared to C and T. However, nowhere was HR significantly higher in treatment groups than in C group. It means than during saddling, the horse did not anticipate travelling. It is known that HR increases when in contact with a human, e.g. during pre-training activities (Janczarek and Kędzierski 2011 b; Hada et al., 2003). However, access to paddocks decreases HR response to these activities, especially in stallions. Analysis of HR measured during walking indicates that being maintained in an off-the-racetrack centre is beneficial for horses. However, access to paddocks in TP did not decrease HR in comparison to horses from T group. In the authors opinion, during walking to a training track, the horse anticipates training session. On the race track, many horses are trained in the same time. They trot and gallop with various speeds, and in different directions, therefore, this situation can increase the emotional arousal of a horse. In the off-the-racetrack centre, horses are trained in small groups and therefore, they are calmer. Finally, we decided to figure out how the analysed factors affected the career of the racehorse. No significant racing performance differences were detected between the experimental groups. Keeping horses in off-the-racetrack centres should not negatively affect racing performance. Considering the lack of similar research studies, it is hard to discuss our results. To sum up, it can be stated that racehorses trained in off-the-racetrack centre, showed an increased HR only at the beginning of the regular transportation period (race-training cycle). The increased HR is possibly associated with more intense psychosomatic arousal, which seems to be the strongest in the moments associated with an imminent journey. Therefore, it is also a good idea to get the horses used to being transported before the racing season. Schmidt et al. (2010 b) suggest that getting the horses used to being transported before the racing season ensures a lack of increased stress reactions of various origin. Conclusions Keeping Purebred Arabian racehorses in an off-the-racetrack training centre resulted in a better psychosomatic state of the animals assessed with HR than keep-
96 I. Janczarek et al. ing them stationed at the racetrack, excluding the period after beginning the regular transporting of the horses from the centres to the racetracks. Then, the horses were still likely acclimating to transportation. The psychosomatic response of the horses, expressed by their HR, when starting to be regularly transported is less pronounced in animals which have been provided with regular access to paddocks. Keeping racehorses in centres outside of the racetrack does not negatively affect their racing performance. References A l e x a n d e r S.L., I r v i n e C.H.G. (1998). Stress in the racing horse: Coping vs not coping. J. Equine Sci., 9: 77 81. A r t T., L e k e u x P. (2005). Exercise-induced physiological adjustments to stressful conditions in sports horses. Livest. Prod. Sci., 92: 101 111. C h a y a L., C o w a n E., M c G u i r e B. (2006). A note on the relationship between time spent in turnout and behaviour during turnout in horses (Equus caballus). Appl. Anim. Behav. Sci., 98: 155 160. D e l C a s t i l l o J., S c h w a r t z L. (1997). Backyard race horse: The training manual, a comprehensive off-track program for owners and trainers. Winter Haven, Florida: Prediction Publication & Productions Press. E v a n s D.L. (2003). Welfare of the racehorse during exercise training and racing. In: The welfare of horses. Springer, Netherlands, pp. 181 201. F a z i o E., M e d i c a P., A r o n i c a V., G r a s s o L., F e r l a z z o A. (2008). Circulating β-endorphin, ACTH and cortisol level of stallions before and after short road transport: stress effect of different distance. Acta Vet. Scand., 50: 50 56. H a d a T., O n a k a T., T a k a h a s h i T., H i r a g a A., Ya g i K. (2003). Effects of novelty stress on neuroendocrine activities and running performance in thoroughbred horses. J. Neuroendocrinol., 15: 638 648. H e n d e r s o n A.J. (2007). Don t fence me in: managing psychological well being for elite performance horses. J. Appl. Anim. Welfare Sci., 10: 309 329. I r v i n e C.H.G., A l e x a n d e r S.L. (1996). Update on equine endocrinology. Proc. 11th International Conference of Racing Analysts and Veterinarians, pp. 86 91. J a n c z a r e k I., K ę d z i e r s k i W. (2011 a). Emotional response to novelty and to expectation of novelty in young race horses. J. Equine Vet. Sci., 31: 549 554. J a n c z a r e k I., K ę d z i e r s k i W. (2011 b). Emotional response of young race horses to a transfer from a familiar to an unfamiliar environment. Anim. Sci. Pap. Rep., 29: 205 212. J a n c z a r e k I., Kędzierski W. (2011 c). Is it a good idea to train fillies and colts separately? J. Appl. Anim. Welfare Sci., 14: 211 219. Jansen F., Van der Krogt J., Van Loon K., Avezzu V., Guarino M., Quanten S., B e r c k m a n s D. (2009). Online detection of an emotional response of a horse during physical activity. Vet. J., 181: 38 42. K u t t e J. (2012). Humans, horses, and hybrids: On rights, welfare, and masculinity in equestrian sports. Malmö högskola, Idrottsvetenskap, Scandinavian Sport Studies Forum, pp. 49 69. L a n d e r s T.A. (2006). Professional care of the racehorse: A guide to grooming, feeding, and handling the equine athlete. Eclipse Press. L e i n e r L., F e n d t M. (2011). Behavioural fear and heart rate responses of horses after exposure to novel objects: Effects of habituation. Appl. Anim. Behav. Sci., 131: 104 109. L i t t l e R., S t r o u p W., F r e u n d R. (2002). SAS for Linear Models. SAS Institute Inc., USA, pp. 269 272. M a c T a g g a r t G., M c G r e e v y P., Wa r a n N., P h i l l i p s C. (2010). Development of a thoroughbred racehorse welfare educational index and associated programme for youth groups. Proc. 3rd Australasian Equine Science Symposium, 3 5.06.2010, 66.
Effect of allowing racehorses to use paddocks on heart rate 97 M i l l s P.C., S m i t h N.C., C a s a s I., H a r r i s P., H a r r i s R.C., M a r l i n D.J. (1996). Effects of exercise intensity and environmental stress on indices of oxidative stress and iron homeostasis during exercise in the horse. Europ. J. Appl. Physiol. O., 74: 60 66. M i r c e a n M., G i u r g i u G., M i r c e a n V., Z i n v e l i u E. (2008). Serum cortisol variation of sport horses in relation with the level of training and effort intensity. Bull. USAMV-CN, Vet. Med., 64: 488 492. Rietmann T.R., Stuart A.E., Bernasconi P., Stauffacher M., Auer J.A., Weisha u p t M.A. (2004). Assessment of mental stress in warmblood horses: heart rate variability in comparison to heart rate and selected behavioural parameters. Appl. Anim. Behav. Sci., 88: 121 136. Schmidt A., Biau S., Mostl E., Becker-Brick M., Morillon B., Aurich J., Faur e J.M., A u r i c h C. (2010 a). Changes in cortisol release and heart rate variability in sport horses during long-distance road transport. Domest. Anim. Endocrinol., 38: 179 189. Schmidt A., Möstl E., Wehnert C., Aurich J., Muller J., Aurich C. (2010 b). Cortisol release and heart rate variability in horses during road transport. Horm. Behav., 57: 209 215. S h a n a h a n S. (2003). Trailer loading stress in horses: behavioral and physiological effects of nonaversive training (TTEAM). J. Appl. Anim. Welfare Sci., 6: 236 274. S t u l l C.I., R o d i e k A.V. (2000). Effect of cross-tying horses during 24 h of road transport. Equine Vet. J., 34: 550 555. Vatistas N.J., Sifferman R.L., Holste J., Cox J.L., Pinalto G., Schultz K.T. (1999). Induction and maintenance of gastric ulceration in horses in simulated race training. Equine Vet. J., 31: 40 44. Visser E.K., van Reenen C.G., van der Werf J.T., Schilder M.B., Knaap J.H., B a r n e v e l d A., B l o k h u i s H.J. (2002). Heart rate and heart rate variability during a novel object test and a handling test in young horses. Physiol. Behav., 76: 289 296. Wa t e r s A.J., N i c o l C.J., F r e n c h N.P. (2002). Factors influencing the development of stereotypic and redirected behaviours in young horses: findings of a four year prospective epidemiological study. Equine Vet. J., 34: 572 579. Wehnert C., Schmidt A., Mostl E., Aurich J., Muller J., Aurich C. (2008). Heart rate and cortisol release in horses during road transport of 1, 3.5 and 8 hours duration. Proc. International Equine Science Meeting, Regensburg, Germany, 44. We r h a h n H., H e s s e l E., Va n d e n We g h e H. (2012). Effects of free exercise on the behaviour in the stable, the behaviour during training and the degree of stress. J. Equine Vet. Sci., 32: 22 31. www.pkwk.pl/handikap2.php Polish Jockey Club official website, 2014. Received: 30 XII 2014 Accepted: 14 VII 2015