Ryo Kusunose

Equine Research Institute, Totigi, Tochigi, Japan

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Publications (23)22.45 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: The objective of this study was to investigate the effect of straw, sawdust, coconut husk (husk), and coconut fiber (fiber) on the welfare of stable horses by observing their resting behavior. Twenty horses with ages ranging from 3 to 21 years were used at the Equine Research Institute of the Japan Racing Association, Utsunomiya, Japan. Five horses were allocated to each bedding condition. The behavior of each horse was recorded by video camera for 3 days and was continuously sampled from 17:00 to 05:00. The total duration, the number of bouts, and the mean and the maximum duration of bouts in standing rest, sternal lying, and lateral lying were calculated and analysed by the Kruskal-Wallis test and post hoc Steel-Dwass test. There was no difference in the standing rest and the sternal lying among beddings. Significant differences were observed in these values in the lateral lying among the different beddings (P<0.05). The values of the means of the total duration, the number of bouts, and the mean and the maximum duration of bout in the lateral lying were greater when husk was used as the bedding material than when sawdust were used (P<0.05). The results of the observations show that the new bedding materials would be as usable as straw. However, lateral lying was observed less frequently when sawdust were used as bedding; this indicates that use of sawdust as bedding material will decrease the welfare of stabled horses.
    Journal of Equine Science 10/2008; 19(3):53-6. DOI:10.1294/jes.19.53
    This article is viewable in ResearchGate's enriched format
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    ABSTRACT: Inflammatory airway disease (IAD) is a common cause of poor performance, interruption of training and premature retirement in racehorses. It is also reported that up to 80% of horses are affected at some point in the first years of training in UK and Australia. However, no studies with regard to the information on occurrence of IAD in Japanese Thoroughbred racehorses have been reported. To investigate the occurrence and the characteristics of IAD, epidemic research including endoscopic examination of the airway tract and trachea wash was conducted for Thoroughbred racehorses presenting coughs or poor performance which airway tract disease was suspected stalled in training facility managed by Japan Racing Association. Fifty-six out of 76 Thoroughbred racehorses (73.7%) presenting coughing or poor performance were diagnosed as IAD. Mean incidence rate of IAD was 0.3% and it has been confirmed that constant number of IAD exists in Japan. Up to 35.7% of IAD horses showed upper airway abnormalities in some extent. There was a trend for IAD horses to use wood shavings for bedding and fed hay from the ground compared with the control group. Therefore, improvement of stabling environment may aid in preventing IAD. This study demonstrated that Japanese Thoroughbred racehorses are affected by IAD likewise other countries as well as demonstrated the characteristics of IAD which may contribute to the clarification of the pathogenesis of IAD.
    Journal of Equine Science 07/2008; 19(2):25-9. DOI:10.1294/jes.19.25
    This article is viewable in ResearchGate's enriched format
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    ABSTRACT: We investigated the effect of two food types (hay or pellet) on operant conditioning of 12 horses. One group was trained using pelleted concentrate (Group P) and the second (Group H) was trained using cut timothy hay as rewards. We investigated the effect of the food type on the time needed to complete the operant conditioning. There was no difference between the groups in the time needed to complete the operant conditioning (P=0.78). Following completion of the operant conditioning, 10-min trials were conducted on five consecutive days. On the 2nd and 3rd days the food rewards (P and H) were switched for the two groups, and on the 4th and 5th days the food rewards were returned to the original type. When the food reward was changed from P to H, the mean number of rewards obtained decreased significantly in Group P (the 1st day (121.8) versus the 2nd day (45.4) and the 3rd day (39.4), P
    Applied Animal Behaviour Science 12/2007; 108(3):342-347. DOI:10.1016/j.applanim.2007.02.010 · 1.63 Impact Factor
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    ABSTRACT: The aim of the study was to determine parameters reflecting equine anxiety trait by comparing results obtained in a behavior test and an anxiety score assessed by familiar caretakers in response to a questionnaire. In the behavior test, horses were individually led into a novel room by their caretakers and loosely tethered to decrease excessive movement using the common cross-tying technique with two leads and breakable plastic cords. The horses initially remained with their caretaker for 2 min; the caretaker then left and the subject animal was left alone for 2 min. The latency to break the plastic cords, heart rate, the number of steps and pawings were recorded. When the horses were left alone, most parameters changed significantly and some showed sexual differences. A correlation analysis revealed that anxiety score assessed by caretakers showed a negative correlation with the latency to break the plastic cord and a positive correlation with heart rate only when horses were isolated. These two were suggested feasible parameters for assessing the anxiety trait of unfamiliar horses. Both the behavioral results and the anxiety scores also indicated that females were more anxious than males. Our results suggest that it would be a useful strategy for assessing other temperament traits as well to combine behavior tests with a questionnaire survey.
    Journal of Veterinary Medical Science 10/2007; 69(9):945-50. DOI:10.1292/jvms.69.945 · 0.88 Impact Factor
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    ABSTRACT: Genetic variation of the behaviour of racehorses is one of the major concerns for racehorse breeders. In this study, the heritabilities of behavioural responses to the inspections of conjunctiva, auscultation and blood sampling and the genetic correlations among them were estimated in the Thoroughbred racehorse. The estimation was done with Bayesian analysis with Gibbs sampling based on the univariate or bivariate threshold animal models. The behavioural responses were scored with four categories at the first entrance quarantine in Miho Training Center of Japan Racing Association from 1993 to 1995. The behavioural responses were treated as categorical or binary traits, with both showing similar results. The estimated heritabilities were in the range of 0.23-0.28, suggesting a genetic component in the variation on these traits. The estimated genetic correlations among the traits were very high (approximately 0.9), suggesting that these behavioural responses may be measures of the same trait. Because of the high genetic correlations, repeatability threshold model was applied assuming the responses to be a genetically identical trait measured with three different tests. The estimated heritabilities (approximately 0.23) were at the lower bound of the former estimates. The revealed high repeatabilities (0.97-0.98) suggest a strong contribution of the individual temperament on the behaviour of racehorses.
    Journal of Animal Breeding and Genetics 09/2007; 124(4):185-91. DOI:10.1111/j.1439-0388.2007.00659.x · 2.06 Impact Factor
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    ABSTRACT: We observed the behaviour of six stabled horses (stallions n=3; geldings n=3) in an attempt to identify behavioural measures of eating satisfaction. The horses were required to perform an operant response (pressing a button with the muzzle) in order to access a food reward in an experimental box stall. After each horse had successfully learned the experimental situation, it participated in the experimental protocol on 4 days. Horses were brought to the experimental box stall for the operant response sessions (1h duration per session), and upon completion, they were returned to their own (home) box stalls. The number of presses for the reward was a Fixed Ratio schedule of either 3 or 12 muzzle presses (FR3, FR12) and the FR procedure for each horse was as follows: FR3 FR12 FR12 FR3 or FR12 FR3 FR3 FR12. Number of rewards obtained during each session, and behaviour and heart rate after each session were recorded for each horse. A repeated measures ANOVA showed that the number of rewards obtained in FR3 was higher than in FR12 (P
    Applied Animal Behaviour Science 08/2007; 106(1):184-189. DOI:10.1016/j.applanim.2006.06.011 · 1.63 Impact Factor
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    Animal Genetics 03/2007; 38(1):81-3. DOI:10.1111/j.1365-2052.2006.01541.x · 2.21 Impact Factor
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    ABSTRACT: Equine anxiety trait is considered an important temperament in various situations, including riding, training, and daily care. This study examined the polymorphism of the equine serotonin transporter (SLC6A4) gene as a candidate genetic element influencing equine anxiety trait. The sequence of the coding region of this gene was highly homologous with those of other mammals, and four single nucleotide polymorphisms were found by comparing the sequences of ten genetically unrelated thoroughbred horses. Radiation hybrid mapping revealed that this gene was located 26.92 cR from neurofibromin 1 on ECA 11. Using two-year-old thoroughbred horses (n=67), the association of these polymorphisms with the anxiety trait was examined, but no significant association was identified between each haplotype of the serotonin transporter gene and the anxiety score.
    Journal of Veterinary Medical Science 07/2006; 68(6):619-21. DOI:10.1292/jvms.68.619 · 0.88 Impact Factor
  • M Oikawa, R Kusunose
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    ABSTRACT: The purpose of this report is to describe the results of epidemiological surveys of racing-related fractures in Thoroughbred horses in Japan. In the period 1987-2000, a total of 10,203 fractures were diagnosed in 556,705 runners, resulting in an overall incidence of 1.83%. The annual incidence of fractures in flat racing during the 14-year period fluctuated between 1.44% and 2.19%. The majority of fractures affected the forelimbs. We found significant effects of track condition on injury incidence. The incidence of fractures decreased as track conditions on turf became softer and increased as track conditions on dirt became muddier. Because of the general trend for the incidence of fractures to vary with track condition, we examined the relationship between track conditions and racing times for winning horses in 4117 races and for 50,564 overall runners for the period 1990-1994 on two tracks. For turf courses, racing times became longer as track conditions became softer. In contrast, for dirt courses, racing time tended to become shorter in muddier conditions. The variation in the incidence of fracture with track condition might be due to the corresponding difference in racing time.
    The Veterinary Journal 12/2005; 170(3):369-74. DOI:10.1016/j.tvjl.2004.08.004 · 2.17 Impact Factor
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    ABSTRACT: The variable number of tandem repeats (VNTR) polymorphism of the dopamine D4 receptor (DRD4) gene has been reported to be associated with the personality trait of novelty-seeking in humans. In the genus Equus, this region includes an 18-bp repeat unit and there are inter- and intraspecies differences in the number of repetitions. Because horses are unique among livestock species in that their temperament is considered important, we investigated the possible role of this region on equine temperament in thoroughbred horses. We simultaneously determined the sequences of this polymorphic region and administered a questionnaire survey to horse caretakers with questions about 20 different traits of their horses' temperament. Although there was no difference in the number of repeats among the 136 thoroughbred horses studied, two single nucleotide polymorphisms (SNPs), one of which might cause an amino acid change (A-G substitution), existed. By analyzing the association between these SNPs and temperament scores, a significant association was revealed between two temperament traits (Curiosity and Vigilance) and the A-G substitution. Horses without the A allele had significantly higher Curiosity and lower Vigilance scores than those with the A allele at the A-G substitution. In addition, similar associations between both temperament scores and each genotype of the A-G substitution were observed in two subgroups divided according to the time of their introduction to the farm. These results suggested that the SNP in the VNTR region of the equine DRD4 gene might be related to individual differences in equine temperament.
    Mammalian Genome 08/2005; 16(7):538-44. DOI:10.1007/s00335-005-0021-3 · 2.88 Impact Factor
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    ABSTRACT: To establish a method for assessing equine temperament by use of a questionnaire, we carried out two surveys. The subject animals were all thoroughbreds maintained at the same farm. Respondents were the primary caretaker and two colleagues working with each horse. Factor analysis was performed on the responses to each survey. In both surveys, five factors were extracted and four of them were common between the two surveys. The common factors were ‘Anxiety’, ‘Trainability’, ‘Affability’, and ‘Gate entrance’. There were sufficient internal consistencies in responses about ‘Anxiety’, ‘Trainability’, and ‘Affability’ in the two surveys to indicate the validity of this questionnaire in evaluating these factors in equine temperament.
    Applied Animal Behaviour Science 07/2005; 92(1):77-84. DOI:10.1016/j.applanim.2004.11.006 · 1.63 Impact Factor
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    ABSTRACT: Aim:  The physiological indexes of the copulatory behavior of the stallion have not been investigated in detail and may differ from those of other species, such as humans and rats.Methods:  In order to understand the breeding capability of various stallions, their behavior during copulation was observed, and heart rate (HR) and the plasma concentrations of norepinephrine (NA) and epinephrine (Ad) were measured sequentially for a total of 13 copulations carried out during 2 days.Results:  The mean HR at rest was 35.3 ± 0.9 beats per minute (b.p.m.) and it peaked during mounting (162.1 ± 5.4 b.p.m.). The HR at ejaculation was 145.7 ± 5.1 b.p.m, which was less than the peak. The plasma concentrations of NA and Ad showed similar changes to the HR; immediately after ejaculation they were, respectively, 4.7-fold and 1.9-fold higher than the resting values and there was a difference in the degree of increase of each catecholamine.Conclusions:  The present results show that in the stallion the HR peaks at mounting and there is a greater change in the activity of the sympathetic nervous system because of the short-term, highly intense exercise performed during copulation. It is considered that this, combined with the particular mental stress placed on the stallion during copulation, has the potential to cause sudden cardiac death. (Reprod Med Biol 2005; 4: 143–148)
    Reproductive Medicine and Biology 05/2005; 4(2):143 - 147. DOI:10.1111/j.1447-0578.2005.00093.x
  • Animal Genetics 05/2005; 36(2):190. DOI:10.1111/j.1365-2052.2005.01265.x · 2.21 Impact Factor
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    ABSTRACT: Five feeding methods were tested in stabled horses: (i) cutting hay (hay was cut into 5 cm lengths), (ii) delaying feeding time (feeding was delayed until 1 h after the usual time), (iii) increasing the feeding frequency (hay was divided into two portions; one half was given at the normal time and the other 1 h later), (iv) increasing the feeding locations (hay was available at three locations), and (v) increasing the hay varieties (three species of hay were used). The behavioral durations in the 2 h after the experimental feedings were compared with those after usual feeding. In the cutting hay treatment, hay-eating time decreased (P < 0.05), whereas bedding-eating time and resting time tended to increase. In the delaying feeding time treatment, bedding investigation time increased (P < 0.01) and hay-eating time tended to increase. In the increasing the feeding frequency treatment, hay-eating time tended to increase. In the increasing the feeding locations treatment, bedding investigation time tended to decrease. In the increasing the hay varieties treatment, resting time tended to decrease and hay-eating time tended to increase. It was suggested that the former two feeding methods might stimulate and the latter three feeding methods might suppress eating frustration in terms of increasing consummatory behavior (eating) and decreasing appetitive (investigating) and displacement behavior (resting).
    Animal Science Journal 09/2004; 75(5):465 - 469. DOI:10.1111/j.1740-0929.2004.00214.x · 1.04 Impact Factor
  • Journal of Equine Science 01/2004; 15(3):67-73. DOI:10.1294/jes.15.67
  • Journal of Equine Science 01/2004; 15(3):61-65. DOI:10.1294/jes.15.61
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    ABSTRACT: We carried out a questionnaire survey of the caretakers, using 86 riding horses kept in the Equestrian Park, Tokyo (Japan Racing Association). The questionnaire survey used a 5-point scale and a 3-point scale to assess several caretakers’ impressions of each horse’s temperament, on the basis of the norm and the horse’s tendencies in ordinary care and daily training. Factor analysis of the temperament scores obtained with the 5-point scale questionnaire revealed three mutually independent factors that we named “anxiety”, “novelty seeking” and “understanding”. In order to verify the reliability of this questionnaire survey, a balloon reactivity test was conducted using the same horses. Each horse was introduced into an unfamiliar indoor arena (7m×12.5m×3m) in the center of which two balloons slowly revolved. The horses’ responses were assessed by recording changes in their behavior and heart rate (HR) during the 5min experimental period. By comparing the questionnaire survey and the balloon reactivity test, it was found that the horses evaluated as highly anxious by the caretakers tended to show greater HR increases and defecate more often during exposure to the balloon stimuli than did the other horses. Additionally, the horses assessed by caretakers to have problems with ordinary care and/or training showed greater increases of HR and frequency of defecation in the balloon reactivity test, and the horses assessed as having ‘a long adaptation time to unfamiliar objects’ were found to be unwilling to touch the balloons. Thus, the horses’ behavior during the balloon reactivity test was highly consistent with their temperament as determined by the questionnaire. These results suggest that the questionnaire survey would be an effective means to assess equine temperamental traits, especially those related to anxiety.
    Applied Animal Behaviour Science 11/2003; 84(2):127-138. DOI:10.1016/j.applanim.2003.08.001 · 1.63 Impact Factor
  • Nihon Chikusan Gakkaiho 01/2003; 74(2):241-250. DOI:10.2508/chikusan.74.241
  • Ryo Kusunose, Akira Yamanobe
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    ABSTRACT: Twelve yearlings were divided into two groups and subjected to two different training schedules: (a) 30min of training daily (the daily trained group); and (b) 30min of training for 4 days, followed by a 3-day rest (the intermittently trained group), in order to compare the effect of two training methods on the ability of the horses to learn to be driven and ridden and to respond to the handlers’ cues. The length of this experimental training was 17 days. The first step of training was surcingling and proceeded to lunging, to driving from the ground, and finally to being ridden at a trot on a track. Both groups were tested four times during the experimental period when they were at the same stage of training. They were driven and then ridden at a walk by a rider on a specified course and evaluated. The time to complete the course, accuracy of traveling the course, and heart rate during the test were used as the indicators of success in training. In three out of the four tests, the daily trained group tended to move faster and with more accuracy than the intermittently trained group. It would appear that daily training without a long interruption is more effective for yearlings.
    Applied Animal Behaviour Science 09/2002; 78(2):225-233. DOI:10.1016/S0168-1591(02)00089-8 · 1.63 Impact Factor
  • Journal of Equine Science 01/2002; 13(3):93-100. DOI:10.1294/jes.13.93

Publication Stats

233 Citations
22.45 Total Impact Points


  • 2001–2008
    • Equine Research Institute
      Totigi, Tochigi, Japan
  • 2005–2007
    • The University of Tokyo
      • Faculty and Graduate School of Agriculture and Life Sceince
      Tokyo, Tokyo-to, Japan
  • 2006
    • Laboratory of Racing Chemistry
      Totigi, Tochigi, Japan