著者
Fumiro KASHIWAMURA Avarzed AVGAANDORJ Keiko FURUMURA
出版者
日本ウマ科学会
雑誌
Journal of Equine Science (ISSN:13403516)
巻号頁・発行日
vol.12, no.1, pp.1-7, 2001 (Released:2001-10-27)
参考文献数
13
被引用文献数
3 9

The body size and weight of 584 Banei draft racehorses at Obihiro Racing Stable in Hokkaido, Japan, was investigated. Almost all the animals (94.7%) were cross-breed heavy draft horses; there were a few Percheron and Percheron grade (4.8%) and a Belgian breed (0.5%). The ages of the animals ranged from 2 to 10 years. Males accounted for 80.3%, females for 17.5%, and 2.2% were castrated. The mean body measurements of 2-year-old Banei draft racehorses were significantly smaller than those of the 3-to 4-year-old or 5-to 10-year-old horses. Hip width, croup width, and rump length of females were greater than those of males. In contrast, males had greater chest width and cannon bone circumference than females. Significant relationships among almost all body measurements were observed. A high correlation was found between body weight and chest girth, croup width and body length. A principle component analysis were applied to investigate the effect of body conformation on racing performance in terms of earnings and the time on the performance test. Performance was significantly related to the principle components of general body size and weight of the horses. The cannon bone, body length, and rump length were suggested to have an effect on earnings per race in 2-year-old male horses. In terms of body size and conformation, the Banei draft racehorses, which are large in general size and well balanced, seemed to show high performance.
著者
Kousuke TANAKA Atsushi HIRAGA Toshiyuki TAKAHASHI Atsutoshi KUWANO Scott Edward MORRISON
出版者
日本ウマ科学会
雑誌
Journal of Equine Science (ISSN:13403516)
巻号頁・発行日
vol.26, no.2, pp.67-71, 2015 (Released:2015-07-02)
参考文献数
12

We applied aluminum hinged shoes (AHSs) to the club foot-associated contracted feet of 11 Thoroughbred yearlings to examine the effects of the shoes on the shape of the hoof and third phalanx (P III). After 3 months of AHS use, the size of the affected hooves increased significantly, reaching the approximate size of the healthy contralateral hooves with respect to the maximum lateral width of the foot, the mean ratio of the bearing border width to the coronary band width, and the mean ratio of the solar surface width to the articular surface width. These results suggest that the AHSs corrected the contracted feet in these yearling horses.
著者
Daniel T. KASPER Rex F. GANDY
出版者
Japanese Society of Equine Science
雑誌
Journal of Equine Science (ISSN:13403516)
巻号頁・発行日
vol.29, no.3, pp.67-74, 2018 (Released:2018-09-19)
参考文献数
13

The 2016 Equibase data set of American Quarter Horse starts in North America was analyzed, with the purpose of ranking the sires of the racehorses. A speed z-score derived from the race times and distances was used as a racing performance measure. Mixed effects models were used on various subsets of the data based on race distance and sire offspring number. The sire categorical variable was considered as a random effect. Various statistical criteria were used to optimize the model. The constructed models were then varied in terms of the random and fixed effects included, and the conditional modes of the sire effects were extracted from these models. The benefit of the sire ranking that comes from this analysis is that it is controlled for track, jockey, trainer, weather, and several other variables that can impact speed. Sires are typically valued for high rankings for offspring earnings and winners. Yet a sire with a low stud fee may still produce offspring with a high ranking using our z-score model. The offspring of this bargain sire have the potential to produce fast offspring that could pay a dividend on a relatively low cost investment. The model sire ranking approach described in this paper is clearly bringing a new approach to the field of sire rankings.
著者
Toshiyuki TAKAHASHI Osamu AOKI Atsushi HIRAGA
出版者
日本ウマ科学会
雑誌
Journal of Equine Science (ISSN:13403516)
巻号頁・発行日
vol.18, no.2, pp.47-53, 2007 (Released:2007-07-11)
参考文献数
9

The purpose of this study was to describe the characteristics of fast race horses by analyzing the running form of Deep Impact, the undefeated Japanese triple crown winner in 2005. A high-speed video data of the Kikuka Syo race (Japanese St. Leger, JPN G1, 3,000 m, turf) was taken at a rate of 250 frames/sec. The high-speed video system was set in a left lateral position about 100 m before the finishing post with a field view width of about 16 m. The speed of Deep Impact, 17.8 m/sec, was the fastest of all horses measured (average 16.1 m/sec), the stride frequency, 2.36 strides/sec, was the third largest (average 2.28 strides/sec), and the stride length, 7.54 m, was the longest (average 7.08 m). The diagonal and airborne step lengths of Deep Impact were longer than the average values. The overlap time of Deep Impact was shorter than the average value. The ratio of overlap time to stride duration of Deep Impact was 8.5 %, whereas the average value was 16.9 %. A shorter overlap time was also observed on a common characteristic of Secretariat, the famous elite race horse in USA and correlated to running speed. Thus, these characteristics may be related to effective running form in elite horses.
著者
Yasuyoshi MORITSU Hiromi FUNAKOSHI Shun ICHIKAWA
出版者
Japanese Society of Equine Science
雑誌
Journal of Equine Science (ISSN:13403516)
巻号頁・発行日
vol.5, no.2, pp.53-58, 1994-09-30 (Released:2010-06-28)
参考文献数
20
被引用文献数
12 12

The sire effect and the fixed effects of sex, training center, type of course, specific racetrack, horse age and track condition were evaluated regarding best racing times of thoroughbred horses. The records of best racing times at the Japan Racing Association were collected from the electronic racing book. The data set was edited so that each sire was required to have at least twenty progeny in the racing distances of 1200m and 1800m. The total numbers o f sires and progeny were 34 and 1486 for 1200m and 34 and 1520 for 1800m. First, the least-squares analysis of variance was carried out by using the linear model which included the sire effect and the six fixed effects. Second, heritabilities for best racing times were calculated, and additionally sire evaluations were carried out by using the sire model of the BLUP method. As a result of analysis of variance, almost all effects included in the linear model were significant for both racing distances. The sire, type of course, horse age and interaction between the type of course and track condition had a highly significant effect on best racing times. Estimates of heritability were 0.11 and 0.09 for 1200 m and 1800 m, respectively. Rankings of sires' breeding values based on progeny records were quite different for the two racing distances. The Spearman rank correlation coefficient for these rankings was 0.350 (P<0.05).
著者
Teruaki TOZAKI Mio KIKUCHI Hironaga KAKOI Kei-ichi HIROTA Shun-ichi NAGATA
出版者
Japanese Society of Equine Science
雑誌
Journal of Equine Science (ISSN:13403516)
巻号頁・発行日
vol.28, no.4, pp.127-134, 2017 (Released:2017-12-12)
参考文献数
32

Body weight is an important trait to confirm growth and development in humans and animals. In Thoroughbred racehorses, it is measured in the postnatal, training, and racing periods to evaluate growth and training degrees. The body weight of mature Thoroughbred racehorses generally ranges from 400 to 600 kg, and this broad range is likely influenced by environmental and genetic factors. Therefore, a genome-wide association study (GWAS) using the Equine SNP70 BeadChip was performed to identify the genomic regions associated with body weight in Japanese Thoroughbred racehorses using 851 individuals. The average body weight of these horses was 473.9 kg (standard deviation: 28.0) at the age of 3, and GWAS identified statistically significant SNPs on chromosomes 3 (BIEC2_808466, P=2.32E-14), 9 (BIEC2_1105503, P=1.03E-7), 15 (BIEC2_322669, P=9.50E-6), and 18 (BIEC2_417274, P=1.44E-14), which were associated with body weight as a quantitative trait. The genomic regions on chromosomes 3, 9, 15, and 18 included ligand-dependent nuclear receptor compressor-like protein (LCORL), zinc finger and AT hook domain containing (ZFAT), tribbles pseudokinase 2 (TRIB2), and myostatin (MSTN), respectively, as candidate genes. LCORL and ZFAT are associated with withers height in horses, whereas MSTN affects muscle mass. Thus, the genomic regions identified in this study seem to affect the body weight of Thoroughbred racehorses. Although this information is useful for breeding and growth management of the horses, the production of genetically modified animals and gene doping (abuse/misuse of gene therapy) should be prohibited to maintain horse racing integrity.
著者
Hajime OHMURA James H. JONES
出版者
日本ウマ科学会
雑誌
Journal of Equine Science (ISSN:13403516)
巻号頁・発行日
vol.28, no.3, pp.99-103, 2017 (Released:2017-09-20)
参考文献数
25

We investigated changes in heart rate (HR) and HR variability as a function of age in newborn foals to old Thoroughbred horses. Experiments were performed on a total of 83 healthy and clinically normal Thoroughbred horses. Resting HR decreased with age from birth. The relationship between age and HR fit the equation Y=48.2X-0.129(R2=0.705); the relationship between age and HR for horses 0–7 years old fit the equation Y=44.1X-0.179(R2=0.882). Seven-day-old horses had the highest HR values (106 ± 10.3 beat/min). The low frequency (LF) and high frequency (HF) powers increased with age in newborn to old horses. These changes in HR and HR variability appear to result from the effects of ageing. Three- to seven-year-old race horses had the lowest HR values (32.9 ± 3.5 beat/min) and the highest LF and HF powers except for the HF powers in the oldest horses. Race training may have contributed to these changes. Horses of ages greater than 25 years old had the highest HF powers and the lowest LF/HF ratios. In individual horses, 8 of the 15 horses over 25 years old had LF/HF ratios of less than 1.0; their HR variability appears to be unique, and they may have a different autonomic balance than horses of younger age.
著者
Daisuke MIYAKOSHI Hiroyuki SENBA Mitsumori SHIKICHI Masaya MAEDA Ryo SHIBATA Kazuhiro MISUMI
出版者
日本ウマ科学会
雑誌
Journal of Equine Science (ISSN:13403516)
巻号頁・発行日
vol.27, no.2, pp.67-76, 2016 (Released:2016-06-21)
参考文献数
14

This study aimed to evaluate the influence of radiographic abnormalities of 2-year-old Thoroughbred horses that were listed at in-training sales in Japan, on whether they started to race or not at 2–3 years of age. Radiographs of 850 2-year-old Thoroughbreds in the in-training sales repository from 2007 to 2010 were reviewed, and 26 categories of radiographic abnormalities were found. Forty-three horses (5.1%, 43/850) did not start a race at 2–3 years of age. In accordance with the racing results for this age category, as determined by Fisher’s exact test and multiple logistic regression analysis, none of the radiographic abnormalities were significantly related to failure to start a race. At 2 years of age, 198 horses (23.3%, 198/850) did not start a race. Horses with enlargement of the proximal sesamoid bones in the fore (9 of 19 horses) and hind limbs (5 of 9 horses) did not start a race at the age of 2 years, and fewer of these horses (fore, P=0.021; hind, P=0.030) started a race at the age of 2 years compared with the population of horses without these radiographic abnormalities. These results suggest that identification of radiographic enlargement of the proximal sesamoid bones during training sales could derail the racing debut of horses at the age of 2 years. However, this might not necessarily indicate a poor prognosis and resulting in retirement from racing at 2–3 years of age.
著者
Toshiyuki TAKAHASHI
出版者
日本ウマ科学会
雑誌
Journal of Equine Science (ISSN:13403516)
巻号頁・発行日
vol.26, no.2, pp.43-48, 2015 (Released:2015-07-02)
参考文献数
8
被引用文献数
1 2

The running performance of Thoroughbred racehorses has been reported to peak when they are between 4 and 5 years old. However, changes in their racing speed by month or season have not been reported. The purposes of this study were to reveal the average racing speed of Thoroughbreds, and observe changes in their average speed with age. The surveyed races were flat races on turf and dirt tracks with firm or standard track conditions held by the Japan Racing Association from January 1st, 2002 to December 31st, 2010. The racing speed of each horse was calculated by dividing the race distance (m) by the horse’s final time (sec). Average speeds per month for each age and distance condition were calculated for each gender group when there were 30 or more starters per month for each age and distance condition for each gender group. The common characteristic change for all conditions was an average speed increase up until the first half of the age of 4 years old. The effect of increased carry weight on average speed was small, and average speed increased with the growth of the horse. After the latter half of the age of 4 years old, the horses’ average speed remained almost constant, with little variation. It is speculated that decreases in the weight carried; and the retirement of less well performing horses; are responsible for the maintenance of average speed.
著者
Kayo TERADA
出版者
日本ウマ科学会
雑誌
Journal of Equine Science (ISSN:13403516)
巻号頁・発行日
vol.11, no.4, pp.83-90, 2000 (Released:2001-08-16)
参考文献数
17
被引用文献数
13 21

The aim of this study was to see if differences in proficiency exist between advanced-and novice-level horseback riders with regard to head movement and EMG activity. Three advanced-and three novice horseback riders rode a horse at a walk, sitting trot and canter whilst their head acceleration and the EMG activity of their rectus abdominis muscle (M. rectus abdominis), erector spinae muscle (M. erector spinae) and abductor magnus muscle (M. adductor magnus) were recorded simultaneously. All results were conducted with Frequency Analysis by the Maximum Entropy Method. At walk, the novice rider showed a frequency distribution dispersion (P<0.1) of the head in the proximal-distal direction which was not observed in the advanced rider, but no distinct primary factors were observed in the muscular discharge frequency distributions-perhaps due to the novice rider's level which was not completely inexperienced. At a sitting trot, unstable movements of the novice rider's upper body were observed in the cranial-caudal direction (P<0.05), mirroring the horse's violent rocking movements. The electromyogram frequency distributions at this gait suggest that the novice rider was unable to balance the erector spinae and rectus abdominis muscles, and therefore unable to cope with the unstable movement. It also suggests that there was instantaneous muscular activity of the adductor magnus muscle in order to stabilize the ill-balanced body. At a canter, there were no significant differences in the dispersion of acceleration frequency distribution or in the electromyogram frequency distribution, but although there were no "significant" differences, the results obtained from the advanced rider at this gait showed a dispersion of acceleration frequency distribution that was slightly greater than that of the novice rider. This situation was only observed at a canter. In conclusion, differences exist in the degree of difficulty of coordination between horse and rider according to the gait. In addition, from the results of this study, we can clearly see that differences also exist in the rider's own skill and ability to "maintain posture".
著者
Yusuke HORI Takatoshi OZAKI Yoshimitsu YAMADA Teruaki TOZAKI Heui-Soo KIM Ayaka TAKIMOTO Maiko ENDO Noboru MANABE Miho INOUE-MURAYAMA Kazuo FUJITA
出版者
日本ウマ科学会
雑誌
Journal of Equine Science (ISSN:13403516)
巻号頁・発行日
vol.24, no.3, pp.31-36, 2013 (Released:2013-09-30)
参考文献数
15
被引用文献数
2 5

Genetic polymorphisms in genes related to neurotransmitters or hormones affect personality or behavioral traits in many animal species including humans. In domestic animals, the allele frequency of such genes has been reported to be different among breeds and it may account for breed differences in behavior. In this study, we investigated breed differences in horses in the dopamine receptor D4 gene (DRD4), which has been reported to affect horse personality. We collected samples from seven horse breeds including those native to Japan and Korea, and compared the sequence of the DRD4 exon3 region among these breeds. We found that there were two types of polymorphisms (VNTR and SNPs) in the exon3 region, and some of them seemed to be breed-specific. In addition, we found that the allele frequency of G292A, reported to be associated with horse personality, differed greatly between native Japanese horses and Thoroughbred horses. The frequency of the A allele which is associated with low curiosity and high vigilance, was much lower in native Japanese horses (Hokkaido, 0.03; Taishu, 0.08) than in Thoroughbreds (0.62). This difference may account for breed differences in personality or behavioral traits. Further studies of the function of these polymorphisms and their effect on behavior are indicated.
著者
Susan ALEXANDER C.H.G. IRVINE
出版者
Japanese Society of Equine Science
雑誌
Journal of Equine Science (ISSN:13403516)
巻号頁・発行日
vol.9, no.3, pp.77-81, 1998 (Released:2001-09-28)
参考文献数
24
被引用文献数
11 10

The hormones of the adrenal axis help athletes adapt to the stress of training and racing. When performance is poor, dysfunction of this axis is often suspected, but confirming this has been difficult. We have found three hallmarks of chronic stress in horses that are easily monitored: 1) loss of the circadian cortisol rhythm, 2) decrease in corticosteroid-binding globulin and an increase in free cortisol, and 3) reduced ACTH (& hence cortisol) response to a small dose (2 μg) of equine/human corticotropin-releasing hormone (CRH). The presence of some or all of these abnormalities is a good indication that the horse is not coping with the stresses imposed upon him.
著者
Jun YAMASHITA Hironori OKI Telhisa HASEGAWA Takeshi HONDA Tetsuro NOMURA
出版者
Japanese Society of Equine Science
雑誌
Journal of Equine Science (ISSN:13403516)
巻号頁・発行日
vol.21, no.2, pp.11-16, 2010 (Released:2010-07-16)
参考文献数
12
被引用文献数
3 2

To investigate the breeding structure in the Japanese Thoroughbred population, we applied a demographic analysis to the populations of foals produced from 1978 to 2005. The migration rate estimated from the proportion of foals produced by imported breeding horses was around 40% over the investigated period. After early 1990s, the migration rate through stallions imported from USA sharply increased. The average generation interval was within range of 10.5-11.5 years. The longer generation interval of Thoroughbred was considered to be a reflection of the fact that Thoroughbred horses begin breeding only after completing their performance in races. After the peak of 729 in 1993, the number of sires of foals progressively declined to 358 in 2005. Although the coefficient of variation of the progeny number of sires was within range of 1.0-1.2 until early 1990s, it gradually increased and reached the value of 1.6-1.7 in recent years. The effective number of sires consistently decreased after the peak of 302.6 in 1992, and reached 120-130 in recent years, which is 25-30% of the actual number of sires. In parallel, the demographic estimate of the effective population size declined after early 1990s. The main cause of the observed change in the breeding structure was inferred to be the intensive use of a limited number of stallions for breeding.
著者
Akira MATSUI Tomoko OSAWA Hirofumi FUJIKAWA Yo ASAI Tohru MATSUI Hideo YANO
出版者
Japanese Society of Equine Science
雑誌
Journal of Equine Science (ISSN:13403516)
巻号頁・発行日
vol.13, no.4, pp.109-112, 2002 (Released:2003-04-10)
参考文献数
13

We examined total sweating rate (SR) and the amount of mineral (Na, K, Ca, Mg, Fe, P, Zn and Cu) loss through sweat in 2-year-old horses during exercise for approximately 2,000 m at a speed of 700 m/min, at cool ambient temperature. The total SR was estimated by the unit area SR on the neck by filter paper within a capsule. Mean total SR was 1.55 ± 0.47 (SD) kg. The ratio of sodium loss to the requirements reported by National Research Council reached 23% and that of potassium was 7%. The ratio of other mineral losses to the requirements reported by National Research Council was 2% or less. These results suggested that sodium had to be supplemented to the horse, but there was no need to add extra minerals to the diet to compensate for mineral losses of calcium, magnesium, iron, phosphorus, zinc and copper through sweat during exercise with light intensity and at a cool ambient temperature.
著者
Hironaga KAKOI Mio KIKUCHI Teruaki TOZAKI Kei-ichi HIROTA Shun-ichi NAGATA Seiji HOBO Masaki TAKASU
出版者
Japanese Society of Equine Science
雑誌
Journal of Equine Science (ISSN:13403516)
巻号頁・発行日
vol.29, no.2, pp.39-42, 2018 (Released:2018-07-06)
参考文献数
23

The distribution of Y chromosomal haplotypes in Japanese native horse populations was investigated to obtain genetic information on these populations. Here, 159 male/gelded horses from eight local populations were investigated, and three Y haplotypes (JHT-1, JHT-2, and JHT-3) were identified by analyzing five Y-linked loci. Five populations had only JHT-1, whereas two populations had only JHT-2. One population had JHT-1 and JHT-3. Based on the geographical distribution of these haplotypes and previously reported haplotypes for other Asian horses, JHT-1 is considered to be a major haplotype in ancestral native horses. The fixation of each haplotype suggests the influence of independent breeding and genetic drift in each population. These findings complement the results from previous genetic studies of Japanese native horses.
著者
Laura CROTCH-HARVEY Leigh-Anne THOMAS Hilary J. WORGAN Jamie-Leigh DOUGLAS Diane E. GILBY Neil R. MCEWAN
出版者
Japanese Society of Equine Science
雑誌
Journal of Equine Science (ISSN:13403516)
巻号頁・発行日
vol.29, no.2, pp.47-51, 2018 (Released:2018-07-06)
参考文献数
13

Anthelmintics are used as anti-worming agents. Although known to affect their target organisms, nothing has been published regarding their effect on other digestive tract organisms or on metabolites produced by them. The current work investigated effects of fenbendazole, a benzimidazole anthelmintic, on bacteria and ciliates in the equine digestive tract and on and their major metabolites. Animals receiving anthelmintic treatment had high faecal egg counts relative to controls. Analysis was performed over two weeks, with temporal differences detected in bacterial populations but with no other significant differences detected. This suggests fenbendazole has no detectable effect on organisms other than its targets. Moreover it does not appear to make a contribution to changing the resulting metabolome.
著者
Felipe Gomes Ferreira PADILHA Kênia Balbi EL-JAICK Liane de CASTRO Aline Dos Santos MOREIRA Ana Maria Reis FERREIRA
出版者
Japanese Society of Equine Science
雑誌
Journal of Equine Science (ISSN:13403516)
巻号頁・発行日
vol.29, no.1, pp.21-24, 2018 (Released:2018-04-07)
参考文献数
13

Polymorphisms in MSTN have previously been associated with equine performance. Therefore, the aim of this study was to identify variants in MSTN intron 1 in 16 Brazilian Sport Horses selected for competition in eventing and their possible effects of selection on performance. Among the nine variants identified, eight had already been reported in previous studies or genomic databases, although they showed differences in frequencies when compared with other horse breeds. Moreover, a new mutation was identified in two horses, both in heterozygous form. Considering the absence of molecular studies in this valuable Brazilian breed, these findings represent an important contribution to the characterization of its genetic profile and may possibly aid in further genotype-phenotype association studies.
著者
Amanda YORKE Judith MATUSIEWICZ Barbara PADALINO
出版者
日本ウマ科学会
雑誌
Journal of Equine Science (ISSN:13403516)
巻号頁・発行日
vol.28, no.3, pp.67-75, 2017 (Released:2017-09-20)
参考文献数
73
被引用文献数
1

This review aims to provide practical outcomes on how to minimise the incidence of transport-related problem behaviours (TRPBs) in horses. TRPBs are unwanted behaviours occurring during different phases of transport, most commonly, a reluctance to load and scrambling during travelling. TRPBs can result in injuries to horses and horse handlers, horse trailer accidents, disruption of time schedules, inability to attend competitions, and poor performance following travel. Therefore, TRPBs are recognised as both a horse-related risk to humans and a human-related risk to horses. From the literature, it is apparent that TRPBs are common throughout the entire equine industry, and a YouTube keyword search of ‘horse trailer loading’ produced over 67,000 results, demonstrating considerable interest in this topic and the variety of solutions suggested. Drawing upon articles published over the last 35 years, this review summarises current knowledge on TRPBs and provides recommendations on their identification, management, and prevention. It appears that a positive human-horse relationship, in-hand pre-training, systematic training for loading and travelling, appropriate horse handling, and the vehicle driving skills of the transporters are crucial to minimise the incidence of TRPBs. In-hand pre-training based on correct application of the principles of learning for horses and horse handlers, habituation to loading and travelling, and self-loading appear to minimise the risk of TRPBs and are therefore strongly recommended to safeguard horse and horse-handler health and welfare. This review indicates that further research and education with respect to transport management are essential to substantially decrease the incidence of TRPBs in horses.
著者
Siriwan TANGYUENYONG Fumio SATO Yasuo NAMBO Harutaka MURASE Yoshiro ENDO Tomomi TANAKA Kentaro NAGAOKA Gen WATANABE
出版者
日本ウマ科学会
雑誌
Journal of Equine Science (ISSN:13403516)
巻号頁・発行日
vol.28, no.3, pp.77-86, 2017 (Released:2017-09-20)
参考文献数
43
被引用文献数
1

This study aimed to compare body growth, metabolic, and reproductive hormonal changes in trained Thoroughbred yearling horses under different climate conditions with and without light supplementation (LS). Thoroughbred yearlings raised at research centers of the Japan Racing Association in Hokkaido (north) or Miyazaki (south) were divided into control and LS groups. In the LS groups, 44 colts and 47 fillies from Hokkaido and 11 colts and 11 fillies from Miyazaki were exposed to LS with an extended photoperiod of 14.5 hr of daylight and 9.5 hr of darkness. One week before and once a month after LS, circulating total thyroxine (T4), insulin-like growth factor-I (IGF-1), prolactin (PRL), cortisol, and progesterone (P4) concentrations were measured by radioimmunoassay and fluoroimmunoassay, respectively. Growth parameters, including body weight, height, girth, and cannon bone circumferences, were measured monthly. Hair coat (HC) condition was scored. Under natural conditions, the T4 concentrations of Hokkaido yearlings tended to be higher, whereas the IGF-1 (colt) and PRL levels were significantly lower than those of yearlings in Miyazaki. Growth parameters and HC scores were lower in Hokkaido yearlings. With LS, the PRL and P4 concentrations in Hokkaido and Miyazaki were higher, and the first ovarian activity tended to be earlier than in the controls. Only LS Hokkaido yearlings showed significantly higher HC scores than the controls. Comparing the different climates among the LS yearlings, the levels of PRL and P4 and the HC scores in Hokkaido yearlings increased and reached levels similar to those in Miyazaki yearlings. The body weight and girth increment percentages of Hokkaido yearlings in January dramatically decreased and then eventually increased to levels similar to those of Miyazaki yearlings. This suggested that yearlings in naturally colder Hokkaido exhibit higher basal metabolism to maintain homeostasis. However, providing LS may help to improve growth and early development of reproductive function in Hokkaido yearlings to levels equal to those of Miyazaki horses.
著者
及川 正明 笠嶋 快周
出版者
日本ウマ科学会
雑誌
Journal of equine science (ISSN:13403516)
巻号頁・発行日
vol.13, no.2, pp.41-56, 2002-06-01
参考文献数
55
被引用文献数
1