著者

Pramod DHAKAL Akiko HIRAMA Yasuo NAMBO Takehiro HARADA Fumio SATO Kentaro NAGAOKA Gen WATANABE Kazuyoshi TAYA

出版者

The Society for Reproduction and Development

雑誌

Journal of Reproduction and Development (ISSN:09168818)

巻号頁・発行日

vol.58, no.5, pp.522-530, 2012 (Released:2012-11-01)

参考文献数

35

被引用文献数

21 17

---

The present study was conducted to elucidate the profile of circulating gonadotropins and gonadal hormones from birth to puberty and relationship between gonadal seasonality and hormonal secretion in both sexes of Thoroughbred horses. Spring-born colts (n=6) and fillies (n=9) were blood sampled weekly from jugular vein from birth to 60 weeks of age. Circulating FSH, LH, prolactin, testosterone, progesterone, estradiol-17β, and immunoreactive (ir)-inhibin were measured by radioimmunoassay. In both sexes, the steroid hormones levels were remarkably high at birth, rapidly dropped within a week and remained at the lower levels until the start of second spring after birth. Ir-inhibin was also high during the birth, remaining lowest during winter and again increasing towards the second summer. There was an increase in FSH concentration in foals during the first summer months after birth and in the next summer, the FSH concentration along with that of LH increased significantly. The seasonal increase in circulating prolactin was remarkable even in the first year, and no differences were noted between the two summers. These results clearly demonstrated that the hypothalamo-pituitary axis is already responsive to changes in photoperiod and secrete prolactin similar to adult horses, but pituitary gonadotrophs for FSH and LH secretion is less sensitive. When the values of these hormones in the second breeding season after birth were compared with adult values of the respective sex in the breeding season, no significant differences were observed, indicating that spring-born fillies and colts have already attained the stage of puberty at the second breeding season after birth.

著者

Fumiaki MIZOBE Motoi NOMURA Tomohiro KATO Yasuo NAMBO Kazutaka YAMADA

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.3, pp.87-97, 2017 (Released:2017-09-20)

参考文献数

26

被引用文献数

3 4

---

Problems associated with the proximal metacarpal region, such as an osseous injury associated with tearing of Sharpey’s fibers or an avulsion fracture of the origin of the suspensory ligament (OISL), are important causes of lameness in racehorses. In the present study, four Thoroughbred racehorses (age range, 2–4 years) were diagnosed as having forelimb OISL and assessed over time by using standing magnetic resonance imaging (sMRI). At the first sMRI examination, all horses had 3 characteristic findings, including low signal intensity within the trabecular bone of the third metacarpus on T1-weighted images, intermediate-to-high signal intensity surrounded by a hypointense rim on T2*-weighted images, and high signal intensity on fat-suppressed images. Following the sMRI examination, all horses received 50 mg of tiludronic acid by intravenous regional limb perfusion once weekly for 3 weeks. Attenuation of the high signal intensity on T2*-weighted and fat-suppressed images was observed on follow-up sMRI in 3 horses. Following rest and rehabilitation, these 3 horses successfully returned to racing. In contrast, the other horse that did not show attenuation of the high signal intensity failed to return to racing. To our knowledge, this is the first report of OISL in Thoroughbred racehorses assessed over time by sMRI under tiludronic acid treatment. Our findings support the use of sMRI for examining lameness originating from the proximal metacarpal region to refine the timing of returning to exercise based on follow-up examinations during the recuperation period.

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

5

---

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

Yoshiro ENDO Takeru TSUCHIYA Fumio SATO Harutaka MURASE Takaya OMURA Kenji KOROSUE Yasuo NAMBO Mutsuki ISHIMARU Yasuhiro WAKUI

出版者

公益社団法人 日本獣医学会

雑誌

Journal of Veterinary Medical Science (ISSN:09167250)

巻号頁・発行日

vol.74, no.8, pp.1079-1081, 2012 (Released:2012-09-03)

参考文献数

15

被引用文献数

5 11 3

---

Prevalence of equine gastric ulcer syndrome in 85 young Thoroughbreds was investigated. The presence of gastric ulcers was confirmed in 27.1% (23/85) of the horses by endoscopic examination. Sixty-two horses without gastric ulcers were allocated randomly to either the treated group (31 horses) or sham-dosed control group (31 horses) in order to investigate the efficacy of omeprazole oral paste in the prevention of gastric ulcers. At the second endoscopic examination conducted after 28 days of administration, only 1 horse in the treated group developed gastric ulcers, while 12 horses developed gastric ulcers in the control group. Based on these data, the efficacy of omeprazole in prevention of equine gastric ulcers in young Thoroughbreds during the training period was confirmed.

著者

Kazutaka YAMADA Fumio SATO Tohru HIGUCHI Kaori NISHIHARA Mitsunori KAYANO Naoki SASAKI Yasuo NAMBO

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.3, pp.81-87, 2015 (Released:2015-09-30)

参考文献数

24

被引用文献数

1 6

---

Bone mineral density (BMD) is one of the indications of the strength and health. BMD measured by quantitative computed tomography (QCT) was compared with that measured by dual energy X-ray absorptiometry (DXA) and radiographic bone aluminum equivalence (RBAE). Limbs were removed from horses that had been euthanized for reasons not associated with this study. Sixteen limbs (left and right metacarpals and metatarsals) from 4 horses were used to compare BMD as measured by QCT with those measured by DXA and RBAE. There was a strong correlation between BMD values measured by QCT and those measured by DXA (R2=0.85); correlation was also observed between values obtained by QCT and those obtained by RBAE (R2=0.61). To investigate changes in BMD with age, 37 right metacarpal bones, including 7 from horses euthanized because of fracture were examined by QCT. The BMD value of samples from horses dramatically increased until 2 years of age and then plateaued, a pattern similar to the growth curve. The BMD values of bone samples from horses euthanized because of fracture were within the population range, and samples of morbid fracture were not included. The relationship between BMD and age provides a reference for further quantitative studies of bone development and remodeling. Quantitative measurement of BMD using QCT may have great potential for the evaluation of bone biology for breeding and rearing management.

著者

Hirotoshi MIZUKAMI Tsuyoshi SUZUKI Yasuo NAMBO Mutsuki ISHIMARU Hiroshi NAITO Kenji KOROSUE Kentaro AKIYAMA Kenji MIYATA Akira YAMANOBE Kentaro NAGAOKA Gen WATANABE Kazuyoshi TAYA

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.49-56, 2015 (Released:2015-07-02)

参考文献数

14

被引用文献数

4 11

---

Development and endocrine changes in Thoroughbreds colts and fillies were compared between those reared at two facilities of the Japan Racing Association, the Hidaka Training and Research Center (Hidaka) and Miyazaki Yearling Training Farm (Miyazaki). Thoroughbred colts and fillies born in Japan between 2003 and 2010 were used. Each colt group and filly group was divided into 2 groups, respectively, and raised in Hidaka or Miyazaki for 7 months from September at 1 year old to April at 2 years old. For the growth parameters, the body weight, height at withers, and girth and cannon circumferences were measured once a month. For parameters of endocrine function, circulating prolactin, luteinizing hormone (LH), follicle-stimulating hormone (FSH), insulin-like growth factor-1 (IGF-1), testosterone, progesterone, and estradiol-17β levels were measured. Regarding growth, the rate of increase over the 7-month period was significantly higher in both colts and fillies raised in Miyazaki than in Hidaka in all 4 parameters: body weight, height at withers, and girth and cannon circumferences. The endocrine changes of the colts and fillies born in 2007 were as follows. In colts, although circulating prolactin tended to be higher in colts reared in Hidaka from October to April, circulating LH, FSH, testosterone, estradiol-17β and IGF-1 tended to be higher in colts reared in Miyazaki than in Hidaka, suggesting that the gonadotropin-releasing hormone-LH/FSH system and the growth hormone-IGF-1 system were more active in colts reared in Miyazaki as compared with those reared in Hidaka. In fillies, circulating prolactin tended to be higher in fillies reared in Hidaka in February and March, but no significant difference was noted in the serum LH, FSH, IGF-1, or progesterone level between the 2 groups. Circulating estradiol-17β tended to be higher in fillies reared in Miyazaki than in Hidaka in October and November. Regarding ovarian function, the initial ovulation occurred by the end of March in 2 (16.7%) of 12 fillies reared in Hidaka and 7 (38.9%) of 18 fillies reared in Miyazaki, suggesting that the ovarian function was more active in fillies reared in Miyazaki as compared with those reared in Hidaka. Based on these findings, it was clarified that development of the body and gonads was faster in Miyazaki compared with Hidaka in both colts and fillies.

著者

Tomoaki ONODA Ryuta YAMAMOTO Kyohei SAWAMURA Harutaka MURASE Yasuo NAMBO Yoshinobu INOUE Akira MATSUI Takeshi MIYAKE Nobuhiro HIRAI

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.25, no.2, pp.29-35, 2014 (Released:2014-06-25)

参考文献数

17

被引用文献数

4

---

We propose an approach of estimating individual growth curves based on the birthday information of Japanese Thoroughbred horses, with considerations of the seasonal compensatory growth that is a typical characteristic of seasonal breeding animals. The compensatory growth patterns appear during only the winter and spring seasons in the life of growing horses, and the meeting point between winter and spring depends on the birthday of each horse. We previously developed new growth curve equations for Japanese Thoroughbreds adjusting for compensatory growth. Based on the equations, a parameter denoting the birthday information was added for the modeling of the individual growth curves for each horse by shifting the meeting points in the compensatory growth periods. A total of 5,594 and 5,680 body weight and age measurements of Thoroughbred colts and fillies, respectively, and 3,770 withers height and age measurements of both sexes were used in the analyses. The results of predicted error difference and Akaike Information Criterion showed that the individual growth curves using birthday information better fit to the body weight and withers height data than not using them. The individual growth curve for each horse would be a useful tool for the feeding managements of young Japanese Thoroughbreds in compensatory growth periods.

著者

Yoshiro ENDO Takeru TSUCHIYA Fumio SATO Harutaka MURASE Takaya OMURA Kenji KOROSUE Yasuo NAMBO Mutsuki ISHIMARU Yasuhiro WAKUI

出版者

JAPANESE SOCIETY OF VETERINARY SCIENCE

雑誌

Journal of Veterinary Medical Science (ISSN:09167250)

巻号頁・発行日

pp.1204080805, (Released:2012-04-13)

被引用文献数

7 11

---

Prevalence of equine gastric ulcer syndrome in 85 young Thoroughbreds was investigated. The presence of gastric ulcers was confirmed in 27.1% (23/85) of the horses by endoscopic examination. For 62 horses without gastric ulcers were allocated randomly to either the treated group (31 horses) or sham-dosed control group (31 horses) in order to investigate the efficacy of omeprazole oral paste in the prevention of gastric ulcers. At the second endoscopic examination conducted after 28 days of administration, only 1 horse in the treated group developed gastric ulcers while 12 horses developed gastric ulcers in the control group. Based on this data, the efficacy of omeprazole in prevention of equine gastric ulcers in young Thoroughbreds during the training period was confirmed.

著者

Kenji KOROSUE Harutaka MURASE Fumio SATO Mutsuki ISHIMARU Takehiro HARADA Gen WATANABE Kazuyoshi TAYA Yasuo NAMBO

出版者

JAPANESE SOCIETY OF VETERINARY SCIENCE

雑誌

Journal of Veterinary Medical Science (ISSN:09167250)

巻号頁・発行日

pp.1203280800, (Released:2012-04-02)

被引用文献数

5 11

---

The purpose of this study was to demonstrate that a barren parous Thoroughbred mare with lactation induced by hormonal treatment can be introduced to an orphan foal at the same farm and that the mare can become pregnant after the end of the hormonal treatment. An additional purpose was to investigate the changes in the plasma concentrations of prolactin, estradiol-17β, progesterone, follicle-stimulating hormone, and luteinizing hormone before, during, and after hormonal treatment. The difference in body weight between the adopted foal and the control foals, which were at the same farm and raised by their natural mothers, was 17 kg at 24 weeks old, when the foals were weaned. However, the adopted foal and the control foals had almost the same weight at 35 weeks old and later. The first ovulation after hormonal treatment was confirmed 10 days after the end of hormonal treatment and then the normal estrous cycle resumed. Furthermore, the changes in plasma progesterone, estradiol-17β, follicle-stimulating hormone, and luteinizing hormone showed regular patterns after the first ovulation. Conception was confirmed in the fifth ovulation. Meanwhile, another study demonstrated that conception was confirmed in the first ovulation after hormonal treatment. The present study is the first to demonstrate the hormonal profiles during and after induction of lactation in a Thoroughbred mare. This approach is useful for solving the economic and epidemic problems of introducing a nurse mare to an orphan foal.