1
|
ISHIMARU M, TSUCHIYA T, ENDO Y, MATSUI A, OHMURA H, MURASE H, KOROSUE K, SATO F, TAYA K. Effects of different winter paddock management of Thoroughbred weanlings and yearlings in the cold region of Japan on physiological function, endocrine function and growth. J Vet Med Sci 2024; 86:756-768. [PMID: 38777756 PMCID: PMC11251821 DOI: 10.1292/jvms.24-0083] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2024] [Accepted: 05/13/2024] [Indexed: 05/25/2024] Open
Abstract
Effects of different winter paddock management of Thoroughbred weanlings and yearlings in Hokkaido, Japan, which is extremely cold in winter, on physiological function, endocrine function and growth were investigated. They were divided into two groups; those kept outdoors for 22 hr in the paddock (22hr group) and those kept outdoors for 7 hr in daytime with walking exercise for 1 hr using the horse-walker (7hr+W group), and the changes in daily distance travelled, body temperature (BT), heart rate (HR), HR variability (HRV), endocrine function and growth parameters were compared between the two groups from November at the year of birth to January at 1 year of age. The 7hr+W group could travel almost the same distance as the 22hr group by using the horse-walker. The 22hr group had a lower rate of increase in body weight than the 7hr+W group in January. In addition, lower in BT and HR were observed, and HRV analysis showed an increase in high frequency power spectral density, indicating that parasympathetic nervous activity was dominant. And also, changes in circulating cortisol and thyroxine were not observed despite cold environment. On the other hand, the 7hr+W group had higher prolactin and insulin like growth factor than the 22hr group in January, and cortisol and thyroxine were also increased. Physiological and endocrinological findings from the present study indicate that the management of the 7hr+W group is effective in promoting growth and maintaining metabolism during the winter season.
Collapse
Affiliation(s)
- Mutsuki ISHIMARU
- International Department, Japan Racing Association, Tokyo, Japan
| | | | - Yoshiro ENDO
- Hidaka Training and Research Center, Japan Racing Association, Hokkaido, Japan
| | - Akira MATSUI
- Hidaka Training and Research Center, Japan Racing Association, Hokkaido, Japan
| | - Hajime OHMURA
- Hidaka Training and Research Center, Japan Racing Association, Hokkaido, Japan
| | | | - Kenji KOROSUE
- Equine Department, Japan Racing Association, Tokyo, Japan
| | - Fumio SATO
- Japan Farriery Association, Tokyo, Japan
| | - Kazuyoshi TAYA
- Laboratory of Veterinary Physiology, Cooperative Department of Veterinary Medicine, Faculty of Agriculture, Tokyo University of Agriculture and Technology,
Tokyo, Japan
| |
Collapse
|
2
|
Gáspárdy A, Gallagher G, Bartha B, Haaland H, Fekete SG. The Effect of Supplemental Lighting during the Late Gestation Period on Post-Partum Mechanical Properties of Mare and Foal Guard Hair. Vet Sci 2024; 11:49. [PMID: 38275931 PMCID: PMC10819961 DOI: 10.3390/vetsci11010049] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2023] [Revised: 01/15/2024] [Accepted: 01/19/2024] [Indexed: 01/27/2024] Open
Abstract
This study investigates Thoroughbred mares exposed or not to supplemental blue light at the end of the gestation. Sixty mares and their 60 foals were selected for the investigation. Guard hair samples were collected from the shoulder just after (within 12 h) the parturition or birth. The foals of the light-treated mares developed significantly (p < 0.05) shorter hair than those of the control mares. A general effect of light treatment on basal hair diameter thinning could be demonstrated (p < 0.005). The maximum force of hair samples of light-treated mares and foals (0.098 and 0.085 N, respectively) was significantly lower than that of the control (0.272 and 0.178 N, respectively). The tensile strength (82.2 N/mm2) of the foal hair samples of the light-treated mares was significantly lower than that of the control foals (121.6 N/mm2). Although no significant difference was found in the elongation (ΔL), the hair of the control animals (mares and foals together) was more elastic than that of the treated animals (335 vs. 262 μm). In conclusion, the supplemental blue light treatment of the pregnant mares has a decreasing effect on both mares and their foals on the mechanical properties of the hair, making it shorter, thinner, and weaker.
Collapse
Affiliation(s)
- András Gáspárdy
- Institute for Animal Breeding, Nutrition and Laboratory Animal Science, University of Veterinary Medicine Budapest, István Street 2, 1078 Budapest, Hungary; (G.G.); (B.B.); (S.G.F.)
| | | | | | | | | |
Collapse
|
3
|
ISHIMARU M, OKANO A, MATSUI A, MURASE H, KOROSUE K, AKIYAMA K, TAYA K. Effects of an extended photoperiod on body composition of young Thoroughbreds in training. J Vet Med Sci 2024; 86:58-65. [PMID: 37967974 PMCID: PMC10849847 DOI: 10.1292/jvms.23-0349] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2023] [Accepted: 11/05/2023] [Indexed: 11/17/2023] Open
Abstract
The effects of an extended photoperiod (EP) on body composition of Thoroughbreds colts and fillies from December at one year old to April at two years old were investigated. Seventy-three Thoroughbreds reared and trained in Hidaka Training and Research Center, Japan Racing Association, Hokkaido were used. Forty-one horses were under the EP conditions from December 20 to April 15, and the 32 horses were under natural light alone as the control group. Body weight (BW), rump fat thickness (RFT), fat free mass (FFM) and percentage of fat (%F) were used as parameters of body composition. The present study revealed that BW and FFM increased with age in the EP group in colts. In fillies, BW increased with age in both the EP and the control group, however FFM increased with age only in the EP group. From December to April, only colts had a higher rate of increase in both BW and FFM in the EP group than in the control group. However, according to the mean rates of increase in FFM from January to March, the EP group was significantly higher than the control group in both sexes. Furthermore, monthly increase rate of FFM in March was significantly higher in the EP group than in the control group in both sexes. These results suggests that EP treatment to young Thoroughbreds in training at Hokkaido, which is shorter daylength in winter, accelerate the increase of FFM, representing muscle mass.
Collapse
Affiliation(s)
- Mutsuki ISHIMARU
- International Department, Japan Racing Association, Tokyo, Japan
| | - Atsushi OKANO
- Ritto Training Center, Japan Racing Association, Shiga, Japan
| | - Akira MATSUI
- Hidaka Training and Research Center, Japan Racing Association, Hokkaido, Japan
| | - Harutaka MURASE
- Hidaka Training and Research Center, Japan Racing Association, Hokkaido, Japan
| | - Kenji KOROSUE
- Hidaka Training and Research Center, Japan Racing Association, Hokkaido, Japan
| | | | - Kazuyoshi TAYA
- Laboratory of Veterinary Physiology, Cooperative Department of Veterinary Medicine, Faculty of Agriculture, Tokyo University of Agriculture and Technology,
Tokyo, Japan
| |
Collapse
|
4
|
ISHIMARU M, MATSUI A, SEKI K, KOROSUE K, AKIYAMA K, MIZUKAMI H, YOSHIDA T, TAYA K. Effects of different winter climates in Japan on body composition of young Thoroughbreds in training. J Vet Med Sci 2022; 84:1585-1594. [PMID: 36244743 PMCID: PMC9791233 DOI: 10.1292/jvms.22-0378] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
Changes in the body composition of 50 Thoroughbreds colts and fillies, born between 2004 and 2010, were compared between those reared at the Hidaka Training and Research Center (Hidaka), Hokkaido, which is extremely cold in winter, and those reared at the Miyazaki Yearling Training Farm (Miyazaki), Kyushu, which is mildly cold in winter. The horses were divided into two sex groups and reared and trained in Hidaka or Miyazaki for 7 months from October of one year of age to April of two years of age. Body weight (BW), rump fat thickness (RFT), fat-free mass (FFM), and percentage of fat (%F) were used as parameters of body composition. This study revealed that BW and FFM were higher, and %F was lower in colts than in fillies at both training sites. Among colts, Miyazaki colts tended to have higher FFM values than Hidaka colts, and %F was significantly lower in Miyazaki colts than in Hidaka colts. Furthermore, from October to April, Miyazaki horses had a higher rate of increase in BW than Hidaka horses in both sexes and a higher rate of increase in FFM in colts. The higher rate of increase in FFM in Miyazaki colts suggests that training young Thoroughbreds in winter under mildly cold climate is more effective, than severely cold climate, particularly in colts.
Collapse
Affiliation(s)
- Mutsuki ISHIMARU
- Hidaka Training and Research Center, Japan Racing Association, Hokkaido, Japan,Department of Animal Health, Faculty of Veterinary Medicine, Rakuno Gakuen University, Hokkaido, Japan,Correspondence to: Ishimaru M: , Hidaka Training and Research Center, Japan Racing Association, Nishicha 535-13, Urakawa-cho, Hokkaido 057-0171, Japan
| | - Akira MATSUI
- Hidaka Training and Research Center, Japan Racing Association, Hokkaido, Japan
| | - Kazuhiro SEKI
- Hidaka Training and Research Center, Japan Racing Association, Hokkaido, Japan
| | - Kenji KOROSUE
- Hidaka Training and Research Center, Japan Racing Association, Hokkaido, Japan
| | | | - Hirotoshi MIZUKAMI
- Miyazaki Yearling Training Farm, Japan Racing Association, Miyazaki, Japan
| | | | - Kazuyoshi TAYA
- Laboratory of Veterinary Physiology, Cooperative Department of Veterinary Medicine, Faculty of Agriculture, Tokyo University of Agriculture and Technology, Tokyo, Japan
| |
Collapse
|
5
|
Toishi Y, Tsunoda N, Nagata SI, Kirisawa R, Nagaoka K, Watanabe G, Yanagawa Y, Katagiri S, Taya K. Evaluation of the chemiluminescent enzyme immunoassay system for the measurement of testosterone in the serum and whole blood of stallions. J Reprod Dev 2017; 64:41-47. [PMID: 29129877 PMCID: PMC5830357 DOI: 10.1262/jrd.2017-099] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Testosterone (T) concentration is a useful indicator of reproductive function in male animals. However, T concentration is not usually measured in veterinary clinics, partly due to the unavailability of reliable and
rapid assays for animal samples. In this study, a rapid chemiluminescent enzyme immunoassay system (CLEIA system) that was developed for the measurement of T concentration in humans use was validated for stallion blood
samples. First, serum T concentrations were measured using the CLEIA system and compared with those measured by a fluoroimmunoassay that has been validated for use in stallions. The serum T concentrations measured by the
two methods were highly correlated (r = 0.9865, n = 56). Second, to validate the use of whole blood as assay samples, T concentrations in whole blood and in the serum were measured by the CLEIA system. T concentrations
in both samples were highly correlated (r = 0.9665, n = 64). Finally, to evaluate the practical value of the CLEIA system in clinical settings, T concentrations were measured in three stallions with reproductive
abnormalities after the administration of human chorionic gonadotropin (hCG). Two stallions with small or absent testes in the scrotum showed an increase in T production in response to hCG administration and one stallion
with seminoma did not. In conclusion, the CLEIA system was found to be a rapid and reliable tool for measuring T concentrations in stallions and may improve reproductive management in clinical settings and in breeding
studs.
Collapse
Affiliation(s)
- Yuko Toishi
- Shadai Stallion Station, Hokkaido 059-1432, Japan.,Laboratory of Veterinary Virology, Department of Pathobiology, School of Veterinary Medicine, Rakuno Gakuen University, Hokkaido 069-8501, Japan
| | | | - Shun-Ichi Nagata
- Genetic Analysis Department, Laboratory of Racing Chemistry, Tochigi 320-0851, Japan
| | - Rikio Kirisawa
- Laboratory of Veterinary Virology, Department of Pathobiology, School of Veterinary Medicine, Rakuno Gakuen University, Hokkaido 069-8501, Japan
| | - Kentaro Nagaoka
- Laboratory of Veterinary Physiology, Cooperative Department of Veterinary Medicine, Faculty of Agriculture, Tokyo University of Agriculture and Technology, Tokyo 183-8509, Japan.,United Graduated School of Veterinarian Science, Gifu University, Gifu 501-1193, Japan
| | - Gen Watanabe
- Laboratory of Veterinary Physiology, Cooperative Department of Veterinary Medicine, Faculty of Agriculture, Tokyo University of Agriculture and Technology, Tokyo 183-8509, Japan.,United Graduated School of Veterinarian Science, Gifu University, Gifu 501-1193, Japan
| | - Yojiro Yanagawa
- Laboratory of Theriogenology, Department of Veterinary Clinical Sciences, Graduate School of Veterinary Medicine, Hokkaido University, Hokkaido 060-0808, Japan
| | - Seiji Katagiri
- Laboratory of Theriogenology, Department of Veterinary Clinical Sciences, Graduate School of Veterinary Medicine, Hokkaido University, Hokkaido 060-0808, Japan
| | - Kazuyoshi Taya
- Shadai Stallion Station, Hokkaido 059-1432, Japan.,Laboratory of Veterinary Physiology, Cooperative Department of Veterinary Medicine, Faculty of Agriculture, Tokyo University of Agriculture and Technology, Tokyo 183-8509, Japan
| |
Collapse
|
6
|
Tangyuenyong S, Sato F, Nambo Y, Murase H, Endo Y, Tanaka T, Nagaoka K, Watanabe G. Comparison of physical body growth and metabolic and reproductive endocrine functions between north and south climates of Japan in trained Thoroughbred yearling horses. J Equine Sci 2017; 28:77-86. [PMID: 28955159 PMCID: PMC5608960 DOI: 10.1294/jes.28.77] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2017] [Accepted: 06/07/2017] [Indexed: 11/07/2022] Open
Abstract
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.
Collapse
Affiliation(s)
- Siriwan Tangyuenyong
- Department of Basic Veterinary Science, United Graduate School of Veterinary Sciences, Gifu University, Gifu 501-1193, Japan.,Laboratory of Veterinary Physiology, Cooperative Department of Veterinary Medicine, Faculty of Agriculture, Tokyo University of Agriculture and Technology, Tokyo 183-8509, Japan
| | - Fumio Sato
- Department of Basic Veterinary Science, United Graduate School of Veterinary Sciences, Gifu University, Gifu 501-1193, Japan.,Equine Breeding Science, Hidaka Training and Research Center, Japan Racing Association, Hokkaido 057-0171, Japan
| | - Yasuo Nambo
- Department of Basic Veterinary Science, United Graduate School of Veterinary Sciences, Gifu University, Gifu 501-1193, Japan.,Department of Clinical Veterinary Science, Obihiro University of Agriculture and Veterinary Medicine, Hokkaido 080-0834, Japan
| | - Harutaka Murase
- Equine Breeding Science, Hidaka Training and Research Center, Japan Racing Association, Hokkaido 057-0171, Japan
| | - Yoshiro Endo
- Equine Breeding Science, Hidaka Training and Research Center, Japan Racing Association, Hokkaido 057-0171, Japan
| | - Tomomi Tanaka
- Department of Basic Veterinary Science, United Graduate School of Veterinary Sciences, Gifu University, Gifu 501-1193, Japan.,Laboratory of Veterinary Reproduction, Cooperative Department of Veterinary Medicine, Faculty of Agriculture, Tokyo University of Agriculture and Technology, Tokyo 183-8509, Japan
| | - Kentaro Nagaoka
- Department of Basic Veterinary Science, United Graduate School of Veterinary Sciences, Gifu University, Gifu 501-1193, Japan.,Laboratory of Veterinary Physiology, Cooperative Department of Veterinary Medicine, Faculty of Agriculture, Tokyo University of Agriculture and Technology, Tokyo 183-8509, Japan
| | - Gen Watanabe
- Department of Basic Veterinary Science, United Graduate School of Veterinary Sciences, Gifu University, Gifu 501-1193, Japan.,Laboratory of Veterinary Physiology, Cooperative Department of Veterinary Medicine, Faculty of Agriculture, Tokyo University of Agriculture and Technology, Tokyo 183-8509, Japan
| |
Collapse
|
7
|
Toishi Y, Tsunoda N, Kume K, Nagaoka K, Watanabe G, Taya K. PATHFAST, a novel chemiluminescent enzyme immunoassay for measuring estradiol in equine whole blood and serum. J Reprod Dev 2016; 62:631-634. [PMID: 27545960 PMCID: PMC5177982 DOI: 10.1262/jrd.2016-038] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A novel chemiluminescent enzyme immunoassay system, PATHFAST, for the measurement of estradiol in horses was evaluated. The concentrations of estradiol in the whole blood and serum of mares were measured using PATHFAST and the estradiol concentrations measured by PATHFAST were compared with those measured by a time-resolved fluoro-immunoassay (FIA). To monitor physiological changes, serum estradiol concentrations in mares were measured using PATHFAST throughout the gestation period. The serum estradiol concentrations correlated highly with those in whole blood samples. The serum concentrations of estradiol measured by PATHFAST also correlated well with FIA. Circulating estradiol increased during mid-gestation and high levels of serum estradiol were maintained in late gestation, followed by an abrupt decline to term. These results demonstrate the utility of PATHFAST in equine clinics as an accurate diagnostic tool for the rapid assay of estradiol within 26 min using unextracted whole blood.
Collapse
Affiliation(s)
- Yuko Toishi
- Shadai Corporation, Hokkaido 059-1432, Japan
| | | | | | | | | | | |
Collapse
|
8
|
Harada T, Nambo Y, Ishimaru M, Sato F, Nagaoka K, Watanabe G, Taya K. Promoting effects of an extended photoperiod treatment on the condition of hair coats and gonadal function in Thoroughbred weanlings. J Equine Sci 2016; 26:147-50. [PMID: 26858581 PMCID: PMC4739146 DOI: 10.1294/jes.26.147] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2015] [Accepted: 11/13/2015] [Indexed: 11/01/2022] Open
Abstract
The effects of an extended photoperiod (EP) treatment (14.5 hr light, 9.5 hr dark) on Thoroughbred colts and fillies from December 25 at 7-9 months old to the following May at 12-14 months old on coat condition and gonadal functions were investigated. Coat condition was evaluated in April. The colts and fillies in the EP treatment group changed from winter to summer coats (molting of winter coats), whereas those in the control group did not. To determine the day of first ovulation, the plasma concentrations of progesterone were measured once a month in fillies. The day of first ovulation was advanced in the EP treatment fillies compared with the control fillies. The present study clearly demonstrated that the EP treatment advanced the molting of winter coats and advanced ovulation in fillies, even in weanlings.
Collapse
Affiliation(s)
- Takehiro Harada
- United Graduate School of Veterinary Sciences, Gifu University, Gifu 501-1193, Japan; Laboratory of Veterinary Physiology, Cooperative Department of Veterinary Medicine, Faculty of Agriculture, Tokyo University of Agriculture and Technology, Tokyo 183-8509, Japan
| | - Yasuo Nambo
- United Graduate School of Veterinary Sciences, Gifu University, Gifu 501-1193, Japan; Department of Clinical Veterinary Science, Obihiro University of Agriculture and Veterinary Medicine, Hokkaido 080-8555, Japan
| | - Mutsuki Ishimaru
- Hidaka Training and Research Center, Japan Racing Association, Hokkaido 057-0171, Japan
| | - Fumio Sato
- United Graduate School of Veterinary Sciences, Gifu University, Gifu 501-1193, Japan; Hidaka Training and Research Center, Japan Racing Association, Hokkaido 057-0171, Japan
| | - Kentaro Nagaoka
- United Graduate School of Veterinary Sciences, Gifu University, Gifu 501-1193, Japan; Laboratory of Veterinary Physiology, Cooperative Department of Veterinary Medicine, Faculty of Agriculture, Tokyo University of Agriculture and Technology, Tokyo 183-8509, Japan
| | - Gen Watanabe
- United Graduate School of Veterinary Sciences, Gifu University, Gifu 501-1193, Japan; Laboratory of Veterinary Physiology, Cooperative Department of Veterinary Medicine, Faculty of Agriculture, Tokyo University of Agriculture and Technology, Tokyo 183-8509, Japan
| | - Kazuyoshi Taya
- Laboratory of Veterinary Physiology, Cooperative Department of Veterinary Medicine, Faculty of Agriculture, Tokyo University of Agriculture and Technology, Tokyo 183-8509, Japan; Shadai Corporation, Hokkaido 059-1432, Japan
| |
Collapse
|
9
|
Suzuki T, Mizukami H, Nambo Y, Ishimaru M, Miyata K, Akiyama K, Korosue K, Naito H, Nagaoka K, Watanabe G, Taya K. Different effects of an extended photoperiod treatment on growth, gonadal function, and condition of hair coats in Thoroughbred yearlings reared under different climate conditions. J Equine Sci 2016; 26:113-24. [PMID: 26858576 PMCID: PMC4739141 DOI: 10.1294/jes.26.113] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2015] [Accepted: 10/23/2015] [Indexed: 12/29/2022] Open
Abstract
One- to two-year-old Thoroughbred colts and fillies being reared in Miyazaki (warm climate) and Hidaka (cold climate), Japan, were administered extended photoperiod (EP) treatment between December 20 and the following April 10, and its effect on growth, endocrine changes, gonadal activation, and hair coat condition was investigated. In colts reared in Miyazaki, no effect of EP treatment was noted on the growth indices, including body weight (BW), height at withers (HW), girth, and cannon circumference (CC), whereas the BWs and CCs of fillies were significantly higher in the EP treatment group than the control. In Hidaka, the BWs and HWs of colts and HWs of fillies were significantly higher in the EP treatment group. Gonadal activation characterized by an increase in circulating hormone concentrations was earlier in the EP treatment group for fillies reared in Miyazaki [luteinizing hormone (LH), follicle-stimulating hormone (FSH), progesterone (P4), and estradiol-17β (E2)] and in colts (LH, testosterone, and E2) and fillies (LH, FSH, P4, and E2) reared in Hidaka. Regardless of sex and climate, prolactin was significantly higher in the EP treatment group, whereas insulin-like growth factor (IGF-I) was not. Initial ovulation occurred before April in more of the EP treatment group than the control regardless of the climate. Molting of the hair coat, examined in March, was advanced in the EP treatment group regardless of sex and climate. These results suggest that EP treatment may promote growth and gonadal activation in fillies reared in Miyazaki and in colts and fillies reared in Hidaka and that the effect may be mediated by prolactin.
Collapse
Affiliation(s)
| | | | - Yasuo Nambo
- Department of Clinical Veterinary Science, Obihiro University of Agriculture and Veterinary Medicine, Hokkaido 080-8555, Japan; United Graduate School of Veterinary Sciences, Gifu University, Gifu 501-1193, Japan
| | - Mutsuki Ishimaru
- Hidaka Training and Research Center, Japan Racing Association, Hokkaido 057-0171, Japan
| | - Kenji Miyata
- Hidaka Training and Research Center, Japan Racing Association, Hokkaido 057-0171, Japan
| | - Kentaro Akiyama
- Hidaka Training and Research Center, Japan Racing Association, Hokkaido 057-0171, Japan
| | - Kenji Korosue
- Miyazaki Yearling Training Farm, Japan Racing Association, Miyazaki 880-0036, Japan
| | - Hiroshi Naito
- Equine Department, Japan Racing Association, Tokyo 105-0003, Japan
| | - Kentaro Nagaoka
- United Graduate School of Veterinary Sciences, Gifu University, Gifu 501-1193, Japan; Laboratory of Veterinary Physiology, Cooperative Department of Veterinary Medicine, Faculty of Agriculture, Tokyo University of Agriculture and Technology, Tokyo 183-8509, Japan
| | - Gen Watanabe
- United Graduate School of Veterinary Sciences, Gifu University, Gifu 501-1193, Japan; Laboratory of Veterinary Physiology, Cooperative Department of Veterinary Medicine, Faculty of Agriculture, Tokyo University of Agriculture and Technology, Tokyo 183-8509, Japan
| | - Kazuyoshi Taya
- Laboratory of Veterinary Physiology, Cooperative Department of Veterinary Medicine, Faculty of Agriculture, Tokyo University of Agriculture and Technology, Tokyo 183-8509, Japan; Shadai Corporation, Hokkaido 059-1432, Japan
| |
Collapse
|