• Journal of Life Science
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• v.32 no.1
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• pp.29-35
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• 2022

This study was conducted to analyze the genetic polymorphisms of dopamine receptor D4 (DRD4) in horse breeds and its association with substrate characteristics in Jeju crossbreds (Jeju Horse × Thoroughbred). Polymorphisms in DRD4 are candidate genes associated with temperament in various mammals, including humans. Single nucleotide polymorphism (SNP) G292A in the exon 3 region of the horse DRD4 has a reported association with curiosity and vigilance in thoroughbreds. Sanger sequencing was used to identify polymorphisms of the mutations in DRD4 in three horse breeds. The SNP frequency in Jeju horses was significantly different from the frequency in other breeds. Character evaluation, conducted in the Jeju crossbreds and scored using a temperament test and contact test, revealed a high correlation between each test. Comparison of the polymorphism in the DRD4 of horses and the results of the character evaluation revealed lower scores for all temperaments in horses carrying allele A. Comparison of the SNP of G292A and blood dopamine levels in Jeju crossbreds showed 2.87 times higher levels for the GA type than for the GG type. This study identified an association between DRD4 polymorphism and various test methods for evaluating horse temperament and levels of neurotransmitters. Further research could validate the use of this gene as a genetic marker for character evaluation.

• Korean Journal of Veterinary Research
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• v.60 no.1
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• pp.33-37
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• 2020

The purpose of the present study was to investigate changes in hematological and serum biochemical parameters in ponies exercising 3 times a day. The study included 10 healthy 4- to 5-year-old Jeju crossbred ponies used in riding lessons at an equestrian riding school. Hematology and serum chemistry samples were obtained before the initial lesson and after the last lesson of the day. The post-exercise results showed that packed cell volume, white blood cell, red blood cell, hemoglobin, and total protein levels increased significantly (p < 0.05). Serum Na⁺ also increased significantly (p < 0.01), but serum Ca⁺⁺ decreased significantly (p < 0.01). Creatinine kinase, aspartate amino transferase, gamma glutamyl transferase, blood urea nitrogen, creatinine, and bilirubin levels increased significantly (p < 0.05), but the glucose level decreased significantly (p < 0.05). Furthermore, the serum cortisol hormone level increased significantly (p < 0.01). The results suggest that participating in riding lessons three times a day may result in various physiological changes, indicating the presence of exercise-related stress in riding ponies.

• Journal of Veterinary Clinics
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• v.32 no.3
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• pp.285-287
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• 2015

Wolf teeth have been reported with incidence rate of 13% to 31.9% in horses of both sexes. However, there is no report about the incidence of wolf teeth in pony breeds. In order to determine the incidence of wolf teeth in Jeju Ponies and Jeju Pony crossbreds, oral examination and palpation of the interdental space of ponies at the Jeju Race Park were performed from 2006 to 2010. Results of this study showed that a total of 90 (3.4%) of the 2,675 examined Jeju Ponies and Jeju Pony crossbreds had wolf teeth. Among 30 Jeju Ponies that had wolf teeth, 22 were male (73.3%) and 8 were female (26.7%). Among 60 Jeju Pony crossbreds that had wolf teeth, 25 were male (41.7%) and 35 were female (58.3%). In Jeju Ponies, wolf teeth were most common in 3-years-old, followed by ${\geq}4$-years-old, then 2-years-old. For Jeju Pony crossbreds, wolf teeth were most common in 3-years-old, followed by 2-yearsold, then ${\geq}4$-years-old. In conclusion, the incidence of wolf teeth in Jeju Ponies and Jeju Pony crossbreds was considerably lower than what has been reported for horses in other countries.

• Journal of Embryo Transfer
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• v.33 no.1
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• pp.17-22
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• 2018

This study was conducted to determine the effect of pentoxifylline levels on sperm motility, survival rate, sperm membrane integrity of frozen semen and fresh-extended equine semen in Jeju cross-bred horses. As a result of sperm characteristic comparison depending on pentoxifylline levles at 30 minutes post-thaw, the progressive motilities were $53.25{\pm}2.87$ (4mM pentoxifylline) and $50.28{\pm}2.14$ (8mM pentoxifylline) and significantly higher compared to the control group($40.09{\pm}5.15$) and other treatment group (16mM pentoxifylline, $41.27{\pm}2.82$). The progressive fast motility were $22.44{\pm}1.62$ (4mM pentoxifylline,) and $22.74{\pm}3.07$ (8mM pentoxifylline) and significantly higher compared to the control group ($13.47{\pm}1.48$) and other treatment group (16mM pentoxifylline, $14.66{\pm}3.68$) (p<0.05). As a result of sperm characteristic comparison depending on pentoxifylline levles at 30 minutes post-thaw were $68.96{\pm}1.64$ (4mM pentoxifylline) and $67.90{\pm}6.72$ (8mM pentoxifylline) and significantly higher compared to the control group ($53.48{\pm}4.84$) and other treatment group (16mM pentoxifylline, $58.14{\pm}2.65$) (p<0.05). In conclusion, these results suggest that treatment groups with 4mM and 8mM pentoxifylline were higher compare to equine seperm mobility and the control group and treatment groups with more than 16mM pentoxifylline has a negative effect on sperm characteristics. After thawing, the total motility in post-thawed equine sperm has increased by 10 percent for 1 hour. these results suggest that pentoxifylline contributes to the improvement of the equine sperm motility and characteristics in post-thawed semen.

• Journal of Life Science
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• v.23 no.9
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• pp.1147-1154
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• 2013

This study was conducted to evaluate the antioxidation activity of Jeju crossbred horse (Jeju native horse ${\times}$ thoroughbred) leg bone extracts (HLBE) and its enzyme hydrolysates by determination of 1,1-diphenyl-2picryl-hydrazyl (DPPH), 2,2-azino-bis(3-ethylbenzo thiazoline-6-sulfonic acid) diammonium salt (ABTS) radical scavenging activity, ferric reducing/antioxidant power (FRAP), and oxygen radical absorbance capacity (ORAC). HLBE was extracted with hot water for 24 hr and lyophilized. The lyophilized HLBE was hydrolyzed using multifect PR6L (MP), pepsin (PS), and a pepsin and pancreatin mixture (PSPC) for 4 hr at 60, 50, and $50^{\circ}C$, respectively. The hydrolysates were separated by a molecular weight of 3 kDa more or less. When the yield of HLBE was 100%, the yield of hydrolysates less than 3 kDa of MP, PS, and PSPC was 10.86, 3.26, and 8.00%, respectively. Enzyme hydrolysates with low molecular weight less than 3 kDa in MP and PSPC showed significantly higher DPPH, ABTS radical scavenging activity, and ORAC compared to HLBE and its hydrolysates with more than 3 kDa. However, the FRAP of the hydrolysates less than 3 kDa in PS was significantly higher than in MP. These results suggest that low molecular weight enzyme hydrolysates less than 3 kDa have more powerful antioxidation activity, especially when they are hydrolyzed by MP and PSPC rather than PS. Therefore, low molecular weight enzyme hydrolysates of HLBE hydrolyzed with MP and PSPC have significant potential as antioxidants in the food industry. Further in vivo studies are required to support the antioxidation activities of the hydrolysates in vitro.