• Genes and Genomics
• /
• v.40 no.11
• /
• pp.1249-1258
• /
• 2018

The Jeju horse is an indigenous Korean horse breed that is currently registered with the Food and Agriculture Organization of the United Nations. However, there is severe lack of genomic studies on Jeju horse. This study was conducted to investigate genetic characteristics of horses including Jeju horse, Thoroughbred and Jeju crossbred (Jeju${\times}$Thoroughbred) populations. We compared the genomes of three horse populations using the Equine SNP70 Beadchip array. Short-range Linkage disequilibrium was the highest in Thoroughbred, whereas $r^2$ values were lowest in Jeju horse. Expected heterozygosity was the highest in Jeju crossbred (0.351), followed by the Thoroughbred (0.337) and Jeju horse (0.311). The level of inbreeding was slightly higher in Thoroughbred (-0.009) than in Jeju crossbred (-0.035) and Jeju horse (-0.038). $F_{ST}$ value was the highest between Jeju horse and Thoroughbred (0.113), whereas Jeju crossbred and Thoroughbred showed the lowest value (0.031). The genetic relationship was further assessed by principal component analysis, suggesting that Jeju crossbred is more genetically similar to Thoroughbred than Jeju horse population. Additionally, we detected potential selection signatures, for example, in loci located on LCORL/NCAPG and PROP1 genes that are known to influence body. Genome-wide analyses of the three horse populations showed that all the breeds had somewhat a low level of inbreeding within each population. In the population structure analysis, we found that Jeju crossbred was genetically closer to Thoroughbred than Jeju horse. Furthermore, we identified several signatures of selection which might be associated with traits of interest. To our current knowledge, this study is the first genomic research, analyzing genetic relationships of Jeju horse, Thoroughbred and Jeju crossbred.

• Korean Journal of Veterinary Research
• /
• v.49 no.4
• /
• pp.351-354
• /
• 2009

Diaphragmatic hernias, whether congenital or acquired (traumatic), are rarely observed in the horse. Acquired diaphragmatic hernias typically occur secondary to trauma or an increase in intraabdominal pressure due to falling, heavy exercise, or parturition. Diaphragmatic herniorrhaphy is difficult to perform in adult horses and the horses with symptomatic diaphragmatic hernias usually die. A 10- year old, 340 kg, Jeju horse (crossbred) broodmare with sudden onset of gait disorder and a moderate emaciation was examined. Findings on physical examination included conjunctivitis, dehydration, shallow breathing, dyspnea, weaken heart beat, lack of auscultatable sounds from the gastrointestinal tract, and anorexia. Rectal temperature was $38.4^{\circ}C$ and respiratory rates were moderately increased. There were slight signs of acute colic. The broodmare died one day after non-specific treatment of fluids, nutriment, antibiotics and non-steroidal anti-inflammatory drug. The cause of death was strangulation of the small intestine through a diaphragmatic hernia. The rent was about 2 cm in diameter and located in the central right part of diaphragm. Around 60 cm of small intestine was protruded into thoracic cavity through the rent. The cause of the hernia could not be ascertained. The broodmare had been pastured with many other horses, and the groom had not noticed any aggressive behavior among them. It was, however, speculated that trauma by stallion's attack may have been the cause of the diaphragmatic hernia, because the new horse may be the object of behaviors ranging from mild threats to seriously aggressive kicking, squealing, rearing, and biting.

• Journal of Animal Science and Technology
• /
• v.63 no.3
• /
• pp.651-661
• /
• 2021

This study aimed to investigate whether breed, sex, and age affected temperament differently (more or less neophobic) in mature horses during a novel object test. The study included Jeju crossbred (n = 12, age = 9.42 ± 4.57 y), Thoroughbred (n = 15, age = 10.73 ± 3.09 y), and Warmblood horses (n = 12, age = 13.08 ± 3.55 y) with the females (n = 22, age = 11.36 ± 4.24 y) and geldings (n = 17, age = 10.65 ± 3.66 y). Jeju crossbreds (Jeju horse × Thoroughbred) are valuable considering their popular usage in Korea, but limited studies have explored temperament of Jeju crossbred horses. A trained experimenter touched the left side of the neck with a white plastic bag (novel object). The test ended when the horse stopped escape response and heart rate (HR) dropped to baseline. Behavioral score and escape duration were measured as behavioral variables. Multiple variables related to HR and heart rate variability (HRV) were measured to reflect emotional state. These included basal HR (BHR), maximum HR (MHR), delay to reach maximum heart rate (Time to MHR), standard deviation of beat-to-beat intervals (SDNN), root mean square of successive differences (RMSSD), and ratio of low to high frequency components of a continuous series of heartbeats (LF/HF). Statistics revealed that Thoroughbreds had significantly higher behavioral scores, and lower RMSSD than Jeju crossbreds (p < 0.05), suggesting greater excitement and fear to the novel object in Thoroughbreds. None of the behavioral or cardiac parameters exhibited sex differences (p < 0.05). Age was negatively correlated with SDNN and RMSSD (p < 0.05), indicating that older horses felt more anxiety to the novelty than younger horses. Thoroughbreds and females had distinct correlations between behavioral and HRV variables in comparison with other groups (p < 0.05), implying that escape duration might be a good indicator of stress, especially in these two groups. These results are expected to improve equine welfare, safety and utility, by providing insights into the temperament of particular horse groups, to better match reactivity levels with specific functions.

• Journal of Practical Agriculture & Fisheries Research
• /
• v.25 no.4
• /
• pp.39-43
• /
• 2024

Little research has been done on investigating the specific characteristics of Jeju Ponies (Korean native horse) and Jeju Pony crossbreds. The authors performed evaluation of skin thickness of the skin of these breeds (n=205) at Jeju Race Park as a way of find of hippological difference. Results of this study showed that the Jeju Pony's skin were thicker than the Jeju Pony crossbred. The male's skin were thicker than the female's skin in two breeds respectively. Especially, in the Jeju Pony show significant differences (P < 0.05). In Jeju Pony crossbreds, as the skin thickness were thinner with age increase. 2-year-old group's skin significantly thinner than 3 and over 4-year-old groups. However, the Jeju Pony's skin were not significantly different by age. In conclusion, the authors thought that causes of the difference of the breeds were origin and genetic differences among the horse and the pony. Furthermore, the modified umbilical herniorrhaphy with rubber rings must be used cautiously in the Jeju Pony. It should be taken into account the animals' skin thickness when the leather goods created by using their skin.

• Journal of Life Science
• /
• v.33 no.12
• /
• pp.995-1001
• /
• 2023

This study investigated the effects of three music genres (classical, new age, and rock) on the stress levels of six Jeju crossbred horses (Jeju horse × Thoroughbred) in a horse stable. The horses were exposed to the three genres for seven days, and their stress levels were measured by analyzing physiological markers, including neurotransmitter (cortisol, β-endorphin, dopamine, serotonin, and oxytocin) plasma levels and creatine phosphokinase (CPK) and aldolase serum levels. The neurotransmitter analysis showed significant differences in cortisol levels between classical and new age music exposure. Dopamine levels decreased significantly only with new age exposure. Although there were no significant differences in β-endorphin levels between the three genres, β-endorphin levels decreased with increasing classical and new age music playback times and increased with increasing rock music playback times. There were no significant differences in serotonin levels between the three genres. Oxytocin levels decreased significantly with exposure to classical and rock music. The CPK and aldolase analyses showed that CPK levels decreased significantly only with exposure to new age music and increased after playback ended, while aldolase levels decreased significantly with classical and new age music exposure and increased after playback ended. These findings suggest that classical music and new age are the optimal music genres for the psychological stability of Jeju crossbred horses. Playing back an appropriate music genre could be used to improve breeding and promote the welfare of Jeju crossbred horses.

• Food Science and Preservation
• /
• v.22 no.5
• /
• pp.644-651
• /
• 2015

To enhance the consumption of horse meat, its nutritional composition was analyzed and compared to that of white meat (i.e., chicken and duck), which consumers consider healthy. Horse meat samples used in the experiment were classified by breed and grade as follows: Jeju horse (grade $1^+$ and 1), Jeju crossbred horse (grade 1 and 2), Thoroughbred (no grade), and cuts (loin, chuck roll, and arm picnic). In an analysis of general components and cholesterol, the horse meat was confirmed as a low-fat, high-protein, and low-cholesterol food material. In an amino acid analysis, horse meat contained a higher proportion of essential amino acids than white meat. The fatty acid compositions were also analyzed. The content of linolenic acid, an essential fatty acid, was significantly higher in all horse meat groups than in Ross chicken and Pekin duck meat. The content of palmitoleic acid showed similar results. In a mineral analysis, the levels of Fe and Zn in horse meat were higher than those of white meat. The mineral content was as follows except for the leg of shite meat: K > P > Na > Mg > Ca > Zn > Fe.

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

• Asian-Australasian Journal of Animal Sciences
• /
• v.31 no.8
• /
• pp.1098-1102
• /
• 2018

Objective: Temperament can be defined as a type of behavioral tendency that appears in a relatively stable manner in responses to various external stimuli over time. The aim of this study was to estimate genetic parameters for the records of temperament testing that are used to improve the temperament of Jeju crossbred (Jeju${\times}$Thoroughbred) horses. Methods: This study was conducted using 205 horses (101 females and 104 males) produced between 2010 and 2015. The experimental animals were imprinted and tamed according to the Manual for Horse Taming and Evaluation for Therapeutic Riding Horses and evaluated according to the categories for temperament testing (gentleness, patience, aggressiveness, sensitivity, and friendliness) between 15 months and 18 months of age. Each category was scored on a five-point linear scale. Genetic parameters for the test categories were analyzed using a multi-trait mixed model with repeated records. The ASReml program was used to analyze the data. Results: The heritability of gentleness, patience, aggressiveness, sensitivity and friendliness ranged from 0.08 to 0.53. The standard errors of estimated heritability ranged from 0.13 to 0.17. The test categories showed high genetic correlations with each other, ranging from 0.96 to 0.99 and high repeatability, ranging from 0.70 to 0.73. Conclusion: The results of this study showed that the test categories had moderate heritability and high genetic correlations, but additional studies may be necessary to use the results for the improvement programs of the temperament of Jeju crossbred horses.

• Food Science of Animal Resources
• /
• v.37 no.4
• /
• pp.486-493
• /
• 2017

The effects of slaughter age (28, 32, or 38 mon) on the proximate composition, collagen content, fatty acid composition, amino acid content, and mineral contents of horse leg bone (femur and tibia) extracts (HLBE) obtained from Jeju crossbred horses (n=14) in Korea. HLBE was extracted for 24 h with boiling water. At those ages, the respective proximate compositions of the HLBE were found as follows: 5.20-6.42% crude protein; fat 0.61-1.65% crude; and 0.10-0.22% crude ash. At 32 and 38 mon, the HLBE showed higher levels of both crude protein and collagen than at 28 mon. The major fatty acids of the horse leg bone extract powder (HLBP) were palmitic acid and oleic acid. Palmitoleic acid and the essential fatty acids were higher in the HLBP at 38 mon compared to that at 28 mon. Nearly all the amino acids were found at higher levels in the HLBP at 38 mon than at 28 mon, except histidine. The P, K, Zn, Se and Fe contents in the HLBP increased significantly with age. These results suggest that some nutrients in the HLBE increase with age, and that extracts from horses older than 32 mon would be more nutritious for human consumers.

• Journal of Embryo Transfer
• /
• v.31 no.3
• /
• pp.227-233
• /
• 2016

This study was conducted to analyze the effect of single nucleotide polymorphisms (SNPs) on the equine chromosomes (ECA) 3 for the body conformations of 12 month of age in Jeju crossbred (Jeju horses ${\times}$ Thoroughbred). A total of 199 Jeju crossbred horse samples were obtained from the National Institute of Subtropical Livestock Research Institute for this study. To correctly estimate the body conformations, we measured thirteen elements relevant to the body conformation such as body weight, wither height, body length for all the 199 horses at 12 month of age. Furthermore, all the horses were genotyped using four SNPs including the BIEC2-808466, BIEC2-808543, BIEC2-808967, BIEC2-809370, of which genomic coordinates range approximately from 105.1Mbp to 110 Mbp in the ECA3. For the phenotypic data sets, the average body weight was $193.7{\pm}24.5kg$ and the height was $124.5{\pm}4.0cm$. As for the genotypic data, the miner allele frequencies of the SNPs were shown to be varied from 0.01 to 0.291. Using the phenotypic and genotypic data sets, analysis of covariance was performed to find any association between those SNP genotypes and body conformations, using year of birth, month of birth, sex, and parity as the covariance components. The result showed that alternative genotypes in the BIEC2-808967 and BIEC2-809370 SNPs were significantly associated with the body length (P<0.05) and the wither height (P<0.05) respectively in the Jeju crossbred horses. Therefore, it is estimated that there are significant associations in the body conformation of 12 month of age of Jeju crossbred for those two SNPs used in this study.