• Journal of Embryo Transfer
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• v.32 no.3
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• pp.153-157
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• 2017

This study was conducted to investigate the optimal artificial insemination (AI) time with diagnostic kit at ovulation time. We already applied the patent about the protein in the cow heat mucose in external reproductive tract. And we would examine the accuracy for detection of cow heat by the kit produced with the protein. Evaluation of optimal heat detection was tried two time at 12 hrs and 24 hrs after the heat. And then, AI service also performed two times with no relation to the results of heat diagnosis by heat detection kit and pregnancy rates were checked with rectal palpation on $60^{th}$ day after AI. Heat diagnostic results by kit in natural heat after 12 hrs in Hanwoo cows were showed 31.3~75.0% on positive in first heat detection and 33.3~100.0% on positve in second heat detection. In the $1^{st}$ positive results were significant different (p<0.05), but $2^{nd}$ positive were not. The results of heat detection showed different result on regional influence and individual cow effects. The pregnancy rates of first trial of heat detection were showed 34.4~78.7% on positive and 21.3~68.8% on negative after the diagnosis by heat detection kit. And the pregnancy rates of next trial of heat detection were showed 33.3~85.7% on positive and 14.3~66.6% on negative after the heat diagnosis. Both positive results of first trial and next trial also were showed significant different (p<0.05), but negative results were not. In positive result, first trial of total pregnancy rates was higher than the next trial of pregnancy, but there showed opposite results on negative results. In conclusion, the optimal heat detection kit is suitable to ordinary Hanwoo cows and it suggested that we have to improve the kit's accuracy by detecting the materials like proteins related optimal AI time.

• Korean Journal of Animal Reproduction
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• v.17 no.1
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• pp.35-41
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• 1993

The study was conducted to investigate the effects on environmental factors on the reproductive performance of Korean native cattle based on the data from 13, 588 records which were surveyed from 1983 to 1992. The results obtained in this study are as follows; 1. Mean performaces of the reproductive traits were 510.2days for the age at 1st service, 525.0days for the age at 1st conception, 808.7 days for the age at 1st calving, 102.5 days for the days to 1st conception postpartum and 388.6 days of the calving inverval. The cows of Chunbuk province were tended to be bred and calved at younger age and showed shorter calving interval than those of other provinces. 2. The effect of birth year was significant for the reproductive performances, especially, in 1986~1987 when the cattle prices dropped sharply and reproductive performances were poor. 3. The times of 1st service and 1st conception of heifers calved in spring tended to be delayed. Days to 1st conception postpartum, calving interval and days to 1st service postpartum of cows calved in fall were shorter than other calving season's cows. 4. Days to 1st conception postpartum, calving interval and days to 1st service postpartum of cow's were shortened and gestation length was prolonged as the number of parity increases.

• Journal of Embryo Transfer
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• v.24 no.3
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• pp.159-167
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• 2009

Ultrasonographic examination was performed to observe the ultrasonographic image of Korean native cows' normal uterus in condition of in vitro and in vivo. The experiment was done 28 slaughtered cows' uterus using immersed in water in vitro, and 41 healthy breeding cows taken rectal ultrasonography in vivo. Ultrasonographic examination of uterine was taken on the reference of cross section of intercornual ligaments' cranial. Each uterus on the experiments was compared by estrous cycle and ultrasonographic frequency. The uterine structure using ultrasonography was 5 layers of uterine horn in vivo as well as in vitro. Uterine horn was observed to be distinguished from inside to outside as endometrium to inner echogenic layer, circular muscle layer to slightly echogenic elliptical layer, stratum vasculare to central echogenic layer, longitudinal muscle layer to slightly echogenic arched layer, and perimetrium to outer echogenic layer, respectively. According to the observation of uterus related to estrous cycle and ultrasonographic examination, uterine endometrium in vitro was constantly founded irrespective of estrous cycle and ultrasonographic frequency. On the low frequency, endometrium and circular muscle layer in estrus were prone to distinguished than in diestrus. On the high frequency, endometrium and circular muscle layer were always distinguished regardless of estrous cycle. In vivo, uterine endometrium and circular muscle layer were observed regardless of estrus and ultrasonographic frequency. On the low frequency, stratum vasculare and longitudinal muscle layer were not likely to be distinguished in diestrus, but estrus. On the high frequency, stratum vasculare and longitudinal muscle layer were observed regardless of estrous cycle. Also, every uterine structure was easily distinguished on high frequency than low frequency owing to precision of distinction in layers. The difference of results followed by the experiments conditions between in vitro and in vivo was that uterine endometrium and circular muscle layer in diestrus in vitro were difficult to be distinguished and uterine lumen was observed during whole estrous cycle. In vivo, It was founded that the distinction of stratum vasculare and logitudinal muscle layer in diestrus was complicated and uterine lumen was observed during only estrus. In view of the result so far achieved, normal uterine structure divided in 5 layers on ultrasonography was accorded with microscopic organization, uterine structure was likely to be observed during estrus than diestrus, high frequency checkup than low frequency, and uterine endometrium, circular muscle, stratum vasculare was easily observed regardless of estrous cycle and ultrasonographic frequency.

• Korean Journal of Agricultural Science
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• v.46 no.1
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• pp.27-31
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• 2019

It is well documented that intensive selection in dairy cattle for economic value such as increased milk yield led to a decline in reproductive performance. Recent studies using genome-wide association studies (GWASs) discovered candidate genes involved in the lower fertility including embryo development and conception rates. However, the information, which showed a lower reproductive performance, is limited to dairy cattle, especially Holstein, and the candidate genes were not examined in the Korean native cattle Hanwoo which has been intensively selected and bred for meat in the last few decades. We selected the candidate genes WBP1 and PARM1 reported to be associated with cow and/or heifer conception in dairy cattle and analyzed the genotype because those genes have non-synonymous single nucleotide polymorphisms (SNPs). To determine the single base change, we used the high resolution melting (HRM) assay which is rapid and cost-effective for a small number of genes. We found that most heifers with higher conception (1: service per conception) have the AA genotype coding Threonine rather than Proline in the WBP1 gene. We did not detect an association for a SNP in PARM1 in our analysis. In conclusion, the genetic variation of WBP1 can be used as a selective marker gene to improve reproductive performance, and HRM assay can be used to identify common SNP genotypes rapidly and cost effectively.

• Korean Journal of Animal Reproduction
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• v.23 no.1
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• pp.69-73
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• 1999

A calf with derodidymus was delivered from a 3-year old Korean-native cow with abortion last ime at Jangheong area in Chonnam Province. The anomaly with body weight of 35 kg was born t the normal time of parturition. During the parturition, however, the calf with twin head was onfirmed and the complete amputation between fore and hind limb was inevitably carried out or safety of the dam. The calf had normal skeleton and extremities but had two heads and cervical vertebrae divided from upper thoracic part. At necropsy, there were found totally 3 pairs of ore limbs including two pairs of hypoplastic ones hided in the thoracic limb and also found one air of sternum. One head had incomplete torsion or unilateral hypoplasia of mandible with artly hypoplastic skull. There were marked fusion and torsion from cervical to 3rd thoracic vertebra. No abnormality was found on all organs in the pleural and abdominal cavities except a rectal stricture formed at 5 cm away from the atresia ani.

• Korean Journal of Veterinary Research
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• v.30 no.2
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• pp.171-175
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• 1990

Radioimmunoassay for progesterone in Korean native cows was developed using the anti-4-pregnen-$11{\alpha}$-ol-3,20-dione-hemisuccinate bovine serum albumin as an antibody. The final dilution of antibody was 1 : 5,000. The percentage recoveries of [$^3H$] progesterone was $83.5{\pm}1.6$. The sensitivity of the assay was 8 pg per ml. The intra- and interassay coefficients of variation for the quality controls were 6.2 and 10.4%, respectively. This radioimmunoassay can be applied to puberty, estrus dectection, pregnancy diagnosis, postpartum period and diagnosis of reproductive disorders in domestic animals.

• Journal of Embryo Transfer
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• v.25 no.1
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• pp.21-27
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• 2010

The increase in the total number of cows on farms, which breed Korean Native Cattle (KNC), is associated with many problems. In particular, the services per conception and calving interval have increased. In this study, we examined the effect of dietary supplementation with vitamin and mineral complex on the estrus rate, pregnancy rate, gestation length, and birth weight of KNC calves. Multiparous or primiparous KNC were divided into 3 groups with 40 heads per group. Experimental group 1 was administered a consisting of 35,000 IU vitamin A, 100 IU vitamin E, 200 mg $\beta$-carotene, 200 mg Zn methionine, and 1.5 mg Se. Experimental group 2 was administered a vitamin complex (100 g/day) consisting of 100 IU vitamin E and 200 mg $\beta$-carotene. In the case of multiparous KNC, the estrus detection rate in the control group was 90.0% and those in the experimental groups were 75.0% to 95.0%. However, the first-service pregnancy rate after parturition in the control group was 41.2%, which was significantly lower than that in the experimental groups (71.0% to 76.7%; p<0.05). The average duration of pregnancy in the group supplemented with the vitamin complex was days, which was similar to that in the case of the control group. The birth weight of calves from cows fed with vitamin complex was 25.3 to 27.0 kg, which was similar to that in the case of the control group (25.2 to 26.0 kg). In the case of primiparous KNC, no differences in the estrus rate, pregnancy rate, gestation length, or the birth weight of calves were noted between the groups. Thus, dietary supplementation vitamin and mineral complex have no effect on the reproductive efficiency in primiparous cows, but the pregnancy rate was observed to have increased in multiparous KNC with these supplements.

• Journal of Embryo Transfer
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• v.11 no.1
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• pp.7-14
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• 1996

The object of this study was to evaluate the effect of uterine epithelial cells on development of Korean native cattle(KNC) oocytes fertilized in vitro. Qocytes were collected from ovaries of slaughtered Korean Native Cows and matured in TCM199 with granulosa cells supplemented with 10% FBS, 5$\mu$g/ml FSH, 10 JU/ml hCG, and 1$\mu$g/ml estradiol-17$\beta$ for 24 hrs. For co-culture of in vitro development of fertilized ova, oviductal epithelial cells (l$\times$l0˚cells /ml) obtained from slaughtered cow and uterine epithelial cells(1$\times$10˚cells /ml) flushed from the superovulated holstein on Day 7 were incubated in 39$^{\circ}C$, 5% $CO_2$, 95% air. Frozen-thawed KNC sperm was capacitated with BO(Brackett & Oliphant, 1975) medium supplemented with 10mM, 5mM-caffein. Matured oocytes were inseminated for 20 hrs. And then fertilized oocytes were washed with culture medium and transferred to oviductal epithelial cells for in vitro development and three days later a portion of embryos were transferred to uterine epithelial cells. Stastical methods of developmental rates on KNC-IVF oocytes was ANOVA-test. Developmental rates of KNC-IVF oocytes was significant higher(P<0.01) when co-cul-tured with uterine epithelial cells(25.2%) than oviductal epithelial cells. Blatocyst cul-tured for 7 to 9 days were frozen by automatic freezer with 1.4M glycerol-PBS. Survival rates of blastocyst was 40.0%. Fourteen frozen-thawed blastocysts were transferred to five holstein heifers on day 7 after natural estrus. Three recipients were observed twin and one recipient was single by ultra-sound systems on days 45 after embryo transfer.

• Journal of Embryo Transfer
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• v.31 no.3
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• pp.261-265
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• 2016

The aim of the present study was to evaluate and estimate timing of artificial insemination (AI) in Hanwoo heifer (Korean native cattle) that is the most popular breed of beef cattle in Korea. To determine changes in body weight of heifers around AI, body weight were measured at different stages either before or after AI. We found that daily body weight gain was higher in the pregnant cows after AI. We also investigate correlation between body mass measured by shoulder height and body length, and conception rates, used (body length+ height)2 instead of height2 for body mass index (BMI), and found that relatively more BMI heifers (>55) showed higher conception rates. Finally, we estimated body weight by measuring should height (SH), heart girth (HG), and body length (BL); $BW=3.93372^*HG-2.90985^*SH-0.021^*BL$. In addition, we observed that HG is most closely correlated with BW; $y(BW)=1.77355^*x(HG)$, $R^2=0.98881$. In summary, we can determine the best timing of AI using body measurement and its application including BMI.

• Korean Journal of Veterinary Research
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• v.11 no.1
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• pp.91-95
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• 1971

During three months from December 1967 to February 1968, 1867 Korean native cows slaughtered in pusan abattoir were investigated for studying the incidence of cystic ovaries. The results obtained in this experiment are summarized as follows: 1. The average frequency of cystic ovaries in 1867 Korean cows was 17 cases, or 0.91%. 2. In 17 cases 1, or 0.3%, occurred in cattle from 1 to 3 years of age; 4 or, 1.02% in four; 7 or, 2.02% in five; 2 or, 0.63% in six; and 3, or 0.63% occurred between 7 and 9 years of age. 3. The incidence of cysts in the respective ovaries, the left ovary was cystic in 23.5% of the cases, the right one in 41.2% and both ovaries in 35.3%. 4. According to the histological findings of cystic ovaries, follicular cysts were 88.2% and luteal cysts 11.8%.