• Journal of Embryo Transfer
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• v.23 no.4
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• pp.257-261
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• 2008

The objective of present study was to investigate the effect of seasons on reproductive performance of Hanwoo and Holstein heifers. Heat stress in summer or cold stress in winter stress to Hanwoo and Holstein heifers may bring reproduction failure, which would pose an important economic loss, even around Daegwallyeong region located in high mountainous area. Seasonal differences in the serum levels of LH, FSH and progesterone ($P_4$) in response to environmental factors (hot and cold) out of 20 pubertal Hanwoo heifers in Daegwallyeong, Gangwon Province and 20 non-lactating Holstein heifers in Chonan city of Republic of Korea at 2-3 years of age were compared. Blood samples for hormonal analysis were from jugular vein after detection of estrus repeatedly over four seasons within four-week intervals (Spring: May to June, Summer: July to August, Autumn: October to November and Winter: January to February). In Hanwoo heifer population, averages of LH and FSH concentration in spring and in summer were greater compared to those in winter (p<0.05). LH or FSH levels tended to be greater (p=0.06) in spring and less (p=0.09) in winter compared to the levels in autumn. Only in summer, cattle seemed to show lower LH or FSH secretion (p<0.05). Similar to the results in Hanwoo heifers, the serum concentrations of LH and FSH in Holstein heifers decreased further by heat stress in summer when P 4 levels were high during luteal phase. The results demonstrate significant effect of summer heat on reproduction of Hanwoo or Holstein heifers. Although parameters indicating the extent of heat stress were not measured in this study, we suggest that serum hormone levels could be considered as successful indicators of summer heat stress condition for Hanwoo and Holstein heifers even under rather cool summer climate.

• 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.

• Journal of Embryo Transfer
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• v.15 no.1
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• pp.47-56
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• 2000

This study was carried out to improve a technique of embryo transfer for twin calves production in Hanwoo cattle. Blastocysts for the donor of embryo transfer were classified into three criteria by accessment of morphology; early blastocyst, blastocyst and expanded blastocyst. Tow embryos were introduced transcervically into utrerine horn either of Hanwoo or Holstein by ipsilaterally or contralaterally to the corpus luteum. Thiry-six out of 57 recipients cows were inseminated by artificially on the next day of estrus, and followed by transfer of embryos into contralaterally. The pregnance rates of recipients following transfer of bovine embryos of day 7, 8 and 9 was 43.5, 18.2 and 8.3%, respectively. These results appeared that these was a significant (P<0.05) difference between on day-7 embryos and day-9 embryos, but not between on day-8 and day-9 embryos. Although there was not significant(P<0.05) difference in the pregnancy rates between the blastocysts(11/25, 44%) and expanded blastocysts(2/19, 10.5%) and between the blastocysts and early blastocysts(2/13, 15.4%), the embryos at blastocyst stage are more suitable than others for obtaining higher rate of pregnancy. There was no significant difference on pregnancy of the embryos transferred prior to presence(6/21, 29%) or absence (9/36, 25%) of artificial insemination. On pregnancy of Holstein, 2(15.4%) out of 13 recipients were pregnant in heifer. Similar Pregnancy rates were obtained between 1∼2 parities and 3∼4 parities by 30% (6/20) and 27.3%(3/11), respectively. Taken together, there was not significant difference in pregnancy rate due to small number of recipients used for this experiment. Both of Hanwoo and Holstein introduced the embryos by contralsterally to the corpus luteum were slightly higher pregnancy rate compare to by ipsilaterally (12/41, 29.3% vs, 3/16, 18.8%). The ratio of production of twin and single calves in Holstein was 20% (9/45) and 2.2% (1/45), respectively. However, in Hanwoo cows both of production of twin and single were similar as 8%. This result suggests that Holstein as recipients was superior to Hanwoo cows for production of twin calves. Out of all 15 pregnant, 12(80%) were produced a total of 22 normal calves in which the others composed of abnormal, as judging as 2(13.3%) for abortion and 1(6.6%) for stillbirth during the pregnant period.

• Journal of Animal Science and Technology
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• v.47 no.4
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• pp.593-606
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• 2005

Present study was conducted to investigate the optimal feeding levels for producing the high quality meat on the basis of the information deriving from the comparison of the growth performance and carcass characteristics among breeds(Holstein vs F1, Holstein♀×Hanwoo♂), sex(steer vs heifer) and interaction between breed and sex. Thirty two animals on 4 treatments(i.e. eight head each) were used for 540 days from seven to 24 months of age. The results obtained are summarized as follows; the range of average daily gains was 0.733 to 1.018, 0.994 to 1.255, 0.947 to 1.259 and 0.736 to 0.824kg for the growing, the early-fattening, the mid- fattening and the finishing periods, respectively. The range of average daily gains for the entire period was 0.882 to 1.061kg. The gains were higher for Holstein(7.3%) and the steers(10.5%) than F1 and the heifers, respectively. Concentrates and total digestible nutrients intakes per kg gain were higher for Holstein and the heifers than F1 and the steers, respectively. These findings may indicate that feed utilization is higher for Holstein than F1, and higher for the steers than the heifers. In carcass characteristics, back fat thickness was thicker for Holstein than F1, and rib-eye area was smaller for Holstein than F1. The rib-eye area per kg carcass weight was larger for F1 and the heifers than Holstein and the steers, respectively. Meat color was better for Holstein than F1, but the sex distinction did not show any differences. In physicochemical properties of longissimus dorsi, shear force, cooking loss, water holding capacity and the panel test scores of juiciness, tenderness and flavor for F1 and the heifers were better than those for Holstein and the steers, respectively. According to the above results, we may conclude that F1 and heifers rather than Holstein and steers are recommended for high quality meat production. In steers and heifers of Holstein and F1, the optimal feeding levels may be 1.9% of apparent body weight for concentrates and 25% of concentrates intake for rice straw.

• Journal of Embryo Transfer
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• v.22 no.3
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• pp.185-190
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• 2007

The objective of this study was to investigate the characteristics of various estrous behavior and ovulation time in dairy cows and heifers. In total, 73 ovulations and 61 estrous detection were observed in 89 Holstein cows. Various estrous behavior were observed during 72 hours from two days after $PGF_2{\alpha}$ injection and their relation with the time of ovulation(ultrasound examinations at 4-h intervals) was investigated. In estrous periods, the rate of sniffing, chin resting, mounting and standing heat was 81%, 78%, 78% and 56%, respectively in cows. In heifers, the rate of sniffing, chin resting, mounting and standing heat was 61%, 68%, 82% and 76%, respectively. Ovulation in cows and heifers occurred $25.58{\pm}7.94\;and\;25.55{\pm}5.72h$ after onset of estrus, and $13.42{\pm}7.14\;and\;7.48{\pm}7.41h$ after end of estrus, respectively. Interval between onset of estrus and ovulation time was significantly (p<0.05) shorter for standing heat ($17.33{\pm}5.83\;h$) than for mounting, sniffing and chin resting ($23.58{\pm}5.12\;h,\;24.25{\pm}6.09\;h,\;23.42{\pm}6.04\;h$) in cows but not significantly different in heifers. Interval between end of standing heat and ovulation time was significantly (p<0.05) shorter for heifer($6.38{\pm}4.80$) than for cows($13.05{\pm}4.53$). Our results show that characteristics of estrous behavior and ovulation in dairy heifers are different to that of cows.

• Journal of Embryo Transfer
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• v.20 no.2
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• pp.89-95
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• 2005

In this study, we investigated the effects of number, grade, stage and day of embryos on pregnancy and abortion rates of Holstein heifer recipients after transfer of in-vitro produced Korean Native Cattle (Hanwoo) embryos. When one, two or three blastocysts were transferred to recipients, pregnancy (32.0, 44.0 and $32.0\%$) and abortion (12.5, 13.6 and $6.3\%$) rates did not differ among treatments. The pregnancy and abortion rates of different grades of blastocysts were $40.8\~44.2\%\;and\;9.4\~16.3\%$, respectively. However, they were not significantly different. According to the stage of blastocyst, the pregnancy rates were similar between $39.1\%\;and\;45.3\%$. However, the abortion rate in hatched blastocyst stage $(20.8\%)$ was significantly higher than that in late blastocyst stage $(9.0\%)$. The pregnancy rates in day $7\cdot7$ and day $7\cdot8$ blastocyst (47.1 and $53.9\%$, respectively) was significantly higher than that in the day $9\cdot9\;and\;8\cdot9$ blastocyst (29.8 and $27.7\%$, respectively). The abortion rate was the highest in the day $9\cdot9$ blastocyst $(30.8\%)$ among treatments, and it was significantly different compared to that in the day $7\cdot7$ blastocyst $(10.1\%)$. Therefore, this study suggested that the pregnancy rate was affected by only day of embryos, while the abortion rate was affected by stage and day of embryos.