• Journal of Animal Science and Technology
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• v.56 no.3
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• pp.8.1-8.6
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• 2014

Background: Artificial insemination (AI) can serve as a powerful tool to the sheep owners for making rapid genetic progress of their flock. The AI in sheep is mostly performed using fresh semen with two reasons i) lambing rate following trans-cervical AI with frozen semen is limited by the inability of frozen-thawed sperm to transit the cervix and ii) the need of circumventing the cervical barrier through laparoscope aided intrauterine AI. Therefore, AI with frozen-thawed semen is not as widespread in sheep as it is in other domestic species. However, to get maximum benefits through the use of AI, frozen-thawed semen is a prerequisite because instead of high fertility, the short shelf life of fresh semen coupled with a limitation on the number of insemination doses achievable per unit time restricts the widespread use of individual sires. Therefore, in order to enhance lambing rate, a total of 240 trans-cervical artificial inseminations with frozen-thawed semen were performed in Bharat Merino ewes during autumn season either once in the evening (G-I, 10 h after onset of estrus, n = 100) or twice (G-II, 14 h and 22 h after onset of estrus, n = 140) i.e. once in the morning and again in the evening. Results: The pregnancy rate (proportion of pregnant ewes confirmed by ultrasonography at day 40) and lambing rate (proportion of ewes lambed) were higher in G-II as compared to G-I (26.4 vs 20% and 19.3 vs 10%, respectively). The difference in lambing rates was statistically (P < 0.05) significant. The depth of insemination within cervico-uterine tract had no significant effect on pregnancy and lambing rates. Conclusions: The results indicate that lambing rate in sheep following TCAI with frozen-thawed semen was significantly influenced by time of inseminations. Two inseminations after 14 and 22 h of onset of estrus enhanced the lambing rates of Bharat Merino sheep as compare to single insemination after 10 h of onset of estrus. The TCAI technique with frozen-thawed ram semen is promising and may serve as a valuable tool for genetic improvement of sheep breeds. Research efforts are going on worldwide to overcome the poor fertility following TCAI with frozen-thawed semen.

• Asian-Australasian Journal of Animal Sciences
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• v.31 no.8
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• pp.1160-1168
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• 2018

Objective: This study was conducted to compare morphological defects, viability, motility (MOT), fertility (F), and hatchability (H) in four Korean native chicken breeds (KNCBs), and to evaluate whether defective segments of spermatozoa are associated with MOT, F, and H. Methods: Four KNCBs, including Korean Ogye (KO), Hwangbong (HB), Hyunin Black (HH), and Hoengseong Yakdak (HY) were used. White Leghorn (WL) was used as a control. Nine cocks from each breed were randomly assigned into three groups. Semen was collected by abdominal massage method. Eosin-nigrosin staining method was used to identify live-dead spermatozoa. Different segments and specific morphological defects of spermatozoa were identified using 4', 6-diamidino-2-phenylidole and MitoTracker Red CMXRos. F and H rates were evaluated following artificial insemination (AI). Results: KO had the highest MOT rate compared to HY. Viable normal sperm rates of KO and HH were high and comparable with WL. HY spermatozoa had the highest viable abnormal sperm (VAS) or morphological defect rate followed by HB. Likewise, HB spermatozoa had the highest dead sperm (dead) rate compared to KO, HY, and WL. Bent, coiled, detached, broken, and knotted were common identified specific morphological defects for all breeds. Most morphological defects were at the head and tail in all breeds. VAS showed strong negative correlation with MOT (r = -0.697) and F (r = -0.609). Similarly, defective tail was negatively correlated with MOT (r = -0.587), F (r = -0.797), and H (r = -0.448). The F and H rates of KO and WL were comparable. Conclusion: These data indicate that most identified specific morphological defects are at the head and tail. VAS and defective tail were associated with poor motility, F, and H. KNCBs showed more morphological defects than WL. Finally, these results will facilitate successful AI and semen cryopreservation.

• Korea journal of population studies
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• v.29 no.3
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• pp.111-137
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• 2006

The purpose of this study is to analyze how to change the fertility behavior at each parity after/before the economic crisis, and to find its significant determinants. The study assumes that because the socioeconomic changes have significant effects on the individual's fertility behavior, the individual's fertility behaviors and the determinants affecting fertility at each parity may change with economic crisis. Such assumption has been proven in this study. After the economic crisis, Korean fertility behavior at each parity has changed. The proportion of women having no child has increased. However, women who want to have a second child or a third one are more likely to do so within shorter period after marriage. The rectangularization of fertility has appeared after the economic crisis, because women married at later ages tends to finish their child bearing within the short period, especially before age 35. Based on the multiple variable analysis, the determinants affecting the fertility behavior have changed after the economic crisis. Interestingly, the men's safety job have the positive effects on the first childbearing while the women's safety careers have the negative effects on it, after the economic crisis. Before the economic crisis, both do not have significant effects on the first childbearing. This findings point out the limitation of women career favor policy, which purpose to raise the fertility rates by making good environments for women having children to work comfortably without the anxiety of child care.

• Journal of Animal Science and Technology
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• v.65 no.4
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• pp.779-791
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• 2023

This study aimed to assess the effects of embryonic developmental stage, quality grade, and fresh or frozen/thawed conditions on the pregnancy rate and sex ratio of live offspring in Hanwoo (Bos taurus coreanae) cows. The quality and developmental stage of in vivo-derived (IVD) transferred embryos were evaluated using the standard criteria of the International Embryo Technology Society. The recipient cows were synchronized using conventional (estradiol benzoate and progesterone) protocols before embryo transfer. Embryos were transferred to 297 cows, and pregnancy was monitored for 60-70 days after embryo transfer. The pregnancy rates of fresh and frozen/thawed embryos were 56.90% and 52.49%, respectively. Pregnancy rates varied according to embryo quality (56.18% for grade 1 vs. 36.67% for grade 2). Pregnancy rates also varied by developmental stage and cryopreservation (67.86% vs. 63.49% for stage 4-1, 64.00% vs. 54.72% for 5-1, and 50.00% vs. 47.83% for 6-1, in fresh embryos vs. frozen/thawed embryos, respectively). For stage 7-1, the pregnancy rates were 72.73% for fresh embryos and 20.00% for frozen/thawed embryos. In 66 fresh embryos, the sex ratio of live offspring was 5:5, whereas it was 4(female):6(male) for frozen/thawed embryos among the 95 frozen/thawed embryos. The miscarriage rate was approximately 3% higher for frozen/thawed embryos than for fresh embryos (18.1% for fresh vs. 21.1% for frozen). Seasonal fertility rates were 33.3% in spring, 55.67% in summer, 52.8% in autumn, 60.0% in winter. The following male-to-female ratios were observed in different seasons: 6.7:3.3 in spring, 4.0:6.0 in summer, 5.5:4.5 in autumn, and 3.3:6.7 in winter. The current data revealed no significant differences in pregnancy rates between fresh and frozen/thawed IVD embryos. However, there was a lower pregnancy rate with advanced-stage frozen/thawed embryos (stage 7-1). The current study provides comprehensive results for the better optimization of embryo transfer in Hanwoo cattle to obtain the desired fertility rate, pregnancy rate, and sex ratio of calves. These results provide important insights into the factors that influence the viability and success of IVD embryo transfer in Hanwoo cows and may have practical applications for improving breeding programs and reducing production costs.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.44 no.3
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• pp.191-196
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• 1999

In rice-barley cropping systems, efficient utilization of barley straw is essential, both to improve the soil fertility and to conserve the environment. In order to identify the effects of barley straw mulch rates in rice cultivation, a rice cultivar, 'Gancheogbyeo', was directly seeded on a no-tillage field synchronized with barley harvesting with five barley straw mulch rates, i.e., 0, 2.5, 5.0, 7.5 and 10.0 ton h $a^{-1}$ and agronomic characters of rice and soil nitrogen were determined. The increasing of barley straw mulch rates. Dominant weed species, chestnut, occurred in large amounts in no mulching or lower mulch rates than in higher mulch rates. The content of N $H_4$$_{＋}$-N in soil applied with high barley straw mulch rates was lower during the month after seeding, and then it was higher at heading date, compared with lower mulch rates or no mulch plot. As the barley straw rate increased, maximum tillering stage was delayed, and plant height was reduced. Although the lodging of rice plants was seldom observed in all plots, the breaking strength of the culm was significantly higher in the mulch rate of 10.0 ton h $a^{-1}$ . With an increase of barley straw mulch rate, the effective tillering rate and spikelet number $m^{-2}$ decreased while ripened grain ratio increased. The rice grain yield was slightly decreased with an increase of barley straw mulch rate, although significant differences were not found all barley straw mulch rates. These results suggest that there is no significant yield loss although the total barley straw production, approximately 5.0 ton h $a^{-l}$ in the present study, apply in the paddy for the following rice cultivation by no-tillage direct seeding.ect seeding.

• Korean Journal of Childcare and Education
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• v.9 no.6
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• pp.197-221
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• 2013

The purpose of this study was to examine the relationship between the child care support policies and the birth rate in 33 OECD countries. In the structural equation modelling, the birth rate was the dependent variable while the cash-support policies, the child-care facility service policies, and the tax benefits policies were the independent variables. The analysis showed that the most effective factor on the birth rate was the child-care facility service policies. Regarding the effectiveness of the policy expenses, the cash-support policies showed stable fluctuation of effectiveness according to the fluctuation of cash amount, the child-care facility service policies. In conclusion, in order to increase the effectiveness of the cash-support policies, the adequate cost calculation to decrease the parents' burden for child-bearing, re-allocation of budget, and support methods and timing should be continually discussed. In addition, for the better effectiveness of the facility service policies, more various, comprehensive and high-quality facility service policies that could balance home and work, should be implemented.

• Clinical and Experimental Reproductive Medicine
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• v.39 no.2
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• pp.58-67
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• 2012

Objective: Previously, we identified that transketolase (Tkt), an important enzyme in the pentose phosphate pathway, is highly expressed at 2 hours of spontaneous maturation in oocytes. Therefore, this study was performed to determine the function of Tkt in meiotic cell cycle regulation, especially at the point of germinal vesicle breakdown (GVBD). Methods: We evaluated the loss-of-function of Tkt by microinjecting Tkt double-stranded RNAs (dsRNAs) into germinal vesicle-stage oocytes, and the oocytes were cultured in vitro to evaluate phenotypic changes during oocyte maturation. In addition to maturation rates, meiotic spindle and chromosome rearrangements, and changes in expression of other enzymes in the pentose phosphate pathway were determined after Tkt RNA interference (RNAi). Results: Despite the complete and specific knockdown of Tkt expression, GVBD occurred and meiosis was arrested at the metaphase I (MI) stage. The arrested oocytes exhibited spindle loss, chromosomal aggregation, and declined maturation promoting factor and mitogen-activated protein kinase activities. The modified expression of two enzymes in the pentose phosphate pathway, Prps1 and Rbks, after Tkt RNAi and decreased maturation rates were amended when ribose-5-phosphate was supplemented in the culture medium, suggesting that the Tkt and pentose phosphate pathway are important for the maturation process. Conclusion: We concluded that Tkt and its associated pentose phosphate pathway play an important role in the MI-MII transition of the oocytes' meiotic cell cycle, but not in the process of GVBD.

• Korean Journal of Social Welfare
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• v.58 no.2
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• pp.223-249
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• 2006

The purpose of this paper is to classify OECD countries in regard to levels of supporting fathers' care work. Several meaningful conclusions were reached. First, examining the level of supporting fathers' care work and the strength of the traditional bread-winner model, OECD countries can be classified into 5 different clusters. The result is different from the mainstream typology of welfare states and suggests the new typology of welfare states. Second, the level of supporting fathers' care work and the strength of the traditional bread-winner model were found to be related to total fertility rates and women's labor market participation rates. Third, in regard to the level of supporting fathers' care work, Korea was the lowest among OECD countries. This result points to one of the important reasons to the low level of total fertility rat, and low rate of women's labor market participation in Korea.

• Informatization Policy
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• v.26 no.4
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• pp.20-35
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• 2019

We empirically analyze the effects of psychological factors, such as the fear of parenting, on fertility rates. An index is calculated based on the share of negative news articles on child care in all social articles from 2000 to 2018. The analysis result shows that as the index increases, the fertility rate after three years falls. This result is repeated in the correlation analysis, simple regression, and VAR analysis. According to Granger causality analysis, it is found that the relation between the index and the fertility rate after three years is not just a simple correlation but a causal relationship. There are differences among age groups. The fertility rate of women in their 20s and 30s shows a significant response to the index, but that of the 40s does not. The index affects the birthrate of first child, but do not affect the birthrate of second or more children. These results are consistent with the intuition that younger women are more likely to be affected by the negative articles about parenting, but not to those who have already experienced childbirth. This study is meaningful in that a significant index for predicting social phenomena is extracted beyond the limited use of news big data such as a simple keyword mention volume monitoring. Also, this big data-based index is a 3-year leading indicator for fertility, which provides the advantage of providing information that helps early detection.

• Korea journal of population studies
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• v.34 no.1
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• pp.1-25
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• 2011

There are two main purposes in this study. First, we compare the effects of wives' characteristics with the effects of the husbands' characteristics on the induced abortion. Second, we analyze whether the determinants of the induced abortion have changed according to parity and conception period. The main findings are follows. First, both wives' and husbands' socioeconomic characters have insignificant effects on the induced abortion at parity 0, in the 1997 and 2000 Korean Fertility Survey data. Second, during the periods of the lowest-low fertility, after 2000 in Korea, wives' employments have positive effects at parity 0 and 1, while husbands' educational levels have negative effects at parity 1 on the induced abortion. The implications are as follows. First, having children had been the universal social phenomenon before 2000 in Korea. however, after 2000, reproductions have become the women's choice, lather than the duty of married women. Women must weight the balance between the benefits and the costs of children so that women's fertility behaviors become a rational choice. Women's employment is the most important factor in these rational calculations. Second, both Western individualism and the traditional Korean familism have significant effects on the fertility behavior and the induced abortions in Korea. This rejects the diffusion theory, which tells that the traditional familism must be replaced by the Western individualism in order to decline the fertility rates in developing countries.