• Korean Journal of Poultry Science
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• v.41 no.1
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• pp.39-44
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• 2014

The goal of this study was to evaluate the growth performance of crossbred strains using Korean native chicken (KNC). The data were collected from 2012 through 2013 at Poultry Science Division, National Institute of Animal Science, Korea. The number of chicks analyzed in this study was 375. Crossbred were (A) $R{\times}S$, (B) $D{\times}H$, (C) $D{\times}S$, (D) $C{\times}Y$ and (E) $Y{\times}H$. The fertility rates of strains were 94.9% in crossbred A, 91.9% in crossbred B, 91.8% in crossbred C, 89.7% in crossbred D and 93.8% in crossbred E, respectively. The fertility was highest in crossbred A, but crossbred C showed the lowest (p<0.05) based on the hatchability. The crossbreds B and C exhibited a superior performance on body weight gains during growing stages but crossbred D showed the lowest (p<0.05). The feed intake was to the pattern of body weight. The feed intake of crossbred D was significantly lower than other crossbreds. Also, feed conversion ratio of crossbred D showed the lowest (p<0.05). Egg production ratio of crossbred D was significantly higher compared to the other crossbreds. These results suggest that the development of new crossbreds of commercial Korean Native Chickens should be required for better performance.

• The Journal of the Korea Contents Association
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• v.14 no.12
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• pp.959-972
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• 2014

This study aims to describe childlessness trends and examine the factors impacting on the childlessness of married couples among Korean provinces between 1990 and 2010. The results are as follows: There have been differences in childlessness rates among provinces and over time as well. Furthermore, social development, transportation, women's status, and economic development have statistically significant positive impacts on ASMCR. It turns out that age-specific marital childlessness rate is rather accurate measurement than general marital childlessness rate in terms of exploring the factors influencing on the childlessness among Korean provinces. Korea's government policy to aid the married couples who are suffering from in-fecundity is strongly recommended to maintain its policy and extend its subjects in order to increase married couples' fertility rate. Furthermore, campaigns to change married couples' recognition and attitudes from unfavorable against childbearing to favorable toward childbearing so that the married couples would be willing to have childbearing in terms of fertility rate increase.

• Korean Journal of Soil Science and Fertilizer
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• v.19 no.1
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• pp.63-69
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• 1986

1. Chemical components of fresh tobacco leaves at topping stages were affected variously by fertilizer application level. The more fertilizers were applicated, the higher nitrogen content of leaves was shown regardless of the soil fertility, but phosphorus content was not affected either by phosphorus rate or soil fertility. Potassium content was higher in the leaves grown in fertile soil than infertile at the same application rate. 2. Maturation of tobacco leaves was delayed by applying high level of nitrogen fertilizer, especially in fertile soil. The excessive accumulation of nitrogen in tobacco leaves at later stage of growth resulted in poor quality index for the high content of nicotine and low content of reducing sugar in cured leaves. 3. Nicotine content of cured leaf was increased significantly as nitrogen content increased, regardless of soil fertility, but reducing sugar content was reduced. Nicotine and reducing sugar content of cured leaf were higher in fertile than in infertile soil. 4. Resulting from the facts that nicotine contents were negatively correlated and reducing sugar contents were positively correlated with grading value (Won/Kg), authors suggested that grading index (Won/Kg) of the Office of Monopoly be based on quality index from chemical components of cured leaves.

• Korean Journal of Soil Science and Fertilizer
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• v.48 no.6
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• pp.641-647
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• 2015

Monitoring of soil fertility by long-term application of fertilizers is necessary to improve the fertility of soil and the productivity of crop. The objective of this study was conducted to investigate the changes of exchangeable Mg by continuous application of fertilizers from 1969 to 2014. The treatments were no fertilization (No fert.) and fertilization (NPK, NPK+C, NPK+S, and NPK+CS). The concentration of exchangeable Mg in No fert., NPK+C, and NPK+S treatments tended to increase from 1965 to 1975, but decrease gradually from 1976 to 1987, and increase again after 1988. Based on these, the changes of exchangeable Mg were divided into period I ('69 ~'75), period II ('76~'87), and period III ('88~'14). Especially, exchangeable Mg decreased in the period II. This was presumed that a significant amount of Mg from topsoil were leached into subsoil by break of plow pan and some of subsoil was incorporated into topsoil according to change of plowing depth by replacement of tillage machinery. It could be possible that exchangeable Mg in NPK, NPK+S, and NPK+CS was accumulated in the depth of 15~20 cm. For the period III, exchangeable Mg in No fert., NPK, NPK+C, NPK+S, and NPK+CS treatments increased at rates of 0.013, 0.018, 0.015, 0.023, and $0.024cmolckg^{-1}{\cdot}yr^{-1}$ respectively. Exchangeable Mg level in NPK+S was lower than the other treatments in the period I and period II, but higher than in the period III. This result was attributed to replacement of silicate fertilizer type from wollastonite (Mg 0.3%) to silicate fertilizer (Mg 3%). Also, exchangeable Mg level of No fert. treatment increased, which showed that Mg concentration of irrigated water had the greatest impact on Mg accumulation of soil. Recently, Mg level of irrigated water tended to increase, indicating that Mg concentration of water will affect greatly the concentration of exchangeable Mg of soil in the future. Like these, the changes of exchangeable Mg were greatly influenced by agricultural environment such as plowing depth, plow pan, content of fertilizer, and quality of irrigated water. Considering these agricultural environment, the proper management of soil is needed for the improvement of soil fertility and crop productivity.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.31 no.2
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• pp.129-142
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• 1986

Fifty-five local collections of buck wheat, Fagopyrum esculentum, were investigated their ratios of long-styled (LS) and short-styled (SS) flowers, fertility, meiosis of megaspore and microspore mother cell, female and male gametogenesis, and egg apparatus in accordance with the sowing seasons (spring, summer), altitudes (20m, 50-100m, 300m), and parent style types (L, S). Also they were embryologically investigated the fertility, fertilizing phenomenon and proembryogenesis by the legitimate and illegitimate pollination. There were no differences in the ratios of long-styled and short-5tyled flowers along with altitudes, but more irregularness was observed in plain area than that in the mountaineous or coastal area. LS versus SS ratios by sowing seasons were significantly separated into 1 : 1 in the summer sowing (P 0.1), but they were irregularly separated in the spring sowing. The segregating ratios by parent style types showed more number of short-styled flower in the spring sowing, and were statistically seperated into 1 : 1 in the summer sowing (P 0.25), regardless to parent style types. In the artificial legitimate union, the seed setting rates of the summer sowing (59-61%) were much higher than those of the spring sowing (about 30%), but in the artificial illegitimate union the seed setting rates were only fructified about 0.8-1.8% in the spring sowing. The seed setting rates in accordance with flowering stages were larger in turn early, middle, late, in the summer sowing. The grain number and grain weight per plant of short-styled flower were more than those of long-styled one regardless to style types. The 1,000 grain weight of long-styled flower was heavier than that of short-styled one in large grain, but it was lighter than that of short-styled flower in small or medium grain. The percentage of normal female and male gametogenesis in the summer sowing were higher than those in the spring sowing. The ovule was atropous and two polar nuclei were a synkarion before flowering. The pollens germinated at 30 minuts after pollination and the pollen tube grew continually and penetrated into micropyle at 1.5-2 hours and the two male nuclei fertilized with egg nucleus at 3 -5 hours after pollination. Flertilizing times in summer were shorter than in autumn. The fertilized egg was divided in a small apical cell toward the interior of the embryo sac and a large basal cell toward the micropyle cell at 15-24 hours after pollination, and division times in summer were shorter than in autumn. The proembryo began the embryogenesis at 7-8 days and formed itself into the perfect embryo at 15 days after pollination.

• Journal of Animal Reproduction and Biotechnology
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• v.34 no.2
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• pp.117-122
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• 2019

The objective of this study was to establish an in vitro culture system for ovarian preantral follicles of B6D2F1. First, we optimized the in vitro preantral-follicle culture by culture duration, follicle stimulating hormone (FSH) type, and activin A concentration. Duration of in vitro culture for 9, 11, and 13 days was sufficient for the normal development of preantral follicles to antral follicles. Formation of cumulus cell-oocyte complex (COC) was induced by treatment with human chorionic gonadotropin (hCG; 2.5 IU/mL) and epidermal growth factor (EGF; 5 ng/mL). In addition, metaphase II (MII) oocytes formed during this in vitro culture of preantral follicles. In vitro preantralfollicle culture for 9 days showed higher rates of growth and maturation, thus yielding a greater number of antral follicles, and there were significant differences (p < 0.05) in the number of MII oocytes (that formed from these preantral follicles via differentiation) between the 9-day culture and 11-day or 13-day culture. The follicles cultured for 9 days contained a tightly packed well-defined COC, whereas in follicles cultured for 11 days, the COC was not well defined (spreading was observed in the culture dish); the follicles cultured for 13 days disintegrated and released the oocyte. Second, we compared the growth of the preantral follicles in vitro in the presence of various FSH types. There were no significant differences in the growth and maturation rates and in differentiation into MII oocytes during in vitro culture between preantral follicles supplemented with FSH from Merck and those supplemented with FSH from Sigma. To increase the efficiency of MII oocyte formation, the preantral follicles were cultured at different activin A concentrations (0 to 200 ng/mL). The control follicles, which were not treated with activin A, showed the highest rate of differentiation into antral follicles and into MII oocytes among all the groups (0 to 200 ng/mL). Therefore, activin A (50 to 200 ng/mL) had a negative effect on oocyte maturation. Thus, in this study, we propose an in vitro system of preantral-follicle culture that can serve as a therapeutic strategy for fertility preservation of human oocytes for assisted reproductive medicine, for conservation of endangered species, and for creation of superior breeds.

• Clinical and Experimental Reproductive Medicine
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• v.28 no.4
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• pp.307-315
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• 2001

Objective: To evaluate the clinical outcomes and influencing factors of in vitro fertilization and embryo transfer (IVF-ET) in patients with failed pregnancy after microsurgical reversal of tubal sterilization. Materials and Methods : From January, 1997 to December, 2000, IVF-ET was performed in two groups; the study TR (tubal reanastomosis) group consisted of 147 cycles in 66 patients with failed microsurgical reversal of tubal sterilization, and the control group of 115 cycles in 67 patients with bilateral tubal occlusion (BTO). The two groups were evaluated and compared for clinical characteristics, clinical pregnancy rates, and factors influencing the outcomes of IVF-ET. Results: Compared with the control BTO group, age and the previous parity were significantly higher ($36.3{\pm}2.7$ vs. $33.6{\pm}2.0$ years, p<0.05; $1.6{\pm}0.7$ vs. $0.2{\pm}0.4$, p<0.05), and the clinical pregnancy rate per cycle was significantly lower (23.8% (35/147) vs. 29.3% (34/115), p<0.05) in the TR group. Difference in the clinical pregnancy rates was age-related, since there was no significant difference between the two groups, except for the previous parity ($1.6{\pm}0.7$ vs. $0.1{\pm}0.3$, p<0.05), when the patients aged 37 years or older were excluded. No difference was found in terms of the following: the proportion of controlled ovarian hyperstimulation (COH) cycles with GnRH agonist ultrashort protocol, the duration of COH, the dosage of gonadotropins used, and the numbers of oocytes retrieved and of embryos transferred, irrespective of age correction. Conclusions: The outcomes of IVF-ET following the failed microsurgical reversal of tubal sterilization depend upon patient age. The previous fertility of patients does not seem to be a factor of better IVF-ET prognosis.

• Korean Journal of Veterinary Research
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• v.40 no.2
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• pp.383-391
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• 2000

Milk urea nitrogen (MUN) determination is being used an indicator of the protein-energy balance in dairy herds. A faulty balance can be corrected to optimize milk production and animal health. This parameter is regarded as a potential tool to evaluate suboptimal feeding practices and reproductive disorders. Therefore, the purpose of this study was to investigate the response of milk composition by regular feeding analysis and to compared the relationship between MUN and milk protein(MP) and fertility at the insemination period in Holstein dairy cows. Total of 355 artificial insemination (AI) for 150 Holstein cows in the herd were used to examine the relationship between MUN and MP content and conception rate. The AI occured for the cows 50 to 150 day in milk, and MUN and MP concentration were determined using automated infrared procedures. The mean${\pm}$standard deviation of MUN and MP concentration in the herd were $15.6{\pm}2.1mg/dl$ and $3.23{\pm}0.38%$, respectively. MUN contents of bulk milk were increase by elevated crude protein intake. The conception rate was lower in the cows in which the level of MUN was lower than > 8.0mg/dl (10.0%) or > higher than 25mg/dl (15.4%) relative to the cows in MUN content of 12.0~17.9 mg/dl (36.7%) at the time of insemination. Also, lower MP than 3.0% or higher MP than 3.25% were associated with a lower conception rates. Consequently, MUN and MP analyses may be used serve as a monitoring tool of protein and energy nutritional balance to improve reproduction efficiency in Holstein dairy cows.

• Land and Housing Review
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• v.13 no.1
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• pp.11-22
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• 2022

This paper estimates the demand of newly married couples for public rental housing in Chungnam. This research attempts to overcome data limitations by linking survey data with administrative data for analysis. First, the results of a binary logit model that analyzes newly married couples' intention to move into public rental housing, based on the Chungnam Social Survey 2019, reveal that residential location, educational level, housing type, and tenure type have a statistically significant effect. By combining the estimated coefficients with another dataset, the statistics of newly married couples for administration purposes acquired from Statistics Korea, this research estimates the demand for public rental housing among the newly married couples in Chungnam. The estimation results show that the total demand for public rental housing in Chungnam is 11,424 units among 43,705 newly married couples. The total demand of 21,685 newly married couples who occupy rental housing is estimated to be 9,436 units. The policy for providing public rental housing to newly married couples in Chungnam aims to increase their fertility rates. Hence, further research should be followed up to evaluate the effect of the supply of public rental housing on fertility rates. Also, a research method should be developed to control for possible endogeneity between the demand for public rental housing and childbirths.

• Journal of Pharmacopuncture
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• v.25 no.2
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• pp.106-113
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• 2022

Objectives: Herbal medicine is a worldwide health topic. Vitex agnus-castus L. (VAC) is a popular plant used for gynecologic problems due to its hormonal effects. The aim of this study is to reveal VAC extract effect on fetus when this herb is used started from antenatal period or during pregnancy. Methods: Performed from starting day of January 2019 till February 2019, 48 rats were assigned in randomly divided eight-member six groups: control (C1), treated group with 365 mg/kg VAC from initiation of insemination (T1) and 30 days prior to pregnancy (T2), control that underwent caesarean section on 15^th day of gestational age (C2) and treated group with 365 mg/kg VAC from initiation of insemination (T3) and 30 days prior to pregnancy (T4) that underwent caesarean section. Weight, sex and number of fetuses, abortion and still birth rate and estradiol level were evaluated using t-test by SPSS software. Results: We showed increased weight among T1 group considering totally and sex-dependent which is significant (all p-value < 0.05). We also detected significantly decreased weight in T2 in total (p-value < 0.0001) and when considering female fetuses (0.043) but not males (0.17). Although the results showed slightly non-significant increased weight among fetuses of T3 (totally or based on the fetus sex) compared to the control group (C2), T4 group had statistically decreased weight compared to control group. Pregnancy rate and pregnancy outcome were affected by VAC usage. The time of VAC initiation also affected live birth and abortion rates. Conclusion: VAC extract may affect pregnancy rate, live birth rate, abortion and stillbirth rates. Its effect on the weight and the sex showed dual pattern depends on the time of initiation and pregnancy trimester of evaluation. Prescribing this medicinal plant for patients being prone to pregnancy should be with caution. Further study is recommended.