• Korean Journal of Animal Reproduction
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• v.8 no.2
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• pp.87-91
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• 1984

This study was conducted to determine the optimum time and the insemination site of frozen in Cheju native cows, and 660 cows first service inseminated with rectovaginal methods by 3 skillful technicians as 3 districts near Cheju City and Sogwipo City areas obtained the following results. Optimum time for insemination was 16-20 hours after the onset of estrus and 80.6% of 67 conceived to first insemination. In the rectovaginal technique used widely at present conception rate for the palpation of ovaries showed 6.6% (index) higher than that of non-palpation. Conception rate of the insemination site; the intra-uterine horn, intra-uterus, just inside the cervix and depositing in mid-cervix were 62.5, 78.4, 74.6, and 80.9% respectively, however, there was no difference in conception rate between cervical and uterine deposition of forzon semen except for the intra-uterine horn.

• Korean Journal of Veterinary Research
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• v.26 no.1
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• pp.163-174
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• 1986

The 587 Holstein cows which calved from January 1983 to December 1984 at an integrated dairy farm in Chung-nom province were examined for the incidence of reproductive disorders and their conception rate after treatment. The results obtained were as follows; 1. The incidence of reproductive disorders was 47.9% (281 heads) among 587 heads which calved. 1) As number of calvings increased, the incidence of reproductive disorders decreased. 2) The cows which calved in spring and summer showed significantly higher incidence of reproductive disorders than those which calved in autumn and winter (p<0.05). 3) Among reproductive disorders, ovarian, uterine, cervical and vaginal diseases figured 54.3%, 43.7%, 0.9% and 0.6%, respectively. 4) Among individual genital diseases, endometritis (40.3%) occurred most frequently. 2. Among 281 heads with reproductive disorders, 216 heads(76.9%) conceived after treatment. 1) After treatment of reproductive disorders, the conception rate by number of calvings was in range from 69.6% to 87.5%. 2) The cows which calved in summer and winter showed significantly higher conception rate after treatment of reproductive disorders than those which calved in spring and autumn (P<0.05). 3) The conception rates after treatment of the cows with ovarian, uterine, cervical and vaginal diseases were 66.5%, 81.2%, 33.3% and 50.0% respectively. 4) The cows with endometritis showed the highest conception rate after treatment (85.9%).

• Journal of Embryo Transfer
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• v.25 no.1
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• pp.51-55
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• 2010

The relationships of scrotal circumference (SC) to semen characteristics and the conception rate (70 days-nonreturn rate) of artificial insemination in farm were studied with 137 heads of bull in Hanwoo. The average and range of SC were $38.27{\pm}3.90$ cm and 26.0~52.5 cm, respectively. Hanwoo bulls were classified with SC, divided into 34 cm below group, 34~39 cm group, and 39 cm over group. The 5,487 semen records of 43 heads of bull from July. 1. 2007 to June. 30. 2008. were used to determine the relationships between SC and semen characteristics. The semen concentration and total sperm number of each group were 11.18, 16.68, and $17.4{\times}10^8/ml$, and 69.83, 101.64 and $114.40{\times}10^8$/ejaculate. The bulls with 34 cm or more SC were higher than the bulls with 34 cm below in semen concentration and total sperm number (p<0.01). But between SC and semen volume have no significant relationship (p>0.05). The 9,862 mating records of 44 farm with 137 heads of bull were used to determine the relationships between SC and conception rate. The conception rate of 1st artificial insemination were 73.31, 74.16, and 77.33 % in each group. Also SC was positively correlated with pregnancy rate (r=0.12, p=0.17). These results indicate that SC correlates positively with semen characteristics, and maybe with pregnancy rate in Hanwoo.

• Journal of Embryo Transfer
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• v.27 no.3
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• pp.133-139
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• 2012

This study was carried out to develop the useful inducing method of estrus for Korean native cows. Under the condition of estrus induction by administering $PGF_{2{\alpha}}$ for the cows in which corpus luteum (CL) in ovaries was detected by ultrasonography, ovarian responses and the changes of progesterone ($P_4$) concentration against $PGF_{2{\alpha}}$ compared with conception rate were observed in cows and heifers. In inducing estrus administering $PGF_{2{\alpha}}$. to the cows which has corpus luteum in ovaries, ovarian reponses, the changes of progesterone concentration, and conception rate were identified and compared. The results attained from the studies were as follows. Significant decreases of CL in size over time after $PGF_{2{\alpha}}$ administration were detected in both cow and heifer groups (p<0.001), but not different between groups in the CL regression rate (p>0.05). In addition, the percentage changes relative to the plasma $P_4$ concentration on day 1 after $PGF_{2{\alpha}}$ treatment were decreased to below 1ng/ml. The growth rate of follicle was observed as 31% on day 1 and 42% on day 2 in cows, and 34% on day 1 and 97% on day 2 in heifers, resulting that growth of heifers are faster than that of cows (p<0.05). The conception rate after $PGF_{2{\alpha}}$ treatment were 60.5% and 64.2% in cows and heifers, respectively. It also indicated that the conception rate after estrus observation with $PGF_{2{\alpha}}$ injection was as high as 66.6% while that with timed-artificial insemination (TAI) regardless of the estrus observation was 56%, which means the pregnancy rate of artificial insemination after estrus observation was higher than that of TAI (p<0.05). In the result of all above, there were significant decreases in CL size and the plasma $P_4$ concentration by days but rapid growth in follicles, which has no differences in cows and heifers. The conception rate was commonly high after estrus observation and more than 50% under TAI.

• Animal Bioscience
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• v.34 no.12
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• pp.1879-1885
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• 2021

Objective: Owing to the lack of a breeding index for efficient and quick fertility evaluations of Holstein bulls when using traditional or genome-wide detection methods, this study aimed to determine whether in vitro fertilization (IVF) could be used as an indicator of conception rate of artificial insemination (AI). Methods: Conventional and sexed frozen semen from nine bulls were used for IVF and AI. Results: The IVF and AI conception rates of each bull were confirmed to be positively correlated between the conventional frozen and sexed frozen semen. The correlation coefficient R values of nine bulls between IVF and AI methods were 0.73 and 0.97 for the conventional frozen and sexed frozen semen, respectively. The average conception rate of three bulls undergoing AI was 69.5% and 64.2%, 61.8% and 58.8%, and 48.2% and 46.2% in first-, second-, and third-born cows when conventional frozen and sexed frozen semen were used, respectively, which showed a positive correlation with the fertilization rate in the same parity. We propose an evaluation standard to assess the fertilization ability of bulls based on their IVF test results, which is categorized into three grades: grade one, normal fertility bull with an AI conception rate of 40%±5% and IVF rate of 45% to 60%; grade two, higher fertility bull with an AI conception rate of 50%±5% and IVF rate of 61% to 80%; and grade three, highest fertility bull with an AI conception rate of 60%±5% and IVF rate of >80%. Conclusion: These findings reveal that IVF results can be used as a breeding index for bulls to evaluate their AI conception ability, which may shorten the time required to select bulls for breeding.

• Reproductive and Developmental Biology
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• v.37 no.3
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• pp.135-141
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• 2013

This study aimed to improve the reproductive efficiency of dairy herds by comparison and analyzing estrous appearance rate, conception and non-conception rate according to the stage of lactation using the lactation and reproductive records of average (less than 10,000 liters milk in 305 days) and high yielding (more than 10,000 liters milk in 305 days) Holstein cows (n=102). Milk production and reproduction data were collected between January 2010 and December 2012 from Holstein cows kept in the commercial dairy farms. Average (n=32) and high yielding (n=24) Holstein cows used to analyze the relationship between milk yield and reproductive performance. Our results showed that estrous appearance rate according to the stage of lactation was 25.0% (30~59d), 40.6% (60~89d), 25% (90~110d) and 9.4% (>111d) in average yielding cows and 16.7% (30~59d), 20.8% (60~89d), 12.5% (90~110d) and 50.0% (>111d) in high yielding cows, respectively. Conception rate according to the stage of lactation was 87.5% (30~59d), 61.5% (60~89d), 75.0% (90~110d) and 66.7% (>111d) in average yielding cows and 25.0% (30~59d), 0% (60~89d), 33.3% (90~110d) and 50.0% (>111d) in high yielding cows, respectively. Days between parturition and conception was 23.7% (<149d), 0% (150~209d) and 0% (>210 d) in average yielding cows and 69.0% (<149 d), 77.8% (150~209d) and 38.9% (>210d) in high yielding cows, respectively. Conception rate from 110 days postpartum in high yielding cows was 41.7% (110~150d), 50.0% (151~180d) and 50.0% (>181d). Body condition score (BCS) in 120 days postpartum was $2.64{\pm}0.1$ in average yielding cows and $2.28{\pm}0.1$ in high yielding cows, respectively.

• Journal of Embryo Transfer
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• v.26 no.2
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• pp.91-96
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• 2011

The purpose of this study was to evaluate the effects of days open on subsequent reproductive performance following to estrus synchronization in the 114 lactating dairy cows. The animals were divided into two groups according to the time of estrus synchronization; viz, ${\leq}$ 85 days, and > 85 days postpartum, respectively. The estrus synchronization protocol consisted of insertion of a controlled internal drug release (CIDR) device containing 1.9 g progesterone with an injection of 250 ${\mu}g$ gonadorelin (Day 0), an injection of $PGF_2{\alpha}$ and removal of the device on Day 7, an injection of 250 ${\mu}g$ GnRH on Day 9, and TAI 17 h later. Pregnancy diagnosis was determined at 30 to 60 days after TAI using both ultrasonography and rectal palpation. The body condition score (BCS) gradually increased over the postpartum period. In estrus synchronized cows until 85 days, conception rate on first service, number of service per conception, interval from estrus synchronization to conception, and interval from calving to conception were not significantly different among two farms (P>0.05). In estrus synchronized cows after 85 days postpartum, conception rate on first service, number of service per conception and interval from calving to conception were significantly different ($P{\leq}0.05$) between herds A and B (26.8 vs 50.0%; $2.1{\pm}1.35$ vs $1.37{\pm}0.54$ times, $237.3{\pm}97.8$ vs $164.7{\pm}69.3$ days, respectively). In estrus synchronized cows after 85 days postpartum interval from estrus synchronization to conception was greater (P<0.01) in herd B than in herd A ($63.6{\pm}57.4$ vs $26.1{\pm}24.9$). These results indicate that the time of estrus synchronization for maximized the reproductive performance is before 85 days postpartum and feeding and management is important factor for high reproductive performance.

• Reproductive and Developmental Biology
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• v.30 no.3
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• pp.225-228
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• 2006

This study was undertaken to investigate the effect of ovulation-synchronization(OVSYNCH) method on conception rate after insemination of dairy cattle. The proportion of conception of normal fertility cows(65%) was higher than that in infertility cows(50%) in dairy cows with OVSYNCH treatment. However, there was no significant difference between experimental groups. In another experiment, when the OVSYNCH method was adapted in multiparous dairy cows, the conception rate of experimental group of $30{\sim}35kg/day$ in milk yield was significantly higher than those in groups of $20{\sim}25kg/day$ in milk yield(p<0.05). In conception rates by OVSYNCH method in experimental groups with different parity, the group of 1st parity was significantly higher than in 3rd parity group(p<0.05). The results suggest that conception rate by OVSYNCH method was affected by various reproductive conditions in dairy cattle, and OVSYNCH method could be used to increase the conception rate for infertility cows with hormone disorder.

• Journal of Embryo Transfer
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• v.18 no.3
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• pp.187-193
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• 2003

Recently a protocol was developed that precisely synchronizes the time of ovulation in Hanwoo. Cows were treated with GnRH on Day 0, PGF$_2$$\alpha$ 7 d later, GnRH 2 d later, and then time-inseminated approximately 24 h after this second treatment with GnRH. Ovarian morphology was monitored cows by trans-rectal ultrasonography 6.5MHz linear transrectal probe(Sonovet - 600., Medison co. Korea) from 24 hr to 31 hrs after second GnRH injection. The result obtained summarized as follows - 1. Induced ovulation were 24 to 31hr after the second GnRH injection, but high induced ovulation was 28hr. 2. Conception rate with HML(High meat lin) and HIL(High milk lin) treatment were 48.1％(38/79) and 43.9％(40/91), respectively. 3. Conception rate of 1∼2 parity and 3∼4 parity was 44.3％ and 55％, respectively. 4. Conception rate of spring, autumn was more increased, 47.3％ than summer.

• Journal of Korean Academy of Nursing
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• v.21 no.3
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• pp.307-322
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• 1991

The purpose of this exploratory study was to analyze nursing role conceptions and test the relationships between nursing role conceptions and professional commitment among selected Korean nurses. Data were obtained from a convenience sample of 262 practising nurses of varying positions, education, and experience. The total sample represents a response rate of 93 percent. Subscales of Nursing Role Conceptions (Pieta, 1976) were used to measure professional, service, and bureaucratic role conceptions 1 the tool to measure professional commitment was developed by the investigator. The results of this study were as follows. 1. Professional role conception and service role conception were positively related(normative r＝ .61 : categorical r＝ .64). Bureaucratic role conception scores(32.6$\pm$4.97) were higher than professional and service role conception scores. 2. Experience was positively related to bureaucratic professional categorical role conception(r＝ .17, p＜ .01), and negatively related to bureaucratic professional role discrepancy(r＝- .12, p＜ .01). There was no relationship between experience and service role conception. This study also showed that nurses who had longer experience tended to have higher role conceptions on all three subscales. 3. Nurses with a master's degree had significantly higher professional and bureaucratic role conceptions scores. Bacealaureates graduates had the lowest bureaucratic categorical role conception scores ; associate nurses had the lowest professional categorical role conception scores. 4. Nursing supervisors and head nurses had significantly higher bureaucratic categorical role coneption scores, whereas they had lower bureaucratic normative and professional role conception scores. 5. Age and experience were positively related to professional commitment (r＝ .24, r＝ .28). Hierarchical multiple regression analyses showed that the combination of nursing role conceptions explained greater variance in professional commitment pair of the variables alone. Further research employing dynamic designs is needed to execute rigorous tests of causal models of nursing role conceptions and professional commitment. The findings of this study suggest that antecedents and moderating variables of nursing role conception and professional commitment need to be explored for further theoretical. specification and empirical evaluation.