• Korean Journal of Animal Reproduction
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• v.24 no.1
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• pp.83-88
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• 2000

This study was conducted to determine the effect of repeated ultrasound-guided transvaginal retrieval of oocytes recovery, estrous cycle and ovarian adhesion in Korean native, Hanwoo heifers. Heifers were at unknown stages of the estrous cycle at the start of experiments in which all follicles $\geq$6mm in diameter were ablated. The results obtained in this study were as follows; Follicle developing number and oocytes collected number were no effected to repeated OPU to nine session, 4 e.a range oocytes collected to repeated OPU session. Oocytes were observated follicles were 8.7$\pm$4.2 e.a, collected oocytes were 4.1$\pm$3.4 e.a to two times collected per week and observated follicles was 10.2$\pm$6.1 e.a, collected oocytes were 4.3$\pm$2.9 e.a to one times collected per week, but no difference significantly(P＜0.05). Ovaries adhesive percentage to repeated OPU was eight ovaries adhisived(20%) of forty ovaries, three ovaries(7.5%) to 1~3 times oocytes collected, four ovaries(l0%) to 4~6 times, one ovaries(2.5%) to 7~9 times oocytes collected session. To repeated OPU effection, ovaries adhisive heifers were long estrous cycle(＞25 day) to 7 heads(87.5%) of 8 head, non-adhesive ovaries heifers were 5 heads(41.7%) were long estrous cycle to repeated OPU 12 heads. Although, now unknown about the dynamics of follicles wave and about functional changes to repeated OPU ovaries, more question about ovaries adhesive cause remain.

• 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.

• Journal of Embryo Transfer
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• v.27 no.4
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• pp.223-228
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• 2012

This study was designed to adopt two estrus synchronization protocols in zebu and crossbred heifers and their effects on pregnancy rate after timed artificial insemination (TAI). A number of 120 cyclic heifers were allotted for two different treatment groups and one control group. Heifers under protocol A were injected with GnRH at first day followed by a single dose of $PGF_{2{\alpha}}$ at Day 11 and injection of GnRH at the day of AI; and heifers belonged to protocol B were treated with GnRH, two $PGF_{2{\alpha}}$ injections at 11 days apart and injection of GnRH at AI. AI was done at fixed time (within 72~96 hours after $PGF_{2{\alpha}}$ injection) in both protocols and pregnancy was confirmed by rectal palpation on 80~120 days of post AI. In control group; local heifers were conceived higher (30%) proportion than that of crossbred heifers (25%; p<0.05). In protocol A, the local breed were conceived higher (38.9%) proportion compared with crossbred (25%; p<0.05). In protocol B, local breed heifers were conceived higher (38.9%) proportion compared with crossbred heifers (33.3%; p<0.05). The overall pregnancy rate in protocol A and protocol B was 33.3% and 36.6%, respectively. The proportion of pregnancy rate of local heifers (38.9%; Protocol A) was significant (p<0.05) in comparison with local heifers (30%) in control group (p<0.05). The overall pregnancy rate between pooled control group (28.3%) and treatment group (35%) was significantly (p<0.05) differ from each other's. Results of present study concluded that estrus synchronization followed by fixed time AI could be applied for higher pregnancy rate in zebu and crossbred heifers.

• Korean Journal of Veterinary Service
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• v.30 no.3
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• pp.429-436
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• 2007

This study was performed to make helpful standard for discrimination of cows from heifers by uterine and ovarian section inspection. A total of 3,736 heifers and 249 cows were inspected from January to November 2006 in Karak Market Slaughter house. Firstly, it was obvious that non-corpus albicans were observed in almost heifers(3,597/3,736, 96.3%), but there were distinctive corpus albicans in all cows (249/249 100%). Secondly, another evident was that the length and diameter of the horn in uterus was below 30mm in 94.5% (3,267/3,736) heifers, but above 30mm in 90.4% (225/245) cows, and it was easy to distinguish between right and left horn by difference of size in 87.6% (218/249) cows. Thirdly the diameters of pelvic cavity was below 220mm in 96.8% (3,615/3,736) heifers, but was over 200mm in 85.1% (212/249) cows. Fourthly another difference was found in second sacrum union condition and 13th thoracic vertebral process's states. In case of heifers, it was distinctive five lines in each second sacrum, but it was non-distinctive or united in the same each lines of the sacrum in cows. Fifthly in the results of 13th thoracic vertebral colors, the ratio between red color and white color was 7 : 3 in heifers (3,385/3,736, 90.6%), but that was 2 : 8 in cows (199/249, 79.9%). Consequently, it was possible to use the method which discriminated cows from heifers by uterine and ovarian section inspection in large scaled field slaughter house.

• Korean Journal of Veterinary Service
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• v.34 no.4
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• pp.369-378
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• 2011

Incidence of mastitis is highest in dairy cows and it is a leader of all diseases and the economic losses, in dairy farms. The objective of this study is to analyse the incidence of clinical mastitis using the lactation number, lactation month and season of calving. In this study, we used 3,779 lactation data and animal health records collected from 1990 to 2006 at the National Institute of Animal Science. Out of 3,779 cows, a total of 1,721 cows were reported with clinical mastitis, which was 46.3%. The frequency of mastitis increased from 36.9% from first lactation to 56.0% by the fifth lactation. As many as 766 cows (46.9%) showed a recurrence of mastitis after 14 days, apart for two or more and chronic mastitis that were recorded for 657 cows (20.3%). This came to a total of 3,010 cases that had clinical mastitis in the herd for sixteen years. The distribution of incidence of clinical mastitis was highest during the first month of lactation at 24.4%, and it reached to 43.4% by the third month. The incidence of mastitis was even higher for cows in first lactation, showing 28.6% in the first month, and 42.9 percent by third month of lactation. Cows calved during the summer and winter months showed higher rate of incidence with 59.9% and 57.9% within 30 days of lactation, respectively. It is urgently needed to establish a preventative management for heifer cows during their expected first lactation and the clinical specific dry-period management strategies that influence the rate of clinical mastitis during the next lactation. The aim of this study is to present information that might be useful to improve clinical mastitis prevention.

• Journal of Veterinary Clinics
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• v.15 no.1
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• pp.131-139
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• 1998

Progesterone을 함유하고 있는 CIDR(Controlled Internal Drug Release)의 질내삽 입은 황체기를 인위적으로 연장시킬 수 있다. CIDR의 삽입이,삽입시 존재했던 우세난포 (dominant follicle)의 반응과 난포의 발육반응 그리고 2회 또는 3회의 난포주기를 가지고 있는 처려우에서 CIDR의 삽입기간동안 난포의 성장 및 발육에 어떠한 영향을 미치는가를 비교검 토하기 위하여 배란후 16일째의 처녀우 4마리에 7일동안 CIDR를 삽입하였다. CIDR의 삽입 은 발정의 발현을 억제시켰으며 그리고 발정주기의 길이를 정상 발정주기보다 유의성있게 연 장시켰다($26.3{\pm} 0.5 vs 20.8{\pm}$ 1.5일, p<0.05). CIDR의 삽입시 혈장 progesterone 농도는 $3.6{\pm}$ 2.7 ng/ml 이었으며, 17일과 23일 사이에는 2.1-4.4 ng/ml($3.6{\pm}1.2 ng/ml$) 사이를 유지했다. 혈 장 estradiol-179의 농도는 난포의 발육 및 배란전 배란난포의 성숙을 나타내는 특징적인 변화 양상을 나타래었다. 4마리의 처녀우중 2마리는 CIDR 삽입전 발정주기당 2회의 난포주기를 가진 반면, 나머지 2마리는 주기당 3회의 난포주기를 가졌다. 그렇지만 CIDR의 삽입기간동안 모든 처녀우는 주기당 3회의 발정주기를 가졌다. CIDR의 삽입전 발정주기당 3회의 난포주기 를 갖는 처녀우에서 CRR의 삽입은 세 번째 난포주기에서 배란성 우세난포의 우세기 (dominant phase)를 연장시켰다. 3회의 난포주기를 갖는 2마리에서 CIDR의 삽입후 배란난포 는 존속시간과 우세기가 유의성있게 연장되었다. CIDR의 삽입전 발정주기당 2회의 난포주기 를 갖는 다른 2마리의 처녀우에서 CIDR의 삽입후 우세난포는 곧바로 퇴행되었고 새로운 난 포주기를 형성하였으며, 우세난포의 우세기와 배란난포의 존속기간을 연장시키지 않았다. CRR의 삽입은 CIDR의 삽입후 이어지는 발정주기동안 난포의 발육 및 성장에 영향을 미치 지 않았으며 발정주기의 길이, 난포주기, 혈장 progesterone 및 estradiol-179 농도에 영향을 미치지 않았다. 결과적으로 황체기 후반부에 CIDR의 삽입은 CIDR삽입전 발정주기동안 3회 의 난포주기를 갖는 처녀우에서 배란성 우세난포의 발육과 배란까지의 기간을 연장시켰고 2회 난포주기를 갖는 처녀우에서는 우세난포를 곧바로 퇴행시킨후, 새로운 난포주기를 형성 하였다.

• Korean Journal of Veterinary Research
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• v.36 no.4
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• pp.919-927
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• 1996

In the last few years, methods for in vitro culture of early embryo stages from oocytes matured and fertilized in vitro using suitable cell culture systems have been established. But the factors affecting pregnancy rates following transfer of bovine embryos produced in vitro were not evaluated enough. So this study was performed to investigate the effects of quality and stage of embryos, parity and Corpus Luteum quality of recipients on pregnancy rates following non-surgical transfer of bovine embryos produced in vitro. Oocytes aspirated from small antral follicles of ovaries obtained at a local slaughter house were matured, fertilized with frozen-thawed semen and co-cultured for 6-7 days by utilizing co-culture system with bovine oviduct epithelial cell in vitro. After co-culture, embryos were transfered to recipients on day 7 (estrus=day 0). Recipients were monitored by ultrasonic scanning method or observation for estrus and rectal palpation after 50 days from transfer. The results of this study are follows. 1. Of the 70 recipients, 70%(49 of 70) had not showed estrus sign between day 0 and day 50, but 22.9%(16 of 70) was diagnosed not pregnant. Therefore the overall pregnancy rate of this study was 47.1%(33 of 70). 2. The pregnancy rate of recipients transfered with excellent(66.7%) and good(54.5%) embryos were higher than that of recipients transfered with fair embryos(15.8%) (p<0.05). 3. The pregnancy rate of recipients transfered with morula, compacted morula, blastocyst and expanded blastocysts were 46.2, 55.0, 62.5 and 50.0%, respectively. 4. The pregnancy rates of recipients transfered to heifer and cow were 54.5 and 55.2%, respectively. 5. The pregnancy rates of recipients with CL score I, II(66.7, 63.6%) were higher than those of recipients with CL score III (10%), (p<0.05). Success of transfer of embryos produced in vitro depends on many variables. The important factors identified in this study were the quality of embryos and the CL score of recipient animals after non-surgical transfer of embryos matured, fertilized and cultured in vitro.

• Current Research on Agriculture and Life Sciences
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• v.4
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• pp.109-113
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• 1986

In order to study the changes of pregnancy rates according to the factors, age, season, repeated utilization, synchrony, of recipients (29 holstein heifers, one Korean native heifer and 3 holstein cows) were transfered one embryo (from morulae stage to advanced blastocyst) to each, and the results are as follows ; 1. The effect of age of recipient on pregnancy rate in cows and 18-24months of aged group are 100% and 78%, respectively. Under 14months of aged group recorded the worst, 67%. 2. In winter (Nov.-Jan.) and spring (Feb.-Apr.), the pregnancy rate were better than others 100%, 83%, respectively. In the autumn (Aug.-Oct.), it was only 50%, the worst. 3. Among 31 recipients which were utilized at the first, 25 were pregnanted (80.7%), but in the second utilization after the failure of the first transfering, 2 heifers, none of pregnancy was obtained. 4. Pregnancy rates related to synchronization of estrus between donor and recipients are;-(before donor)12hrs. (100%), -6hrs. (86%), +( after donor)6hrs. (67%), + 12hrs. (79%), and +over 12hrs. (50%), respectively. 5. Differences in the pregnancy rate of the recipients +over 12hrs. were significantly large, so in order to ger good pregnancy rate in embryo transfer, the differences of the synchronization must be reduced inner ${\pm}12hrs$. In general, recipients estrus before donor showed better pregnancy rate than estrus after donor.

• Current Research on Agriculture and Life Sciences
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• v.4
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• pp.102-108
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• 1986

This study was carried out to examine the effects of seasonality, age, abnormalities of reproductive tract and the frequency of superovulatory treatments on the superovulatory responses and rate of pregnancy in repeat breeder for embryo transfer. Thirty eight eggs were obtained from 6 donors by flushing the uterine horns and 33 embryos were transfered to 33 recipients. (29 holstein heifers, 3 holstein cows and 1 Korean native heifer). From this study, the following results could be obtained: 1. It seemed that spring (Feb.-Apr.) was the better season than any others to produce good embryos. Rate of pregnancy decreased significantly after August because of low heating rate. 2. Rate of pregnancy in the cows with normal reproductive tract showed much better superovulatory responses (80%) than the cows with abnormal reproductive tract (33%), as expected. 3. 8 years old cows produced higher rater of pregnancy than 4 years old cow (79.3 vs 50), and also in superovulatory responses, 8 years old cows showed slightly better results than 4 years old cow. 4. The number of ovulated eggs and rate of pregnancy in the repeated superovulatory treatment more than once were 41 eggs and 85.7%, and those of the donors treated the first superovulatory treatment were 32 eggs and 68.4%, respectively. 5. These results are showing the possibility that utilizing the repeat breeders as donors in embryo transfer could be able to elevate their economic values.

• Animal Bioscience
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• v.35 no.3
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• pp.503-510
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• 2022

Objective: This study was performed to determine the effects of stress after road transportation and oral administration of chromium and meloxicam on growth performance, plasma cortisol, serum metabolites, and behavior in dairy calves. Methods: A total of 50 Holstein heifers (average body weight [BW]: 172±4.19 kg; average age: 5.53±0.12 months) were randomly assigned to five groups including NL (not transported + D-lactose; 1 mg/kg BW), TL (transported + D-lactose; 1 mg/kg BW), TC (transported + chromium; 0.5 mg/kg dry matter [DM] feed), TM (transported + meloxicam; 1 mg/kg BW), and TMC (transported + combination of meloxicam and chromium; 1 mg/kg BW and 0.5 mg/kg DM, respectively). Doses of D-lactose monohydrate, meloxicam, and chromium were prepared for oral administration by suspension in 15 mL of water in a 20-mL dosing syringe. Blood was collected before transportation, immediately after 120 km of transportation (IAT), and at 6, 24, and 48 h after transportation. Results: Neither transportation nor administration of meloxicam and/or chromium affected (p = 0.99) average daily gain and feed intake. Plasma cortisol concentrations in the NL group (average 0.13 and 0.18 nmol/L, respectively) were lower (p<0.001) compared to the TL group (average 0.39 and 0.61 nmol/L, respectively) at IAT and 48 h after transportation. At 48 h after transportation, cortisol concentrations were lower (p<0.05) in the TC group (average 0.22 nmol/L) than in the TL group (average 0.61 nmol/L), and TC calves had similar cortisol concentrations to NL calves. Lying duration (min/d) was shorter (p<0.05) in the TL group than in the NL group at 2 d after transportation. Lying duration was longer (p<0.05) for the TC and TMC groups than for the TL group at 2 d after transportation. Conclusion: Transportation increased cortisol concentrations and affected lying behavior, while chromium administration reduced cortisol concentrations and changed lying behavior. Thus, chromium administration before transportation may be a viable strategy to alleviate stress elicited by road transportation.