Embryos produced with serum show the alterations in their ultrastructure, impaired compaction, abnormal blastulation, aberrant mRNA expression profiles and large calf syndrome with greater incidences of stillbirths and deaths after birth. The aim of the present study was to describe in vitro embryo production by analyzing embryo production, fetal production and pregnancy rate in free-serum medium. The OPU-IVP data used in this study from 2016. Approximately, sixteen cows (Hanwoo), which belonged to the Institute of Gyeongsang National University, were used. Two experimental group is used in this study. Serum groups were conducted in March to July and free-serum group was conducted in September to December. The recovered cumulus-oocyte complexes were morphologically classified to four grades based on the compaction of cumulus cells layers and homogeneity of the cytoplasm. The number of oocyte was significantly greater in serum groups than that in free-serum groups (29.61 ± 0.63 vs. 15.6 ± 0.62; p < 0.05). Between serum and free-serum groups indicate that average of 1st and 2nd grade oocytes were no difference (2.38 ± 1.67 vs. 2.38 ± 1.48; p > 0.05), but number of 3rd and 4th grade oocytes were greater in serum groups than that in free-serum groups (7.31 ± 7.64 vs. 5.60 ± 6.29; p < 0.05). Embryo cleaved competence was higher in rate in free-serum groups than that in serum groups (62.1% vs. 58.3; p < 0.05). However, blastocyst developmental rate was no difference between serum and free-serum groups (33.1% vs. 43.5%; p < 0.05). 986 recipients were used for embryo transfer. Pregnancy rate was indicated that between serum and free-serum group was no difference (54.6% vs. 56.3%; p < 0.05). In conclusion, we developed the free-serum system for production of in vitro bovine embryos in order to meet the developmental and qualitative requirements for large scale commercial use.

Up-to-date artificial insemination (AI) using frozen sperm consider as the most widely using technology for improvement of Korean Native Cow (Hanwoo) embryo production. However, it is time consuming, required at least 15~20 years to make more than 6 generations, and their offspring number is limited. To overcome such limitations, superovulation and in vitro fertilization have been developed. For superovulation, the number of produced embryos are not enough for commercialization and donor cows need rest period. This led to use of slaughterhouse ovary for in vitro fertilization, but it is impossible to repeat the collection from the same individual and it only can improve the genetic merits of offspring for one generation. Production of embryos using Ovum Pick-Up (OPU) technique, where oocytes can be repeatedly collected from living elite donor, might overcome these limitations. In this study, we investigated the possibility of using OPU technique from donors at different age and different session periods for mass-embryo-production. Oocytes were collected from 26 donor cows twice per week, 3 - 4 months per year, between 2013 and 2016. Results showed that, the average number of embryo produced in first year used donor was significantly higher than that in second year used donor (3.89 ± 2.85 vs 3.29 ± 2.70), however, there was no significant difference between third year used donor (3.51 ± 3.32) and other groups. Taken together, our data showed that repeated using of donor up to three years is possible for in vitro embryo mass-production. Moreover, OPU can be used as suitable embryo producing technique for livestock breed improvement.

현재까지 한우개량을 위해 가장 보편적으로 활용되고 있는 기술은 웅성 유전자원의 동결용 정액을 활용하는 인공수정기술로서 개량에 최소 6 세대 이상 즉, 암송아지만을 생산한다는 가정에서 15~20 년 이상의 시간이 소요될 뿐만 아니라 생산되는 산자 수 또한 한정적이다. 가축개량 효율을 높이기 위해 수정란이식 기술이 개발되었으며, 호르몬 투여에 의한 과배란 유래 체내 수정란 및 체외 수정란 생산 방법이 개발되어 활용되어 왔다. 체내 수정란 생산방법은 혈통관리는 정확하나 수정란 생산을 위해 호르몬 과다 투여에 의한 휴식기간 등이 필요하며 수정란의 생산량의 한계로 산업화 적용에 비효율적이고, 근래에 체외수정란을 활용되면서 도축 유래 수정란을 활용하는 경향이 있으나 친자 검정의 한계로 인한 친자 불일치 및 고도근친 위험성 등이 상존하고 있다. 이러한 문제를 극복하고 효율적인 이식 가능한 수정란의 생산이 가능한 OPU 유래 수정란 생산기술은 살아있는 공란우에서 난자를 채취하여 체외수정란을 생산함으로써 혈통관리가 정확하고 우수유전 자원을 선발 활용함으로써 계획 교배에 의한 근친도와 개량의 폭을 예측할 수 있는 장점이 있다. 또한 수정란의 생산 가능 량은 3~4 개월에 약 60 여 개의 이식 가능한 수정란을 대량 생산으로 산업화에 적합한 수정란 생산기술이다. 본 연구에서는 선발된 공란우의 반복 사용으로 우수 유전자원의 수정란을 대량생산에 활용하기 위해서 2013-2016 년까지 매년 3-4 개월 동안 주 2 회 채란 및 수정란을 생산하였고 채란 완료 후 일정 기간의 휴식한 다음 다시 채란에 활용으로 2 회 이상 수정란 생산으로 수정란의 반복 생산 가능성 및 생산 효율에 대하여 조사하였다. 2 반복의 공란우는 총 24 두와 3 반복은 7 두를 3-4 개월 동안/년 매주 2 회 총 1,626 회 채란으로 평균 3.6±2.9 개의 수정란이 생산되었다. 특히 채란 시 생산된 수정란은 채란 횟수당 1 회 반복에서 3.9±2.8 개, 2 회 반복은 3.3±2.7 개 및 3 회 반복은 3.5±3.3 개로 확인되었고, 3 회 이상의 반복 채란된 개체 7 두를 분석한 결과 1 회 반복 채란에서 평균 3.63±2.79 개, 2 회 반복은 평균 3.70±2.84 개 및 3 회 반복은 년 3.51±3.32 개로 반복 채란에 수정란 생산에 활용하였으며 반복 채란에 의한 수정란의 생산효율에는 유의적인 차이를 보이지 않았다. 따라서 가축개량을 위해 산업화에 가장 적합한 수정란 생산방법으로 유전능력이 우수한 한우에서 대량의 수정란을 생산하여 우량한우 집단구축을 위하여 약 3-4 개월 동안 매주 2 회 수정란을 생산하고 일정기간을 휴식한 다음 공란우로써 재활용 가능성을 확인하였고 또한 OPU 유래 수정란 생산방법은 우수한 유전자원을 보유한 개체를 연속적이며 반복적으로 활용할 수 있는 가능성을 확인하였다

Sex preselection has always generated great interest among livestock producers due to an increase in the profitability of the cattle industry through the production of offspring with desired sex, such as females for dairy or males for meat production. Among the prevalent sorting methods, the embryo developmental potential is still very low as expected, and there is distinguished evidence that sex sorting has a negative effect on sperm quality with an altered pattern of sperm motility, ultimately reducing lifespan. The consequence is a very low embryo development rate using sex-sorted semen, and its negative impact influences the progress of the dairy industry. Here, we established a new approach with reduced stress by using WholeMom® and observed no significant differences (P < 0.05) in early cleaving embryos between sorted X sperm and the control group, although there was a remarkable significant difference in embryos of the Y sperm group, 81.82 ± 2.71% vs. 87.44 ± 3.02% vs. 54.21 ± 2.21%, respectively. The percentage of embryos that developed into blastocysts (Day 7) was also significantly (P < 0.05) higher in the control and X Sperm group compared to the Y sperm group, 35.53 ± 1.92% and 29.76 ± 2.38% vs. 21.90 ± 1.54%. Moreover, B-SRY F2 and B-SRY R2 gene expression data exhibited 81.03% accuracy for the female embryos and 72.54% for the male embryos produced in vitro. And also the field trials for the heifer production using WholeMom by Artificial Insemination technique demonstrated 76% female and 24% male in vivo. In conclusion, the combination of pre-selected sex semen and OPU derived elite cattle embryo production is highly recommended to apply to the mass production in the dairy industry with rapid genetic up-gradation.

OPU 유래 수정란 생산 및 이식은 기존의 체내 및 체외 수정란 생산과 이식의 단점을 해결하고 한우 개량을 촉진 시킬 수 있는 기술이다. 특히 살아있는 공란우를 활용하므로 모계와 부계에 대한 혈통관리가 정확하고 또한 선발된 공란우와 계획 교배를 통하여 가장 적합한 동결정액을 사용하여 개량의 효과를 극대화가 가능하고 또한 현재까지 생산효율이 가장 높은 생산기술이다. 따라서 기존의 수정란 생산방법보다 공란우의 선발강도를 더 높일 수 있어 개량의 효과를 극대화 할 수 있는 장점이 있다. 본 연구실에서는 2009 년도부터 OPU 유래 수정란을 생산하여 이식하여 수정란이식이 산업화로 전개될 수 있도록 진행하고 있다. 특히 한우에 대한 우수성 확보, 개량 및 그 다음 세대 후대의 근친적인 문제가 발생되지 않도록 수정란이식에 의해 탄생된 송아지 혈통관리를 위한 친자검정으로 수정란에 대한 신뢰성을 높여 수정란 이식이 산업화가 될 수 있도록 진행하였다. 본 연구에 대한 조사는 2013 년도 7 개의 시·군을 시작으로 ‘14 년도 11 개, ‘15 년도 15 개, ‘16년도 17 개의 시·군으로 점진적으로 확대됨에 따라 공란우의 두수도 ‘13 년도 35 두를 시작으로 ‘16 년도는 71 두로 증가되었다. 조사된 4 년동안 각 지역에서 선발된 유전능력이 우수한 공란우는 총 211 두에서 수정란을 총 18,839 개, 두당 89.3 개를 생산하였다. 두당 생산 효율도 ‘13 도에는 회당 3.0±4.5 개에서 ‘16 년도에는 4.8±2.2 로 회당 이식 가능한 수정란의 생산량이 년도에 따라 꾸준히 향상되었다. 생산된 수정란은 자연발정 또는 발정동기화를 통하여 매주 2 회 이상 이식으로 ‘13 년 49.7%, ‘14 년 51.9%, ‘15 년 52.9%와 ‘16 년 47.9%의 수태율을 확인하였다. 이는 년도가 증가되면서 수정란의 생산성의 향상과 적정 수준의 수태율의 성과는 시술자와 농가의 적극적인 참여에 의한 결과로 판단되고 또한 유전능력이 우수한 수정란의 대량생산 및 공급으로 개량의 효과가 증가되고 우수한 한우 집단 구축으로 한우산업이 지속적으로 발전 할 것으로 판단된다.

This study investigated the effect of Charcoal:Dextran Stripped fetal bovine serum (CDS FBS) and heat-inactivated FBS (HI FBS) in embryo culture medium on their ability to support in vitro development of bovine embryos. The developmental ability and quality of bovine embryos were determined by assessing their cell number, lipid content, mitochondrial activity, gene expression, and cryo-tolerance. The percentages of embryos that underwent cleavage and formed a blastocyst were significantly (P<0.05) higher in medium containing CDS FBS than in medium containing HI FBS (42.84 ± 0.78% vs. 36.85 ± 0.89%, respectively). Furthermore, the beneficial effects of CDS FBS on embryos were associated with a significantly reduced intracellular lipid content, as identified by Nile red staining, which increased their cryo-tolerance. The post-thaw survival rate of blastocysts was significantly (P<0.05) higher in the CDS FBS than in the HI FBS group (85.33 ± 4.84% vs. 68.67 ± 1.20%). Quantitative real-time PCR showed that the mRNA levels of acyl-CoA synthetase long-chain family member 3, acyl-coenzyme A dehydrogenase long-chain, hydroxymethylglutaryl-CoA reductase, and insulin-like growth factor 2 receptor were significantly increased upon culture with CDS FBS. Moreover, the mRNA levels of sirtuin 1, superoxide dismutase 2, and anti-apoptotic associated gene B-cell lymphoma 2 in frozen-thawed blastocysts were significantly (P<0.05) higher in the CDS FBS group than in the HI FBS group, however, the mRNA level of the pro-apoptotic gene BCL2-associated X protein was significantly reduced. Taken together, these data suggest that supplementation of medium with CDS FBS improves in vitro bovine embryo developmental competence and cryo-tolerance.

This study was designed to know the possibility in repeat uses of elite donor cows for getting mass production of OPU-derived embryo production (OPU-IVP). Ultrasound transvaginal ovum pick-up (OPU) performed in 6 Korean native cows was aged 4 to 10 years old. The aspiration of immature oocytes for OPU derived embryo was carried out 2 times per week, and OPU-IVP of 1st period was carried out 22∼48 sessions from each donors. And the break time for OPU-IVP of 2nd period after 1st OPU from each donors were 2∼25 months. The OPU-IVP of 2nd period each donors conducted total 15∼65 times for 2∼8 months by an ultrasonographic, was guided follicular aspiration system. The average numbers of collected oocytes, grade 1 + grade 2(G1+G2) oocytes and cleavage embryo from 1st period OPU-IVP were significantly differences between donors (p<0.05). Total collected oocytes of donor D were significantly higher compared with donors of A, B, C, E and F (average 17.0 per session vs. 11.2, 10.1, 8.5, 10.2 and 9.6; p<0.05) and also oocytes of G1+G2 were significantly higher compared with r A and D and subsequently to donors of B, C, E and F (average 7.9 and 8.5 per session vs. 5.0, 2.7, 6.0 and 1.6; p<0.05). Cleavage rate of donor D was significantly higher compared with donors of A, B, C, E and F (average 13.1 per session vs. 10.1, 9.1, 6.9, 8.9 and 6.7; p<0.05). The average numbers of OPU-IVP for 1st period was significantly higher from donors of B, D and E than those from donors of A, C and F (average 6.5, 7.1 and 6.5 per session vs. 3.5, 4.2 and 2.8; p<0.05). The possibility investigation of 2nd OPU-IVP was carried out after 2∼25 months rest periods from 1st period OPU session. Total average numbers of collected oocytes, cleavages and blastocyst development rates were significantly higher from 1st period OPU compared with 2nd period one (p<0.05). The OPU-IVP efficiency by break for more embryo production from elite cow was analysis comparing without rest of donor A, under 6 months rest period as B and over 6 months rest period as C and then the average numbers of collected oocytes, cleavages and blastocysts were significantly higher from A group (11.8, 9.5 and 5.2 per session) than those from B and C groups (7.9, 6.2 and 2.6 vs. 9.2, 7.5 and 3.9, p<0.05), and also C group was significantly higher than B group. In conclusion, 1st period OPU-IVP was more efficient compared with 2nd period repeated uses of donor, and the break times for additional production of embryo on donor were needed more than over 6 months after 1st period OPU-IVP. This repeating uses of elite donor cows given more emphasis for getting the opportunity on mass production of elite cow OPU-IVP embryo should be increased G1+G2 possibility of genetic improvement of livestock within short period.

This study was designed to evaluate the possibility of increase through dairy female offspring’s ratio by transfer of pre-selected transferrable blastocyst that was produced by pre-selected X-bearing semen with OPU derived oocytes. Elite dairy female cow is demanded strongly compared with male, the so called, farmer wants to produce only an elite female dairy offspring as a candidate female dairy cow for producing milk. In our study, we selected 2 elite dairy bull semen from National Agricultural Cooperative Federation to pre-select X-bearing semen and 5 elite dairy female cows as donor for collecting of OPU derived oocytes. OPU derived embryo production system was carried out an aspiration of immature oocytes from 5 donor cows 2 times per week, total 200 times for 2 to 7 months by an ultrasonographic guided follicular aspiration system and then produced in vitro-produced blastocysts by in vitro maturation, fertilization and culture. Dairy donor semen selected H-319, 320 bull in National Agricultural Cooperative federation was sorted X-bearing semen by flow-cytometer and frozen for using IVF with OPU derived oocytes. Donor cows were selected 5 elite dairy cows from Gyeongju Dairy Cow Community and then disease tests such as 4 kinds of disease before selecting was checked. Oocyte proportion of grade 1 to 3 from total collected oocytes was significantly lower in donor A and B than those in donor C, D and E (82.16 and 70.03% vs. 90.0, 91.78 and 93.57%), respectively (p<0.05). However, number of oocytes per session in donor A, C and E was significantly higher than those in donor B and D (7.77 ± 3.26, 5.85 ± 2.10 and 7.03 ± 2.14 vs. 4.68 ± 2.61 and 5.21 ± 1.97 oocytes), but donor A was significantly higher than donor C (p<0.05). Development to blastocyst in donor B, C and E was significantly higher than those in donor A and D (31.0, 25.0 and 25.0% vs. 14.3 and 4.5%), but donor A was not different in donor C and E (p<0.05). Nine out of 10 blastocysts (90.0%) derived from OPU blastocysts were confirmed male embryos that was induced with Y-bearing semen to confirm sex ratio only. Total 96 blastocysts derived from female bearing semen were transferred into synchronized recipients and then confirmed 42 recipients (43.8%) pregnancy rate, 36 offspring (37.5%) and 91.7% female sex ratio (33 female vs. 3 male offspring). Taken together all data, elite dairy female offspring could be produced effectively by in vitro production system between pre-selected x-bearing semen and OPU derived oocytes that would be influential breeder in the breeding of dairy farm to increase effectively elite dairy offspring ratio as well as net income in the dairy farmer.