Effective estrus detection and artificial insemination (AI) are necessary for profitable management of dairy herd. In current study, 45 crossbred lactating cows have been selected with the complaint of unobserved oestrus for more than sixty days postpartum. All cows had functional corpus luteum as examined by transrectal ultrasonography. Cows were treated with PGF2α analogue and AI was performed with observed oestrus and then single dose of GnRH was administered. Similar synchronization protocol has been repeated after 14 days in cows that did not repose to first treatment. Remaining cows received additional PGF2α after 14 days of second treatment and timed AI was performed following GnRH administration. Among 45 cows, 28.89% showed estrus after first treatment and 78.79% responded to second hormonal intervention. A higher conception rate (88.89% vs 26.66 and 72.72%) was observed in cows after triple administration of PGF2α and timed AI. We noticed a significant differences in body condition score (BCS, 1～5 scale), postpartum period, and daily milk production between cows that either responded of non-responded following first and second hormonal treatment. In addition, there was a significant positive correlation between daily milk production and BCS, age and postpartum days, milk production and estrus/BCS, and milk production/BCS/estrus and conception rate. Depending upon the findings we conclude that hormonal intervention with PGF2α and GnRH enhances postpartum ovarian cyclicity and help decreasing the days open of dairy herd. Therefore, this finding might provide an excellent guideline for target breeding system for profitable dairy herd management.

The objective of this work was to analyze the concentrations of progesterone (P4) and estrogen (E2) hormones changed during estrus synchronization in dairy heifers. Estrus synchronization was carried out with CIDRⓇ (Controlled Intravaginal Drug Release) devices. Corpus luteum (CL) was classified into three grades based on its size and palpable characteristics. The concentrations of P4 and E2 were measured by enzyme-amplified chemiluminescence. Serum P4 concentration was markedly low at the estrus stage (36 hrs after removal of CIDR) compared to other stages, while E2 concentration was kept high during estrus stage. The serum P4 concentration was highest in the CL classified into gradeⅠ. These results indicate that P4 concentration could be used as a criteria for determining recipients for artificial insemination or embryo transfer in dairy cattle.

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 at Day 11 and injection of GnRH at the day of AI; and heifers belonged to protocol B were treated with GnRH, two injections at 11 days apart and injection of GnRH at AI. AI was done at fixed time (within 72~96 hours after 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.

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, 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 gonadorelin (Day 0), an injection of and removal of the device on Day 7, an injection of 250 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 () between herds A and B (26.8 vs 50.0%; vs times, vs 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 ( vs ). 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.

This study examined pregnancy and fetal loss rates according to different estrus synchronization protocols and injection of gonadotropin releasing hormone (GnRH) after transfer of Korean Native Cattle embryos to Holstein recipients. In Experiment 1, recipients received no treatment (Control, n = 119); two injections of prostaglandin ( ) 11 days apart (PGF group, n = 120); GnRH (day 0)- (day 7)-GnRH (day 9) (Ovsynch group, n = 120); and CIDR (day 0)- and CIDR removal (day 7)-GnRH (day 9) (CIDR group, n = 110). In Experiment 2, the control group was received no treatment of GnRH. The treatment groups were received GnRH at embryo transfer (ET) (day 0), 7 days later, 14 days later, ET and 7 days later, 7 and 14 days later, or ET, 7 and 14 days later. Recipients were assigned to treatment randomly and received two in vitro produced blastocysts. Pregnancy was diagnosed at day 60 by palpation per rectum. Fetal loss to term was determined by palpation every 90 days thereafter. In Experiment 1, the pregnancy rate in the CIDR group (59.1%) were higher than in the Control group (42.0%) (p<0.01); fetal loss rates were similar for all groups (12.0 to 18.5%). In Experiment 2, the pregnancy rate in Day 0+7+14 group was higher (60.2%) than the control (40.2%) (p<0.01) and resulted in a lower fetal loss (p<0.05) than the control (4.6 vs. 11.4%). There were no significant difference between other treatment and the control (p>0.05). These results show that pregnancy rates of bovine embryos can be enhanced by CIDR insertion or GnRH treatment. Additionally, fetal loss may be reduced with GnRH treatment after ET.

더러브렛종 암말의 번식 능력을 향상시키기 위해 호르몬 투여 및 인공 조명에 의한 인위적으로 발정 조절을 실시한 결과는 다음과 같다. 발정 주기에 있는 암말의 또는 altrenogst투여에 의한 발정 발현율은 100%이었으며, 수태율은 각각 95.2% 및 71.4%였다. 전년도 공태마에 대하여 altrenogest단독 또는 altrenogest과 estradiol 병행 투여시 3월 이내 100% 발정이 발현되었으며, 발정 발현일은 altrenogest 투

본 연구는 공여 세포의 종류, 수핵 난자의 유래 및 수란 산양 발정 동기화 조건이 복제 산양 생산에 미치는 영향을 알아보고자 실시되었다. 공여 세포는 귀 유래 섬유아세포를 분리 배양하여 사용하였으며, 체내 성숙 난자는 성숙한 미경산 재래 산양에 과배란을 유기하여 외과적인 방법으로 난관 관류를 통해 회수하였으며, 배란이 되지 않은 난포란은 난포로부터 흡입 채취한 후, 22시간 동안 체외 성숙을 실시하여 사용하였다. 핵이식은 zona drilling 후,

본 연구는 재래 흑염소의 인공수정기술을 개발하여 우수한 재래 흑염소의 이용효율을 극대화시키는데 그 목적을 두고 축산연구소 가축유전자원 시험장에서 사육하고 있는 재래 흑염소의 정액을 채취하여 이를 동결보존한 후 필요시 사용하였다. 발정동기화 처리로 인위적으로 발정을 유기한 개체에 인공수정을 실시하여 처리방법별 발정 유기율, 호르몬의 변화양상 및 분만율을 조사하였다. 발정동기화 방법 중 CIDR+ 방법에서 , CIDR+PMSG 방법에서 발정이 발현되었다.

본 연구는 한우에 PGF₂α와 GnRH+PGF₂α+GnRH(Ov-synch)를 처리하여 발정 및 배란을 동기화 시켰으며, 2차 GnRH 투여후 배란시간, 2차 GnRH 투여후 시간 경과에 따른 수태율과 발정ㆍ배란 동기화법에 의한 수태율을 조사하고자 실시하였다. 시험축은 총 4개 농가에서 경산우 150두를 무작위로 선발하여 시험에 공시하였으며, 발정ㆍ배란동기화 방법에 따라 발정을 유기한 후 1회 인공수정을 실시하고 수태율에 미치는 영향을 조사하였다. 호르몬처리 방법으로는 GnRH+PCF₂α+GnRH(Ov-synch)와 PGF₂α를 이용한 발정동기화 방법을 사용하였다. 2차 GnRH 투여 후 배란시간을 알아보기 GnRH 투여 후 24시간 후부터 32시간까지 2시간 간격으로 초음파 Sonovet-600(Medison. Korea)를 이용하여 난소를 촬영하였다. 1. 호르몬 투여후 발정동기 화율은 PGF₂α 투여구에서 40.0%와 GnRH+PGF₂α+GnRH(Ov-synch)처리구에서 91.3%로 나타났다. 2. 2차 GnRH 주사후 24시간에 배란이 시작되어 32시간에 배란이 종료되었으며, 배란율은 28시간째에 46.6%가 배란되어 가장 높게 나타났다. 3. 2차 GnRH주사후 6∼24시간에 수정한 군이 6시간 이전과 30시간 이후에 수정시킨 군에 비해 높은 수태율을 나타냈다. 4. 호르몬 처리별 수태율은 PGF₂α, CIDR 및 GnRH+PGF₂α+GnRH(Ov-synch)에서 각각 50.0, 36.0와 76.9%로 GnRH+PGF₂α+CnRH(Ov-synch)군에서 가장 높은 수태율을 나타냈다.