Ui-Hyung Kim

Efficacy of a Cue-Mate Intravaginal Insert and Injection of Prostaglandin F 2α for Synchronizing Estrus in Hanwoo Cattle

The present study was performed on farm animals to test the effectiveness of progesterone-releasing intravaginal device (Cue-Mate® 1.56 g) and injection of prostaglandin F2α (PGF2α) for synchronization estrus in Hanwoo cattle. The cattle were at random stage of the estrus cycle. The cows were artificially inseminated at day 7 after Cue-Mate withdrawal, using commercial semen from Korean native bulls. There was a season effect on the estrus synchronization rate. It was higher in spring (94.3%) followed by winter (93.3%), autumn (90.4%) and summer (67.2%). In summary, The results of this study revealed that season has influences on estrus behavior of cattle with no significant effect on pregnancy rate. In summary, we suggest summer reproductive management to alleviate the effects of heat stress. It should be based on intensive cooling combined with hormonal treatment. Given that different subgroups of cows benefit differently from the treatments, selective hormonal administration should be considered.

116 EFFECTS OF EARLY PREGNANCY DIAGNOSIS USING ULTRASONOGRAPHY ON THE SUBSEQUENT EMBRYO AND FETAL LOSS IN DAIRY COWS

Under on-farm condition, pregnancy diagnosis can be rapidly and accurately diagnosed using ultrasound. However, the risk of the incidence of embryo and fetal loss following early pregnancy diagnosis has not been fully determined. This study assessed, using ultrasonography, the incidence of embryo and fetal loss in dairy cows following early pregnancy diagnosis after artificial insemination. A positive pregnancy was the recognition of the vesicle, embryo, or fetus by ultrasonography (Sonoace 600 with 5.0- or 7.5-MHz linear array transducer; Medison Co., Ltd., Seoul, Korea). Pregnancies (n = 702) were divided into three groups according to the number of days pregnant diagnosed: early A group (27 to 40 days, n = 143), early B group (41 to 50 days, n = 172), or standard group (51 to 70 days, n = 387). Following a positive pregnancy diagnosis, embryo or fetal loss included all cows with observed abortions and also cows found open after the positive pregnancy diagnosis. Data were analyzed by chi-square test or Fishers exact test using an SAS program (SAS Institute, Inc., Cary, NC, USA). The incidence rate of embryo or fetal loss within 7 days after pregnancy diagnosis was 1.4, 0.6, and 0.3% for the early A, early B, and standard groups, respectively (P > 0.05). The incidence rate of the embryo or fetal loss during 8 to 30 days after pregnancy diagnosis was not different (P > 0.05) among the early A (0%), early B (1.2%), and standard groups (1.0%). Furthermore, the cumulative incidence rate of the embryo or fetal loss before calving was not different (P > 0.05) among the early A (9.8%), early B (9.3%), and standard groups (5.9%). In conclusion, early pregnancy diagnosis using ultrasonography does not significantly increase the risk of embryo and fetal loss in dairy cows. This work was supported by the research grant of the Chungbuk National University in 2007.

235 FOLLICULAR WAVE EMERGENCE AND DEVELOPMENT FOLLOWING ESTRADIOL PLUS PROGESTERONE AT A GROWING OR A STATIC PHASE OF THE DOMINANT FOLLICLE IN CIDR-TREATED, LACTATING DAIRY COWS

Treatment with estradiol benzoate (EB), compared to GnRH, in a controlled internal drug release (CIDR)-based timed AI protocol induced relatively asynchronous follicular wave emergence, resulting in ovulation of smaller ovulating follicles (Kim et al. 2005 Theriogenology 63, 260-268). In this study, we compared new follicular wave emergence and development following treatment with EB (2 mg) plus progesterone (50 mg) at a growing (Day 3 after ovulation) or a static (Day 8) phase of the dominant follicle during the first follicular wave in CIDR-treated, lactating dairy cows. Previously synchronized, lactating dairy cows received CIDRs (InterAg, Hamilton, New Zealand; Day 0) 3 days after ovulation and were assigned to two treatment groups and a control group. Cows in the T1 group (n = 11) received 2 mg EB (SY Esrone; Samyang, Seoul, Korea) and 50 mg P4 (SY Ovaron; Samyang) i.m., and those in the control group (n = 10) received no treatment at that time. Other previously synchronized cows received a CIDR (Day 0) with injections of 2 mg EB plus 50 mg P4 i.m. 8 days after ovulation (T2 group, n = 10). Thereafter, all cows received PGF2± (Lutalyse; Pharmacia & Upjohn, Puurs, Belgium) at the time of CIDR removal on Day 7, and GnRH (Conceral; Dongbang Co., Seoul, Korea) on Day 9. Ovaries of each cow were examined by transrectal ultrasonography (Sonoace 600 with 7.5 MHz linear-array transducer; Medison Co., Ltd, Seoul, Korea) every 24 h from Days 0 to 9, on Day 11, and on Day 14 of treatment to observe changes in ovarian structures (follicles and corpora lutea (CL)). Data were analyzed by Fishers exact test, Kruskal-Wallis test, and ANOVA using an SAS program (SAS Institute, Inc., Cary, NC, USA). Follicular wave emergence occurred within 7 days in 3/10 of the control group, 9/11 of the T1 group, and 9/10 of the T2 group (P 0.05) among groups (3.7 ± 1.2, 4.8 ± 0.5, 5.9 ± 0.3 days, respectively). While the diameters of dominant follicles on Day 0 were greater (P 0.05). In conclusion, administration of 2 mg EB plus 50 mg P4 at both a growing and a static phase of the dominant follicle during the first follicular wave results in synchronous follicular wave emergence and development and also synchronized ovulation in CIDR-treated, lactating dairy cows.

16 A CIDR-BASED TIMED AI PROTOCOL RESULTED IN A HIGHLY ACCEPTABLE THERAPEUTIC OUTCOME ON OVARIAN FOLLICULAR CYSTS IN LACTATING DAIRY COWS

Ovarian follicular cysts are a major reproductive failure in lactating dairy cows, prolonging the calving-to-conception interval and resulting in great economic loss. Treatment with GnRH is currently the most common therapy used for ovarian follicular cysts in dairy cows, but definitive results remain inconclusive. Recently, the Ovsynch protocol has been introduced as a therapeutic strategy for ovarian cysts in dairy cows (Bartolome et al. 2000 Theriogenology 53, 815–825). The objective of the present study was to evaluate the therapeutic effect of a CIDR-based timed AI (TAI) protocol on ovarian follicular cysts in lactating Holstein cows. Lactating Holstein cows with ovarian follicular cysts were randomly assigned to two treatments: (1) insertion of a CIDR intravaginal progesterone device (CIDR™, InterAg, Hamilton, New Zealand) with an injection of 100 μg GnRH (Conceral®, Dongbang Co., Seoul, Korea) on Day 0, an injection of PGF2α (Lutalyse®, Pharmacia & Upjohn, Puurs, Belgium) and removal of the device on Day 7, an injection of GnRH on Day 9, and TAI 16 h after the GnRH injection (CIDR+GnRH-PGF2α-GnRH group, n = 30); and (2) an injection of 100 μg GnRH on Day 0, and AI at estrus (AIE) within 2 months after treatment with GnRH (GnRH group, n = 72). Day 0 was the day of initiation of the experiment. Pregnancy diagnosis was determined at 60 days after AI using both ultrasonography and rectal palpation. Pregnancy rates between groups were compared by chi-square analysis. Treatment-to-conception interval for cows that conceived by 150 days post-treatment was compared by Students t-test. The pregnancy rate after TAI following the CIDR+GnRH-PGF2α-GnRH protocol (46.7%) was higher (P < 0.05) than that after AIE following GnRH injection (25.0%). The treatment-to-conception interval (mean ± SEM) was shorter (P < 0.01) in the CIDR+GnRH-PGF2α-GnRH group (46 ± 12 days) than in the GnRH group (88 ± 10 days), representing 21.9% more cows being pregnant by 150 days after treatment. These results indicate that the CIDR-based TAI protocol can be used as an efficient therapeutic tool for ovarian follicular cysts in lactating dairy cows. Follicular dynamics and endocrine changes during the CIDR+GnRH-PGF2α-GnRH protocol is being determined to clarify the beneficial outcome in this study. This work was supported by a Chungbuk National University Grant in 2004.