• Korean Journal of Animal Reproduction
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• v.10 no.1
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• pp.49-57
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• 1986

Studies were conducted to investigate the relationship between hormone leveles and nutritional levels for improving performance of Cheju native cattle. In June 1984 a trial was initiated using 8 Cheju native calves after weaning, fed at two su, pp.ementary feeding levels (NRC 100% and 70%). The body weight, breedng performence, change in progesterone level during pregnancy and estrus cycle were evaluated. Mean body weight at 6 months of age was 155kg when fed 100% NRC ration but it was only 137kg when heifers received the 70% NRC ration. At 10, 15 and 20 months of age the body weight was 66, 160 and 115kg, respectively, showing that heifers fed the standard ration gained weight rapidly (P<0.01). Average size of the lefe ovary in the standard group was 2.1${\times}$1.6cm and right ovary was 2.6${\times}$1.8cm. However in the restricted feeding group the ovaries were found to be smaller. Diameter of graffian follicles showed a similar tendency to ovarian size in the two groups. The first oestrus in the standard feeding group a, pp.ared at 14.6 months when body weight was 265kg. Age at first calving was on average 28.9 months at a body weight of 436kg. On the other hand when heifers were fed the restricted ration the first oestrus a, pp.ared at 23.0 months at a body weight of 250kg. Average age at first calving was 38.9 months which was 10 months later than the average in the standard feeding group (P<0.01). In standard feeding group the progesterone level was 2.0ng/ml at two weeks after pregnancy and gradully increased up to 4 weeks and peaked at 18 weeks. This peak (6.4-6.5ng/ml) was maintained up to 24 weeks when progesterone level decreased until it reached 2.1ng/ml at the end of pregnancy. In the restricted group progesterone level up to 16 weeks followed a similar pattern to the standard group but there was a tendency in the restricted group to have lower progesterone levels(P<0.01). The standard and srstricted groups showed similar patterns of progesterone concentration during the oestrus cylce. There were no statistically significant differences in progesterone levels between standard and restricted groups but there was variation between induvidual animals.

• Development and Reproduction
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• v.6 no.2
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• pp.105-110
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• 2002

Numerous hormones are involved in the regulation of reproduction. Among them, estrogen and progesterone are the most important ovarian steroid hormones regulating female fertility. On the other hand, diverse stressors impede female receptivity and fertility. Since norepinephrine(NE) and epinephrine(E) are released from the adrenal during stress, it might play a role in stress-induced disruptions of fEmale reproductive parameters. The present study was performed to analyze the changes in adrenal catecholaminergic activities in cycling rats. The tissue content and secretion level of catecholamines were determined by high performance liquid chromatography coupled with electrochemical detector(HPLC-ECD). Adrenomedullary content of norepinephrine(NE) was increased on proestrus stage (59.47 $\pm$ 6.86 ug/gland), peaked on diestrus I stage(65.22 $\pm$ 5.99 ug/gland), and was nadir on diestrus II stage(41.63 $\pm$ 1.33 ug/gland). The highest E content was observed on proestrus stage(361.86 $\pm$ 15.58 ug/gland) while the lowest level was on diestrus II stage(285.58 $\pm$ 12.25 ug/gland). In addition to these observations, a significant reduction of the NE : E ratio was observed (1 : 4.81 on diestrus I vs 1 : 6.13～7.02 on other stages). In vitro secretion of adrenal NE and E was increased on proestrus stage, peaked on estrus stage, and decreased on diestrus II stage. Interestingly, the NE : E ratio in conditioned media was significantly increased on estrus stage (1 : 3.32 vs 1 : 2.34～2.65 on other stages. The biosynthesis of NE and E is mediated by tyrosine hydroxylase(TH) and phenylethanolamine-N-methyltransferase(PNMT) which acts conversion of tyrosine into DOPA and NE into E, respectively. These finding demonstrated that sex steroids, during setrous cycle, seem to be able to modify the adrenal catecholamines biosynthesis and secretion with stage-specific manner by modulation of the enzyme activities.

• Development and Reproduction
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• v.5 no.2
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• pp.175-180
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• 2001

The ectopic expression of gonadotropin releasing hormone(GnRH and luteinizing hormone(LH) in several tissues is a quite intriguing phenomenon. Recently, the presence of GnRH and its receptor has been clearly demonstrated in rodents and human mammary gland. In this context, one can postulate that the presence of local circuit composed of GnRH and LH in the gland. The present study was undertaken to elucidate whether there is a correlation between the LH expression in rat mammary gland and physiological status during the process of mammary differentiation. LH contents in mammary gland from cycling to weaning rats were measured by radioimmunoassay(RIA). In cycling rats, changes of the LH level in both serum and mammary gland showed similar pattern as the highest level in proestrus and the lowest level in diestrus II stage. While the serum LH levels were fluctuated from pregnant through involution stage, a sharp decline of mammary LH contents was observed in the lactating rats. This decrement was recovered in involuting rats to the level of proestrus stage. Reverse transcription-polymerase chain reaction (RT-PCR) and Southern blot analyses demonstrated that the transcriptional activities of the mammary LH and GnRH were increased from diestrus I stage to estrus stage, and the increased levels were maintained in pregnant, lactation and involution stages. To test the hypothesis that the alteration in mammary LH expression might be steroid-dependant, ovariectomy(OVX) and steroid supplement model was employed. As expected, supplement of estradiol(E$_2$) after OVX remarkably decreased serum LH level compared to that in serum from vehicle-only treated rats. Likewise, administration of E$_2$ significantly reduced the mammary LH content. The present study demonstrated that (i) the LH expression in mammary gland could be altered by some physiological parameters such as estrous cycle, pregnancy, lactation and involution, and (ii) ovarian steroid especially estrogen seems to be one of major endocrine factors which are responsible for regulation of mammary LH expression.

• Korean Journal of Animal Reproduction
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• v.21 no.3
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• pp.255-264
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• 1997

The purpose of this study was attempted to investigate the number changes of the growing and mature follicles in ovary following repeats of pregnant mare serum gonadotropin(PMSG) treatments for superovulation in nulliparous rats. Thirty two rats(Sprague-Dawely, about 200~250 gm) were randomized into 4 groups. Control group rats were sacrified at estrus phase confirmed by vaginal smear. PMSG-treated group 1 rats, PMSG-treated group 2 rats and PMSG-treated group 3 rats were sacrified at 48 hrs after injection once with PMSG 25 IU, after 2 repeated injection by a week interval, and 3 repeated injection, respectively. The uteri and ovaries of rats were removed and weighed and then were observed grossly and serial sections of all ovaries and some sections of uteri by paraffin embedding were stained with H-E. Number of ovarian follicles about 3 grades of small, middle and large follicles from seondary and follicles were investigated by LM photographies of ovary preparations. The criteria of the small, middle, and large follicles were based as small follicle with preantral follicles with 2~4 layers of granulosa cells surrounding the oocyte, as secondary follicles with more than 5 layers of granulosa cells and early signs of antral cavity or with small clefts on either side of the oocytes, and as tirtiary follicles with a single medium sized antral cavity or large well-formed antral cavity, respectively. In gross findings, the wall of the uteri in control group were thin, and those in 3 PMS-treated group were markedly thickened and some uterine lumen of those filled with fluid. In histological findings, the walls of the uteri from 3 PMSG-treated groups were hypertrophied and their blood and lymph vessels were dilated than those of control group. The ovaries fo 3 PMSG-treated groups were more increased in size and the cortexes were more developed and increased in width but there are no difference of development and changes in 3 PMSG-treated groups. The weight of the uteri and ovaries per rat in PMSG -treated group 1, 2 and 3 were a, pp.ared to be significantly increased 171.4$\pm$47.6%, 162.3$\pm$43.9%, 206.9$\pm$30.4%, respectively than those of control groups. The mean number of follicle per ovary in control group were a, pp.ared to be 17.1$\pm$3.5, 46.2$\pm$14.5, and 74.3$\pm$22.7 at large, middle and small follicles, respectively and total number of these 3 grade follicles per ovary were a, pp.ared to be 137.7$\pm$31.7. The mean number of follicle per ovary in PMSG-treated group 1 were a, pp.ared to be 25.6$\pm$7.3, 78.1$\pm$29.9, and 83.2$\pm$34.0, at large, middle and small follicles, respectively and total number of these 3 grade follicles were a, pp.ared to be 187.5$\pm$58.8. The mean number of follicle per ovary in PMS-treated group 2 were a, pp.ared to be 21.9$\pm$5.2, 67.8$\pm$16.8, and 68.0$\pm$14.9 at large, middle and small follicles, respectively and total number of these 3 grade follicles were a, pp.ared to be 157.7$\pm$26.2. The mean number of follicle per ovary in PMS-treated group 3 were a, pp.ared to be 21.7$\pm$4.8, 61.5$\pm$17.0, and 59.7$\pm$16.2 at large, middle and small follicles, respectively and total number of these 3 grade follicles were a, pp.ared to be 143.5$\pm$29.6. The number of follicles in PMSG-treated group 1 a, pp.ared to be more number than other 2 PMSG-treated gruops and tended to be decreased by frequency of PMSG-treatment.

• Journal of Embryo Transfer
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• v.21 no.3
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• pp.217-223
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• 2006

This study was carried out principally to obtain the basic data for the improvement of the reproductive performance and production using plasma progesterone assay and ultrasonography in dairy cow. The results obtained from this studies were as follows. The results of reproductive examination in 85,983 cows were ovarian diseases 40,399 (47.0%), uterine diseases 11,912 (13.9%), pregnancy or pregnant failures 26,587 (30.9%), adhesion of reproductive tracts 172 (0.2%), freemartin 8 (0.01%), and others 6,905 (8.3%), respectively. The treatment status of reproductive dysfunction in 30,241 cows were silent heat or error of estrus detection 14,909 (49.3%), follicular cysts 3,750 (12.4%), luteal cysts 907 (3.0%), inactive ovaries 665 (2.2%), granulosa cell tumor of ovary 3 (0.01%) and endometritis 6,986 (23.1%), respectively. The indices of reproductive efficiency after the periodical examination of reproductive status were as follows; the mean intercalving inteual was reduced from 475 days at the first examination to 381 days at the last examination of reproductive status, the mean interval calving to conception was reduced from 186 to 98 days, the mean interval calving to first service was reduced from 106 to 66 days, the cows showing heat by 60 days postpartum were increased from 32 to 90%, the mean conception rate to first service was increased from 42 to 64%, and the mean service per conception was reduced from 2.6 to 1.8 times, respectively.