• Korean Journal of Animal Reproduction
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• v.7 no.2
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• pp.72-85
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• 1983

This presentation firstly is discussed the characteristics of estrus, the time of first postpartum estrus, and the relative accurate of various estrus detection aids and secondly discussed the abnormalities of estrus and ovarian function and its control by treatment of exogenous hormones in cattle and pig. Longer estrus cycles as well as the shorter than 18 day cycles showed the lowered conception rates as compared to the normal cycles of 18 to 25 days. Other characteristics of est겨s such as duration of estrus, intensity of estrus and time of estrus are reviewed to affect fertility. The first postpartum ovulation and estrus in cows usually occurs about 20 to 30 days and 40 to 50 days after parturition, respectively. Irregularities in estrus cycle length have been conducted during early postpartum period. In sows, weaning is followed by ovulation and estrus although there is some individual variation. The most common method of estrus detection is direct visual observation on standing estrus behavior, but various aids of estrus detection have been empolyed with varying degree of effectiveness. The results from heat detector devices are about as accurate as twice-daily observation(about 90%). The abnormal estrus can be classified into three types; irregular or continuous estrus, silent estrus and anestrus. Cystic ovarian disease, follicular cysts and luteal cysts, is a serious cause of reproductive failure in cattle and pig. The follicular cysts are much more common than luteal cysts and the incidence of ovarian cysts in dairy cattle is higher than beef cattle and pig. The occurrences of ovarian cysts have been closely associated with levels of milk production, stages of postpartum period, nutritional levels and seasons. The luteal cysts and persistent corpora lutea are responsive to the luteolytic effects of the recently synthetic analogues of PGF2$\alpha$ in cows and sows and recently GnRH or LH-RH has been successfully used as a treatment for cows and sows with ovarian follicular cysts.

• Korean Journal of Veterinary Research
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• v.24 no.1
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• pp.120-125
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• 1984

The study was carried out to find out the changes of hormone levels in blood serum and milk of Holstein cows during the estrous cycle. The progesterone, estradiol-$17{\beta}$ from the blood serum and milk samples were assayed by radioimmunoassay methods. The results of this study were summarized as follows; 1. The progesterone levels in blood serum during the estrous cycles began to decline rapidly at 2 days before estrus, decreased to $0.27{\pm}0.18ng/ml$ at on the day of estrus, and reached a peak mean level of $3.33{\pm}0.47ng/ml$ at 15 days after estrus. 2. The progesterone levels in milk during the estrous cycles began to decline rapidly at 2 days before estrus, decreased to $0.80{\pm}0.18ng/ml$ on the day of estrus, and increased a peak mean level of $3.80{\pm}0.36ng/ml$ at 15 days after estrus. 3. The estradiol-$17{\beta}$ levels in blood serum during the estrous cycles showed a peak mean level of $9.79{\pm}1.72pg/ml$ on the day of estrus, and decreased from $4.79{\pm}1.82pg/ml$ to $5.73{\pm}0.96pg/ml$ at luteal phase. 4. The estradiol-$17{\beta}$ levels in milk during the estrous cycles showed a peak mean level of $36.80{\pm}2.04pg/ml$ on the day of estrus, and decreased from $18.93{\pm}0.84pg/ml$ to $19.50{\pm}1.12pg/ml$ at luteal phase. 5. During 20 to 25 days after artificial insemination, the accuracy of pregnancy diagnosis from the blood serum progesterone levels were 87.5% for non pregnant cows (<2.0ng/ml), and 83.3% for pregnant cows ($${\geq_-}$$3.0 ng/ml). The accuracy of pregnancy diagnosis from the milk progesterone levels were 75.0% for non-pregnant cows (<2.4 ng/ml), and 94.4% for pregnant cows ($${\geq_-}$$3.2 ng/ml).

• Korean Journal of Animal Reproduction
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• v.15 no.1
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• pp.59-66
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• 1991

This study was carried out to investigate the length of the estrous cycle and duration of estrus in Korean native goats. The effects of the type of last estrus : induced or natural, and the length of preceeding estrous cycle on the subsequent cycle and duration of estrus in goats were also examined. From 481 observations, the mean length of estrous cycles was 18.1${\pm}$0.5days. The cycle length was significantly(P<0.05) shorter following induced estrus (15.2${\pm}$0.8 d) than natural estrus(19.0${\pm}$0.6 d). Significantly higher(P<0.05) incidence of short estrous cycle was observed following induced estrus(40%) than natural estrus(27%). The frequency distribution in the estrous cycle was 30%, 3%, 56% and 11% for short(3-11 d), medium(12-16 d), normal(17-24 d) and long(${\geqq}$25 d), respectively. The most frequent type of short estrous cycle was 6 days in length. Mean duration of estrus was 34.0${\pm}$0.5 h with a range of 18 to 84 h. Duration of estrus was not significantly different the preceeding natural (33.8${\pm}$0.6 h) and induced estrus (34.4${\pm}$1.1 h), and was not significantly affected by the last cycle length. These results suggest that the short estrus cycles are more frequent following induced estrus than natural one, and the duration of estrus are affected greatly by the various intrinsic and extrinsic factors.

• Korean Journal of Veterinary Research
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• v.32 no.2
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• pp.259-265
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• 1992

A study was conducted to improve the reproductive performance of Korean native goats. The length of estrous cycle and plasma progesterone concentrations during each cycles were determined by both radioimmunoassay and estrus behaviours, and the results were used in the early pregnancy diagnosis. The estrous cycles were classified into the short(l8 days or shorter, average 16.7 days), normal(19 to 22 days, average 20.9 days) and long(23 days and longer, average 23.8 days)cycle. The average length of the 19 estrous cycles was 20.8 days. Plasma progesterone concentrations in 12 normal cycles were the lowest(0.10 ng/ml) at estrus, remained high from 6 to 16 days(range : 4.43~7.93 ng/ml) and drastically decreased thereafter to reach minimal concentrations at the next estrus. Plasma progesterone concentrations were measured for early pregnancy diagnosis at 0, 10 and 20 days after mating in the 12 Korean native goats. Plasma progesterone concentrations in the pregnant goats at 20 days after mating were significantly higher than in the non-pregnant goats(p<0.001). Of the 12 goats, 10 were confirmed pregnancy by both progesterone concentrations and kidding. The accuracy of the pregnancy diagnosis based on plasma progesterone concentrations was 100% for positive as well as for negative.

• Korean Journal of Veterinary Research
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• v.39 no.3
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• pp.455-462
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• 1999

This study was designed to investigate the number of the growing and mature follicles in each stage of estrus cycle in mature rats. Eighteen mature rats(Sprague-Dawley, initially 190~230gm) were randomly alloted into 4 groups(proestrus, estrus, metestrus, and diestrus) according to estrus cycles. The uteri and ovaries of rats were collected and then alternative sections of paraffin embedding ovaries were stained with H-E. Numbers of large, middle and small follicles or only large and middle follicles from secondary and tertiary follicles were investigated by LM photography of preparations. Small follicles were defined as secondary follicles with 2~5 cell layers of granulosa cells surrounding the oocyte, and middle follicles were defined as secondary follicles with more than 5 cell layers or with early signs of antral cavity or with more than one small cleft on either side of the oocytes and large follicles were defined as tertiary follicles with a single medium or large antral cavity. The number of follicles in a pair ovary per rat was appeared to be ranged from 207 to 370 and the mean number of these follicles was $270.4{\pm}52.6$ and the mean number of follicles per ovary was $134.9{\pm}32.0$. The mean number of large, middle and small follicles per ovary was appeared to be $16.4{\pm}4.4$($12.2{\pm}3.3%$), $36.2{\pm}8.6$($26.8{\pm}6.4%$), and $82.7{\pm}24.0$($61.3{\pm}17.8%$), respectively. The mean number of large and middle follicles in each stage group of estrus cycle was appeared to be $17.8{\pm}2.1$ and $38.3{\pm}7.4$ at proestrus stage group, $15.7{\pm}5.2$ and $38.0{\pm}10.0$ at estrus stage group, $16.5{\pm}3.5$ and $33.8{\pm}7.0$ at metestrus stage group, $16.7{\pm}5.8$ and $29.7{\pm}5.5$ at diestrus group, respectively. In histological findings of large follicles during each estrus cycle, the large follicles in proestrus group contain single small antrum, thick granulosa cell layers, and were $300{\sim}500{\mu}m$ in diameter and were growing follicles with PCNA-positive cells in the granulosa cell layers, and other luteinizing follicles of proestrus cycle stage were decreased in size and were thicker in wall thickness and more luteinized than those in metestrus and diestrus stage groups. The large follicles in estrus stage group contain thick granulosa cell layers and nonprominent cumulus-oocyte complexes in antrum, and were $400{\sim}700{\mu}m$ in diameter and were growing follicles with PCNA-positive cells in the granulosa cell layers. The large follicles in metestrus and diestrus stage groups contain enlarged antrums, thinner layers of walls and prominent cumulus-oocyte complexes, and were $700-950{\mu}m$ in diameter, and were nongrowing follicles without PCNA-positive cells or another large follicles contain cells with dark stainability and distinct boundary.

• Korean Journal of Animal Reproduction
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• v.14 no.3
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• pp.175-182
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• 1990

Behavioural estrus and short estrous cycles were observed and serum concentrations of estradiol-17$\beta$(E2) before and after of estrous were measured following superovulation treatments in 30 pluriparous Korean native goats. The goats were divided into 2 groups. Fifteen goats were injected IM with 1,000IU PMSG on Day 12 of the estrous cycle followed by 10mg PGF2$\alpha$ 48h later(P4＋PMSG), and the other 15 goats were injected IM with 10mg progesterone(P4)in oil once daily for 10d beginning at any days of estrous cycle followed by 1,000IU PMSG and 10mg PGF2$\alpha$ at the 8th day of progesterone treatment(P4＋PMSG group). After injection of PGF2$\alpha$, onset of standing estrus occurred in 12 of 15 goats(80.0%) at 50.0$\pm$7.7h and in 11 of 15 goats(73.3%) at 135.6$\pm$10.1h in PMSG and group and P4＋PMSG group, respectively. The mean interval from PGF2$\alpha$ injection to first estrus was significantly(P<0.01) earlier in PMSG group than in P4＋PMSG group. This result indicate that the delayed infusion of P4 in P4＋PMSG group caused the later exhibition of their estrous behaviors. However, duration fo frist estrus(31.5$\pm$2.6h vs 26.2$\pm$2.3h), length of estrous cycle(14.1$\pm$3.3d vs 16.6$\pm$3.8d) and percentage of short estrous cycle(50.0% vs 45.5%) were not different between PMSG and P4＋PMSG group. The mean concentration of serum E2 in 4 goats showing normal estrous cycle in P4＋PMSG group(PP-NEC) was higher than in 6 goats showing normal(P-NEC) or in 6 goats showing short estrous cycle(P-SEC) in PMSG group. The peak level of serum E2 was observed at the time of onset of standing estrus in PP-NEC(67.6pg/ml), 6h earlier in P-NEC(53.1pg/ml) and 6h later in P-SEC(52.3pg/ml) than the onset of standing estrus. The profiles of serum concentration of E2 during the period of peri-estrus was similar in the goats of PMSG or P4＋PMSG and also in the goats showing the subsequent estrous cycle of normal or short length.

• Journal of Embryo Transfer
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• v.24 no.3
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• pp.131-137
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• 2009

In dogs, correct diagnosis of estrus is important and the exact time of ovulation can be determined by variouse methods. Vaginal cytology has commonly used in conjunction with the physical examination, clinical history, vaginoscopy, and hormonal assays to determine the stage of the reproductive cycle. This study was therefore investigated the effectiveness of direct ovulation detector designed by changes of electrical resistance in vaginal mucus following different estrus cycles with several methods; vaginal cytology, concentration of plasma estrogen and progesterone, and direct examination by laparotomy. A total of 12 bitches was selected for the study and observed estrus signs. The bitches were evaluated clinical sign (vulvar swelling and bleeding), cytological examination (keratocyte and RBC), electrical resistance, plasma estrogen and progesterone concentration for estrus assessment. Accuracy of ovulation detection by vaginal cytology was significantly (p<0.05) lower than those by electrical resistance and plasma progesterone concentration, based on the confirmation by laparotomy. Vaginal smear is not confidential method compared to detection of electrical resistance and plasma progesterone concentration at ovulation. Although the value of electrical resistance was varied at the same points of estrus in individuals, ovulation was occurred at the first day which shown the peak of electrical resistance and mating time was third day after peak. In conclusion, ovulation detector designed by changes of electrical resistance is an effective and economic instrument for predicting estrus and ovulation in bitches.

• Journal of Veterinary Clinics
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• v.9 no.1
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• pp.323-332
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• 1992

The present study was carried out to examine the effect of oviduct epithelium and its conditioned medium on e development of early bovine embryos in vitro. Oocytes obtained from ovarian follicles of slaughtered cows were cultured in TCM199 with 10% fetal calf serum for 22-24hrs and then fertillzed in vitro using frozen-thawed semen treated with BO-caffein, BO-BSA(20mM heparin added). Oviduct epithelium was collected in each stage of the estrus cycle and conditioned medium was the medium in which oviduct epithelium in early luteal stage was cultured. In vitro fertilized bovine embryos of 1～2 cell were co-cultured with oviduct epithelium from different estrus cycles, cultured in conditioned medium, and cultured in rabbit oviduct. The cleavage rates of in vitro fertilized early bovine embryos co-cultured with oviduct epithelial cell from early luteal, luteal and follicular phase of estrus cycle(67.2～70.8%) and cultured in conditioned medium(56.7%) were significantly(p<0.05) higher than that of the control(44.2%) The rate of development to morula or blastocyst stage in oviduct epithelial cell co-culture(15.3～32.5%) from three phase of estrus cycles and conditioned medium(14.5%) were significantly(p<0.05) higher than that of the control(5.2%). The oviduct epithelial cell from early luteal phase gave a significantly( p<0.05) higher rate of development to morula or blastocyst stage than both luteal and follicular phase. The results of in vivo culture in rabbit oviduct of early bovine embryos were 52.1% for the cleavage rate and 26.7% for the rate of development to morula or blastocyst stage.

• Korean Journal of Animal Reproduction
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• v.16 no.3
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• pp.225-230
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• 1992

Many transgenic mice expressing human growth hormone gene were infertile. To investigate the infertility of these transfenic mice, it was looked into the estrus cycle and sexual behaviour and also tested through in vitro fertilization whether the germ cells of these mice normal or not. The infertile female transgenic mice were mated to the fertile males of ICR strain, but in almost all of them the vaginal plugs were not detected and their estrus cycles by vaginal smear were almost irregular which kept up estrus or diestrus stage. Many male transgenic mice did not have the ability of sexual behaviour. Therefore the viability of germ cells in infertile male transgenic mice was investigated by in vitro fertilization, but the sperm were normally fertilized with the eggs and the transgene of parent was passed on to the progeny. These results consequently suggest that the infertility of transgenic mice experssing human growth hormone gene may be due to the physiological activity of human growth hormone, not germ cells.

• Journal of Animal Reproduction and Biotechnology
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• v.36 no.4
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• pp.230-238
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• 2021

This study attempted to determine the characteristic features of postpartum dairy cows during their return to estrus. Moreover, it investigated the effects of abnormal ovarian cycles (AOC) on subsequent reproductive performance and the relationship between normal ovarian cycles (NOC) and the blood urea nitrogen (BUN) level postpartum. Incidentally, 56.3% of the Holstein cows and 66.7% of the Jersey cows had NOC, whereas the 43.7% and 33.3% of the Holstein and Jersey, respectively, had AOC. Within 100 days of calving, the cows with AOC had significantly lower rates of artificial insemination (AI) submission as well as pregnancy and a significantly longer interval to first AI, as compared to that in the cows with NOC. Additionally, the cows with NOC had a significantly higher first AI conception rate than that in the cows with AOC. In this study, of the 32 Holstein cows, 8 resumed their ovarian cycle within 20 days of calving, 10 resumed the cycle with 21-40 days of calving, 8 within 41-60 days of calving, while the remaining 6 did not resume their ovarian cycles until 60 days postpartum. Furthermore, the likelihood ratios of incidence of NOC are 0.93, 1.94, and 0.38, respectively, in the groups with BUN levels < 15, 15-19.9, and ≥ 20 mg/dl. In conclusion, AOC postpartum adversely affects reproductive performance such as AI submission rate, pregnancy rate, interval to first AI and first AI conception rate; moreover, an increase or decrease in the BUN levels beyond 15-19.9 mg/dL leads to the AOC postpartum.