• Journal of Animal Reproduction and Biotechnology
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• v.35 no.2
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• pp.171-176
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• 2020

Advancing the estrous cycle of mares is an essential breeding strategy that is routinely conducted by Thoroughbred breeders to improve economic outcomes. For this purpose, Equilume light masks have been developed as an alternative to existing technologies such as artificial lighting or hormonal treatments because they are considered as valid as existing methods with additional animal welfare advantages. For example, with the Equilume light masks, horses can be let out into the pasture, whereas they have to be kept indoors during lighting treatment. Because the function of Equilume light mask on the estrous cycle of mares is influenced by environmental factors such as nutrition condition and temperature, Equilume light mask should be studied in various environments. The objective of the present study was thus to verify the effect of Equilume light masks on the onset of the estrous cycle in Thoroughbred mares in South Korea. Mares were randomly selected and separated into two groups at two Thoroughbred horse breeding farms. The mares in the treatment group were equipped with Equilume light masks from November 18 to February 10 the following year. The body condition, the number and size (> 35 mm) of uterine follicles, and the uterine horn score of the mares were assessed on January 6 and February 10. The body condition scores were not different between the two groups. The treatment with the Equilume light mask had no positive effects on developing follicles and the reproductive tract. In conclusion, the use of Equilume light masks did not influence the seasonal resumption of the estrus cycles in Thoroughbred mares in South Korea.

• Journal of Veterinary Clinics
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• v.33 no.4
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• pp.200-204
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• 2016

This study investigated whether presynchronization with GnRH 6 days before initiation of the Ovsynch program improved reproductive outcomes in dairy cows. Additionally, postponement of initiation of the Ovsynch program for cows during the metestrus phase by 5 days was investigated to determine if it improved reproductive outcomes. To accomplish this, 941 Holstein dairy cows with unknown estrous cycle were randomly allocated into an Ovsynch group (n = 768; $100{\mu}g$ gonadorelin [a GnRH analogue], $500{\mu}g$ of cloprostenol [$PGF_{2{\alpha}}$ analogue] seven days later, $100{\mu}g$ gonadorelin 56 h later and timed artificial insemination [AI] 16 h after) and a G6-Ovsynch (n = 173) that received $100{\mu}g$ GnRH followed by the Ovsynch program 6 days later. Additionally, 272 dairy cows with known estrous cycle (metestrus stage) received the Ovsynch 5 days later (Day 5-Ovsynch group, n = 272). The odds ratio (OR) for pregnancy was analyzed by logistic regression using the LOGISTIC procedure in SAS. The treatment group (p < 0.001) and AI season (p < 0.05) significantly affected the probability of pregnancy, whereas farm, cow parity, calving to AI interval, and body condition score had no affect (p > 0.05). The Day 5-Ovsynch group had a higher probability of pregnancy (OR: 1.71) than the Ovsynch group, while that of the G6-Ovsynch group was intermediate (p > 0.05). Cows inseminated during winter had a higher OR (1.39) than those inseminated during spring. Overall, additional GnRH treatment 6 days before the Ovsynch did not improve reproductive outcomes, whereas postponement of the initiation of Ovsynch by 5 days for cows during metestrus improved reproductive outcomes.

• Korean Journal of Veterinary Research
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• v.31 no.4
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• pp.529-534
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• 1991

Plasma progesterone concentrations were measured from 97 Che-ju native mares throughout the estrous cycle, Day 20 to 23, 5 to7 months of pregnancy, and gestation period (<1 to 7 months) using the radioimmunoassay techniques for pregnancy diagnosis. Plasma progesterone concentrations during the estrous cycle were the lowest (<1.0ng/ml) at estrus, remained high from 9 to 18 days (3.7~7.6ng/ml) and drastically decreased thereafter to reach minimal concentrations at the next estrus. Plasma progesterone concentrations at Day 21 to 24 were a significantly different between in pregnant mares (>5.7ng/ml) and in non-pregnant mares (<1.0ng/ml). The accuracy of the pregnancy diagnosis based on plasma progesterone concentrations at Day 20 to 23 was 86.7% for positive and 100% for negative, whereas on 5 to 7 months was 66.7% for positive and 71.0% for negative, respectively. Plasma progesterone concentrations during the gestation period(1 to 7 months) increased after 1 month of pregnancy, with peak concentrations(>8.0ng/ml) occurring between 60 to 100 days of pregnancy, and decreased below 1.7ng/ml after 6 months of pregnancy.

• Asian-Australasian Journal of Animal Sciences
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• v.21 no.1
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• pp.35-41
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• 2008

This study was undertaken to investigate the distribution of major histocompatibility complex class II positive (MHC II+) (HLA-DP-like) cells in the cow uterus (cervix, corpus and cornu uteri) and to compare these cells between the estrus and diestrus phases of the estrous cycle. Twenty-nine multiparous cows were used. Tissue samples from the middle of the cervix, the corpus and the right cornu were taken immediately after slaughter at the estrus or diestrus phase. Streptavidin-biotin peroxidase complex staining was used to detect MHC II+ cells. The number of MHC II+ cells per unit area of tissue was counted using image analysis software under a light microscope. Numerous MHC II+ cells were found in the endometrium (cervix, corpus and cornu uteri) in both estrus and diestrus. MHC II+ cells were found in the surface epithelium of the cervix uteri in diestrus, but in the corpus uteri in both estrus and diestrus and in the cornu uteri in estrus. MHC II+ cells were also found freely in the lumen of the glands and between the gland epithelia of the corpus and cornu uteri in both estrus and diestrus. There were also MHC II+ cells in the connective tissue of the myometrium and perimetrium (outside the endometrium) and around the blood vessels. Endothelial cells were frequently positive for MHC II staining. More MHC II+ cells were found in the endometrium than outside the endometrium in both estrus and diestrus (p<0.001). However, there was no difference in the numbers of positive cells between estrus and diestrus either in the endometrium or outside it. These results are the first evidence for HLA-DP-like MHC II+ cells in the bovine uterus. They indicate that antigen presentation by HLA-DP-like MHC II+ cells of the uterus is not influenced by hormonal status.

• Reproductive and Developmental Biology
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• v.33 no.4
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• pp.203-209
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• 2009

The present study was performed to identify changes of plasminogen activator (PA) and plasminogen activator inhibitor (PAI) in porcine oviduct epithelial cells (POECs) during the estrous cycle. POECs obtained from ovary in pre-ovulatory (Pre-Ov), early to mid-luteal stage (Early-mid L) and post-ovulatory stage (Post-Ov). For the examine of PA activity, $1{\times}10^5$ fresh cells of POECs were cultured in DMEM/Ham F-12 containing 10% FBS and 0.2% amphotericin under humidified atmosphere of 5% $CO_2$ in air and $38^{\circ}C$. The urokinase-type PA (uPA) was observed at 7 days of POECs culture. PA activity was measured with culture prolonged of 0, 3, 6, 12 and 24 h after culture of 7 days. The PA activity were high significantly (p<0.05) at 12 h of culture, but PA activity were decreased with culture periods increased. The PA activity in POECs of Post-Ov stage were higher significantly (p<0.05) than that of Early-mid L and Pre-Ov stage. When PAI-1 and PAI-2 were added during the POECs culture, the PA were observed significant low activity (p<0.05). The PA activity and protein expression were decreased by PA inhibitor. This results suggest that PAI-1 and PAI-2 have a suppressive action on change of PA activity during the estrous cycle of pigs. Specifically, this study using PA inhibitor was effect the PA activity and PAI expression in oviduct epithelial cells in pigs.

• Journal of Veterinary Clinics
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• v.20 no.3
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• pp.384-388
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• 2003

To establish the method of estrus induction using the injection of PGF$_2$$\alpha$ㆍ the 60 dairy cows treated by PGF$_2$$\alpha$ㆍ at 6, 8, 10, 12, 14, and 16 day of estrous cycle, recpectively. The plasma progesterone concentrations at day of injection of PGF$_2$$\alpha$ㆍ were $1.5\pm$1.3 (mean$\pm$SD) ng/ml at 6 days of estrous cycle, 3.7$\pm$1.4 ng/ml at 8 days, 6.5$\pm$1.8 ng/ml at 10 days, 7.9$\pm$2.0 ng/ml at 12 days, 6.5$\pm$2.5 ng/ml at 14 days, and 2.5$\pm$1.2 ng/m] at 16 days, respectively. The percentages of induction of estrus after PGF$_2$$\alpha$ㆍ treatment were 52.8% at 3th day after treatment, 21.7% at 4th day, 8.3% within 2th day, and ] 7.2% after 5th day, respectively. The percentages of cows conceived at first service after induction of estrus were 73.3% on 16 days of estrous cycle at treatment, 66.7% on 10 and 14 days, 63.3% on 8 and 12 days, and 53.3% on 6 day, respectively. The percentages of cows conceived on first service were 70.5% at 3th day after induction, 66.7% at 4th day and 65% at 5th day, respectively. These results suggest that the PGF$_2$$\alpha$ㆍ treatment at regressing stage of corpus luteum showed high induction of estrus and pregnancy rate, and there were high induction of estrus and pregnancy rate at 3th and 4th day after PGF$_2$$\alpha$ㆍ treatment.

• Journal of Embryo Transfer
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• v.31 no.1
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• pp.53-59
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• 2016

This study was to investigate effect of progesterone ($P_4$) on prostaglandin (PG) synthases and plasminogen activators (PAs) system in bovine endometrium during estrous cycle. Endometrium tissues were collected from bovine uterus on follicular and luteal phase and were incubated with culture medium containing 0 (Control), 0.2, 2, 20 and 200 ng/ml $P_4$ for 24 h. The $PGF_{2{\alpha}}$ synthase (PGFS), $PGE_2$ synthase (PGES), cyclooxygenase-2 (COX-2), urokinase PA (uPA), and PA inhibitors 1 (PAI-1) mRNA in bovine endometrium were analyzed using reverse transcription PCR and PA activity was measured using spectrophotometry. In results, COX-2 was higher at 2 ng/ml $P_4$ group than control group in luteal phase (p<0.05), but, it did not change in follicular phase. Contrastively, PGES was significantly increased in 2 ng/ml $P_4$ group compared to control group in follicular phase, but there were no significant differ among the treatments in luteal phase. uPA was no significant difference between $P_4$ treatment groups and control group in both of different phase. PAI-1 was decreased in 20 ng/ml $P_4$ group compared to control group in follicular phase (p<0.05). PA activity was decreased in 2 ng/ml $P_4$ group compared to other groups in follicular and luteal phase (p<0.05). In conclusion, we suggest that $P_4$ may influence to translation and post-translation process of PG production and PA activation in bovine endometrium.

• Asian-Australasian Journal of Animal Sciences
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• v.32 no.9
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• pp.1355-1362
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• 2019

Objective: S100A7A, a member of the S100 protein family, is involved in various biological processes, including innate immunity, antimicrobial function, and epithelial tumorigenesis. However, the expression and function of S100A7A in the endometrium during the estrous cycle and pregnancy are not well understood in pigs. Therefore, this study determined the expression and regulation of S100A7A at the maternal-conceptus interface in pigs. Methods: We obtained endometrial tissues from pigs throughout the estrous cycle and pregnancy, conceptus tissues during early pregnancy, and chorioallantoic tissues during midto late pregnancy and analyzed the expression of S100A7A in these tissues. We also determined the effects of steroid hormones, estradiol-$17{\beta}$ ($E_2$) and progesterone, and interleukin-$1{\beta}$ (IL1B) on S100A7A expression in endometrial tissues. Results: We found that S100A7A was expressed in the endometrium during the estrous cycle and pregnancy in a pregnancy status- and stage-dependent manner and was localized to endometrial luminal epithelial (LE) and superficial glandular epithelial cells with strong intensity in LE cells on day 12 of pregnancy. Early stage conceptuses and chorioallantoic tissues from day 30 to term pregnancy also expressed S100A7A. The expression of S100A7A was increased by $E_2$ and IL1B in endometrial tissues. Conclusion: S100A7A was expressed at the maternal-conceptus interface at the initiation of implantation in response to conceptus-derived estrogen and IL1B and could be a unique endometrial epithelial marker for conceptus implantation in pigs. These findings provide an important insight into the understanding of conceptus-endometrial interactions for the successful establishment of pregnancy in pigs.

• Journal of Embryo Transfer
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• v.32 no.3
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• pp.165-170
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• 2017

Pigs have been extensively used as mediators of xenotransplantation research. Specifically, the Massachusetts General Hospital (MGH) miniature pig was developed to fix major histocompatibility antigens for use in xenotransplantation studies. We generated transgenic pigs for xenotransplantation using MGH pigs. However, it has not been studied yet whether these pigs show similarity of reproductive physiological characteristics to wild types of MGH miniature pig. In this study we analyzed the estrous cycles and pregnancy characteristics of wild type (WT) and transgenic MGH miniature pigs, which were ${\alpha}1,3$-galactosyltransferase (GalT) heterozygous and homozygous knock-out, and membrane cofactor protein (MCP) inserted in its locus, $GalT^{-MCP/+}$ and $GalT^{-MCP/-MCP}$ pigs. Estrous cycles of WT, $GalT^{-MCP/+}$ and $GalT^{-MCP/-MCP}$ pigs were $20.9{\pm}0.74$, $20.1{\pm}1.26$, and $17.3{\pm}0.87days$, respectively, and periods of estrous were $3.2{\pm}0.10$, $3.1{\pm}0.12$, and $3.1{\pm}0.11days$. The periods of gestation of WT, $GalT^{-MCP/+}$ and $GalT^{-MCP/-MCP}$ pigs were $114.2{\pm}0.37$, $113.3{\pm}0.67$, and $115.4{\pm}0.51days$, respectively. Litter sizes of WT, $GalT^{-MCP/+}$ and $GalT^{-MCP/-MCP}$ pigs were $4.8{\pm}0.35$, $4.8{\pm}1.11$ and $3.0{\pm}0.32$ respectively. There were no significant differences on estrous cycle, periods of estrous and gestation, and litter size among WT, $GalT^{-MCP/+}$ and $GalT^{-MCP/-MCP}$ pigs, meaning that GalT knock-out and additional expression MCP of the MGH miniature pig did not effect on reproduction traits. These results provide relevant information to establish breeding system for MGH transgenic pig, and for propagation of $GalT^{-MCP/-MCP}$ pig to supply for xenotransplantation research.

• 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).