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Yamaguchi-shi, Japan

Yamashita Y.,Prefectural University of Hiroshima | Okamoto M.,Laboratory of Theriogenology | Kawashima I.,Hiroshima University | Okazaki T.,Livestock Research Institute | And 5 more authors.
Biology of Reproduction | Year: 2011

During in vitro maturation of porcine cumulus-oocyte complexes (COCs), follicle-stimulating hormone (FSH) increases both prostaglandin E2 (PGE2) production and the expression levels of EGF-like factors. The ligands act on cumulus cells by the autocrine system due to their specific receptors, EP2, EP4, or EGF receptor. When each pathway is suppressed by inhibitors, complete cumulus expansion and oocyte maturation do not occur. In this study, we examined the relationship between both of these pathways in cumulus cells of porcine COCs. When COCs were cultured with FSH, Fshr mRNA expression was immediately decreased within 5 h, whereas Ptger2, Ptger4, and Ptgs2 expression levels were significantly increased in cumulus cells in the culture containing FSH for 5 or 10 h. The PTGS2 inhibitor NS398 significantly suppressed not only PGE2 secretion at any culture time point but also Areg, Ereg, and Tace/Adam17 expression in cumulus cells at 10 and 20 h but not at 1 or 5 h. During the early culture period, phosphorylation of MAPK3 and MAPK1 (MAPK3/1) was not affected by NS398; however, at 10 and 20 h, phosphorylation was suppressed by the drug. Furthermore, down-regulations of MAPK3/1 phosphorylation and expression of the target genes by NS398 was overcome by the addition of either PGE2 or EGF. FSH-induced cumulus expansion and meiotic progression to the MII stage were also suppressed by NS398, whereas these effects were also overcome by addition of either PGE2 or EGF. These results indicated that PGE2 is involved in the sustainable activation of MAPK3/1 in cumulus cells via the induction of EGF-like factor, which is required for cumulus expansion and meiotic maturation of porcine COCs. © 2011 by the Society for the Study of Reproduction, Inc. Source

Gautam G.,Laboratory of Theriogenology | Nakao T.,Laboratory of Theriogenology | Yamada K.,Nemuro Chiku Shebetsu Large Animal Medical Center | Yoshida C.,Laboratory of Theriogenology
Theriogenology | Year: 2010

The objectives of this study were to derive a useful case definition of delayed resumption of ovarian activity, based on factors associated with reduced fertility, and to assess its impact on subsequent reproductive performance in Holstein cows (Bos taurus). Milk samples were collected twice weekly from 219 cows from four commercial herds, and whole-milk progesterone concentrations were determined with an enzyme-linked immunosorbent assay. Ovulation was considered to have occurred 5 d before the first rise of milk progesterone concentration above the basal level. Survival analysis was used to derive a case definition of delayed resumption of ovarian activity postpartum based on factors that were predictive of reduced pregnancy rate. First postpartum ovulation occurring beyond 35 d postpartum was associated with a reduced pregnancy rate (hazard ratio [HR] = 0.50; P < 0.001) and was defined as delayed resumption of ovarian activity; overall, 75 (34.9%) cows were in this category. These cows were more likely not to conceive on first artificial insemination (odds ratio [OR] = 2.85; P = 0.01) and more likely not to become pregnant within 100 d (OR = 3.30; P = 0.001) and 210 d (OR = 3.20; P < 0.001) postpartum compared with cows with normal resumption of ovarian activity. Furthermore, 13 (6%) cows that ovulated within 35 d postpartum had a prolonged (≥14 d) interval between either first and second or second and third luteal phases postpartum. A prolonged interluteal interval was also associated with a reduced pregnancy rate (HR = 0.35; P = 0.02). Days open (mean ± SEM) were greater (P = 0.0002) in cows with delayed resumption of ovarian activity (213 ± 13 d) and in cows with prolonged interluteal interval (220 ± 37 d) than in cows with normal resumption of ovarian activity (152 ± 9 d). In conclusion, first ovulation occurring beyond 35 d postpartum was defined as delayed resumption of ovarian activity, and the first ovulation occurring within 35 d postpartum but the absence of luteal activity ≥14 d between two consecutive luteal phases was defined as a prolonged interluteal interval; both abnormalities adversely affected the subsequent reproductive performance of Holstein cows. © 2010 Elsevier Inc. All rights reserved. Source

Ranasinghe R.M.S.B.K.,Laboratory of Theriogenology | Nakao T.,Laboratory of Theriogenology | Yamada K.,Nemuro NOSAI Shibetsu Large Animal Clinic | Koike K.,Laboratory of Theriogenology
Theriogenology | Year: 2010

The objectives of the current study were to determine the incidence of silent ovulation (based on walking activity and milk progesterone profiles), identify risk factors for silent ovulation, and investigate its impact on reproductive performance in high-yielding dairy cows in free-stall housing. Overall, 277 lactations in 161 Holstein Friesian cows from a commercial dairy herd in northern Japan were studied. Walking activity (measured with pedometers) >80% above the mean for the preceding 2 d was defined as estrus, whereas day of ovulation was estimated using milk progesterone concentrations. Ovulation not preceded by increased walking activity was considered silent ovulation; the incidence was 55.2%, 23.8%, 21.3%, and 10.5% at the first, second, third, and fourth ovulations postpartum, respectively. Moderate and high milk yield significantly increased the risk of silent ovulation at second (odds ratio [OR] = 2.7 and 1.2; P = 0.04) and third and/or fourth ovulations (OR = 6.7 and 12.9; P = 0.03). Based on survival analysis, silent ovulations at the first, second, third, and/or fourth ovulations were associated with 28% (hazard ratio [HR] = 0.72), 55% (HR = 0.45), and 47% (HR = 0.53) reductions in pregnancy rate, respectively, and 41% (HR = 0.59), 66% (HR = 0.34), and 65% (HR = 0.35) reductions in artificial insemination (AI) submission rate. Cows with at least one silent ovulation (with the exception of the first ovulation) had a longer interval from calving to first AI (72 vs. 54 d, P < 0.001) and to achievement of pregnancy (133 vs. 80 d, P < 0.001). In conclusion, approximately one third of the ovulations (based on milk progesterone concentrations) in Holstein cows within 90 d postpartum were silent. Silent ovulations at the second to fourth ovulations were associated with high milk yields and at all ovulations were associated with impaired reproductive performance. © 2010 Elsevier Inc. All rights reserved. Source

Gautam G.,Laboratory of Theriogenology | Nakao T.,Laboratory of Theriogenology | Koike K.,Laboratory of Theriogenology | Long S.T.,Laboratory of Theriogenology | And 3 more authors.
Theriogenology | Year: 2010

It has been stated that postpartum endometritis in dairy cows has a tendency to cure without intervention. The objectives of this field study, therefore, were to determine the proportions of cows with spontaneous clinical recovery or persistence of postpartum endometritis and to determine some risk factors for its persistency in dairy cows (Bos taurus). Holstein-Friesian cows (n = 441 lactations) from seven dairy herds were examined monthly by vaginoscopy and transrectal palpation. A cow was considered to have "postpartum endometritis" if it had pus in the cervico-vaginal discharge at the first postpartum examination during Days 15 to 60 (Day 0 = day of calving); this was classified as mild, mucopurulent, or purulent endometritis, or endometritis with fluid in uterus. Furthermore, a cow with evidence of endometritis at least once during Days 61 to 150 was considered to have "persistence (or recurrence) of endometritis." A total of 104 (23.6%) lactations had postpartum endometritis, of which 25.3% had persistence or recurrence of clinical endometritis. Cows with persistence or recurrence of endometritis became pregnant at a slower rate (hazard ratio [HR] = 0.28; P < 0.001) than those with no endometritis until Day 150. Calving in summer (odds ratio [OR] = 7.00; P = 0.04), early postpartum complications (OR = 6.58; P = 0.05), moderate (OR = 4.03; P = 0.08) and severe (OR = 30.99; P = 004) degrees of urovagina, and mucopurulent (OR = 9.54; P = 0.02) and purulent (OR = 5.70; P = 0.04) endometritis were risk factors for the persistence or recurrence of endometritis. Furthermore, 10.6% of cows that had not shown signs of postpartum endometritis had a new diagnosis of endometritis during Days 61 to 150. Some risk factors for the new diagnosis of endometritis beyond Day 60 were early postpartum complications (OR = 2.82; P = 0.03) and moderate (OR = 5.00; P = 0.001) or severe (OR = 12.63; P < 0.001) degrees of urovagina. In conclusion, approximately one quarter of cows with postpartum endometritis had persistence of endometritis until or beyond the breeding period. Risk factors for the persistence of clinical endometritis were summer calving, early postpartum complications, clinically relevant urovagina, and clinically relevant endometritis within 2 mo postpartum. © 2010 Elsevier Inc. All rights reserved. Source

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