論文 - 大澤 健司
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Association of inflammatory cytokine profiles in the cervical mucus with the mode of calving ease after induction of parturition in overdue cows 査読あり
Takuto Hashiguchi, Go Kitahara, Kazuyuki Kanemaru, Mizuho Uematsu, Takeshi Osawa
Animal 2025年12月
担当区分：最終著者, 責任著者 記述言語：英語 掲載種別：研究論文（学術雑誌）
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Dynamics of macrophages and inflammatory cytokine concentrations in the cervix of late pregnant cows 査読あり
Kanemaru K., Kitahara G., Hashiguchi T., Hemmi K., Kobayashi I., Osawa T.
Theriogenology 238 117357 2025年2月
担当区分：最終著者, 責任著者 記述言語：英語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Theriogenology
Cervical ripening is associated with M1 macrophages and inflammatory cytokines in mice and rats, but its mechanism in cattle is unclear. In this study, to elucidate some of the mechanisms of normal cervical maturation in cows, we examined the expressions of M1 macrophages and mRNA of interleukin (IL)-1α, 1β, 6, 8, and 10, as well as TNFα in cervical tissue and the mRNA expressions and protein concentrations of these cytokines in cervical mucus from late pregnancy to parturition. Forty-one Japanese Black cows were sampled at 200, 230, and 260 d of gestation and then at 7 d intervals until parturition to obtain cervical mucus and tissue samples. The collected tissues were fluorescently immunostained with anti-Iba-1 antibodies, and the macrophage infiltration was checked. Cervical mucus was mixed with PBS, the concentrations of the above cytokines in the supernatant after centrifugation were measured, and the concentration per protein weight was used as the measurement. Total RNA was extracted from the cervical tissue and mucus, and the mRNA expression of various cytokines was analyzed using real-time PCR. In cervical tissue, macrophages stained with anti-Iba-1 antibody were observed from five to six weeks before calving until the week of calving. There was also a trend toward a concurrent increase in the mRNA expression of inflammatory cytokines, especially IL-6, three weeks before calving (P < 0.05). In cervical mucus, the concentrations of IL-1α, IL-1β, IL-8, and TNFα increased (P < 0.05) zero to three weeks before calving compared to 12–14 weeks before calving. In addition, IL-1α mRNA increased three weeks before and during the week of parturition, and IL-8 mRNA increased three weeks before and two weeks after (P < 0.05). These results suggest that cervical ripening in cows begins five to six weeks before calving when macrophages infiltrating cervical tissue may produce large amounts of IL-6, inflammatory cells infiltrate cervical mucus, and IL-1α, IL-1β, IL-8, and TNFα levels in the mucus increase toward calving.
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Profile of uterine flush lipid mediators in cows with subclinical endometritis: pilot study. 査読あり
Maehara T, Osawa T, Kitahara G, Satoh H, Murata T
The Journal of veterinary medical science advpub ( 0 ) 2024年3月
記述言語：英語 掲載種別：研究論文（学術雑誌） 出版者・発行元：公益社団法人 日本獣医学会
Subclinical endometritis affects reproductive outcomes and causes economic losses in dairy cows, thus, it is important to understand disease progression mechanisms and develop diagnostic procedures for better disease management. We measured the levels of 146 lipid mediators in uterine flush samples using lipid chromatography-mass spectrometry. We detected 25 lipid mediators in the uterine flush of both the control and subclinical endometritis cows; 15 of the 25 lipid mediators were AA-derived metabolites. Among the AA-derived metabolites, cyclooxygenase (COX)-generated mediators were the most abundant. Specifically, levels of 11β-13,14-dihydro-15-keto prostaglandin (PG)F<sub>2α</sub>, PGE<sub>2</sub>, PGA<sub>2</sub>, 13-hydroxyoctadecadienoic acid, and PGD<sub>1</sub> were elevated in all the cows with subclinical endometritis. This study may provide new insights for the management of subclinical bovine endometritis.
DOI： 10.1292/jvms.23-0450
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Misaka M., Uematsu M., Hashimoto K., Kitahara G., Osawa T., Sasaki Y.
Preventive Veterinary Medicine 207 105716 2022年10月
記述言語：英語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Preventive Veterinary Medicine
Calf mortality severely affects productivity in the beef industry. The present study was conducted to assess the calf mortality risk (CMR) in Japanese Black calves and investigate potential associations between calf/cow information and the CMR. Records for calves born between April 2006 and March 2010 were extracted from an existing database, which included production data on commercial cow-calf operations in Miyazaki, Japan. The study group comprised 40,462 calves born to 15,600 cows on 908 farms. Because calves on the studied farms were weaned at approximately 4 months of age, the calf records were collected from birth to 120 days. The CMR was calculated as the number of dead calves divided by the number of surviving calves. Mixed-effect multivariable logistic regression modeling was used to determine potential associations between the CMR and the factors hypothesized to influence that risk. CMR analyses were performed separately for the following production stages: days 0–30, days 31–60, days 61–90 and days 91–120 after birth. Of the 40,462 calves, 1465 died during days 0–120 after birth, and the CMR was 3.6 %. Of the 1465 dead calves, 35.9 % died within 10 days after birth. During the 0–30-day period, the CMR was associated with dam parity, calving status, gestation length, sex, birth season and twin births (P < 0.05), but not with the number of inseminations to conception. Low parity, dystocia, gestation lengths < 280 days and > 301 days, male calves, calves born in autumn and winter and twin births yielded higher CMRs. Low dam parity also yielded higher CMRs during the 31–60-day, 61–90-day and 91–120-day periods (P < 0.05), but no other factors were associated with the CMR during these periods. Thus, various cow and calf factors were shown to be associated with CMRs in Japanese Black calves, and calves with these factors should be considered high-risk calves.
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Inflammatory changes and composition of collagen during cervical ripening in cows 査読あり
Yamanokuchi E., Kitahara G., Kanemaru K., Hemmi K., Kobayashi I., Yamaguchi R., Osawa T.
Animals 12 ( 19 ) 2022年10月
担当区分：最終著者, 責任著者 記述言語：英語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Animals
Dystocia and stillbirths in cows pose a high risk of loss of both dams and fetuses, thereby resulting in high economic losses. One of the causes of these problems is birth canal abnormalities. Thus, to prevent these occurrences, it is necessary to understand the mechanisms underlying cervical ripening. Although physiological inflammatory responses and changes in collagen composition have been reported in humans and mice, related information is scarce for cows. We observed inflammatory changes and changes in the collagen composition in the cervix from late pregnancy to parturition to clarify some of the physiological changes associated with cervical ripening during normal calving in cows. Cervical mucus and tissue samples were collected from 41 Japanese Black cows at 200, 230, and 260 days of gestation and at 7-day intervals thereafter until parturition. The percentage of polymorphonuclear neutrophils (PMN%) in the mucus was calculated, and interleukin (IL)-8 concentration was determined by enzyme-linked immunosorbent assay. Blood samples were collected from the jugular vein, and leukocyte counts were determined. Picrosirius red-stained cervical tissue specimens were observed under a polarizing microscope, and the percentage of type I and type III collagen areas in the cervical tissue were calculated. The PMN% in cervical mucus was lowest at 200 days gestation (12–13 weeks before delivery), significantly increased 5 weeks before (21.7 ± 0.04), and was highest 1 week before calving (50.9 ± 0.04). IL-8 levels were increased at 295 days compared with those at 200 days of pregnancy (p < 0.05). No significant changes were observed in the white blood cell counts. The percentage of type I collagen in the cervical tissue reached a maximum (91.4 ± 0.02%) on day 200, significantly decreased after 274 days (3 weeks before calving), and continued to decrease thereafter until the week of parturition. There was no significant change in type III collagen levels. The results suggest that cervical ripening progresses when PMNs begin to infiltrate the cervix at around 260 days of gestation (5–4 weeks before parturition), IL-8, which increases at the end of pregnancy, mobilizes PMNs, and enhances inflammation, and that type I collagen changes are useful as an indicator of cervical ripening.
DOI： 10.3390/ani12192646
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Maeda T., Kitahara G., Osawa T.
Reproduction in Domestic Animals 57 ( 9 ) 1029 - 1037 2022年9月
担当区分：最終著者, 責任著者 記述言語：英語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Reproduction in Domestic Animals
This study aimed to clarify the relationship between the maternal pelvis and calf size in normal and dystocia groups (Experiment 1) and to establish a method to predict dystocia due to physical imbalance between foetus and maternal pelvis before calving based on the parameters found in Experiment 1 (Experiment 2). In Experiment 1, 26 pairs of dams and their offspring were tested immediately after calving, and various parameters of offspring size and maternal pelvis were measured in normal and dystocia cases. The longitudinal diameter of the maternal pelvis was smaller (p <.01), and ratios of the offspring's birth weight and the width of the hoof crown (hoof width; measured using callipers) to the longitudinal diameter of the maternal pelvis were larger (p <.01) in the dystocia group than those in the normal group. In Experiment 2, 37 cows were tested, and in addition to the measurement items of Experiment 1, the inner pelvic diameter and the foetal hoof width were measured via ultrasonography at 285 days of gestation. The ratio of the internal diameter of the maternal pelvis (longitudinal diameter, transverse diameter and area) to the foetal hoof width was compared and was greater (p <.01) in the dystocia group than in the normal group. In conclusion, the risk of dystocia can be estimated by the ratio of the foetal hoof width to the longitudinal diameter of the maternal pelvis before calving.
DOI： 10.1111/rda.14169
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Association of herd size with stillbirth and dystocia rates in Japanese Black cattle 査読あり
Misaka M., Uematsu M., Kitahara G., Osawa T., Sasaki Y.
Animals 12 ( 15 ) 2022年8月
記述言語：英語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Animals
The objective of this study was to investigate the effect of herd size on stillbirth and dystocia rates; the relationships between herd size, calving season, parity, and gestation length in Japanese Black cattle were also explored. Data were collected for 41,184 calvings from 15,512 animals on 905 farms between 2006 and 2010. In this study, herds were classified into three groups based on size: small (1–10 cows), medium (11–50 cows), and large (≥51 cows). Herd size had an effect on the dystocia rate (p < 0.05) but not the stillbirth rate. Additionally, interactions between herd size and gestation length were associated with the dystocia rate (p < 0.05), and the dystocia rate was the highest in small herds, followed by medium and large herds for cows with a gestation length of 281–300 days, which is considered a pregnancy of normal duration. In summary, in Japanese Black cattle, there were different effects of herd size on the stillbirth rate and dystocia rates, as herd size was associated with the dystocia rate but not with the stillbirth rate.
DOI： 10.3390/ani12151994
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Elgendy O., Kitahara G., Taniguchi S., Osawa T.
Journal of Reproduction and Development 68 ( 4 ) 271 - 277 2022年
担当区分：最終著者, 責任著者 記述言語：英語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Journal of Reproduction and Development
High summer temperatures have deleterious effects on oocyte developmental competence. The antioxidant and autophagy-related properties of 5-aminolevulinic acid (5-ALA) gives the compound a broad range of biological activities. This study aimed to evaluate the effects of: 1) a high temperature-humidity index (THI) on the developmental competence of bovine oocytes, and 2) 5-ALA administration in combination with sodium ferrous citrate (SFC) during in vitro maturation (IVM) on bovine oocyte developmental competence evaluated at high THI. Bovine ovaries were collected from a local slaughterhouse at moderate environmental temperature (MT; THI of 56.2) and high environmental temperature (HT; THI of 76.7) periods; cumulus-oocyte complexes (COCs) were aspirated from medium-sized follicles, matured in vitro for 22 h, fertilized, and cultured for 10 days. For COCs collected during the HT period, 0 (control), 0.01, 0.1, 0.5, or 1 µM 5-ALA was added to the maturation medium in combination with SFC at a molar ratio of 1:0.125. The results showed that HT adversely affected blastocyst and hatching rates compared with MT. Adding 5-ALA/SFC (1 µM/0.125 µM) to the maturation medium of oocytes collected during the HT period improved cumulus cell expansion and blastocyst rates compared with the no-addition control. In conclusion, this study showed that high THI can disrupt bovine oocyte developmental competence. Adding 5-ALA to SFC ameliorates this negative effect of heat stress and improves subsequent embryo development.
DOI： 10.1262/jrd.2021-145
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Tani M., Tani C., Tasaki H., Harumoto S., Yoshimatsu R., Ito S., Koutaka T., Hattori N., Moritomo Y., Osawa T.
Australian Veterinary Journal 99 ( 11 ) 469 - 472 2021年11月
担当区分：最終著者, 責任著者 記述言語：英語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Australian Veterinary Journal
This study aimed to clarify the effectiveness of foetal body weight estimation by measuring foetal coronet width using transrectal ultrasonography in beef cows during near-term pregnancy. A characteristic ‘gull wing’ pattern was obtained from the foetal coronet cross-section from the dewclaw side using ultrasonography. This pattern was matched to the bone surface of the distal part of the middle phalanx. Then, the relationship between coronet width and body weight at birth of 22 Japanese Brown calves was analysed and a high correlation coefficient of 0.8965 (P < 0.001) was obtained. In conclusion, the coronet width of the fetus is depicted as a ‘gull wing’ hyperechoic structure and can be measured by ultrasonography per rectum during near-term pregnancy. This technique may be a useful tool to identify high-risk cows with dystocia before calving. High foetal coronet values may predispose cattle to dystocia.
DOI： 10.1111/avj.13112
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Osawa T.
Journal of Reproduction and Development 67 ( 5 ) 291 - 299 2021年10月
担当区分：筆頭著者, 責任著者 記述言語：英語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Journal of Reproduction and Development
A certain level of endometrial bacterial infection and inflammation is involved in bovine uterine involution during the puerperal period. Factors that hamper normal uterine involution expose the uterine environment to pathological conditions, causing different endometritis levels. The lack of proper diagnostic tools extends the time to conception. Efforts have been made to elucidate the postpartum uterine environment, including bacterial flora, changes in transient endometrial inflammation, and the pathophysiology of endometritis, to improve bovine reproductive performance. E. coli and Trueperella pyogenes in the uterus are likely to cause persistent infection, and Mycoplasma bovigenitalium infection is associated with dystocia and cytological endometritis in postpartum dairy cows. Due to the widespread use of cytobrush as a diagnostic tool for bovine subclinical endometritis (SE) that enables quantification of the degree of inflammation, we found that endometritis at week 5 postpartum was associated with delayed first ovulation. Approximately 30% of open cows have SE during the postpartum period, and cows with low blood glucose during prepartum have a high risk of developing SE. Additionally, cows with purulent vaginal discharge do not always have endometritis but only vaginitis and/or cervicitis. Intrauterine infusion of polyvinylpyrrolidone-iodine (PVP-I) improves fertility and promotes endometrial epithelial cell regeneration after inducing transient uterine inflammation, suggesting that PVP-I could be a good alternative to antibiotics. In conclusion, prepartum management to prevent glucose deficiency, prompt diagnosis to identify causative agents and intrauterine inflammation levels, and appropriate treatment to minimize antimicrobial resistance is beneficial for tackling endometritis and improving reproductive performance in bovine herds.
DOI： 10.1262/jrd.2021-052
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Wu X, Kitahara G, Suenaga T, Naramoto K, Sekiguchi S, Goto Y, Osawa T
Journal of Reproduction and Development 2021年10月
担当区分：最終著者, 責任著者 記述言語：英語 掲載種別：研究論文（学術雑誌） 出版者・発行元：公益社団法人 日本繁殖生物学会
The aim of this study was to clarify the influence of <i>Lactobacillus </i>spp. on the degree of endometrial inflammation in the postpartum period and the relationship between <i>Lactobacillus </i>spp. and pathogenic bacteria in the endometrium of postpartum dairy cows. Endometrial samples were collected from 41 Holstein-Friesian cows at 4 and 8 weeks postpartum using cytobrushes for polymorphonuclear neutrophil (PMN) count and bacterial culture to isolate <i>Lactobacillus </i>spp., <i>Escherichia coli</i>, and<i> Trueperella pyogenes</i>. The 4-week samples were divided into four groups (E + L +), (E + L −), (E − L +), (E − L −) according to whether endometritis was diagnosed (E +) and <i>Lactobacillus </i>spp. was isolated (L +). The diagnostic criterion for cytological endometritis was > 18% PMN. The average PMN% in the E + L + group was lower than that in the E + L-group (P < 0.05) at 8 weeks postpartum. There were no significant correlations between the number of colonies of <i>Lactobacillus</i> spp. and <i>E. coli</i> or between that of <i>Lactobacillus</i> spp. and <i>T. pyogenes</i>. <i>Lactobacillus </i>spp. could reduce PMN% in dairy cows with endometritis during the puerperal period. In conclusion, the intrauterine presence of <i>Lactobacillus </i>spp. may have a positive effect on uterine involution in postpartum dairy cows.
DOI： 10.1262/jrd.2021-023
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The effect of heat and cold stress on oxidative stress of follicular microenvironment in beef cattle 査読あり 国際共著
Kanada K., Elgendy O., Hemmi K., Kobayashi I., Sato R., Osawa T., Kitahara G.
Journal of Veterinary Medical Science 87 ( 11 ) 1336 - 1345 2025年11月
記述言語：英語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Journal of Veterinary Medical Science
This study hypothesized that heat and cold stress affect the balance between oxidants and antioxidants (oxidative stress) of oocytes and follicular fluid (FF) in beef cattle and the oxidative stress between blood and FF is correlated. Thirty-two Japanese Black cattle that were divided into four seasonal groups [fall, winter (WG), spring (SpG), and summer (SmG) group]. Plasma and FF were measured diacron-reactive oxygen metabolites (d-ROMs), biological antioxidant potential (BAP), and oxidative stress index (OSI). Reactive oxygen species (ROS) were measured in oocytes. Temperature-humidity index was lower in WG and higher in SmG than in the other three groups (P<0.05). d-ROMs value was lower in FF than in plasma in all groups, BAP value was lower in FF than in plasma in WG, SpG, and SmG, and OSI was lower in FF than in plasma in WG and SpG (P<0.05). In FF, d-ROMs and BAP values were positively correlated in WG, SpG, and heifer groups (HG, P<0.05). d-ROMs or OSI values between plasma and FF were positively correlated in all animals and cow group (CG), SpG, CG, and HG (P<0.05). ROS levels in oocytes were higher in WG and SpG than in SmG (P<0.05). In conclusion, oxidative stress in the blood and FF are linked, and oxidative stress of oocytes increases in winter and spring in beef cattle that are kept on pasture, except in winter.
DOI： 10.1292/jvms.24-0323
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Kohigashi S.S., Uematsu M., Kitahara G., Osawa T.
Journal of Reproduction and Development 71 ( 3 ) 175 - 184 2025年5月
担当区分：最終著者, 責任著者 記述言語：英語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Journal of Reproduction and Development
This study aimed to clarify the association between the percentage of follicle number by size over antral follicle count (AFC) and subsequent reproductive performance. A total of 306 Japanese Black cattle underwent timed artificial insemination (TAI) 41–62 days postpartum; the AFC and numbers of small, medium, and large follicles were recorded 10 days before TAI. The cross-sectional and blood flow areas of the dominant follicle (DF) on the day of TAI and the corpus luteum (CL) six days after TAI were recorded. The total number of follicles ≥ 2 mm was defined as the AFC, and the percentages of follicle number by each size defined as small (S-AFC%; 2–2.9 mm), medium (M-AFC%; 3–8.4 mm), and large (L-AFC%; ≥ 8.5 mm) follicles. The AFC and S-, M-, and L-AFC% were further grouped into low, medium, and high tertiles, and the subsequent reproductive performance compared among the groups. Plasma anti-Müllerian hormone (AMH) levels were quantified on the day of AFC measurement. No differences were observed in reproductive performance between the AFC and L-AFC% groups. The high-S-AFC% group showed a 20.6% lower conception rate, 0.58 more AI numbers, and 21.9 longer days open than those of the low-S-AFC% group (P < 0.05). The low-M-AFC% group showed an 18.0% lower conception rate after TAI and 0.54 more AI numbers than those of the high-M-AFC% group (P < 0.05). DF and CL parameters did not differ among the AFC, S-, M-, and L-AFC% groups. Plasma AMH levels in the low-AFC group were the lowest in the tertile. In conclusion, the percentage of follicles by size could be used to estimate subsequent reproductive performance.
DOI： 10.1262/jrd.2024-075
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Fertility Traits in Japanese Black Cows in Farms Classified by Calving Intervals Using Epidemiological Methods. 査読あり
Suzuki O, Uematsu M, Kitahara G, Osawa T, Sasaki Y
Reproduction in domestic animals = Zuchthygiene 60 ( 4 ) e70058 2025年4月
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Profile of cytokine gene expression of the endometrium and its relationship to inflammation and fertility in postpartum dairy cows. 査読あり 国際共著
Naramoto K, Kitahara G, Nazhat SA, Yasuda M, Osawa T
The Journal of veterinary medical science 2024年12月
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Misaka M., Uematsu M., Kitahara G., Osawa T., Sasaki Y.
PLoS ONE 19 ( 6 June ) e0304867 2024年6月
記述言語：英語 掲載種別：研究論文（学術雑誌） 出版者・発行元：PLoS ONE
We aimed to characterize the change in the incidence of stillbirth (IS) in Japanese Black cattle during and after animal movement restrictions and suspended insemination because of a foot-and-mouth disease (FMD) outbreak in Miyazaki Prefecture in 2010. Calving data from 2006 to 2018 were collected from approximately 900 farms. Post-FMD period was divided into three based on the median IS per month (1.80%): period 1 (May 2011 to February 2013), period 2 (March 2013 to August 2015), and period 3 (September 2015 to December 2018). The ISs were similar during the Pre-FMD period and Post-FMD period 1, then substantially decreased during Post-FMD period 2 (p < .05), before returning to the value before the FMD outbreak period during Post-FMD period 3. Compared with the Pre-FMD period, Post-FMD period 1 was associated with a higher proportion of calvings by primiparous cows and Post-FMD period 2 was associated with a smaller number of calvings per month (p < .05). There were high ISs in primiparous cows during the Pre-FMD period, Post-FMD period 1, and Post-FMD period 3 (p < .05), but not during Post-FMD period 2. In summary, after the animal movement restrictions and suspended insemination introduced because of the FMD outbreak, the IS temporarily decreased and consequently returned to the pre-FMD level.
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Comparison of serum concentrations of pregnancy-associated glycoproteins and estrone sulphate during pregnancy in eutocia and dystocia beef cattle. 査読あり
Maeda T, Kitahara G, Osawa T
The Veterinary Journal (London, England : 1997) 106147 2024年5月
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Use of platelet lysate for in-vitro embryo production and treatment of repeat breeding in cows 査読あり 国際共著
Hassaneen A.S.A., Rawy M.S., Yamanokuchi E., Elgendy O., Kawano T., Wakitani S., Kitahara G., Osawa T.
Theriogenology 210 199 - 206 2023年10月
担当区分：責任著者 記述言語：英語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Theriogenology
Platelet-rich plasma (PRP) is a biological hemocomponent derived from blood after the complete removal of red blood cells and the partial or complete removal of white blood cells to concentrate platelets in an appropriate volume of plasma. Platelets have important growth factors, cytokines, and active metabolites that improve the endometrial environment and positively affect implantation. This study evaluated the effect of the addition of activated PRP (platelets lysate; PL) on in vitro bovine oocyte maturation and embryonic development and the effect of intrauterine (IU) infusion of autologous PL in repeat breeder (RB) cows. Experiment 1 examined the effects of allogeneic PL, fetal calf serum (FCS), mixed PL + FCS, or platelet-poor plasma (PPP) supplementations to in vitro maturation and development media on in vitro oocyte maturation and embryo development in good- and poor-quality oocytes of Japanese Black cows. Experiment 2 examined the IU infusion of autologous PL, 24 h post-insemination, in 21 RB Holstein-Friesian dairy cows. The cleavage rate of good-quality oocytes was higher in the PL group (85.93 ± 2.50%) than in the PPP group (67.16 ± 3.41%) (P < 0.05), while the cleavage rate of the poor-quality oocytes was higher in the PL alone (76.13 ± 4.04%) and mixed PL + FCS treated (73.59 ± 4.22%) groups than in the PPP group (54.64 ± 2.93%) (P < 0.05). The blastocyst rate of the good-quality oocytes was higher in the PL group (40.97 ± 3.03%) than in the FCS (27.97 ± 3.31%) and PPP (25.33 ± 2.15%) groups (P < 0.05). The blastocyst rate of poor-quality oocytes and the hatching rates of both good and poor-quality oocytes showed no significant differences among all groups. The conception rate in the autologous PL-treated group was 41.67% (5/12), while it was 11.11% (1/9) in the control group. The platelets' count in the pregnant PL-treated cows (n = 5; mean ± SEM, 1.07 ± 0.10 × 109/mL) was higher than in the non-pregnant ones (n = 7; 0.67 ± 0.10 × 109/mL) (P < 0.05). In conclusion, allogeneic PL was effective in stimulating the in vitro oocyte maturation and embryonic development in both good and poor-quality bovine oocytes, and post-insemination IU infusion of autologous PL derived from high platelets’ count-PRP would be recommended for the treatment of RB cows.
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Elgendy O., Kitahara G., Yamada K., Taniguchi S., Osawa T.
Journal of Reproduction and Development 69 ( 5 ) 261 - 269 2023年
担当区分：最終著者 記述言語：英語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Journal of Reproduction and Development
A high temperature-humidity index during summer has deleterious effects on mitochondrial function, reducing oocyte developmental competence. 5-Aminolevulinic acid (5-ALA) and sodium ferrous citrate (SFC) are both known to support mitochondrial function and have strong anti-oxidant and anti-apoptotic activities. This study aimed to determine the mechanism of action of 5-ALA/SFC on oocyte quality. Bovine oocytes were collected from medium-sized follicles during summer (July–September, temperature-humidity index:76.6), cultured with 0, 1, 2, 4, and 8 µM 5-ALA with SFC at a molar ratio of 1:0.125, fertilized, and cultured for 10 days. The addition of 8/1 µM 5-ALA/SFC had a deleterious effect on oocyte cleavage rate in comparison with control oocytes, but did not affect the blastocyst rate, while 1/0.125 µM 5-ALA/SFC had a significantly higher increase in blastocyst rate than 8/1 µM 5-ALA/SFC. The addition of 1/0.125 and 2/0.25 µM 5-ALA/SFC improved oocyte quality by increasing the mitochondrial distribution pattern and metaphase-II oocytes, reducing reactive oxygen species and upregulating nuclear factor erythroid-2-related factor 2, heme oxygenase-1, and superoxide dismutase-1 in oocytes, and nuclear factor erythroid-2-related factor 2 and mitochondrial transcription factor A in cumulus cells. These results indicate that 1/0.125 and 2/0.25 µM 5-ALA/SFC may support oocyte quality and developmental competence and provide anti-oxidant actions in cumulus-oocyte complexes.
DOI： 10.1262/jrd.2023-038
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Tanimura K., Uematsu M., Kitahara G., Osawa T., Sasaki Y.
Theriogenology 189 177 - 182 2022年9月
記述言語：英語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Theriogenology
Repeat breeding (RB) has been defined as failure to conceive from three or more regularly spaced services in the absence of detectable abnormalities, and cause economic loss on the farm owing to a declining conception rate. This study aimed to evaluate the reproductive characteristics of RB in Japanese Black cattle by assessing the longitudinal effect of RB at a low parity on subsequent fertility raised in commercial cow–calf operations. Data used in this study were collected from 764 farms in Miyazaki. Data from 2005 until 2014 comprised 158,945 AI records with 80,453 parity records for 22,565 cows. The effect of RB at heifers and parities 1 and 2 cows on subsequent fertility and survival on four consecutive parities was investigated. The results showed that cows with the number of inseminations to conception (INS) of ≥4 at a low parity had a higher probability of being RB again at subsequent parities compared with cattle with INS 1 or 2. Additionally, the degree of the negative effect of an INS ≥4 on fertility and survival increased as they became older. On the other hand, cows with an INS of 2 had similar fertility and survival with those with an INS of 1. In summary, this study suggests that repeat breeders at a low parity have a higher probability of RB again at subsequent parities compared with cattle with INS 1 or 2, and the negative effect of an INS ≥4 increases as parity increases.