{"created":"2021-03-01T06:34:14.669252+00:00","id":28433,"links":{},"metadata":{"_buckets":{"deposit":"e23eda92-6fc9-4306-bc0d-b741e0d25ad6"},"_deposit":{"id":"28433","owners":[],"pid":{"revision_id":0,"type":"depid","value":"28433"},"status":"published"},"_oai":{"id":"oai:niigata-u.repo.nii.ac.jp:00028433","sets":["453:456","485:872:1583:1604"]},"item_7_alternative_title_1":{"attribute_name":"その他のタイトル","attribute_value_mlt":[{"subitem_alternative_title":"乳牛における発情徴候の短縮化と発情徴候を抑制しうる内分泌的機序"}]},"item_7_biblio_info_6":{"attribute_name":"書誌情報","attribute_value_mlt":[{"bibliographicIssueDates":{"bibliographicIssueDate":"2006-08","bibliographicIssueDateType":"Issued"},"bibliographicIssueNumber":"1","bibliographicPageEnd":"9","bibliographicPageStart":"1","bibliographicVolumeNumber":"59","bibliographic_titles":[{"bibliographic_title":"新潟大学農学部研究報告"},{"bibliographic_title":"新潟大学農学部研究報告","bibliographic_titleLang":"en"}]}]},"item_7_description_4":{"attribute_name":"抄録","attribute_value_mlt":[{"subitem_description":"The milk yield of dairy cows has recently been significantly increased, owing to the genetic improvement as well as better nutritional management. Their reproductive performance, however, has been drastically declining. Difficulty in heat detection is one of the main causes of poor reproductive performance in today's dairy cows, since cows are generally bred artificially after detection of estrus. The detection of estrus is based on visual observation of cows for estrous signs. If cows do not express clear signs of estrus, it is difficult to breed them at an optimum time. According to the visual observation on a dairy herd, 64.3% were observed in standing estrus. The average duration of standing estruses was 6.6±6.3 h and 42 percent of the standing estrus was shown for 4 hours or shorter. This result suggests that about one third of cows in heat do not show standing estrus and duration of standing estrus has been drastically shortened. Suprabasal progesterone concentrations in follicular phase may inhibit estrous expressions. In cows, which showed only vaginal changes without any sexual activity, had significantly higher plasma progesterone concentrations than cows with standing estrus. The results showed that suprabasal progesterone levels are associated with weakened estrus in dairy cows. Some earlier studies suggest that progesterone concentrations in plasma in absence of corpus luteum are originated from the adrenal cortex. It has been already shown in cattle that plasma progesterone concentrations increased after an administration of exogenous ACTH. Three of the 4 ovariectmized lactating Holstein cows showed a significant increase of plasma progesterone concentrations after repeated ACTH challenge at 25 IU. Peak plasma progesterone levels after the first and second ACTH challenges were 3.7±0.6ng/ml and 2.1±1.0ng/ml, respectively. Significant increase of plasma progesterone concentrations was observed after 12 IU ACTH treatment in three lactating ovariectomized cows too. The mean peak plasma progesterone concentration was 1.5±0.1ng/ml and concomitant plasma cortisol concentration was 23.3±5.1ng/ml. The results suggest that the adrenal cortex can secrete sufficient amount of progesterone in response to 12 IU of ACTH or equivalent degree of stresses and concomitant plasma cortisol levels were 23.3±5.1ng/ml. There are several possible factors which affect on estrous behavior. In 7 of the 10 cows plasma cortisol levels increased significantly after milking. There were significant positive correlations between increments of plasma cortisol concentrations after milking and duration for milking or milk yield (r=0.6, P<0.05 and r=0.74, P<0.01, respectively). It is suggested that milking could cause a degree of stress equivalent to the doses of 12IU ACTH to which cows responded with a significant rise of plasma progesterone levels. It was concluded that the duration of standing estrus has been substantially shortened in lactating dairy cows, and more than one third of cows did not show standing estrus. Suprabasal progesterone concentrations in plasma were shown in cows with weakened estrus. Lactating cows may secrete a significant amount of progesterone from the adrenal cortex in response to acute stress. Resulting in high plasma progesterone concentrations, which may be sufficient to suppress estrous expression. Milking may cause adrenocortical response to secrete cortisol. It has also been suggested that stresses may play an important role in suppression of estrous signs in cows.","subitem_description_type":"Abstract"},{"subitem_description":"遺伝的改良や飼養管理の改善によって乳牛の泌乳量は飛躍的に増加している。その反面、乳牛の繁殖成績は急激に低下している。乳牛においては、発情を確認し、人工授精を実施することによって交配するが、今日の低い繁殖成績の主要な原因は、発情発見の困難さであると考えられる。乳牛の発情発見は、肉眼観察が基本である。もし、牛が明瞭な発情徴候を表さないと、授精の適期を判断することが困難となる。ある牛群での肉眼観察による発情観察の結果、64%の牛がスタンディング発情を示した。平均の発情持続時間は6.6±6.3h(±S.D.)であり、そのうち42%は4時間未満であった。このことは、牛群の3分の1の牛がスタンディング発情を示さないこと、発情の持続時間が著しく短縮していることを示唆している。卵胞期の基底値以上の血漿中Progesterone濃度は、発情徴候を抑制すると考えられる。発情時に、外陰部の変化のみで行動の変化を見せなかった微弱発情牛においては、スタンディングを示した牛に比べ、血漿中Progesterone濃度が有意に高かった。このことは、乳牛において、卵胞期に血漿中Progesterone濃度が基底値以上である場合、微弱発情となることを示している。黄体の無い時期の血漿中Progesterone濃度は、副腎皮質由来であることが過去に報告されている。牛においても、外因性のACTHを投与することにより、血漿中Progesterone濃度が増加することが知られている。卵巣を割去した泌乳牛で25IUのACTH負荷試験を行ったところ、4頭中3頭で血漿中Progesterone濃度が有意に上昇した。1回目および2回目のACTH負荷試験後の血漿中Progesterone濃度は、それぞれ3.7±0.6ng/mlおよび2.1±1.0ng/mlであった。3頭の卵巣を割去した牛を用いた12IUのACTH負荷試験でも、血漿中Progesterone濃度の有意な上昇が認められた。血漿中Progesterone濃度のピーク値の平均は、1.5±0.1ng/mlであり、同じ時に分泌された血漿中Cortisol濃度は23.3±5.1ng/mlであった。このことから、12IUのACTHもしくはそれと同等のストレスが負荷されると、副腎皮質は発情徴候を抑制しうる濃度のProgesteroneを分泌し、その時の血漿中Cortisol濃度は23.3±5.1ng/mlであることが示唆された。乳牛における発情徴候を抑制する諸要因については、これまで報告があり、泌乳もその一つといわれている。10頭中7頭の乳牛において、搾乳後に血漿中Cortisol濃度の有意な上昇が認められた。搾乳後の血漿中Cortisol濃度の増加と乳量および搾乳時間との関係には相関が見られた(それぞれr=0.6,P＜0.05およびr=0.74，P<0.01)。このことから、搾乳が12IUのACTH負荷試験と同様のストレスとなると、血漿中Progesterone濃度も有意に上昇する可能性が示唆された。以上のことから、乳牛の発情持続時間は短縮化しており、3分の1以上の牛がスタンディング発情を示さないこと、さらに、微弱発情牛において血漿中Progesterone濃度が高いこと、泌乳牛において急激なストレスの負荷によって副腎皮質より相当の濃度のProgesteroneが分泌され得ること、基底値以上の血漿中Progesterone濃度によって、発情徴候が抑制される可能性があることが示唆された。搾乳の刺激により副腎皮質が反応し、Cortisolが分泌されることが示され、これらのことより、ストレスは、乳牛の発情徴候の抑制に重要な影響を及ぼしていることが示唆された。","subitem_description_type":"Abstract"}]},"item_7_full_name_3":{"attribute_name":"著者別名","attribute_value_mlt":[{"nameIdentifiers":[{"nameIdentifier":"163604","nameIdentifierScheme":"WEKO"}],"names":[{"name":"吉田, 智佳子"}]}]},"item_7_publisher_7":{"attribute_name":"出版者","attribute_value_mlt":[{"subitem_publisher":"新潟大学農学部"}]},"item_7_select_19":{"attribute_name":"著者版フラグ","attribute_value_mlt":[{"subitem_select_item":"publisher"}]},"item_7_source_id_11":{"attribute_name":"書誌レコードID","attribute_value_mlt":[{"subitem_source_identifier":"AN00183393","subitem_source_identifier_type":"NCID"}]},"item_7_source_id_9":{"attribute_name":"ISSN","attribute_value_mlt":[{"subitem_source_identifier":"03858634","subitem_source_identifier_type":"ISSN"}]},"item_creator":{"attribute_name":"著者","attribute_type":"creator","attribute_value_mlt":[{"creatorNames":[{"creatorName":"Yoshida, Chikako"}],"nameIdentifiers":[{"nameIdentifier":"163603","nameIdentifierScheme":"WEKO"}]}]},"item_files":{"attribute_name":"ファイル情報","attribute_type":"file","attribute_value_mlt":[{"accessrole":"open_date","date":[{"dateType":"Available","dateValue":"2019-08-20"}],"displaytype":"detail","filename":"17_0047.pdf","filesize":[{"value":"727.9 kB"}],"format":"application/pdf","licensetype":"license_note","mimetype":"application/pdf","url":{"label":"17_0047.pdf","url":"https://niigata-u.repo.nii.ac.jp/record/28433/files/17_0047.pdf"},"version_id":"8639fa65-d191-49d4-86b7-1c67423e77fa"}]},"item_keyword":{"attribute_name":"キーワード","attribute_value_mlt":[{"subitem_subject":"adrenal progesterone","subitem_subject_scheme":"Other"},{"subitem_subject":"cortisol","subitem_subject_scheme":"Other"},{"subitem_subject":"dairy cows","subitem_subject_scheme":"Other"},{"subitem_subject":"duration of estrus","subitem_subject_scheme":"Other"},{"subitem_subject":"milking","subitem_subject_scheme":"Other"},{"subitem_subject":"副腎プロジェステロン","subitem_subject_language":"en","subitem_subject_scheme":"Other"},{"subitem_subject":"コルチゾール","subitem_subject_language":"en","subitem_subject_scheme":"Other"},{"subitem_subject":"乳牛","subitem_subject_language":"en","subitem_subject_scheme":"Other"},{"subitem_subject":"発情持続時間","subitem_subject_language":"en","subitem_subject_scheme":"Other"},{"subitem_subject":"搾乳","subitem_subject_language":"en","subitem_subject_scheme":"Other"}]},"item_language":{"attribute_name":"言語","attribute_value_mlt":[{"subitem_language":"eng"}]},"item_resource_type":{"attribute_name":"資源タイプ","attribute_value_mlt":[{"resourcetype":"departmental bulletin paper","resourceuri":"http://purl.org/coar/resource_type/c_6501"}]},"item_title":"Shortened Estrous Expressions and a Possible Endoclinological Role in Suppression Estrous Signs in Dairy Cows","item_titles":{"attribute_name":"タイトル","attribute_value_mlt":[{"subitem_title":"Shortened Estrous Expressions and a Possible Endoclinological Role in Suppression Estrous Signs in Dairy Cows"},{"subitem_title":"Shortened Estrous Expressions and a Possible Endoclinological Role in Suppression Estrous Signs in Dairy Cows","subitem_title_language":"en"}]},"item_type_id":"7","owner":"1","path":["456","1604"],"pubdate":{"attribute_name":"公開日","attribute_value":"2007-04-18"},"publish_date":"2007-04-18","publish_status":"0","recid":"28433","relation_version_is_last":true,"title":["Shortened Estrous Expressions and a Possible Endoclinological Role in Suppression Estrous Signs in Dairy Cows"],"weko_creator_id":"1","weko_shared_id":null},"updated":"2022-12-15T03:58:32.552024+00:00"}