{"created":"2023-05-15T15:18:29.195927+00:00","id":4879,"links":{},"metadata":{"_buckets":{"deposit":"4c67cefb-0db2-4cd0-807c-816090b254b6"},"_deposit":{"created_by":12,"id":"4879","owners":[12],"pid":{"revision_id":0,"type":"depid","value":"4879"},"status":"published"},"_oai":{"id":"oai:obihiro.repo.nii.ac.jp:00004879","sets":["6:8"]},"author_link":["6757"],"control_number":"4879","item_3_alternative_title_1":{"attribute_name":"その他（別言語等）のタイトル","attribute_value_mlt":[{"subitem_alternative_title":"抗菌性物質の適正使用と乳生産効率の改善に向けた牛乳房炎における免疫応答の監視と調節","subitem_alternative_title_language":"ja"}]},"item_3_date_granted_12":{"attribute_name":"学位授与年月日","attribute_value_mlt":[{"subitem_dategranted":"2023-03-20"}]},"item_3_degree_grantor_10":{"attribute_name":"学位授与機関","attribute_value_mlt":[{"subitem_degreegrantor":[{"subitem_degreegrantor_language":"ja","subitem_degreegrantor_name":"帯広畜産大学"}],"subitem_degreegrantor_identifier":[{"subitem_degreegrantor_identifier_name":"10105","subitem_degreegrantor_identifier_scheme":"kakenhi"}]}]},"item_3_degree_name_9":{"attribute_name":"学位名","attribute_value_mlt":[{"subitem_degreename":"博士（農学）","subitem_degreename_language":"ja"}]},"item_3_description_11":{"attribute_name":"学位授与年度","attribute_value_mlt":[{"subitem_description":"2022","subitem_description_language":"ja","subitem_description_type":"Other"}]},"item_3_description_18":{"attribute_name":"フォーマット","attribute_value_mlt":[{"subitem_description":"application/pdf","subitem_description_type":"Other"}]},"item_3_description_7":{"attribute_name":"抄録","attribute_value_mlt":[{"subitem_description":"The major reason for giving dairy cows antibiotics is to prevent or treat mastitis, but among these therapies, some are probably unnecessary or inefficient. This thesis aimed to improve antibiotic stewardship in mastitis control. In Chapter 1, we investigated the usefulness of selective dry cow therapy (SDCT). SDCT reduced antibiotic use by 33%, but poor herd hygiene and shortened duration of external teat sealant adherence led to increased risks of dry-period intramammary infections (IMI). In Chapter 2, we investigated the dynamics of somatic cell score (SCS) and macrophage proportion (MAC; equivalent to 100 – differential somatic cell count [DSCC]) during mastitis and their effects on the California Mastitis Test (CMT). Results showed positive associations between SCS, MAC, and CMT scores. The high MAC during healing and chronic stages of mastitis may cause samples with relatively low SCS to show positive CMT reactions. In Chapter 3, we used generalized additive models (GAM) to estimate the nonlinear interaction between SCS and DSCC and its effect on milk production. Milk loss and composition change were severe in cows with high SCS and low DSCC. Especially for high-parity cows, milk yields were reduced by half. In Chapter 4, we investigated how the severity and causative pathogen of mastitis influence immune responses. We found a sharp drop in the albumin/globulin ratio after severe mastitis occurred, and that blood leukocyte count changed drastically in coliform or severe mastitis, slightly increased in streptococcal mastitis but remained stable in staphylococcal mastitis. There was a pathogen-dependent, non-linear relationship between DSCC and SCS. When cows recovering from Streptococcus dysgalatiae mastitis, DSCC decreased while SCS remained high, indicating a healing process with a large number of macrophages involved. In Chapter 5, we conducted two experiments to evaluate the immunomodulatory effects of chitosan on preventing dry period IMI and recurrent clinical mastitis. The oral administration of chitosan failed to modulate cows’ immune systems or to benefit mastitis management. To summarize, to implement SDCT, sound herd hygiene and the concurrent use of teat sealants are required to prevent new IMI. Treatment of clinical mastitis should not be extended solely based on a positive CMT reaction. Instead, a milk culture test is necessary to determine the cure for mastitis. Since the immune response in mastitis differs depending on the causative pathogen and severity, treatment should be planned correspondingly. The damage of chronic IMI, characterized by high SCS and low DSCC, to milk yield is most significant in high-parity cows. Antibiotics may be ineffective in this case, early drying and culling should thus be considered. We believe antibiotic use in mastitis control can benefit from our findings but further research efforts are required.","subitem_description_language":"en","subitem_description_type":"Abstract"},{"subitem_description":"乳房炎は、酪農産業に最大の経済的損失をもたらす疾病の一つであり、従前から、抗菌性物質がその被害の低減、すなわち、乳房炎の治療や予防に用いられてきた。しかし、近年、生産性の向上と共に抗菌性物質の慎重使用が求められている。本研究は、乳房炎における免疫応答の監視と調節を通し、抗菌性物質の使用削減および生産性向上を目的として行われた。第1章では、日本における選択的乾乳期治療(SDCT)の有用性を検討した。SDCTを用いた場合、盲目的に行われている乾乳期治療と比べ、抗菌性物質の使用が約33%減少した。SDCTの成功の要因として、新たな乾乳期乳腺感染を防ぐため、乾乳期の環境衛生管理と内部乳頭シーラントの注入の必要性が示された。また、治療の必要性を正確に判断するための検査法の精度の検討も必要と考えられた。そこで、第2章では、乳汁体細胞スコア(SCS)とマクロファージの割合がCMT変法の結果に及ぼす影響を調査した。SCSとマクロファージの割合はどちらもCMTスコアと正の相関があった。乳房炎の回復期と慢性期において、マクロファージの割合が高くなるため、SCSが低くてもCMT変法の陽性反応を引き起こす可能性が明らかとなった。この結果から、単独にCMT変法を用いて乳房炎の回復状況を判断するのは危険であり、また、慢性乳房炎の摘発にはCMT変法が有用であることが示された。慢性乳房炎が乳量への被害を引き起こす可能性が従前から指摘されてきたが、詳細に検証されていなかった。第3章では、体細胞数および種別体細胞数（DSCC；多形核好中球とリンパ球の割合；％）と乳量の関係を検討し、乳房炎の各ステージにおける乳量の変化を調査した。SCSとDSCCが両方とも高い（初期乳房炎）牛では乳量の減少はほとんど見られなかったが、SCSが高くDSCCが低い（慢性乳房炎）牛では乳量の損失が深刻であった。乳房炎のステージによって、乳牛の生産性が大きく変化し、乳房炎における免疫応答は生産性に深刻な影響を及ぼすことが明らかとなった。第4章では、乳房炎の重症度と原因菌が牛の免疫応答に与える影響を調査した。大腸菌群や重度の乳房炎では、白血球数の急激な上昇が見られたが、ブドウ球菌による乳房炎では変化が認められなかった。重度の乳房炎ではA/G比が急激に低下し、この低下は乳生産の低下にも関連していると考えられた。第3章と第4章により、効率的な乳生産を達成するには、重症度と慢性乳房炎をコントロールする必要がある。しかし、乳房炎が慢性期に推移すると、抗菌性物質の効果が低下すると言われ、抗菌性物質の適正使用を達成するには、免疫療法など抗菌性物質に代わる治療法が必要であると考えられる。そこで、第5章では、乾乳期乳腺感染と乳房炎再発予防に対するキトサンの免疫調節効果を評価した。しかし、キトサンによる乾乳期乳腺感染と乳房炎の発生抑制は認められず、免疫機能の調節効果も認められなかった。 \n以上の結果から、乳房炎の病態により、免疫応答が異なることが判明し、ＣＭＴ変法、SCS、DSCCおよびA/G比などの動態から、生産性に問題のある慢性や重度の乳房炎の個体を特定できる可能性が示唆された。このことは、乳房炎対策における治療や淘汰方針の確立に有効である。また、適切な治療や淘汰などの牛群管理は抗菌性物質の使用削減および生産性の向上につながると考えられた。","subitem_description_language":"ja","subitem_description_type":"Abstract"}]},"item_3_dissertation_number_13":{"attribute_name":"学位授与番号","attribute_value_mlt":[{"subitem_dissertationnumber":"甲第125号"}]},"item_3_publisher_5":{"attribute_name":"公開者","attribute_value_mlt":[{"subitem_publisher":"帯広畜産大学","subitem_publisher_language":"ja"}]},"item_3_rights_14":{"attribute_name":"権利","attribute_value_mlt":[{"subitem_rights":"Huang Che Hsuan","subitem_rights_language":"en"}]},"item_3_subject_20":{"attribute_name":"日本十進分類法","attribute_value_mlt":[{"subitem_subject":"645","subitem_subject_scheme":"NDC"}]},"item_3_version_type_19":{"attribute_name":"著者版フラグ","attribute_value_mlt":[{"subitem_version_resource":"http://purl.org/coar/version/c_970fb48d4fbd8a85","subitem_version_type":"VoR"}]},"item_access_right":{"attribute_name":"アクセス権","attribute_value_mlt":[{"subitem_access_right":"open access","subitem_access_right_uri":"http://purl.org/coar/access_right/c_abf2"}]},"item_creator":{"attribute_name":"著者","attribute_type":"creator","attribute_value_mlt":[{"creatorAffiliations":[{"affiliationNameIdentifiers":[{"affiliationNameIdentifierScheme":"ISNI","affiliationNameIdentifierURI":"http://www.isni.org/isni/"}],"affiliationNames":[{"affiliationNameLang":"ja"}]}],"creatorNames":[{"creatorName":"Huang, Che-Hsuan","creatorNameLang":"en"}],"familyNames":[{"familyName":"Huang","familyNameLang":"en"}],"givenNames":[{"givenName":"Che-Hsuan","givenNameLang":"en"}],"nameIdentifiers":[{"nameIdentifier":"6757","nameIdentifierScheme":"WEKO"}]}]},"item_files":{"attribute_name":"ファイル情報","attribute_type":"file","attribute_value_mlt":[{"accessrole":"open_date","date":[{"dateValue":"2024-04-02"}],"displaytype":"detail","filename":"Huang.pdf","filesize":[{"value":"6.9 MB"}],"format":"application/pdf","licensetype":"license_note","mimetype":"application/pdf","url":{"label":"全文　Full text","objectType":"fulltext","url":"https://obihiro.repo.nii.ac.jp/record/4879/files/Huang.pdf"},"version_id":"decc1192-52ee-4c9d-bb02-b82a563db77e"},{"accessrole":"open_date","date":[{"dateType":"Available","dateValue":"2023-04-20"}],"displaytype":"detail","filename":"Abstract(Huang).pdf","filesize":[{"value":"194.0 kB"}],"format":"application/pdf","licensetype":"license_note","mimetype":"application/pdf","url":{"label":"全文の要旨　Abstract","url":"https://obihiro.repo.nii.ac.jp/record/4879/files/Abstract(Huang).pdf"},"version_id":"2c32c04c-65a6-479b-bef1-4dcc004c69e5"},{"accessrole":"open_date","date":[{"dateType":"Available","dateValue":"2023-04-20"}],"displaytype":"detail","filename":"Evaluation(Huang).pdf","filesize":[{"value":"185.3 kB"}],"format":"application/pdf","licensetype":"license_note","mimetype":"application/pdf","url":{"label":"審査の要旨　Evaluation","url":"https://obihiro.repo.nii.ac.jp/record/4879/files/Evaluation(Huang).pdf"},"version_id":"5205f528-fea1-457f-afd3-394bbd1954c4"}]},"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":"doctoral thesis","resourceuri":"http://purl.org/coar/resource_type/c_db06"}]},"item_title":"Monitor and modulate immune responses in bovine mastitis to improve antibiotic stewardship and efficiency in milk production","item_titles":{"attribute_name":"タイトル","attribute_value_mlt":[{"subitem_title":"Monitor and modulate immune responses in bovine mastitis to improve antibiotic stewardship and efficiency in milk production","subitem_title_language":"en"}]},"item_type_id":"3","owner":"12","path":["8"],"pubdate":{"attribute_name":"PubDate","attribute_value":"2023-04-20"},"publish_date":"2023-04-20","publish_status":"0","recid":"4879","relation_version_is_last":true,"title":["Monitor and modulate immune responses in bovine mastitis to improve antibiotic stewardship and efficiency in milk production"],"weko_creator_id":"12","weko_shared_id":-1},"updated":"2024-03-11T00:07:35.295538+00:00"}