Departmental Bulletin Paper 広大農場乳牛における除籍状況からみた牛群管理の方向性
A preliminary proposal of policy for dairy herd health management from the viewpoints of culling in the Hiroshima University Farm

黒川, 有三  ,  森, 久史  ,  沖田, 美紀  ,  窪田, 浩和  ,  山城, 英和  ,  積山, 嘉昌  ,  近松, 一朗  ,  山口, 哲平  ,  木原, 真司  ,  田中, 明良  ,  脇, 良平  ,  北村, 亜紀  ,  川口, 信治  ,  小櫃, 剛人

(15)  , pp.8 - 12 , 2017-10 , 広島大学大学院生物圏科学研究科附属瀬戸内圏フィールド科学教育研究センター
In Japan, mean value for parity of dairy cows at culling has decreased to 3.4; measures to improve this are required. The aim of the present study is to understand the trends of culling of dairy cows at the Hiroshima University Farm. For that purpose, the farm’s records for dairy cow culling during the period of 2000–2015 were analyzed. At the farm, 20–27 dairy cows are regularly being milked. In March 2011, the milking system at the farm was changed from a milking parlor system to an automatic milking system. During the 16 years analyzed, 67 cows sold for meat and 16 cows that died at the farm totaled to 83 culled cows. The proportion of culled cows for each parity to total culled cows increased with increasing parity, and the number of cows culled at their 6th parity was the highest. The proportion of culled cows to cows that delivered at each parity gradually increased to more than 40% at the 5th parity, and drastically increased to more than 77.8% at the 6th parity. The reasons for culling were reproductive difficulty and diseases, such as mastitis. Therefore, general measures for improving reproductive performance and disease prevention should be taken for the cows at the 4th or lower parity. In addition, for dairy cows at the 5th or higher parity, a diagnostic decision on whether they are artificially inseminated for further delivery or not might be required depending on the individual cow’s record of reproduction and diseases.

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