@article{oai:obihiro.repo.nii.ac.jp:00004366,
 author = {前野, 和利 and 松井, 伸一 and 河合, 孝弘 and 鈴木, 真生 and 千葉, 友行 and 横山, 直明 and 猪熊, 壽},
 issue = {4},
 journal = {産業動物臨床医学雑誌},
 month = {},
 note = {application/pdf, 牛小型ピロプラズマ病が発生している北海道東部の２共同牧野において，マダニの活動時期に合わせて殺マダニ剤を利用したマダニ対策プログラムを４年間実施してきた．その結果，入牧中の<i>Theileria orientalis</i>（TO）の陽転率が低下する一方で，ホルスタイン種放牧育成牛の授精率と受胎率が高い水準で維持された．次に，放牧育成牛のTO感染歴の違いにより陰性群，陽転群および陽性群の３群に分類し，入牧中の繁殖成績を比較した．陰性群に比べ陽性群では，赤血球数が入牧時に有意な低値を示し，授精率と受胎率の低下が認められた．また陽転群では，赤血球数が入牧時に比べ入牧後２カ月目に低下し，初回授精までの期間の延長と授精率の低下が認められた．</p><p>当該牧野では，TO感染は放牧育成牛の繁殖成績を低下させる要因の１つと考えられ，殺マダニ剤によるマダニ対策プログラムの実施は放牧育成牛の繁殖成績に好影響を与えることが示唆された．, <i>Theileria orientalis</i>（TO）infection may have a negative effect on the reproductive performance of cattle. In the present study, we investigated the effect of a tick control programme for TO infection on the reproductive performance of Holstein heifers. Grazing heifers on two selected pastures with histories of TO infection in the eastern part of Hokkaido were treated with acaricides for four consecutive years. The animals were categorized into three groups based on their TO infection status determined by a diagnostic PCR assay: negative; negative to positive conversion; and positive.After the introduction of the programme, the number of animals converting to TO-positive started to decrease, while the overall reproductive performance improved every year．Compared to TO-negative animals, TO-positive animals had a significantly lower red blood cell count（RBC）at the beginning of the grazing season, and animals that converted to TO-positive also showed lower RBC after 2 months of grazing. TO-negative animals showed higher insemination and conception rates than TO-positive animals as well as a shorter time to the first insemination and a higher insemination rate than animals that became TO-positive. Taken together, these findings suggest that tick control measures improve the reproductive performance of grazing heifers in TO endemic regions.},
 pages = {169--174},
 title = {牛小型ピロプラズマ病対策を目的としたマダニ対策プログラムが北海道共同牧野のホルスタイン種放牧育成牛の繁殖成績に与えた影響},
 volume = {7},
 year = {2016}
}