Departmental Bulletin Paper 乳用子牛の健康状態を知る新しいカウシグナルの検討

古村, 圭子  ,  塚本, 夢乃

38pp.1 - 12 , 2017-10 , 帯広畜産大学
Description
子牛は下痢や肺炎などに罹患しやすい。子牛の体調の不具合を早期に発見し、不具合の要因を知り解決することが、子牛を健康に飼育するために重要である。測定項目数が多く器具を使用する従来のカウシグナル(CS)と比較して、測定器具を使わず、簡単で瞬時に判定可能な新たなカウシグナル(NCS)を見つけることが有益である。そしてその方法は子牛の飼養管理の省力化と疾病の早期発見に繋がる。本実験は2014 年7月末から10 月初旬にかけて出生した雌子牛から、離乳後の6頭を供試した。スコアリングは2014 年11 月から2015 年3月まで行った。新たなカウシグナル(NCS)は、顔に集中する3項目(鼻鏡の乾き、白目の色の変化、下まぶたのくぼみ)のスコア値を各々定義して、スコア表を設計した。従来のカウシグナルのスコア表とNCS スコア表による健康評価を、120 回(20 回/頭)行い、両スコアによる評価の一致率を分析した。NCS の発生要因を検討するため、5つの症状(脱水、発熱、下痢、咳、鼻水)もスコアリング時に測定した。これらの症状とNCS との関係性を、Excel 分析ツール(2013)およびSAS(ver9.4)で分析した。子牛の体全体を評価するCS と、顔の部位のみの観察で評価するNCS とを比較して、両者の健康評価の一致率は82.5%であった(Kappa 係数= 0.48)。NCS の3項目は、発熱症状と関係性が強く、特に鼻鏡の乾きとの間に、最も高いクラメール連関係数が得られた(V=0.48)。発熱群(直腸温度≧ 39.3℃)と非発熱群(直腸温度≦ 39.2℃)において、鼻鏡の粘液の分泌量には有意な差がみられた(P ≦ 0.0001)。特に直腸温度が40.0℃を超えるような高温の症例(N=8)では、鼻鏡の乾きが全症例で発生した。鼻鏡の乾き度合いを、直腸温度の測定が必要な子牛のスクリーニングの指標として用いることで、個体管理の省力化を実現できるだろう。NCS の鼻鏡の乾きのみでは発熱症状の陽性判定は58.1%であったが、鼻鏡の乾きに白目の色および下まぶたのくぼみの観察を含めることで、77.8%の陽性判定となり、擬陽性率は19.7%減少し、より直腸温度を測る必要のある子牛をみつける精度を向上できた。
Calves are susceptible to diarrhea and pneumonia. It is important for early detection of malfunction of calves and knowing and solving the cause of malfunction in order to keep calves healthy. It is useful to find a new cow signal (NCS) that can easily and instantaneously judged calf health without using measuring instruments, compared with the conventional cow signal (CS) which uses a large number of measurement items. The method leads to labor saving of calf feeding management and early detection of diseases. In this experiment six weaned calves were chosen from the end of July 2014 to the beginning of October.Scoring went from January 2014 to March 2015. In the New Calf Signal (NCS), a score table was designed by defining score values of 3 items focused on the face (drying degree of muzzle, color of white eyes, dent of lower eyelid), respectively. Health assessment using the score table of the conventional Cow Signal and the NCS score table was conducted 120 times (20 times / head) and the coincidence rate of the evaluation by both scores was analyzed. In order to examine factors causing NCS, five symptoms (dehydration, fever, diarrhea, cough, nasal discharge) was also measured at scoring. The relationship between these symptoms and NCS was analyzed with Excel analysis tool (2013) and SAS (ver. 9.4). For the CS that evaluates the whole calf body, the coincidence rate between the health evaluation of both were 82.5% (Kappa coefficient = 0.48) in the NCS for observation and evaluation of only the face part. Three items of NCS were strongly related to fever symptoms, and the highest Cramer relationship number (V = 0.48) was obtained especially with the drying degree of muzzle. There was a significant difference (P ? 0.0001) in the amount of nasal mucus volume between the exothermic group (rectal temperature ≧ 39.3°C) and the non-exothermic group (rectal temperature ≦ 39.2°C). Especially when the rectal temperature exceeds 40.0 °C (N=8), the dryness of the muzzle occurred in all cases. By using the drying degree of muzzle as an indicator of calf screening that requires measurement of rectal temperature, labor saving of individual management will be realized. With dryness of the muzzle of NCS alone, the positive judgment of the fever symptom was 58.1%, but by including the observation of the color of white eyes and the dent of lower eyelid in dryness of the muzzle, 77.8% was judged as positive. In other words, the false positive rate decreased by 19.7%, and the accuracy of finding calves that need to measure the rectal temperature could be improved.
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