乳中尿素態窒素測定法の比較と測定値に及ぼす乳汁採取・保存方法の影響

兵庫県立淡路農業技術センター（〒656-0402　兵庫県三原郡三原町八木養宜中560-1）

（1999年6月21日受付・1999年11月17日受理）

要　　　　　約

乾式血液自動分析装置（ドライケム）を用いて17頭の乳牛から同時に採取した血液と乳汁の尿素態窒素（BUN，MUN）を測定したところ，高い相関が認められた（r＝0.982，P＜0.01）．ドライケム測定値と，吸光度法，差動pH法および赤外線法との測定値の間には高い相関が認められた（r＝0.891〜0.941，P＜0.01）が，試験紙法との間には有意な相関は認められなかった．乳汁を室温で保存した場合，24時間後のMUN濃度は有意に低下した（P＜0.05）．右前分房では搾乳の前後でMUN濃度に有意差が認められた（P＜0.01）．MUNは，飼料摂取後3〜5時間で最高値に達したのち低下した． ―キーワード：血中尿素態窒素，乳牛，乾式血液自動分析装置，乳中尿素態窒素． --------------------日獣会誌　53，285〜288（2000） Methods of Analysis for Milk Urea Nitrogen and Influence of Sampling and Storage on Its Concentrations Kentaro IKUTA, Mutsumu KOKAMO, Kazumi SASAKURA and Etsuji HAKOGI Hyogo Prefectural Awaji Agricultural Institute, 560h1 Yougi-naka, Yagi, Mihara, Hyogo 656-0402, Japan SUMMARY   Blood and milk samples were taken simultaneously from 17 dairy cows to determine concentration of urea nitrogen. Dry chemical autoanalyzer (DRICHEM) was used to determine blood urea nitorogen (BUN) and milk urea nitrogen (MUN). Significant correlation (r＝0.982, P＜0.01) was observed between concentrations of BUN and MUN. Although significant correlations were observed between DRICHEM and 3 other methods (r＝0.891〜0.941, P＜0.01) (Absorbance, Differential pH, and Infrared spectroscopy), no significant correlation was observed with the quick dipstick method. In samples stored at room temperature, MUN concentrations decreased significantly at 24 h after sampling. In the right front quarter of the udder, significant difference was observed in MUN concentration between pre-milking and post-milking. MUN concentrations increased after feed intake and reached a peak from about 3 to 5 h after feeding. ―Key words : blood urea nitrogen, dairy cow, dry chemical autoanalyzer, milk urea nitrogen. --------------------J. Jpn. Vet. Med. Assoc., 53, 285〜288 (2000)