The objective of this study was to evaluate a newly designed on-farm blood testing system (OFBTS) for monitoring blood concentrations of non-esterified fatty acids (NEFA) and β-hydroxybutyrate (BHBA) in dairy cows. Whole blood samples from 230 Holstein dairy cows between −86 and 343 days in milk were collected into heparinized tubes. A drop of whole blood was used to determine NEFA and BHBA using the OFBTS. Plasma from the remainder of the blood was used to determine both items using a commercial kit (gold standard). The repeatability of the OFBTS was evaluated by using a blood sample and measuring NEFA and BHBA 10 times from each sample. The coefficients of variation for NEFA and BHBA were 6.4% and 4.9%. The slope and coefficient of determination of OFBTS analysis of NEFA compared to the gold standard were 0.76 and 0.90. Those for BHBA were 0.94 and 0.98. The sensitivity and specificity of NEFA at a cutpoint of 0.4 mEq/L were 93.5% and 99.4%. Increasing the NEFA cutpoint to 0.6 mEq/L changed them to 87.9% and 100%. The sensitivity and specificity of BHBA at a cutpoint of 1.2 mM were 94.7% and 99.5%. The reaction time for the NEFA to reach 0.6 mEq/L was 7 min. The BHBA reaction reached 1.2 mM within 2 min. In conclusion, the OFBTS has excellent performance for detecting cows with high blood NEFA or BHBA concentrations and could be a useful tool for on-farm monitoring of cows with negative energy balance and/or ketosis.

这项研究的目的是评估一种新设计的农场血液测试系统（OFBTS），用于监测奶牛中非酯化脂肪酸（NEFA）和β-羟基丁酸酯（BHBA）的血液浓度。将在−86至343天之间从牛奶中取出的230头荷斯坦奶牛的全血样本收集到肝素化试管中。使用OFBTS滴一滴全血来测定NEFA和BHBA。使用市售试剂盒（黄金标准），使用剩余血液中的血浆确定两个项目。通过使用血液样本并从每个样本中测量NEFA和BHBA 10次来评估OFBTS的可重复性。NEFA和BHBA的变异系数分别为6.4％和4.9％。NEFA的OFBTS分析与金标准物相比的斜率和测定系数为0.76和0.90。BHBA的那些是0。94和0.98。临界点为0.4 mEq / L时，NEFA的敏感性和特异性分别为93.5％和99.4％。将NEFA临界点提高到0.6 mEq / L会将其分别变为87.9％和100％。临界点为1.2 mM时，BHBA的敏感性和特异性分别为94.7％和99.5％。NEFA达到0.6 mEq / L的反应时间为7分钟。BHBA反应在2分钟内达到1.2 mM。综上所述，OFBTS在检测血液中NEFA或BHBA浓度高的母牛方面具有出色的性能，并且可能是对能量负平衡和/或酮症的母牛进行农场监测的有用工具。NEFA达到0.6 mEq / L的反应时间为7分钟。BHBA反应在2分钟内达到1.2 mM。综上所述，OFBTS在检测血液中NEFA或BHBA浓度高的母牛方面具有出色的性能，并且可能是对能量负平衡和/或酮症的母牛进行农场监测的有用工具。NEFA达到0.6 mEq / L的反应时间为7分钟。BHBA反应在2分钟内达到1.2 mM。综上所述，OFBTS在检测血液中NEFA或BHBA浓度高的母牛方面具有出色的性能，并且可能是对能量负平衡和/或酮症的母牛进行农场监测的有用工具。