Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, AB, Canada, T6G 2P5.
Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, AB, Canada, T6G 2P5; Livestock Research and Extension Branch, Alberta Agriculture and Forestry, Edmonton, AB, Canada, T6H 5T6.
J Dairy Sci. 2019 Apr;102(4):3615-3621. doi: 10.3168/jds.2018-15692. Epub 2019 Feb 1.
The in-line milk analysis system (IMAS) is an automated biosensor technology that samples and quantifies milk progesterone concentrations (P4c) at frequent intervals starting early postpartum until pregnancy. The objective was to validate the use of pregnancy notifications (PregN) generated by an IMAS based on P4c profiles after artificial insemination (AI) to determine pregnancy and nonpregnancy status in dairy cows. Records of 1,821 AI events from 715 Holstein cows that had milk P4c (ng/mL) measured every 2.2 ± 1.9 d (mean ± standard deviation) between 24.5 ± 8.2 and 173.4 ± 49.3 d in milk through a real-time IMAS (Herd Navigator, DeLaval International, Tumba, Sweden) were evaluated. Based on variations in adjusted milk P4c (< vs. ≥ the 5.0 ng/mL threshold), the system determined the sampling frequency, onset and cessation of luteal phases, and pregnancy. If a luteal phase initiated (P4c increased to ≥5.0 ng/mL) after AI and remained uninterrupted, a PregN was generated starting at (mean ± standard deviation) 31.0 ± 4.3 d until 53.4 ± 7.9 d after AI, when sampling stopped, unless a decline in P4c (to <5.0 ng/mL) occurred indicating nonpregnancy and imminent estrus. The assessment of IMAS PregN at 4 weekly intervals was tested, and a confirmed calving occurrence between 262 and 296 d after AI, with no other subsequent AI recorded, was the gold standard for pregnancy. In total, 14.1 (256/1,821), 41.0 (746/1,821), and 50.7% (924/1,821) of AI events were followed by a decline in P4c before 19, 23, and 30 d after AI, respectively. Frequency of the last 3 sampling events preceding P4c decline was greater if P4c decline occurred between 18 and 25 d after AI (1.4 ± 0.5 samples per day) compared with before 17 or beyond 26 d after AI (1.0 ± 0.5 samples per day). At 30 ± 3 (27 to 33) d after AI, PregN occurred in 46.8% (853/1,821) of AI events, of which 15.2% (130/853) had a decline in P4c between 30 and 55 d after AI and 17.1% (146/853) was later confirmed nonpregnant based on the gold standard. A total of 40.7% (742/1,821) of AI events was confirmed pregnant by the gold standard, which was no different than the proportion of PregN at 51 ± 3 (48 to 54) d (40.9%; 744/1,821). At any time point between 27 and 54 d after AI, sensitivity and negative predictive values for PregN were greater than 95.0 and 96.0%, respectively, whereas specificity values were less than 90.0% for PregN before 40 d but greater than 94.0% for PregN beyond 41 d after AI. In conclusion, IMAS is able to diagnose pregnancy based on P4c profiles with high precision and determine early nonpregnancy based on the spontaneous cessation of the luteal phase. However, for accuracy greater than 95.0%, pregnancy declaration based on IMAS notifications alone should occur no earlier than 41 d after AI.
INLINE 牛奶分析系统（IMAS）是一种自动化生物传感器技术，可在产后早期开始频繁采样并定量牛奶孕激素浓度（P4c），直到怀孕。目的是验证基于人工授精（AI）后 P4c 曲线的妊娠通知（PregN）在奶牛妊娠和非妊娠状态中的应用。评估了 715 头荷斯坦奶牛的 1821 个 AI 事件的记录，这些奶牛在通过实时 IMAS（DeLaval International 的 Herd Navigator，Tumba，瑞典）测量牛奶 P4c（ng/mL）时，每隔 2.2±1.9 天（平均值±标准偏差）测量一次，牛奶 P4c 范围在 24.5±8.2 至 173.4±49.3 d。根据调整后的牛奶 P4c（<与≥5.0 ng/mL 阈值）的变化，系统确定了采样频率、黄体期的开始和结束以及妊娠。如果 AI 后黄体期开始（P4c 增加到≥5.0 ng/mL）且没有中断，从（平均值±标准偏差）31.0±4.3 d 开始到 AI 后 53.4±7.9 d 之间会生成 PregN，除非 P4c 下降（至<5.0 ng/mL）表示非妊娠和即将发情。每隔 4 周评估一次 IMAS PregN，并以 AI 后 262 至 296 d 之间确认分娩发生，且没有其他后续 AI 记录为妊娠的金标准。总共有 14.1%（256/1821）、41.0%（746/1821）和 50.7%（924/1821）的 AI 事件在 AI 后 19、23 和 30 d 之前分别出现 P4c 下降。在 AI 后 18 至 25 d 之间出现 P4c 下降时，最后 3 次采样事件的频率更高（每天 1.4±0.5 个样本），而在 AI 前 17 天或之后 26 天出现 P4c 下降时，频率为每天 1.0±0.5 个样本。在 AI 后 30±3（27 至 33）d，PregN 发生在 46.8%（853/1821）的 AI 事件中，其中 15.2%（130/853）在 AI 后 30 至 55 d 之间出现 P4c 下降，17.1%（146/853）根据金标准后来被确认未妊娠。根据金标准，共有 40.7%（742/1821）的 AI 事件被确认为妊娠，与 PregN 在 51±3（48 至 54）d 的比例（40.9%；744/1821）相同。在 AI 后 27 至 54 d 之间的任何时间点，PregN 的敏感性和阴性预测值均大于 95.0%和 96.0%，而在 AI 前 40 d 的 PregN 特异性值小于 90.0%，但在 AI 后 41 d 以上的 PregN 特异性值大于 94.0%。总之，IMAS 能够基于 P4c 曲线准确诊断妊娠，并基于黄体期的自发终止来早期判断非妊娠。但是，要达到 95.0%以上的准确性，应在 AI 后 41 d 以上才基于 IMAS 通知来宣布妊娠。
