Symposium review: In-line milk progesterone monitoring as a tool for precision reproductive management and early identification of non-pregnant cows

• Published in: JDS communications 2024-10
• Main Authors: Bruinjé, Tony C., Ambrose, Divakar J., LeBlanc, Stephen J.
• Format: Article
• Language: English
• ISSN: 2666-9102; 2666-9102
• DOI: 10.3168/jdsc.2024-0649

In-line milk progesterone (IMP4) monitoring (Herd Navigator, DeLaval) is a technology that uses a built-in lateral flow immunoassay module to measure real-time milk progesterone (P4) and determine postpartum onset of cyclicity, estrus, and pregnancy. Sampling starts at 20 DIM and occurs on average every 2 d until pregnancy, with sampling frequency adjusted according to the estimated stage of the estrous cycle. Estrus is detected based on a decline in P4 concentrations below a threshold, and pregnancy is assessed from 30 to 55 d after AI in cows without return to estrus. Here, we review the potential of IMP4 as a tool for reproductive management. In a series of observational studies with up to 158,961 IMP4 records from 4,353 AI events, we characterized predictors of P/AI and investigated IMP4 profiles in cows returning to estrus. Some of the predictors were short or prolonged luteal phases (LP) before first AI and suboptimal P4 profiles (such as prolonged LP or inadequate P4 concentrations) immediately before and after AI. Over a third of cows had at least one characteristic of P4 profile unfavorable to P/AI. However, these variables had low predictive abilities (ROC AUC