Blood perfusion and diameter of bovine corpus luteum as predictors of luteal function in early pregnancy

A feasible and non-invasive luteal function assessment which enables timely intervention to improve progesterone (P4) support at early pregnancy is not well-established. The aim of this study was to determine the correlation among morphological and functional assessment methods of corpus luteum (CL) on Day 5 (D5) following timed-artificial insemination effect on luteal blood perfusion (LBP), CL diameter and serum P4 concentration. Beef heifers (n = 89) were synchronized and inseminated (D0). On D5, CL was scanned by colour-Doppler ultrasonography using an LBP score (0 = absent; 3 = high blood perfusion); CL diameter was obtained and blood was collected. Diameter of CL had a positive linear effect on P4 concentration (p