Association of follicular fluid parameters at the time of ovum pick-up with in vitro blastocyst formation in Holstein heifers: a multi-level analysis

Abstract Pooled follicular fluid is easily accessible during ovum pick-up (OPU) and can be a potential source of non-invasive biochemical predictors for oocyte competence. Using the OPU procedure, oocytes recovered from a total of 60 Holstein heifers were used in in vitro embryo production. Pooled follicular fluid was collected at the time of OPU in order to establish a relationship between follicular biochemical components and the formation of blastocyst. The oocytes from each heifer were pooled together, matured in in vitro maturation medium for 24 h and then fertilized with sperm cells. The resulting zygotes were cultured for 7 days and the formation of blastocyst was recorded. Next, heifers were classified on the basis of the blastocyst formation, cleaved heifers and failed heifers. Follicular glucose concentrations were higher and the amount of C-reactive protein (CRP) was lower in cleaved heifers than in failed heifers. Moreover, the receiver operator characteristic (ROC) curve, clustering and network analysis showed the closeness between CRP, total bilirubin, and blastocyst yield. In conclusion, the findings imply that CRP follicular concentrations, which have been linked to heifer blastocyst formation, should be investigated further.