In Vitro Developmental Competence Predicts Pregnancy Outcomes Following Transfer of Beef Embryos to Dairy Recipients:...

Area of Science:

• Reproductive Biology
• Embryology
• Veterinary Science

Background:

• Recipient factors and embryo grade are known predictors of pregnancy success in bovine embryo transfer (ET) using in vitro-produced (IVP) embryos.
• The specific impact of laboratory-derived developmental competence on pregnancy rates requires further characterization.

Purpose of the Study:

• To evaluate factors influencing pregnancy rates in dairy recipients following the transfer of IVP beef embryos.
• To determine the relative importance of recipient, laboratory, and environmental factors on pregnancy success in bovine ET.

Main Methods:

• Retrospective analysis of medical records from 462 bovine embryo transfer procedures.
• Evaluation of recipient factors (parity, body condition, estrus synchronization, corpus luteum characteristics).
• Assessment of laboratory factors (cleavage, blastocyst formation, degeneration, embryo grade, developmental stage, cryopreservation).
• Inclusion of environmental factors (temperature-humidity index, transport time).
• Statistical analyses including mean comparison, chi-square tests, and binary logistic regression.

Main Results:

• Significant differences in pregnancy rates were associated with corpus luteum volume, cleavage rates, blastocyst formation rates, degeneration rates, and embryo grade.
• Increased blastocyst formation rate positively correlated with pregnancy odds (1.45-fold increase).
• Increased degeneration rate and poorer embryo grade negatively correlated with pregnancy odds (0.74-fold and 0.56-fold decrease, respectively).
• No recipient or environmental variables independently predicted pregnancy rates.

Conclusions:

• The developmental competence of in vitro-produced embryos is a more critical determinant of pregnancy success than recipient or environmental factors in bovine ET.
• Optimizing in vitro production systems to maximize embryo quality is the most effective strategy for enhancing reproductive efficiency in embryo transfer.