Effects of inbreeding coefficients on the development of in vitro produced embryos in Hanwoo cattle

초록

Background: Although the high inbreeding coefficient (F ) can induce inbreeding depression in livestock, its stage-specific effects on in vitro fertilization (IVF) embryo development remain poorly characterized. Methods: This study investigated the effects of embryo inbreeding levels on the primary developmental and degeneration indicators of Hanwoo IVF embryos. A total of 3,294 embryos across 208 cows were produced using semen from a single proven sire to strictly eliminate paternal genetic variations. The embryos were categorized into three distinct groups based on pedigree F values: Low F (F < 2.0), Mid F (2.0 ≤ F < 4.0), and High F (4.0 ≤ F). Stage-specific morphological indicators, including the rates of cleavage, 8- to 16-cell formation, morula formation, blastocyst formation, degeneration, and arrest, were systematically evaluated using the Kruskal-Wallis test and correlation analyses. Results: Comparative analyses revealed no statistically significant differences among the Low, Mid, and High F groups across any evaluated stage-specific parameters (p > 0.05). In particular, the blastocyst formation rate did not differ significantly across all categories despite a minor increase observed in the High F group. Furthermore, both Pearson and Spearman correlation coefficients for all six developmental parameters were extremely low (p > 0.05), demonstrating that elevations in F values do not affect stage-specific embryo development or degeneration patterns. Conclusions: In conclusion, an average increase in the F value up to 8.59% does not compromise the early in vitro developmental competence of Hanwoo embryos, establishing a practical genetic threshold for fertilization strategies in commercial bovine IVF programs.

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