Estimation of Genetic Parameters for OPU‐IVF‐Related Traits in Japanese Black Cattle

ABSTRACT Ovum pick‐up (OPU)‐in vitro fertilization (IVF), a technique in which cumulus oocyte complexes (COCs) are aspirated from the ovaries of cows and embryos are produced through IVF, is a method that allows repeated oocyte collection and embryo production without the need for slaughtering cattle and is used in breeding of Japanese Black cattle. However, there is no research on OPU‐IVF‐related traits in Japanese Black cattle from a breeding perspective. Therefore, we estimated genetic parameters of OPU‐IVF‐related traits in Japanese Black cows farmed in Hiroshima Prefecture. We used four OPU‐related traits (numbers of follicles [NF], collected COCs [CCOC], collected excellent COCs [ACCOC], and collected COCs used for IVF) and five IVF‐related traits (numbers of cleavage, eight‐cell stage, morula‐stage, blastocyst‐stage, and excellent or good blastocyst‐stage embryos) for OPU‐IVF‐related traits. Variance components were estimated using Bayesian approach. The estimated heritability of OPU‐IVF‐related traits ranged from 0.22 ± 0.09 (ACCOC) to 0.39 ± 0.22 (NF and CCOC) and showed for the first time that genetic improvement of OPU‐IVF‐related traits in Japanese Black cattle is feasible.