# Optimization of the Embryo Transfer Technique in the Korean Native Cattle: Effects of Key Influencing Factors

## TL;DR

This study found that farm management, particularly feed strategies, significantly affects embryo transfer success in Korean native cattle, more than embryo type or parity.

## Contribution

The study identifies farm-specific metabolic profiles and feed management as key factors influencing embryo transfer success in cattle.

## Key findings

- Embryo type and parity did not significantly affect conception rates.
- Metabolic differences among farms correlated with pregnancy rates and were linked to feed management.
- Metabolic profile tests can serve as a numerical criterion for managing recipient cows.

## Abstract

This study investigated the factors that contribute to the success rate of embryo transfer, with a particular focus on the influence of embryo type, parity, and farm management. Furthermore, a metabolic profile test was conducted to determine the factors underlying the observed differences in conception rates across farms. The analysis revealed no statistically significant differences in the conception rate according to embryo type or parity. However, differences in the conception rate were observed among the farms, with significant differences observed in the glucose, cholesterol, non-esterified fatty acid, total protein, globulin, albumin/globulin, and aspartate aminotransferase levels of the recipients. The findings revealed that differences in conception rate were not observed based on the type of embryo or parity, although differences were observed between farms. This outcome can be attributed to the effect of feed management strategies employed between the farms, which highlights the significance of optimal management of recipient cows. Furthermore, substantial disparities between farms were observed based on the metabolic profile test analysis. The findings show that metabolic profile tests can provide a standard numerical criterion for the prospective management of recipient cows.

The success rate of embryo transfer (ET) is influenced by various factors, including embryo quality, environmental conditions, and recipient cows. This study examines the impact of ET on embryo success rates using embryos produced using the ovum pickup method, with fresh and frozen embryos generated on day 7 after in vitro fertilization and subsequently implanted into recipient cows. The factors that contributed to the success rate of ET were investigated, with a focus on embryo type, parity, and farm management. Furthermore, metabolic profile tests were conducted to determine the factors underlying the observed differences in pregnancy rates across the farms. The analysis revealed that pregnancy rates did not significantly differ according to embryo type or parity. However, significant differences (p < 0.05) were observed in the glucose, cholesterol, non-esterified fatty acid, total protein, globulin, albumin/globulin, and aspartate aminotransferase levels of the recipients. Furthermore, a comparison of farms with high and low pregnancy rates revealed significant differences in the glucose, cholesterol, total protein, albumin, globulin, and albumin/globulin levels (p < 0.05). Differences between farms were associated with the feed management strategy, which highlights the significance of optimal recipient cow management.