# Effects of Short-Term Differences in Concentrate Feeding on the Recovery of In Vivo Embryos in Hanwoo Donor Cows through Superovulation Treatment

## TL;DR

This study shows that changing the amount of concentrate feed in Hanwoo cows can affect embryo production during superovulation.

## Contribution

The study reveals that short-term changes in concentrate feeding influence embryo yield in Hanwoo cows undergoing superovulation.

## Key findings

- The low concentrate group had the highest number of harvested embryos.
- The low concentrate group showed the greatest weight change and lowest body condition score.
- Physiological markers like estradiol and cholesterol did not differ significantly between groups.

## Abstract

Superovulation is a hormonal treatment used to produce multiple oocytes in cows simultaneously, which is essential for embryo transfer. Its success depends on various factors such as hormone levels, protocols, timing of insemination, weather, and nutrition. However, the impact of feed changes, specifically the energy levels in the concentrate, on embryo production is not well understood. This study explores how changes in concentrate intake, with unlimited access to hay, affect embryo production in indigenous Korean (Hanwoo) cows. We compared embryo production and physiological changes between cows with altered concentrate intake and those with consistent intake. The results offer new insights for managing superovulation in relation to feed concentrate.

Superovulation is a technique used to increase the number of oocytes released for fertilization. This study investigated the effects of short-term differences in concentrate feed intake on in vivo embryo production through superovulation in indigenous Korean (Hanwoo) cows. The cows were given fresh water and hay ad libitum and randomly divided into three groups (control (CON, n = 9): 2.0 kg/day (unchanged diet); low concentrate (LC, n = 10): 0 kg/day; and high concentrate (HC, n = 8): 4.0 kg/day) according to the amount of formula they were fed. This feeding treatment began seven days before the start of the hormonal treatment for superovulation. From the results, the LC group had the greatest weight change and the lowest body condition score at harvest, followed by the CON and HC groups (p < 0.05). The LC group had the highest number of harvesting embryos, followed by the HC and CON groups (p < 0.05). Estradiol, progesterone, glucose, total cholesterol, high-density lipoprotein, low-density lipoprotein, total protein, and blood urea nitrogen concentrations did not differ between the groups, except for a temporary increase in the HC group on day 0. These findings suggest that more embryos may be harvested when short-term changes in concentrate intake are made during superovulatory responses in Hanwoo cows.