Article

Improvement of Conception Rate on Hanwoo Cows; The Key Hormones and Novel Estrus Detector

Young Ho Joo1, Seung Min Jeong2, Dimas Paradhipta2,3, Hyuk Jun Lee2, Seong Shin Lee1, Jeong Seok Choi2, Hyeon Tak Noh2, Hong Hee Chang1,4, Eun Joong Kim5, Sam Churl Kim1,2,4,*
Author Information & Copyright
1Institute of Agriculture and Life Science, Gyeongsang National University, Jinju 52828, Korea.
2Division of Applied Life Science (BK21Four), Gyeongsang National University, Jinju 52828, Korea.
3Faculty of Animal Science, Universitas Gadjah Mada, Yogyakarta 55281, Indonesia.
4Department of Animal Science, Gyeongsang National University, Jinju 52828, Korea.
5Department of Animal Science, Kyungpook National University, Sangju 37224, Korea.
*Corresponding Author: Sam Churl Kim, Institute of Agriculture and Life Science, Gyeongsang National University, Jinju 52828, Korea, Republic of. Division of Applied Life Science (BK21Four), Gyeongsang National University, Jinju 52828, Korea, Republic of. Department of Animal Science, Gyeongsang National University, Jinju 52828, Korea, Republic of. Phone: +82-55-772-1947. E-mail: kimsc@gnu.ac.kr.

© Copyright 2021 Korean Society of Animal Science and Technology. This is an Open-Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Received: Jul 28, 2021; Revised: Oct 13, 2021; Accepted: Oct 25, 2021

Published Online: Nov 23, 2021

Abstract

Two field experiments were conducted to improve the conception rate of Hanwoo cow. The first experiment aimed to investigate the physiological condition of Hanwoo cows on estrus, including metabolic profiles and body condition score. The second experiment investigated the effect of a novel estrus detector on the artificial insemination (AI) conception rate for Hanwoo cows. For the first experiment, 80 Hanwoo cows (2.5±0.10 of parity), approximately one month before estrus, were housed in 16 pens and offered the experimental diets twice daily with free water access. The body condition scores (BCS) were recorded, and blood was collected from the jugular veins just before AI. The collected blood was used to measure physiological conditions, such as metabolite and hormone levels. For the second experiment, each cow was equipped with a neck-mounted estrus detector collar, which had a sensor connected through the internet. Approximately one month before estrus, three hundred sixty Hanwoo cows (2.4±0.21 of parity) were assigned into groups with or without W-Tag collar treatments. The animals were managed the same as in the first experiment. The pregnancy rate reached 55% in the first experiment. The concentration of luteinizing hormone (LH) was higher (<italic>p </italic>&lt; 0.012; 1.56 vs. 1.08 ng/mL) in cows that were not pregnant (NPG) than in cows that were pregnant (PG) after AI. The BCS and other concentrations of metabolites and hormones in the blood were not different in both NPG and PG cows. The ranges of estrogen, LH, and follicle-stimulating hormone for PG cows were 11.9 to 39.0 pg/mL, &lt;0.25 to 1.98 ng/mL, and &lt;0.50 to 0.82 ng/mL, respectively. In the second experiment, cows with the estrus detector had lower days open (<italic>p</italic> &lt; 0.001; 78.1 vs. 84.8 d), insemination frequency (<italic>p</italic> &lt; 0.001; 1.26 vs. 2.52), and return of estrus (<italic>p</italic> &lt; 0.001; 70.9 vs. 79.1 d) than those in cows without the estrus detector. In conclusion, the present study indicated that lower LH concentration just before AI potentially increased the pregnancy rate of Hanwoo cows. Furthermore, the application of estrus detectors to Hanwoo cows could improve the conception success rate for AI.

Keywords: Artificial insemination; Conception rate; Estrus detector; Hanwoo cow; Luteinizing hormone