Article

Dietary supplementation with L-glutamine enhances immunity and reduces heat stress in Hanwoo steers under heat stress conditions

Yves Kamali1, Yong-Ho Jo1, Won-Seob Kim2, Jalil Ghassemi Nejad1, Jae-Sung Lee1, Hong-Gu Lee1,*
Author Information & Copyright
1Department of Animal Science and Technology, Sanghuh College of Life Sciences, Konkuk University, Seoul 05029, Korea.
2Department of Animal Science, Michigan State University, East Lansing, MI 48824, United States.
*Corresponding Author: Hong-Gu Lee, Department of Animal Science and Technology, Sanghuh College of Life Sciences, Konkuk University, Seoul 05029, Korea, Republic of. Phone: +82-2-450-0523. E-mail: hglee66@konkuk.ac.kr.

© Copyright 2022 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: Jun 15, 2022; Revised: Aug 18, 2022; Accepted: Sep 28, 2022

Published Online: Oct 21, 2022

Abstract

This study investigated the effects of L-glutamine (Gln) supplementation on growth performance, physiological traits, heat shock proteins (<italic>HSP</italic>s), and gene expression related to muscle and adipose tissue development in Hanwoo steers under heat stress (HS) conditions. Eight Hanwoo steers (initial body weight (BW) 570.7±43.6 kg, months of age 22.3± 0.88) were randomly separated into two groups, control and treatment, and supplied with the concentration (1.5% of BW kg/day/head) and rice straw (1.5 kg/day/head). The treatment group were fed the Gln supplementation (0.5% of concentration, as-fed basis) once a day at 0800 h. Blood samples for the assessment of haematological and biochemical parameters and the separation of peripheral blood mononuclear cells (PBMCs) were collected four times, at 0, 3, 6, and 10 weeks of the experiment. Feed intake was measured daily. BW to analyze growth performance and hair follicle collection to analyze the expression of <italic>HSPs</italic> were executed four times at 0, 3, 6, and 10 weeks. To analyze gene expression, <italic>longissimus dorsi</italic> muscle samples were collected by biopsy at the end of the study. As a result, growing performance, including final BW, average daily gain, and gain-to-feed ratio, were not different between the two groups. Leukocytes including lymphocytes and granulocytes, tended to increase in the Gln supplementation group (<italic>p </italic>= 0.058). There were also no differences in biochemical parameters shown between the two groups, except total protein and albumin, both of which were lower in the Gln supplementation group (<italic>p </italic>&lt; 0.05). Gene expressions related to muscle and adipose tissue development were not different between the two groups. As temperature–humidity index increased, <italic>HSP70</italic> and <italic>HSP90</italic> expression in the hair follicle showed a high correlation. <italic>HSP90 </italic>in the hair follicle was decreased in the treatment group compared with the control group at 10 weeks (<italic>p </italic>&lt; 0.05). Collectively, dietary Gln supplementation (0.5% of concentration, as-fed basis) may not be influential enough to affect growth performance and gene expression related to muscle and adipose tissue development in steers. However, Gln supplementation increased the number of immune cells and decreased <italic>HSP90</italic> in the hair follicle implying HS reduction in the corresponding group.

Keywords: L-glutamine; Hanwoo steer; heat shock protein; heat stress; immunity