Dietary effects of melatonin on growth performance by modulation of protein bioavailability and behavior in early weaned rats and pigs

Min-jin Kwak1, Kyeong Su Chae2, Jong Nam Kim3, Kwang-Youn Whang2, Younghoon Kim1,*
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1Department of Agricultural Biotechnology and Research Institute of Agriculture and Life Science, Seoul National University, Seoul 08826, Korea.
2Division of Biotechnology, College of Life Science and Biotechnology, Korea University, Seoul 02841, Korea.
3Department of Food Science & Nutrition, Dongseo University, Busan 47011, Korea.
*Corresponding Author: Younghoon Kim, Department of Agricultural Biotechnology and Research Institute of Agriculture and Life Science, Seoul National University, Seoul 08826, Korea, Republic of. E-mail:

© Copyright 2023 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 ( which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.


Melatonin, which is produced from tryptophan, exerts various biological functions, including the regulation of circadian rhythm, sedative agents, and antioxidant ability. Therefore, we conducted two experiments with early weaned rats and pigs to investigate the antioxidant effect and reductive effect of energy-wasting behavior. In the rat experiment, a total of 42 rats (21 days old) were used, and the antioxidant capacity was determined. Next, we used 120 early-weaned piglets (21 days old) to conduct a 5-week experiment to evaluate the reductive effect of melatonin on energy-wasting movement, including roaming and fight states. Dietary melatonin supplementation significantly improved growth in both rats and pigs compared to the control groups. Additionally, rats fed a melatonin-supplemented diet showed advanced antioxidant capacity with a decrease in hepatic malondialdehyde concentration compared to rats fed a basal diet. Moreover, dietary melatonin ingestion increased resting and feeding behaviors and reduced roaming and fight behaviors during Days 8-21 compared to the control diet group. Collectively, early weaned animals given dietary melatonin supplementation showed improved growth through upregulation of hepatic antioxidant capacity and minimization of energy-wasting behavior, including roaming and fight states, after pigs’ social hierarchy establishment.

Keywords: Antioxidant; Behavior; Growth performance; Melatonin; Pig; Rat