AUTHOR=Xue Shuqun , Xia Banghua , Zhang Bitao , Li Linyuan , Zou Yuning , Shen Zhentao , Xiang Yifang , Han Ying , Chen Weixing 

TITLE=Mannan oligosaccharide (MOS) on growth performance, immunity, inflammatory and antioxidant responses of the common carp (Cyprinus carpio) under ammonia stress

JOURNAL=Frontiers in Marine Science

VOLUME=Volume 9 - 2022

YEAR=2022

URL=https://www.frontiersin.org/journals/marine-science/articles/10.3389/fmars.2022.1062597

DOI=10.3389/fmars.2022.1062597

ISSN=2296-7745

ABSTRACT=This study evaluated the potential effects of mannan oligosaccharide (MOS) on the health status of common carp under ammonia stress. The experimental fish were equally divided into four groups. The control group was fed with a basal diet. The ammonia stress group (Am group) was fed with a basal diet and set in the culture environment with 0.15 mg/L NH3. The MOS group was fed 0.2% MOS with a basal diet. The treatment group (MOS/Am group) was fed 0.2% MOS feed under ammonia exposure (NH3, 0.15 mg/L). These groups were fed for 30 d. The results showed that under ammonia stress, the growth performance decreased significantly, and the activities of non-specific immune factors, intestinal digestive enzymes, and antioxidant enzymes decreased significantly. Malondialdehyde (MDA) and reactive oxygen species (ROS) contents increased, and the gene expression levels of antioxidant enzyme and heat shock protein were increased in the AM group (P < 0.05). Dietary supplementation of MOS, the growth performance, the activities of non-specific immune factors, intestinal digestive enzymes, and antioxidant enzymes increased. The contents of MDA and ROS decreased, and the messenger RNA (mRNA) expression levels of growth genes and antioxidative enzymes increased significantly in the Am group (P < 0.05).The activities of serum proinflammatory cytokines, such asinterleukin-1β (IL-1β), interleukin-6 (IL-6), interleukin-8 (IL-8), interferon-gamma (IFN-γ), and tumor necrosis factor-α (TNF-α), increased significantly in the AM group, and IL-6, IL-8, TNF- α decreased significantly in the MOS group (P < 0.05). Histopathological studies showed that adding MOS reduced liver, gill, and intestine tissue damage under ammonia exposure. Ammonia stress led to the decline of growth performance, immunity and antioxidant capacity, and inflammatory response of the common carp. Our study suggests that adding MOS to the diet can improve growth performance, immunity, antioxidant capacity, and intestinal health of the common carp. MOS can effectively alleviate the oxidative damage and inflammatory response caused by ammonia poisoning to common carp.