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Diseases of Aquatic Organisms

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DAO 129:99-106 (2018)  -  DOI: https://doi.org/10.3354/dao03235

Phytogenic feed-additive effects on channel catfish rhamnose-binding lectin levels, and susceptibility to Edwardsiella ictaluri

Brian C. Peterson1,*, E. Peatman2, D. D. Ourth3, G. C. Waldbieser4

1USDA/ARS National Cold Water Marine Aquaculture Center, Franklin, ME 04643, USA
2The Fish Molecular Genetics and Biotechnology Laboratory, Department of Fisheries and Allied Aquacultures and Program of Cell and Molecular Biosciences, Aquatic Genomics Unit, Auburn University, Auburn, AL 36849, USA
3Department of Biological Sciences, Life Sciences Bldg., The University of Memphis, Memphis, TN 38152-3560, USA
4USDA/ARS Warmwater Aquaculture Research Unit, Thad Cochran National Warmwater Aquaculture Center, PO Box 38, Stoneville, MS 38776, USA
*Corresponding author:

ABSTRACT: We investigated the effects of a phytogenic feed additive on disease susceptibility to Edwardsiella ictaluri in channel catfish Ictalurus punctatus and regulation of 6 rhamnose-binding lectin (RBL) genes. Juvenile catfish (n = 250, 13.4 ± 0.1 g) were allotted to the following treatments: control (floating diet) or EO (floating diet supplemented with essential oils; Digestarom® P.E.P. MGE). The fish were fed their respective diets for 6 wk. Following subjection to different feed treatments, all fish were exposed to pathogenic E. ictaluri by bath immersion. Another group of fish were not challenged (non-challenged controls, fed control feed). Mucosal tissue samples were taken to quantify gene expression levels of RBL on Days 1 and 2 post-challenge. After challenge, survival was higher (64.4 vs. 48.0%) in fish fed EO compared to controls (p < 0.05). Relative to non-challenged controls, gill RBL1a mRNA was higher in fish fed EO (p < 0.05) on Day 1 while gill RBL3b was higher in fish fed EO (p < 0.01) on Days 1 and 2, respectively. RBL5a in the skin and proximate small intestine did not change significantly relative to non-challenged fish on Days 1 and 2 of the disease challenge. Results demonstrate that Digestarom® P.E.P. MGE improved survival of channel catfish challenged with E. ictaluri. One of the mechanisms through which essential oils may improve survival is through upregulation of RBL1a and RBL3b in the gill.


KEY WORDS: Channel catfish · Essential oils · Rhamnose-binding lectin · Immune response


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Cite this article as: Peterson BC, Peatman E, Ourth DD, Waldbieser GC (2018) Phytogenic feed-additive effects on channel catfish rhamnose-binding lectin levels, and susceptibility to Edwardsiella ictaluri. Dis Aquat Org 129:99-106. https://doi.org/10.3354/dao03235

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