title: Effects of a phytogenic feed additive on growth performance, susceptibility of channel catfish to Edwardsiella ictaluri and levels of mannose binding lectin.
abstract: A study was conducted to investigate the effect of a phytogenic feed additive (Digestarom® P.E.P. MGE; containing the essential oils carvacrol, thymol, anethol, and limonene) on growth performance and disease susceptibility to Edwardsiella ictaluri. Two hundred and fifty juvenile channel catfish, Ictalurus punctatus (7.2 ± 0.1 g) were allotted into the following treatments: Control (floating diet) and EO (floating diet supplemented with essential oils). The fish were fed their respective diets for 6 weeks. At the end of the study, all fish were exposed to virulent E. ictaluri by bath immersion (1.9 × 10(7) cfu/mL; final concentration). Plasma and tissue samples were taken to quantify protein and mRNA expression levels of mannose binding lectin (MBL). Weight gain and food conversion ratio were similar between treatments. After exposing fish to virulent E. ictaluri and monitoring mortality for 21 days, survival was 43% higher (69.5 vs 48.4%) in fish fed EO compared to fish not treated with EO (P < 0.05). One day after challenge, plasma MBL levels were down-regulated in the non-treated fish compared to non-challenged fish. In the EO fish, MBL levels were similar to non-challenged fish but significantly higher than non-treated fed fish (P < 0.001). By d 7, plasma MBL levels increased in non-treated fed fish to levels observed in the EO and non-challenged fish. On d 14, MBL mRNA levels were upregulated 15-fold in fish fed EO compared to non-treated fed fish and non-challenged fish (P < 0.001). The results demonstrate that essential oils improved survival of channel catfish challenged with E. ictaluri. Mechanisms through which essential oils improve survival may involve MBL.
authors: USDA/ARS Warmwater Aquaculture Research Unit, Thad Cochran National Warmwater Aquaculture Center, PO Box 38, Stoneville, MS 38776, USA. Electronic address: brian.peterson@ars.usda.gov.
authors: Brian C
authors: BC
authors: Peterson
authors: The 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.
authors: E
authors: E
authors: Peatman
authors: Department of Biological Sciences, The University of Memphis, Life Sciences Bldg., Memphis, TN 38152-3560, USA.
authors: D D
authors: DD
authors: Ourth
authors: USDA/ARS Warmwater Aquaculture Research Unit, Thad Cochran National Warmwater Aquaculture Center, PO Box 38, Stoneville, MS 38776, USA.
authors: G C
authors: GC
authors: Waldbieser
mesh_terms: D000821:Animal Feed / Q000032:analysis; D000818:Animals; D004032:Diet / Q000662:veterinary*; D019587:Dietary Supplements / Q000032:analysis; D004198:Disease Susceptibility / Q000382:microbiology / Q000662:veterinary; D020610:Edwardsiella ictaluri / Q000502:physiology*; D004756:Enterobacteriaceae Infections / Q000382:microbiology / Q000662:veterinary*; D005393:Fish Diseases / Q000382:microbiology*; D007059:Ictaluridae / Q000254:growth & development / Q000276:immunology* / Q000382:microbiology; D037601:Mannose-Binding Lectin / Q000008:administration & dosage / Q000276:immunology*; D009822:Oils, Volatile / Q000008:administration & dosage
chemical_list: D037601:Mannose-Binding Lectin; D009822:Oils, Volatile
keywords: Channel catfish; Essential oils; Innate immune response; Mannose binding lectin