Dietary Microencapsulated Blend of Organic Acids and Plant Essential Oils Affects Intestinal Morphology and Microbiome of Rainbow Trout (Oncorhynchus mykiss).

David Huyben,John S Lumsden,Mohiuddin A Kabir Chowdhury,Marcia Chiasson,Phuc H Pham

doi:10.3390/microorganisms9102063

David Huyben, John S Lumsden + Show 3 more

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https://doi.org/10.3390/microorganisms9102063

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Journal: Microorganisms	Publication Date: Sep 30, 2021
Citations: 19	License type: CC BY 4.0

Affiliation: University of Guelph

Abstract

A study was conducted on 500 juvenile rainbow trout (122 ± 4 g) fed either a control diet or a treatment diet containing 300 mg/kg of a microencapsulated blend of organic acids and essential oils to elucidate effects on intestinal morphology and microbiome. Proximal intestinal villi length was significantly increased in fish fed the treatment diet. Despite no differences in gut inflammation scores, edema, lamina propria inflammation and apoptosis were completely absent in the distal intestine of fish fed the treatment diet. Next-generation sequencing of the 16S rDNA showed no differences in alpha and beta diversity, and gut bacteria were mainly composed of Firmicutes, Bacteroidetes and Proteobacteria. On the genus level, LefSe analysis of indicator OTUs showed Bacteroides, Sporosarcina, Veillonella, Aeromonas and Acinetobacter were associated with the control diet whereas Streptococcus, Fusobacterium and Escherichia were associated with the treatment diet. Aeromonas hydrophila and Acinetobacter spp. are opportunistic pathogens and several strains have been found to be resistant to antibiotics. The increase in villi length and reduction of specific pathogens indicates that feeding a microencapsulated blend of organic acids and essential oils improves gut health and may serve as a part of an effective strategy to reduce antibiotic use in aquaculture.

Highlights

Many animal and plant proteins have been used to reduce the use of fish meal in aquafeed
Organic acids and essential oils hold high potential to improve nutrient uptake and gut health of fish as alternative to antibiotics, most studies to date have focused on warm water fish and shrimp species
It was worth noting that edema, inflammation of the lamina propria and necrosis/apoptosis had a mean score of 0.0 in the distal intestine for fish fed the treatment diet

Summary

Introduction

Many animal and plant proteins have been used to reduce the use of fish meal in aquafeed. The use is severely restricted because of their imbalanced amino acid profile, presence of anti-nutrients, poor palatability and reduced digestibility [1]. Several nutritional strategies such as supplementation of amino acids and enzymes have been adopted to improve the utilization of these protein sources and to improve nutrient uptake [2,3]. Organic acids and essential oils hold high potential to improve nutrient uptake and gut health of fish as alternative to antibiotics, most studies to date have focused on warm water fish and shrimp species

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