This study evaluated the effect of dietary mannan oligosaccharide (MOS) on L. vannamei production performance under intensive culture conditions in Ec

Effect of mannan oligosaccharides on microbiota, productivity of Pacific white shrimp in Ecuador

ECUADOR
Wednesday, April 14, 2021, 06:40 (GMT + 9)

The following is an excerpt from an article published by the Global Aquaculture Advocate:

Shrimp cultured with MOS-added feed had 30 percent higher survival in intensive production conditions

Regarding disease management in aquaculture, prevention is more advisable than treatment. One such strategy is to modify the intestinal microbiota [ecological communities of microorganisms found in and on all multicellular organisms] of the cultured animal to promote the colonization of beneficial bacteria and to prevent the colonization of potentially pathogenic bacteria.

Mannan oligosaccharides (MOS) are glucides [organic compounds that contain a carbohydrate] obtained from the Saccharomyces cerevisiae yeast cell. The use of MOS to block pathogen colonization is based on the knowledge that certain polysaccharides [large molecules made of many smaller simple sugars] could be used to block the mechanism of recognition and adhesion of potential pathogens to molecules on the surfaces of host tissues (competition for attachment sites). This action would reduce the adhesion of the pathogens to the digestive tract, leaving them to be excreted in the feces. This may lead to improvement of the integrity and performance of the intestinal epithelial barrier.

Productivity outcomes. Graphic representation of the average harvested biomass (Kg) and yield (Kg/Ha) of L. vannamei in ponds supplemented with mannan oligosaccharides (MOS) and ponds with a commercial diet (Control).

There are no previous publications using deep, Next Generation Sequencing (NGS, a technology to determine the sequence of DNA or RNA to study genetic variation associated with diseases or other biological phenomena) to assess the effects of MOS in the microbiota of Pacific white shrimp (Litopenaeus vannamei). Several studies have reported the effects of MOS on crustacean culture performance including parameters such as growth rates, survival, changes in gastrointestinal (GI) morphology and others. But these previous investigations were conducted under laboratory conditions and involved only cultivable bacteria. These observations have not been validated at a commercial farming scale, limiting the application of those prebiotics. And for cultured crustaceans such as L. vannamei, available information on the functionality and structuring of their microbiota is very limited.

This article – adapted and summarized from the original publication [Gainza, O., Romero, J. Effect of mannan oligosaccharides on the microbiota and productivity parameters of Litopenaeus vannamei shrimp under intensive cultivation in Ecuador. Sci Rep 10, 2719 (2020)] –reports on a study using NGS to assess the effects of the dietary inclusion of a prebiotic (MOS) on production parameters in intensive cultivation conditions of, and the composition of the intestinal microbiobiota of L. vannamei in Ecuador.

Comparison of relative abundance at the phylum level. Shrimp microbiota composition (relative to OTU composition) at the phylum level. Comparison between Control and MOS shrimp microbiota including the 11 phyla showing the highest abundance. Taxonomic summary of the observed relative abundance of abundant phyla across all samples divided by culture condition.| Click image to enlarge

Study setup

The study was carried out at the Santa Ana intensive shrimp farm in El Oro Province, Ecuador. Approximately 1,780,000 L. vannamei juveniles (average initial weight of 2.2 ± 0.53 grams) were distributed in four, 0.5-hectare ponds under greenhouses, each with controlled water temperature (32 to 34 degrees-C), 5 ppt salinity, and dissolved oxygen saturation above 60 percent. To minimize the factors that could influence the results of the experiment, we standardized conditions such as pond maturation stage to avoid interfering with the experimental cultured shrimp.

The shrimp were cultured for 59 days until they reached harvest weight. They were fed four times per day with a commercial feed (Nicovita Classic Camarón; Vitapro, Callao, Peru) with 35 percent protein and 5 percent fat. MOS (Bio-Mos®, Alltech Inc., Nicholasville, KY, US) at 0.5 percent weight per weight (w/w) was added to the feed through the dilution of MOS in distilled water (0.125 g/mL) plus commercial gelatin (0.125 g/mL), sprayed onto the feed (0.04 mL/g) in a mechanical hopper for homogenization. The food for the two control ponds was prepared with the same protocol with the addition of commercial gelatin without MOS. Several shrimp samples were collected for different laboratory analyses.

Comparison of the relative abundance of the most abundant genera between Control and MOS shrimp microbiota. Microbiota composition (relative to OTUs composition) at genus level, between Control and MOS supplemented microbiota. Taxonomic summary of observed relative abundance of abundant genera across all samples divided by culture condition.| Click image to enlarge

For detailed information on the experimental design and husbandry protocols; sampling procedures; DNA extraction and PCR amplification; high-performance mass sequencing and data processing; and statistical analyses, refer to the original publication. (continues...)

Author: Oreste Gainza, Ph. D. and Jaime Romero, Ph. D. / Global Aquaculture Advocate | Read the full article by clicking the link here

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