The production of environmentally sustainable aquaculture feeds starts with the selection of high-quality raw materials that may need to be supplemented with specific nutrients. Nevertheless, different competences for developing tools and methodologies are needed to assess and predict nutrient requirements or status of fish, going further than just identifying differences in growth parameters. Thus, the challenge is to screen and make the best use of a given tool, but also to integrate new knowledge arising from transcriptomics, proteomics, metagenomics and metabolomics in order to define a reliable healthy fish phenotype. Of particular value are biomarkers that precede the onset of metabolic disturbances or those that predict the capacity to cope with dietary, environmental and age-related stresses. Hence, changes in the intestinal transcriptome, integrity of intestinal barrier, intestinal mucus proteome and gut microbiota mostly reflect a pro-inflammatory condition in fish fed plant-based diets, but dietary butyrate helps to restore the wild phenotype resulting in improved diseases outcomes in fish challenged with bacteria and enteric parasites. Currently, a new promising omics approach is metabolomics, and more than 15,000 m/z ions have been detected in the serum metabolome of juvenile fish with around 850 highly discriminant features between fed and short-term fasted fish, using ultra-high performance liquid chromatography (UHPLC) coupled to high resolution mass spectrometry (HRMS). When comparing the serum metabolome of fish fed marine and plant-based diets, several lipid related compounds, including phosphocholines, lysophosphocholines and sphingolipids raised as highly discriminatory compounds. A number of exogenous compounds (cysteinolic acid, tauropine, trimethylamine N-oxide, arsenobetaine, hercynin) also contributed to discriminate fish with different nutritional backgrounds. However, from a functional point of view, it is of special relevance that the abundance of N-aryl amino acids, with repair properties in epithelial mucosa, is consistently reduced in fish fed plant-based diets. Conversely, circulating levels of pyrimidine and related nucleosides, especially markers of DNA degradation (deoxycytidine) and methylation (methylcytosine) were increased by plant-based diets, which is viewed as part of a pro-inflammatory condition and/or overall cellular DNA instability. This opens new research issues to alleviate or mitigate the drawback effects of plant based diets in marine carnivorous farmed fish.

Trabajo presentado en el 18th International Symposium on Fish Nutrition and Feeding (ISFNF), celebrado en Las Palmas de Gran Canaria (España), del 3 al 07 de junio de 2018

Peer reviewed