Recently, a research article entitled “Metabolomics investigation of dietary effects on flesh quality in grass carp (Ctenopharyngodon idellus)”, was published on GigaScience, an international academic journal. It was jointly written by Professor Li Dapeng’s research team from College of Fisheries in Huazhong Agricultural University and Jeff Xia’s research team from McGill University in Canada. The research first revealed the differences on growth, physiology, biochemistry and metabolomics between grass carp fed with grass diet (Sudan grass, wheat grass and ryegrass) and with common artificial diet. Further, researchers analyzed the correlation of the differences and discussed potential regulation mechanism of these differences.
The ultrahigh density intensive farming model of grass carp may elicit growth inhibition, decrease flesh quality, and increase disease susceptibility of fish. The degradation in quality and excessive fat accumulation in cultured C. idellus have long been attributed to possible alterations in the lipid metabolism of fish muscle tissues as a result of overnutrition from artificial diets. However, few studies have investigated the dietary effects on fish muscle metabolism and possible associations between changes in fish flesh quality characteristics and metabolic alterations.
Based on metabolomics analysis by liquid chromatography-mass spectrometry (LC-MS/MS), the team found the differences in muscle metabolites and metabolic patterns among grass carp fed on different diets. The result was that Docosapentaenoic acid (DPA), Dihomo-gamma-linolenic acid and arachidonic acid (ARA) were found to be high in the muscle of grass carp fed on artificial diet, while many n-3 unsaturated fatty acids (n-3UFAS) such as aseicosapentaenoic acid(EPA) eicosanoids, alpha-linolenic acid and gamma-linolenic acid were found in the muscle of grass carp fed on grass diet. This indicated that natural grass is a better source of dietary FA and protein compared to conventional artificial fish feed. This is because grass is more efficiently absorbed and converted into beneficial polyunsaturated fatty acid (PUFA) and other nutrients, thereby improving the ratio of n-3/n-6 PUFA in fish flesh. Correspondingly, the differential metabolites were significantly enriched in steroid hormone biosynthesis, ARA, and lenoleic acid metabolisms, as well as primary bile acid biosynthesis pathways. Therefore, the changes of lipid metabolism in muscle may be a potential regulatory mechanism for the difference of lipid deposition between grass carp fed on artificial diet and on grass diet. Furthermore, significantly upregulated nutritious and functional compounds (EPA, ALA, GLA and Eicosanoids) in grass-fed fish have been proved to help prevent cardiovascular and inflammatory diseases in humans. Thus, grass-fed fish meets consumers’ demand for high-quality, safe, and healthy aquatic products.
Doctor graduate student Zhao Honghao from College of Fisheries in HZAU is the first author and Professor Li and Jeff Xia are the corresponding authors. The research was funded by Talents of National Technology System for Conventional Freshwater Fish Industries, National Natural Science Foundation of China, and Sci-Tech Innovation Fund of HZAU.
Source: http://news.hzau.edu.cn/2018/1011/52836.shtml
Translated by Yang Chengzhi
Supervised by Wang Xiaoyan
