Diet Affects Muscle Quality and Growth Traits of Grass Carp (Ctenopharyngodon idellus): A Comparison Between Grass and Artificial Feed

Abstract

Fish muscle, the main edible parts with high protein level and low fat level, is consumed worldwide. Diet contributes greatly to fish growth performance and muscle quality. In order to elucidate the correlation between diet and muscle quality, the same batch of juvenile grass carp (Ctenopharyngodon idellus) were divided into two groups and fed with either grass (Lolium perenne, Euphrasia pectinata and Sorghum sudanense) or artificial feed, respectively. However, the different two diets didn't result in significant differences in all the detected water quality parameters (e.g., Tm, pH, DO, NH3/NH4+-N, NO3--N, NO2-, TN, TP, and TOC) between the two experimental groups. After a 4-month culture period, various indexes and expression of myogenic regulatory factor (MRFs) and their related genes were tested. The weight gain of the fish fed with artificial feed (AFG) was nearly 40% higher than the fish fed with grass (GFG). Significantly higher alkaline phosphatase, total cholestrol, high density cholestrol and total protein were detected in GFG as compared to AFG. GFG also showed increased hardness, resilience and shear force in texture profile analysis, with significantly bigger and compact muscle fibers in histologic slices. The fat accumulation was most serious in the abdomen muscle of AFG. Additionally, the expression levels of MyoG, MyoD, IGF-1, and MSTNs were higher, whereas Myf-5, MRF4, and IGF-2 were lower in most positional muscles of GFG as compared to AFG. Overall, these results suggested that feeding grass could promote muscle growth and development by stimulating muscle fiber hypertrophy, as well as significantly enhance the expression of CoL1As. Feeding C. idellus with grass could also improve flesh quality by improving muscle characteristics, enhancing the production of collagen, meanthile, reducing fat accumulation and moisture in muscle, but at the cost of a slower growth.

Metabolomics investigation of dietary effects on flesh quality in grass carp (Ctenopharyngodon idellus)

“…In this study, we found significantly different growth performance between the AF and natural GF groups. This observation is consistent with the previous study, whereby feeding C. idellus with natural grass resulted in significantly lower WG in both FGF and MGF groups [ 21 , 27 ]. The negative correlation between enhanced dietary fibers and low-fat diet with reduced WG was also demonstrated in Barbodes altus and Oncorhynchus mykiss [ 28 , 29 ].…”

“…In line with the previous findings, the increased arachidic acid (20:0), stearic acid (18:0), and palmitic acid (16:0) were detected in our GF groups; therefore, the flesh of GF C. idellus would be harder than that of AF fish. This conclusion is consistent and proven by our previously published test results of textures, shear force detection, and fatty acid content measurements of the two feeding groups' C. idellus flesh [ 21 , 27 ]. Previous research has also shown that higher arachidic acid can interfere with essential fatty acid metabolism by inhibiting the Δ-6 desaturase enzyme, which reduces the formations of DGLA (20:3n-6) and ARA (20:4n-6) [ 43 ].…”

“…In our study, a large amount of metabolites were detected and differentially enriched in energy metabolism between the two feeding groups, indicating that metabolic alteration is the main mechanism by which fish respond to different feeding patterns. Furthermore, the potential associations between physiological changes (the muscle characteristics, together with nutrients and textures measured in our previously published studies) [ 21 , 27 ] and metabolic profiles in different feeding conditions are systematically examined below.…”

“…It is widely accepted that long-term feeding of artificial diets likely contributes to the decline of fish flesh taste [ 21 ]. 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.…”

Feeding Faba Beans (Vicia faba L.) Reduces Myocyte Metabolic Activity in Grass Carp (Ctenopharyngodon idellus)

“…Our study showed a reduction in energy metabolism activity, which may be one of the reasons for subdued myogenesis in grass carps. Interestingly, muscle texture quality was influenced when fish were exposed to starvation conditions or low energy diets (Bugeon et al, 2004;Zhao et al, 2018). Our study showed that the energy was mostly deposited in some visceral tissues (adipose tissue and hepatopancreas) of FBFGs, whereas no difference in muscle lipid content was found between the two diet groups, which could further exacerbate the energy shortage in the muscle FIGURE 7 | Schematic overview of the proposed energy metabolic flux of grass carp in response to faba bean.…”