Search

Simple Summary: Yellow River Carp (Cyprinus carpio haematopterus) is a major commercial farmed species belonging to Cyprinus carpio, which has been cultivated widely, especially in Northern China. However, no relative literature focused on appropriate dietary protein level for large-sized Cyprinus carpio haematopterus. The present study investigated the effects of different dietary protein levels on the growth performance, physicochemical indexes, quality, and molecular expression of Cyprinus carpio haematopterus and aimed to determine which dietary protein level was most appropriate for Cyprinus carpio haematopterus. It was found that the optimal dietary protein level for Cyprinus carpio haematopterus (160.24 ± 15.56 g) is 250–280 g/kg based on different aspect analysis. This study is also helpful in laying the foundations for the breeding of new carp varieties with low dietary protein levels. A 12-week rearing trial was carried out to estimate effects on the growth performance, physicochemical indexes, quality, and the molecular expression of Yellow River Carp (Cyprinus carpio haematopterus) using five practical diets, including dietary protein levels of 220, 250, 280, 310, and 340 g/kg. The results illustrated that the fish's weight gain (WG) and specific growth rate (SGR) were significantly influenced, with an ascending dietary protein level of up to 250 g/kg (p < 0.05). The carp muscle contents of total saturated fatty acids (∑SFA), monounsaturated fatty acids (∑MUFA), polyunsaturated fatty acids (∑PUFA), and fatty acids (∑FA) decreased significantly with the ascending dietary protein levels, except for the 250 g/kg protein diet (p < 0.05). Only the glutamic acid and total essential amino acid (∑EAA) contents were significantly influenced by the ascending dietary protein levels (p < 0.05). The relative GH expression of the carp muscle significantly decreased with the increase in the dietary protein level up to 310 g/kg, and then it significantly increased (p < 0.05). In the intestines, the peak relative TOR expression was observed on the 220 g/kg protein diet, while the relative 4EBP1 expression was significantly influenced by the dietary protein level up to 250 g/kg (p < 0.05). In the muscle, the peak relative TOR and 4EBP1 expression levels were observed on the 250 g/kg protein diet. In gills, the lowest relative Rhag, Rhbg, and Rhcg1 expression levels were observed on the 250 g/kg protein diet. Based on all of the aforementioned results, the optimal dietary protein level for Cyprinus carpio haematopterus (160.24 ± 15.56 g) is 250–280 g/kg. [ABSTRACT FROM AUTHOR]

Common carp (Cyprinus carpio) is an economically important fish worldwide, with many of its species bred for consumption. However, there are few reports on the comprehensive comparative analysis of the muscle nutritional quality and stress resistance characteristics of different common carp species. In this study, after 15 months of feeding in the same environment, the nutritional components, serum biochemical indices, liver antioxidant and intestinal digestive enzyme activities, and muscle growth-related gene expression were determined in Songpu mirror carp (SPM; Cyprinus carpio Songpumirror), Heilongjiang wild carp (HLJ; Cyprinus carpio haematopirus), cold-resistant strain of purse red carp (CPR; Cyprinus carpio 'Red purse cold-resistant'), Songhe carp (SH; Cyprinus carpio 'Songhe'), and Songpu carp (SP; Cyprinus carpio Songpu). Muscle nutrient composition showed that HLJ had a significantly lower crude fat content and higher docosahexaenoic acid (DHA) + eicosapentaenoic acid (EPA) proportion than the other four common carp species (p < 0.05). The contents of lysine (Lys) and aspargine (Asp) were significantly higher in the CPR than in other species (p < 0.05). Serum biochemical parameters showed that total protein (TP), total cholesterol (T-CHO), triglycerides (TG), and low-density lipoprotein (LDL) were significantly lower in SPM than in the other species (p < 0.05). The results of tissue enzyme activity showed that the activities of superoxide dismutase (SOD) and catalase from Micrococcus lysodeikticus (CAT) in the liver were significantly higher, while the activities of lipase (LPS), trypsin (TRS), and α-amylase (α-AMS) in the intestine were significantly the lower in HLJ than in the other species (p < 0.05). In addition, the relative expression levels of growth hormone (GH), growth hormone receptor (GHR), insulin-like growth factor 1 (IGF1), insulin-like growth factor receptor (IGF1R), and myoblast determination factor (MyoD) in SP and SH were significantly higher than those in the other species, while the relative expression of myostatin (MSTN) in HLJ was significantly higher (p < 0.05). Therefore, there were significant differences in muscle nutritional quality, serum biochemical indices, liver, and intestinal enzyme activities, and muscle growth potential among the five species of common carp. This study could provide a theoretical basis for the germplasm evaluation and variety improvement of common carp. [ABSTRACT FROM AUTHOR]

Megalobrama terminalis, which inhabits the Sino-Russian Heilong-Amur River Basin, has decreased critically since the 1960s. It has been listed in the Red Book of Endangered Fish Species by the Russian Federation in 2004. To guide the utilization and conservation programs of M. terminalis in the Heilong River (MTH), 3.1 kb of mitochondrial DNA (mtDNA) concatenated sequences and sequence-related amplified polymorphism (SRAP) markers (15 primer combinations) were applied to explore the genetic divergence and population differentiation of MTH within the genus Megalobrama. Clear genetic divergence between MTH and six other populations of the genus Megalobrama was found by haplotype network (mtDNA) and principal component (SRAP) analyses. Moreover, the STRUCTURE analysis based on SRAP data showed that MTH could be assigned to a particular cluster, whereas conspecific M. terminalis in the Qiantang River and Jinsha River Reservoir belonged to the same cluster. Analysis of molecular variance (AMOVA) and Fst statistics for the mtDNA and SRAP data revealed significant genetic variance and differentiation among all detected populations. Taken together, the results suggest that MTH has a strong genetic differentiation from other populations within the genus Megalobrama, which contributes to effective utilization in artificial cultivation and breeding of MTH. Furthermore, these results also provide a scientific basis for the management of MTH as a separate conservation unit. [ABSTRACT FROM AUTHOR]