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The objective of the present study was to evaluate the effects of replacing fish meal (FM) with spray-dried blood meal (SDBM) on growth performance, antioxidant capacity, digestive enzyme activity, tissue Fe content, gene expression related to inflammation, and the TOR pathway in juvenile swimming crab (Portunus trituberculatus). Four isonitrogenous (47.0% protein) and isolipidic (9.0% lipid) diets were formulated to contain different levels of SDBM, with FM replaced by SDBM at 0, 10%, 20%, and 30%, respectively. The results showed that crabs fed diet SDBM30 exhibited the lowest survival among all treatments, and crabs fed the SDBM20 diet had the highest final weight, percent weight gain, specific growth rate and feed efficiency among all treatments. In addition, the protein content of the crab hepatopancreas decreased significantly and the lipid content increased significantly as SDBM replaced FM in the diets. Compared to other diets, crabs fed the SDBM30 diet had the lowest activities of antioxidant enzymes and the highest concentration of malondialdehyde in the hepatopancreas and hemolymph. The Fe contents in hepatopancreas and gill increased significantly, and the color of the hepatopancreas got darker as replacement of FM with SDBM increased from 0% to 30%. The expression of genes related to TOR (tor, akt, s6, and s6k1) and antioxidant (gpx) pathways in the hepatopancreas were down-regulated significantly with increased replacement of dietary FM with SDBM. In contrast, expression levels of genes related to protein translation (4ebp1, eif4e1a, eif4e2, and eif4e3) and inflammation pathways (myd88, traf6, relish, and irak4) were up-regulated significantly in crabs fed diets with SDBM supplementation. In summary, replacing FM with less than 20% of SDBM can promote the growth, but can darken the hepatopancreas, negatively affect antioxidant capacity, and induce an inflammatory response.

An 8-week feeding trial was conducted in Pacific white shrimp (Litopenaeus vannamei) to evaluate the effects of dietary choline supplementation on choline transport and metabolism, hepatopancreas histological structure and fatty acid profile, and regulation of lipid metabolism. Six isonitrogenous and isolipidic diets were formulated to contain different choline levels of 2.91 (basal diet), 3.85, 4.67, 6.55, 10.70 and 18.90 g/kg, respectively. A total of 960 shrimp (initial weight, 1.38 ± 0.01 g) were distributed randomly into twenty-four 250-L cylindrical fiber-glass tanks, with each diet assigned randomly to 4 replicate tanks. The results indicated that dietary choline significantly promoted the deposition of choline, betaine and carnitine (P

The intestinal function of hibernating animals undergoes seasonal changes, during which they are in a fasting state, which also affects the morphology, structure, and function of intestine. The aim of this study was to analyse the histological differences in the intestinal structure, goblet cells, and mucosa of the initial (ISI), anterior (ASI), middle (MSI) and posterior (PSI) of small intestine of Pelodiscus sinensis during the whole hibernation process and to investigate the role of the key enzyme creatine kinase (CK) in regulating energy homeostasis during hibernation. The results of HE staining showed that the intestinal mucosa of the P. sinensis during hibernation presented detachment and atrophy of villus, and narrowing of gaps while the villous length of the ISI, ASI, MSI, and PSI were significantly decreased than those in normal stage. As hibernation progresses, the intestinal crypt of the ISI first increased and then decreased significantly. The AB-PAS staining results revealed that as hibernation progressed, the number of type Ⅰ goblet cells in the ISI significantly increased, while the number of type Ⅲ goblet cells significantly decreased. The immunohistochemical results revealed that CK-MB was highly expressed in the intestinal villus of P. sinensis. During hibernation, the expression of CK-MB in P. sinensis continued to increase in the ISI and decrease in the PSI. In summary, the results of this study suggested that hibernation process could alter the morphological structure of the ISI and ASI of P. sinensis, making them more vulnerable. Meanwhile, the ISI may protect the mucosal tissue during hibernation by increasing type Ⅲ goblet cells and decreasing type I goblet cells. During this process, the continuously increasing expression of CK in the ISI may participate in the adaptation of P. sinensis to intestinal hibernation by regulating energy metabolism.

ABSTRACT: The eggshell color of avian species is an important trait that is predominantly determined by the pigments biliverdin and protoporphyrin. Various factors affect eggshell pigment deposition and coloration; however, the underlying mechanisms remain unclear. We analyzed the hepatic transcriptomes and metabolomes of Changshun green-shell hens laying dark green and light green eggs to investigate the potential role of the liver in regulating the intensity of the green eggshell color. In total, 350 differentially expressed genes and 211 differentially altered metabolites were identified. Gene set enrichment analysis revealed that the enriched pathways and Gene Ontology (GO) terms were mainly associated with energy, immunity, and nutrient metabolism. Metabolite set enrichment analysis revealed that the enriched pathways were mainly associated with amino acid, vitamin, bile acid, and lipid metabolism. Moreover, gene–metabolite interaction network analysis revealed 1 subnetwork. Most genes and metabolites in this subnetwork were determined to be related to melanin metabolism and transport. In conclusion, our results suggest that hepatic melanin metabolism and transport are critical for eggshell coloration. Six candidate genes (CDKN2B, DDC, PYCR1, ABCG5, SLC3A1, and P2RX2) and 7 candidate metabolites (serotonin, 5-hydroxyindoleacetic acid, ornithine, acetylcholine, L-tryptophan, D-ornithine, and ADP) were suggested to play important roles in this process. Meanwhile, this study suggests that changes in hepatic energy metabolism, immune status, antioxidation activity, nutrient availability, and bile acid synthesis can impair eggshell coloration.

An eight-week feeding trial was conducted to determine the optimal dietary histidine requirement of juvenile swimming crab (Portunus trituberculatus). Six isonitrogenous and isolipidic diets (45.0% crude protein and 8.0% crude lipid) were formulated to contain 0.43%, 0.68%, 0.97%, 1.24%, 1.45% and 1.79% histidine, respectively. Each diet was randomly assigned to triplicate groups of 30 juvenile crabs (approximately initial weight 17.63 ± 0.08 g). The results indicated that the highest percent weight gain (PWG) and specific growth rate (SGR) was presented in crabs fed the diet with 1.24% histidine (P

The physiological processes involved in adaptation to osmotic pressure in euryhaline crustaceans are highly energy demanding, but the effects of dietary lipids (fat) on low salinity adaptations have not been well evaluated. In the present study, a total of 120 mud crabs (Scylla paramamosain, BW = 17.87 ± 1.49 g) were fed control and high-fat (HF) diets, at both medium salinity (23‰) and low salinity (4‰) for 6 wk, and each treatment had 3 replicates with each replicate containing 10 crabs. The results indicated that a HF diet significantly mitigated the reduction in survival rate, percent weight gain and feed efficiency induced by low salinity (P

An 8-week feeding trial was conducted to evaluate the effects of replacing fish meal with spray-dried egg meal (SEM) on growth performance, anti-oxidative capacity, mTOR pathway, and cholesterol metabolism in juvenile Portunus trituberculatus. The results showed that the highest percent weight gain was observed in crabs fed diet with 10% replacement of fish meal with SEM. Essential amino acids in the muscle and hepatopancreas significantly decreased with the increase of dietary replacement levels of fish meal with SEM. The lowest content of MDA in hepatopancreas was occurred at those fed diet with 40% replacement of fish meal with SEM, the activities of T-AOC, GSH-PX and content of GSH in hepatopancreas significantly increased with dietary SEM replacement fish meal increasing from 10% to 50%. The expression of akt, eif4e1a, eif4e2, eif4e3, and 4ebp1 significantly up-regulated, however, the expression of tor was showed significantly linear down-regulated, and the highest expression of akt, eif4e2 and 4ebp1 were found in crabs fed diet with 20% replacement of fish meal with SEM, the highest expression of eif4e1a was observed in those fed diet with 10% replacement of fish meal with SEM, the highest expression of eif4e3 was occurred in crabs fed diet with 30% replacement of fish meal with SEM. In cholesterol metabolism, the expression of abcg1 and lrp2 significantly down-regulated and the expression of npc1 significantly up-regulated with increase of replacement level of fish meal with SEM. The content of T-CHO in hemolymph and hepatopancreas significantly linear increased. In conclusion, based on quadratic broken-line regression analysis of PWG against the dietary replacement of fish meal with SEM, the optimal replacement level of fish meal with SEM was estimated to be 15.94% for juvenile swimming crab.

Cholesterol, as an indispensable nutrient, regulates molting and growth in crustacean. As crustaceans are unable to biosynthesize cholesterol de novo, it is central to understand how dietary cholesterol affects molting in crustaceans. An 8-week feeding trial was conducted to evaluate the effects of dietary cholesterol level (0.12%, 0.43%, 0.79%, 1.00%, 1.30% and 2.50%) on growth, cholesterol metabolism and expression of genes related to lipid and ecdysone metabolism in female swimming crabs (Portunus trituberculatus). A total of 192 crabs (1.41 ± 0.05 g) were randomly distributed into 192 aquaria. Each treatment had 4 replicates with each replicate containing 8 crabs. Crabs fed the 1.00% cholesterol diet showed best growth performance, and thus based on percent weight gain, the optimal dietary cholesterol requirement was calculated at 1.01%. Tissue cholesterol concentrations were positively correlated with dietary cholesterol level. The contents of functional fatty acids in hepatopancreas significantly increased as dietary cholesterol increased from 0.12% to 2.50% (P

The present study aimed to evaluate the effects of dietary inositol level on the growth performance and barriers function of hemolymph and intestine of Litopenaeus vannamei. Six isonitrogenous and isolipidic diets were formulated with analyzed inositol levels being 0.86 (basal diet), 1.34, 1.40, 2.30, 3.88, and 7.50 g kg−1, respectively. The results indicated that appropriate dietary inositol could improve the growth performance of Litopenaeus vannamei. The optimal dietary inositol requirement was 1.44 g kg−1 according to broken-line regression analysis with the WGR as the evaluation index. The activities of non-specific immune enzymes (SOD, ACP, ALP and NOS) in hemolymph and the expression levels of genes involved in the Toll signaling pathway (toll, pelle and traf6) in hemocyte of shrimp fed diet containing 1.40 g kg−1 inositol significantly higher than those in shrimp fed diet containing 0.86 g kg−1 inositol, and the activities of PO and SAHR in hemolymph and the expression levels of genes involved in immune enzymes (Mn-sod, Cu/Zn sod, acp, akp and po) in hemocyte of shrimp fed diet containing 1.40, 2.30, 3.88 and 7.50 g kg−1 inositol significantly higher than those in shrimp fed diet containing 0.86 g kg−1 inositol, suggesting that appropriate dietary inositol can improve hemolymph immunity by increasing the activities of antioxidant and immune enzymes in the hemolymph. In addition, the intestinal VH and the expression levels of genes involved in intestinal health (zo-1, cyclC, tgfβ and il2) in shrimp fed diet containing 1.40 g kg−1 inositol were the highest. Meanwhile, the inositol content, VW, and the expression levels of genes involved in the IMD pathway (imd) and anti-lipopolysaccharide factor (alf) in the intestine were significantly correlated with dietary inositol level. These results suggested that appropriate inositol can improve intestinal health by improving intestinal morphology and the expression of health-related genes. Although dietary inositol had no significant effect on the microbial composition spectrum diversity in the hemolymph and intestine of L. vannamei, it contributed to increasing the abundance of beneficial bacteria and decreasing the abundance of opportunistic pathogens. KEGG analysis showed that dietary inositol level had significantly positive effects on multiple immune and metabolic pathways. In conclusion, dietary appropriate inositol enhanced hemolymph homeostasis and host immune defense by improving the barrier function of immune and microbial in hemolymph and improved the intestine health status by enhancing the barrier function of physical, immune and microbial in intestine.

A 22-week feeding experiment was executed to assess the impact of dietary ARA supplementation on the growth, tissue proximate composition, hemolymph biochemical, tissue fatty acids profile, ARA metabolite and sex steroid hormone, and the mRNA expression of ovarian development related gene of female mud crab in the pre-devolopmental stage. Crabs were fed with six diets containing different ARA levels (0.04%, 0.25%, 0.46%, 0.89%, 1.25%, and 1.57%, dry matter). The results showed that the increasing dietary ARA levels had significant effects on survival, percent weight gain (PWG), specific growth rate (SGR), and feed efficiency (FE), which showed an increasing trend initially and then showed a decreasing trend. According to the two-slope broken-line model and quadratic curve model for the relationship between PWG and dietary ARA levels, optimal dietary ARA levels were estimated to be 0.46% and 0.70%. The lipid contents in muscle and hepatopancreas decreased significantly with the increasing dietary ARA levels. Similarly, total cholesterol (T-CHO) and triglyceride (TG) concentrations were significantly decreased with the increasing dietary ARA levels. In the hepatopancreas and muscle, ARA contents significantly increased with the increasing dietary ARA levels. In hemolymph and hepatopancreas, progesterone (Prog), pregnenolone (Preg), estradiol (E2) and vitellogen (Vtg) concentrations presented earlier increase and later decrease trend. In the hepatopancreas, prostaglandin E2 (PGE2) and 5-hydroxyeicosatetraenoic acid (5-HETE) concentrations showed an upward trend. In the muscle, PGE2 concentration presented earlier increasing and later decreasing trend. In the ovary, the increasing dietary ARA levels produced similar effects on the expressions of genes, including steroidogenic acute regulatory protein (star), 3β-hydroxysteroid dehydrogenase (3βhsd), vitellogenin (vtg) and vitellogenin receptor (vtgr). Thus, moderate dietary ARA levels promoted growth, improved ARA deposition and metabolism, increased sex steroid hormone and Vtg levels, and enhanced ovarian development of female mud crab in the pre-developmental stage.

Three isonitrogenous diets (41% crude protein) with 4.87%, 10.75% and 16.10% lipid were designed to evaluate the effects of dietary lipid levels growth, antioxidant capacity, expression levels of genes related to lipid and glucose metabolism of juvenile Scylla paramamosain. Each diet was fed to four replicates of 32 crabs with initial weight 5.10 ± 0.05 g for 6 weeks. The results indicated that crabs fed diet with 10.75% lipid exhibited significantly higher percent weight gain (PWG) and specific growth rate (SGR) than those fed diet with 4.87% lipid (P

Vegetable oil (VO) is increasingly replacing fish oil (FO) in the commercial diet of crustaceans, partly due to a global shortage of FO. But little is known about how different amounts of substitution affect the health and metabolism of crustaceans. A six-week feeding trial was conducted to evaluated the effects of different replacement levels of FO with linseed oil (LO) on growth performance, antioxidant and digestive capacity and fatty acid metabolism in swimming crab, Portunus trituberculatus. Five isonitrogenous and isolipidic diets (480 g kg−1 protein and 120 g kg−1 lipid) were formulated to contain graded levels of LO, and FO was replaced with LO at 0%, 25%, 50%, 75% and 100%, respectively. The results showed that 50% of FO could be replaced by LO without affecting the growth performance and feed utilization for juvenile swimming crab. In hemolymph, 100% dietary replacement of FO with LO, the activities of alanine aminotransferase (ALT) and aspartate transaminase (AST) exhibited significantly higher than those fed the other diets, the concentrations of triacylglycerol (TAG), total cholesterol (T-CHO) and high-density lipoprotein cholesterol (HDL-C) significantly increased with increase of dietary replacement of FO with LO, which may lead to hyperlipidemia in swimming crabs. The number of R cells and their lipid droplets in hepatopancreas gradually increased with increase of replacement of FO with LO, the results confirmed the occurrence of lipid accumulation in the hepatopancreas. The activities of glutathione (GSH), and glutathione peroxidase (GPX) in hepatopancreas significantly decreased with increase of replacement of FO with LO, and crabs fed diet with 50% replacement of FO with LO had higher activities of trypsin and lipase (LPS) than those fed the other diets. Long-chain polyunsaturated fatty acids (LC-PUFA), n-3/n-6 PUFA in hepatopancreas and muscle significantly decreased with the increase of substitution level of FO with LO. Moreover, the expression of genes related to LC-PUFA synthesis as well as fatty acid β-oxidation, such as elongase 4 (elovl4), hepatocyte nuclear factor 4-α (hnf4α), retinoid X receptor (rxr), carnitine palmitoyltransferase 2 (cpt2) and acyl-CoA oxidase (acox2), were down-regulated with increase of dietary replacement of FO with LO. In conclusion, it is suggested that the optimal substitution ratio of LO for FO should be less than 50% in the diet of Portunus trituberculatus.

Image anomaly detection is a trending research topic in computer vision. The objective is to build models using available normal samples to detect various abnormal images without depending on real abnormal samples. It has high research significance and value for applications in the detection of defects in product appearance, medical image analysis, hyperspectral image processing, and other fields. This paper proposes an image anomaly detection algorithm based on feature distillation and an autoencoder structure, which uses the feature distillation structure of a dual-teacher network to train the encoder, thus suppressing the reconstruction of abnormal regions. This system also introduces an attention mechanism to highlight the detection objects, achieving effective detection of different defects in product appearance. In addition, this paper proposes a method for anomaly evaluation based on patch similarity that calculates the difference between the reconstructed image and the input image according to different regions of the image, thus improving the sensitivity and accuracy of the anomaly score. This paper conducts experiments on several datasets, and the results show that the proposed algorithm has superior performance in image anomaly detection. It achieves 98.8% average AUC on the SMDC-DET dataset and 98.9% average AUC on the MVTec-AD dataset.

An 8-week feeding trial was conducted to determine the optimal dietary phenylalanine requirement of juvenile swimming crab (Portunus trituberculatus). Six experimental diets (45.0% crude protein and 8.0% crude lipid) were formulated to contain 0.89%, 1.15%, 1.41%, 1.64%, 1.90% and 2.18% phenylalanine, respectively. Each diet was randomly divided into triplicate groups with 30 juvenile swimming crabs (initial weight 22.87 ± 0.03 g). The highest percent weight gain (PWG) and feed efficiency (FE) were presented in crabs fed with 1.64% phenylalanine diet, and the lowest PWG and FE were observed in crabs fed diet with 0.89% phenylalanine (P 0.05). Crabs fed the diet containing 0.89% phenylalanine had the lowest content of crude lipid in hepatopancreas among all treatments (P

Cholesterol, which acts as a substrate for the synthesis of ovarian sex hormones, could promote ovarian development. However, crustaceans cannot synthesize cholesterol and must obtain it from diet for growth, molt and gonadal development. Three isonitrogenous and isolipidic diets were formulated to contain 0.12%, 1.00% and 2.50% cholesterol, respectively. The results showed that dietary 1.00% and 2.50% cholesterol significantly increased percent weight gain (PWG) and specific growth rate (SGR), moreover, crabs fed diet with 1.00% cholesterol had the highest gonadosomatic index (GSI) among all treatments. Cholesterol (CHO) and triglyceride (TG) concentrations in tissues significantly increased with dietary cholesterol levels increasing from 0.12% to and 2.50%. Targeted metabolomics analyses indicated that crabs fed 1.00% cholesterol diet exhibited higher steroid hormones, such as progesterone, pregnenolone, estrone, estradiol and estriol than those fed the other diets. In addition, crabs fed the 1.00% cholesterol diet significantly up-regulated the expression of genes related to cholesterol transport, steroid hormone synthesis and ovarian development in hepatopancreas and ovary. Transcriptomics analyses revealed that DEGs (differentially expressed genes) in crabs fed 1.00% cholesterol diet were associated with “metabolism of xenobiotics by cytochrome P450″ and “progesterone-mediated oocyte maturation”. In conclusion, the results of present study demonstrated that dietary 1.00% cholesterol promoted growth and ovarian development by improving the cholesterol transport and steroid hormone synthesis for female swimming crabs.

Hexavalent chromium (Cr6+) is a metallic contaminant that in organisms and poses a great threat to biological health and ecology due to its toxicity and biomagnification. However, the potential health risks to mud crabs and humans from dietary excessive Cr6+ were currently unknown. Therefore, a 9-week feeding trial was conducted to evaluate the toxic effects of dietary Cr6+ levels (1.4, 77.5 and 312.2 mg/kg) for mud crab (Scylla paramamosain). The results indicated that dietary Cr6+ levels had no significant effect on growth performance for mud crab. Cr concentrations in hepatopancreas and muscle significantly increased with dietary Cr6+ levels increasing from 1.4 to 312.2 mg/kg. The antioxidant capacity of mud crab was enhanced by increased the activities of superoxide dismutase (SOD) and scavenging capability for hydroxyl free radical (SCHR) to resist the Cr6+ toxicity. However, there was no statistical difference in the rate of apoptosis in hemocytes among all treatments. Expression levels of caspase 2 gene related to apoptosis in hemocytes significantly up-regulated with dietary Cr6+ level increasing from 1.4 to 312.2 mg/kg. For food safety, crabs fed diets with 77.5 and 312.2 mg/kg Cr6+ had target hazard quotient (THQ) values greater than 1 for the hepatopancreas, indicating a serious risk for human consumption. According to the target cancer risk (TCR) analysis, people who consumed muscle in mud crab fed diet with 312.2 mg/kg Cr6+ were at unacceptable cancer risk. Overall, the results of the present study indicated mud crab had a strong resistance to Cr6+ toxicity, and dietary excessive Cr6+ did not decline growth performance and survival, oxidative stress and apoptosis in mud crab. Excess Cr6+ were accumulated in tissues such as hepatopancreas and muscle, and consumption of crabs tissues fed diets with 77.5 and 312.2 mg/kg Cr6+ will provoke health and cancer risk in humans.

An eight-week feeding trial was conducted to investigate the effects of dietary lipid sources on growth performance, fatty acids composition in tissue and expression of genes related to lipid metabolism in juvenile largemouth bass (Micropterus salmoides). Four experimental diets were formulated to contain 6% coconut oil (CO), rapeseed oil (RO), linseed oil (LO) and fish oil (FO), respectively. Each diet was fed to triplicate groups of juvenile for 8 weeks. The results indicated that final body weight (FBW), percent weight gain (PWG), specific growth rate (SGR), feed efficiency (FE), survival, hepatopancreas index (HSI), viscerosomatic index (VSI) and intraperitoneal fat ratio (IPF) were not significantly influenced by dietary different lipid sources (P＞0.05). Moreover, proximate composition in whole body, dorsal muscle and liver were also not significantly affected by dietary different lipid sources (P ＞0.05). Fish fed with FO diet was significantly higher MDA concentration in hepatic and serum than those fed with CO, RO and LO diets (P

Chromium (Cr) is an essential micronutrient for all animals, which is also an important component of glucose tolerance factor. The present study was conducted to evaluate the effect of dietary Cr levels on growth, Cr accumulation in tissues, glucose and lipid metabolism and insulin signal pathway of juvenile mud crab. Six isonitrogenous and isolipidic diets were formulated to contain 1.4 (basal diet), 1.7, 2.0, 2.2, 2.6 and 3.7 mg kg−1 Cr, respectively. The results indicated that crabs fed with 2.2 and 2.6 mg kg−1 Cr diets had the highest percent weight gain (PWG) and specific growth rate (SGR) among all treatments. Cr concentration in hepatopancreas significantly increased with increase of dietary Cr levels. Crabs fed with 3.7 mg kg−1 Cr diet exhibited lower antioxidant enzyme activities and higher malondialdehyde (MDA) in hepatopancreas and hemolymph than those fed the other diets. Crabs fed the diets with 2.2 and 2.6 mg kg−1 Cr showed higher activities of hexokinase (HK), phosphofructokinase (PFK) and pyruvate kinase (PK). The expression levels of genes related to insulin signaling pathway, glycolysis and fat synthesis, glycolipid metabolism (such as phosphatidylinositol 3-kinase (pi3k), hexokinase (hk), and fatty acid synthase (fas)) in hepatopancreas were significantly up-regulated. The expression levels of genes related to gluconeogenesis and lipolysis such as fructose-1,6-bisphosphatase (fbp) and carnitine palmitoyltransferase 1 (cpt1) were significantly down-regulated in crabs fed with optimal Cr diets. In conclusion, the optimal dietary Cr requirement was estimated to be 2.34 mg kg−1 for juvenile mud crab based on two slope broken-line regression analysis of PWG against dietary Cr levels, the results of present study indicated that optimal dietary Cr promoted the growth and Cr accumulation in tissues, and modulated insulin signaling pathway to trigger glycolysis and glycogenesis to maintain glucose homeostasis.

An eight-week feeding trail was carried out to investigate the impacts of different dietary arachidonic acid (ARA) supplementations on growth performance, antioxidant capacity, tissue fatty acid profiles, and lipid metabolism of mud crab (Scylla paramamosain) juvenile. Six isonitrogenous (480 g kg-1 crude protein) and isolipidic (80 g kg-1 crude lipid) diets were formulated to contain 0.40, 2.50, 4.60, 8.90, 12.50, and 15.70 g ARA kg-1 (dry matter), respectively. Each experimental treatment included 24 mud crab juveniles (initial weight 11.29±0.09 g) and was assigned to triplicate groups (n=3). Crabs fed diets with 2.50, 4.60, and 8.90 g kg-1 ARA presented significantly higher percent weight gain (PWG) and specific growth rate (SGR) than those fed the other diets. Based on two-slope broken-line and quadratic curve regression analysis of PWG against dietary ARA levels, optimal dietary ARA levels were determined to be 5.20 g kg-1 and 6.20 g kg-1, respectively. Crabs fed with 4.60 g kg-1 ARA diet showed the lowest activities of alanine aminotransferase (ALT) as well as aspartate aminotransferase (AST) in hemolymph among all treatments. In hemolymph and hepatopancreas, total antioxidant capacity (T-AOC), the activities of total superoxide dismutase (T-SOD), and glutathione peroxidase (GSH-Px) as well as the contents of reduced glutathione (GSH) rose first and then dropped with the increase of dietary ARA levels, while the concentration of malondialdehyde (MDA) showed an opposite trend. Tissue fatty acid profiles reflected diets fatty acid compositions. The ARA contents in hepatopancreas and muscle significantly increased with the increase of dietary ARA levels. Furthermore, the areas of blasenzellen (B) cells and restzellen (R) cells were significantly downregulated with the increase of dietary ARA levels. Crabs fed with 0.40 g kg-1 ARA diet showed significantly higher gene expression levels of fatty acid synthase (fas) as well as acetyl-CoA carboxylase (acc) among all treatments. Relative gene expression levels of 6-phosphogluconate dehydrogenase (6pgd) as well as glucose-6-phosphate dehydrogenase (g6pd) have been significantly upregulated in 0.40 and 2.50 g kg-1 ARA groups. Relative gene expression level of fatty acid binding protein 1 (fabp1) significantly increased in 4.60, 8.90, 12.50, and 15.70 g kg-1 ARA groups. However, the gene expression levels of fatty acid binding protein 4 (fabp4) as well as scavenger receptor class 2 (srb2) have not been influenced by dietary ARA levels. What is more, crabs fed diets with 4.60, 8.90, 12.50, and 15.70 g kg-1 ARA had a significantly higher expression level of carnitine palmitoyltransferase 1 (cpt1) than those fed diets with 0.40 and 2.50 g kg-1 ARA. In summary, optimum dietary ARA can promote growth, enhance antioxidant capacity, and improve health of mud crab juveniles. It also demonstrated that lipogenesis has been restrained with the increasing dietary ARA levels. These findings could provide theoretical guidance and reference for the lipid nutrition research as well as the development of the commercial diet in mud crab.

An 8-week feeding trial was carried out to assess the effect of dietary krill meal on growth performance and expression of genes related to TOR pathway and antioxidation of swimming crab (Portunus trituberculatus). Four experimental diets (45% crude protein and 9% crude lipid) were formulated to obtain different replacements of fish meal (FM) with krill meal (KM); FM was replaced with KM at 0% (KM0), 10% (KM10), 20% (KM20), and 30% (KM30); fluorine concentration in diets were analyzed to be 27.16, 94.06, 153.81, and 265.30 mg kg-1, respectively. Each diet was randomly divided into 3 replicates; ten swimming crabs were stocked in each replicate (initial weight, 5.62±0.19 g). The results indicated that crabs fed with the KM10 diet had the highest final weight, percent weight gain (PWG), and specific growth rate (SGR) among all treatments (P

An eight-week feeding trial was conducted to investigate the effects of dietary carbohydrate sources on growth performance, glycogen content in tissue, insulin signaling pathway, hepatic glucose transport and metabolism in juvenile swimming crab (Portunus trituberculatus). Four isonitrogenous (approximately 45.4% crude protein) and isolipidic (approximately 9.0% crude lipid) experimental diets were formulated to contain corn starch, wheat starch, dextrin and potato starch. Each diet was randomly assigned to triplicate groups of 30 juvenile swimming crabs (approximately 5.6 ± 0.1 g) that were stocked in rectangle plastic baskets. The results indicated that crabs fed with corn starch, wheat starch and dextrin diets had significantly higher final body weight (FBW), weight gain (WG), specific growth rate (SGR) and feed efficiency (FE) than those fed with potato starch diet. However, crabs fed with potato starch diet had the highest feed intake (FI) among all treatments. Crabs fed with corn starch, wheat starch and dextrin diets exhibited significantly higher glycogen in tissue and ATP content in hepatopancreatic than those fed with potato starch diet. The lowest concentration of insulin-like and hyperglycemic hormone were observed in crabs fed with potato starch diet. The lowest relative expression levels of PK, FBpase, PEPCK, GLUT1, GLUT2, GK, G6PDH, 6PGDH, ACC, IGF1R, PI3K and FOXO were occurred at crabs fed with dextrin diet. In conclusion, swimming crab could make better use of corn starch, wheat starch and dextrin, however, potato starch is not suitable as carbohydrate source. The results demonstrated that the ratio of amylose/amylopectin in diets was positively correlated with expression levels of genes related to glycolipid metabolism, glucose transport and insulin pathway.

An 8-weeks feeding trial was conducted to evaluate the effects of different dietary phosphorus (P) levels on growth performance, P concentrations in tissue, haemolymph biochemistry and hepatopancreatic metabolic enzyme activities for juvenile swimming crab (Portunus trituberculatus). Five semi-purified diets (46 % protein, 7.5 % lipid) were formulated to contain different P levels of 6.4, 10.8, 16.2, 21.0 and 25.7 g kg−1, respectively. Each diet was randomly assigned to triplicate groups of 30 juvenile swimming crab (initial weight was 12.82 ± 0.15 g) that were reared in single crab unit. The results indicated that percent weight gain (PWG) were significantly influenced dietary P levels, the highest PWG were observed in crabs fed the diet containing 16.2 and 21.0 g kg−1 P. Moreover, P contents in muscle, hepatopancreas and carapace significantly increased with dietary P levels increasing from 6.4–21.0 g kg−1. P retention rate (PRR) in hepatopancreas and muscle significantly decreased with dietary P levels increasing from 6.4 to 25.7 g kg-1. Furthermore, dietary deficient P (such as 6.4 and 10.8 g kg−1 P) levels reduced ATP content, activities of PK and SDH in hepatopancreas. Crabs fed the diet with 6.4 g kg−1 P also showed significantly lower expression of genes involved in electron transport chain complex, such as nd1, sdhc and coxIII in hepatopancreas than those fed the other diets. The expression of genes related to mitochondrial energy metabolisms, such as Atpase6, sirt1, and nrf1 in hepatopancreas were significantly up-regulated in crabs fed 16.2 and 21.0 g kg−1 P diets. Overall, based on the two slope broken-line and quadratic regression analysis of PWG against the dietary total P levels, the optimum dietary P requirement was estimated to be 15.91 and 16.83 g kg−1, respectively.

Salinity is one of the important factors affecting the physiological state of crustaceans in marine environments. Lipid plays major roles in energy supply and is main sources of essential fatty acids for membrane integrity, which is critical in adaptations to changes in salinity. Here we evaluated the effects of salinity (medium, 23 ppt and low, 4 ppt) and dietary lipid source (fish oil, FO and soybean oil, SO) on intestinal health of the marine crustacean mud crab Scylla paramamosain. The results indicated that low salinity and dietary SO (LSO group) significantly affected intestinal histomorphology, with a significant decrease of intestinal fold height and width as well as down-regulation of intestinal mRNA levels of tight junction genes compared to crab reared at medium salinity and fed FO diets (MFO group). Crabs reared at low salinity and fed SO showed an increased inflammatory response in intestine, which stimulated a physiological detoxification response together with apoptosis compared to crab in the MFO group. Low salinity and SO diets also could be responsible for multiply the pathogenic bacteria of Photobacterium and inhibit the beneficial bacteria of Firmicutes and Rhodobacteraceae in intestine, and act on a crucial impact on the development of intestinal microbial barrier disorders. The results of microbial function predictive analysis also support these inferences. The findings of the present study demonstrated that soybean oil as the main dietary lipid source could exacerbate the adverse effects of low salinity on intestinal health of mud crab, and provided evidence suggesting that dietary lipid source and fatty acid composition may play vital roles in intestinal health and the process of adaptation to environmental salinity in marine crustaceans.

An six-week feeding trial was conducted to evaluate the effects of dietary n-3 polyunsaturated fatty acid (n-3 PUFA) lipid sources on growth performance, antioxidant capacity, tissue fatty acid profiles, and expression levels of genes involved in lipid metabolism of juvenile green mud crab (Scylla paramamosain) (initial weight 45.3 ± 0.07 g). Three isonitrogenous and isoenergetic experimental diets were formulated to contain fish oil (FO), krill oil (KO) and linseed oil (LO), respectively. The results indicated that crabs fed the KO diet had significantly higher percent weight gain (PWG), specific growth rate (SGR) and feed efficiency (FE) than those fed the LO diet, while no statistic differences were observed between KO and FO diets. Dietary FO could significantly increase the concentrations of malondialdehyde (MDA) and lipid hydroperoxide (LPO) in hemolymph and hepatopancreas compared to dietary KO and LO, similar results were found in the levels of hepatopancreas 8-hydroxy-2-deoxyguanosine (8-OHDG). Crabs fed the KO diet could significantly increase the activities of total superoxide dismutase (T-SOD) and catalase (CAT) in comparison with FO and LO diets. Crabs fed with FO and KO had significantly higher contents of 20:5n-3 (EPA) and 22:6n-3 (DHA) in hepatopancreas and muscle than those fed with LO. While dietary LO could significantly promote the accumulation of C18:3n-3 (ALA) in hepatopancreas and muscle. The anabolic pathway relevant genes: fas and 6 pg d were up-regulated in KO diet. The catabolic pathway relevant genes, hsl, was up-regulated in FO and KO diets, cpt1, was up-regulated in KO diet. Moreover, crabs fed diet supplemented with KO could significantly increase the expression levels of srb2, srebp1 and hnf4α. These findings will provide the reference for the development of the diet for the growth stage of S. paramamosain, and could contribute to deepen the understanding of the physiological metabolism of dietary fatty acids for S. paramamosain.

A three-month feeding trial was conducted to investigate the effects of faba bean (Vicia faba L.) on growth performance, intramuscular collagen content, muscle cellularity and fillet texture of Yellow River carp, Cyprinus carpio haematopterus. Carps with an initial weight 500 ± 20 g were randomly divided into two treatments: commercial feed group (CFG) and faba bean group (FBG). Compared to CFG, the results indicated that carps fed with faba bean had poor growth performance, higher intramuscular collagen content, smaller fiber diameter and wider intermyofibrillar space. However, the fiber density was not influenced (P > 0.05). The faba bean components showed lower crude protein and amino acid imbalance, especially, the deficiency in the sulfuric amino acid. The raw-fillet and cooked-fillet texture of FBG were both significantly greater than that of CFG (P 0.05). In summary, faba bean could improve the fillet quality for Yellow River carp. These findings would contribute to define the optimal nutritional conditions of pond culture to improve the flesh quality of Cyprinus carpio haematopterus.