High dietary starch impaired growth performance,liver histology and hepatic glucose metabolism of juvenile largemouth bass,Micropterus salmoides

A 60‐day experiment was carried out to investigate dietary starch levels on growth performance, hepatic glucose metabolism and liver histology of largemouth bass, Micropterus salmoides. Fish (initial weight 22.00 ± 0.02 g) were fed five graded levels of dietary corn starch (0, 50, 100, 150 and 200 g/kg). Fish fed low (0 and 50 g/kg) dietary starch showed significantly higher weight gain than other groups (p < .05). Liver lipid and glycogen accumulations were induced when dietary starch higher than 100 g/kg. After 20 days of feeding, hexokinase activity and mRNA expression were decreased in fish fed dietary starch higher than 150 g/kg (p < .05) and the pyruvate kinase showed the opposite tendency. Insulin receptor 1 (irs1), glucagon‐like peptide‐1 receptor and glucose transport protein 2 (glut2) mRNA expression were decreased with the increasing dietary starch after 10 days of feeding (p < .05). These results indicated gluconeogenesis was depressed and β‐oxidation was enhanced in response to high dietary starch, while the glycolysis was inhibited and endocrine system was impaired when fish fed high dietary starch; then, glucose homeostasis was disturbed and finally led to the glucose intolerance of largemouth bass.     

Estimation of dietary vitamin A requirement of juvenile soft‐shelled turtle,Pelodiscus sinensis

A feeding trial was conducted to evaluate the dietary vitamin A requirement of the soft‐shelled turtle Pelodiscus sinensis. Turtles with an approximate body weight of 6.8 g were fed diets containing 0–4.58 mg kg^?1 (15 251 IU) vitamin A (retinyl acetate) for 8 weeks. Turtles fed diets without vitamin A showed the lowest growth performance. The animals gradually gained weight when dietary vitamin A increased from 0 to 3.6 mg kg^?1. Liver vitamin A gradually increased with supplementation of dietary vitamin A of up to 2.7 mg kg^?1. Beyond this concentration, the vitamin A in the liver significantly increased. Data analysis using a polynomial regression or exponential model showed that the estimated dietary vitamin A requirement for juvenile soft‐shelled turtles based on weight gain, red blood cell count and liver vitamin A measurements was 3.48, 2.84 and 2.58 mg kg^?1, respectively.     

Effects of fishmeal replacement with cottonseed meal protein hydrolysate on growth,digestion and intestinal histology of juvenile Chinese soft‐shelled turtle,Pelodiscus sinensis

A 60‐day feeding experiment was conducted to evaluate the effects of fishmeal (FM) replacement with cottonseed meal protein hydrolysate (CPH) on growth, digestion and intestinal histology of juvenile Chinese soft‐shelled turtle (Pelodiscus sinensis). Five diets were formulated to replace 0, 50, 100, and 150 g/kg fishmeal protein by CPH (CPH0, CPH5, CPH10, CPH15) and CPH15L (CPH15 with micro capsule‐L‐lysine). Weight gain, feed conversion rate and protein efficiency ratio showed no significant differences compared to control group (p > .05). The highest feed intake indicated in CPH15 (p < .05). The composition of whole‐body varied slightly in each groups (p > .05). The trypsin activity significantly elevated when dietary fishmeal protein was replaced by CPH at 30–90 g/kg (p < .05). A significantly higher lipase activities in CPH5 than control group (p < .05). The CPH5‐10 groups showed higher villus height than the other groups (p < .05). The microvillus length in turtles with CPH showed a significant increasing length (p < .05). The results indicated that replacing up to 90 g/kg of dietary fishmeal protein with CPH did not hamper growth or reduce feed intake of turtles. Moreover, CPH replaced 60 g/kg FMP can increase intestine digestive enzymes activities and improve intestinal development.     

Molecular cloning and characterization of the cathepsin L gene in Pelodiscus sinensis and its expression in response to bacterial challenge

Cathepsin L is one of the most important lysosomal cysteine proteases for the initiation of protein degradation, and it is involved in the immune response in many vertebrates. However, its function in the innate immune system of turtles remains poorly understood. Here, we cloned the cathepsin L gene from the Chinese soft‐shelled turtle Pelodiscus sinensis. We then examined the mRNA expression in different tissues and at different time points after infection by Aeromonas hydrophila or Vibrio parahemolyticus. The full‐length cDNA sequence cloned from P. sinensis was 1,805 bp with a 1,071 bp open reading frame, which encodes a 40.39 kDa polypeptide of 356 amino acids. The deduced protein sequence contained an active triad of Cys, His and Asn, and conserved ERWNIN and GNFD motifs. Homology analysis showed that the deduced amino acid sequence shared 77%–96% identity with other known species. Sequence alignment, phylogenetic analysis and structural comparisons revealed that cathepsin L is a member of the cathepsin family. Real‐time PCR analyses showed that turtle cathepsin L mRNA is ubiquitously expressed in various tissues, and the expression level is higher in the liver than in other tissues. The expression level in the liver peaks 24 hr after A. hydrophila infection and at two times (12 and 72 hr) after V. parahemolyticus infection. These results suggest that the cathepsin L gene of P. sinensis is likely involved in the process of the antibacterial response to A. hydrophila and V. parahemolyticus. This study is of great importance for future work exploring the molecular mechanism of antibacterial immune responses in P. sinensis.     

Effects of dietary protein to energy ratios on growth,body composition and digestive enzyme activities in Chinese mitten‐handed crab,Eriocheir sinensis

This study aimed to determine the optimal protein to energy ratio (P/E ratio) and evaluate the effect of dietary protein and lipid levels on growth performance, body composition and digestive enzymes activities in Chinese mitten‐handed crab, Eriocheir sinensis. Nine practical diets containing three levels both for protein (DP 30%, 35% and 40%) and lipid (DL 2%, 7% and 12%) with P/E ratios ranging from 13.69 to 19.79 mg KJ^?1 were fed to four replicates of crabs (3.39 ± 0.10 g) for 10 weeks. Weight gain increased significantly with the increase in DP level at each DL level. Moreover, weight gain increased in crabs fed with diets containing DL level from 2% to 12% and DP level from 30% to 35%. However, the diet containing 40% DP and 12% DL levels significantly decreased the growth performance and protein efficiency of the crabs. The whole crab and hepatopancreas lipid contents also increased as dietary lipid increased, but not dietary protein. The total protease activity increased significantly with the increase in dietary protein at each lipid level. The lipase activity was statistically comparable among different DL levels at each DP level. Taken together, the crab fed the diet containing 35% protein and 12% lipid levels with P/E 15.77 mg KJ^?1 revealed optimal growth, feed utilization efficiency and digestive enzymes activities. Moreover, our study indicated that the higher dietary lipid level at a relatively lower dietary protein level could provide protein sparing effect in Eriocheir sinensis.     

Effects of hypoxia on immune responses and carbohydrate metabolism in the Chinese mitten crab,Eriocheir sinensis

In aquaculture, hypoxia is an important stressor that can inhibit the healthy development of Chinese mitten crab, Eriocheir sinensis. The aim of this work was to research on how hypoxia (1 mg/L) followed by reoxygenation affects the immune response and carbohydrate metabolism in the Chinese mitten crab. The activities of immune‐related enzymes including lysozyme (LZM), acid phosphatase (ACP), alkaline phosphatase (AKP), superoxide dismutase (SOD) and phenoloxidase (PO) and concentration changes in haemolymph glucose, trehalose and hepatic glycogen were evaluated after 8 hr of hypoxia followed by 12 hr of reoxygenation. After 8 hr of hypoxia, the activities of LZM, PO, SOD and hepatic glycogen concentration significantly decreased to the minimum when compared to the control group, but the activities of ACP and AKP, and haemolymph glucose concentration significantly increased. After 12 hr of reoxygenation, the activities of LZM, ACP, AKP and SOD recovered to the normal level except SOD in plasma, while the PO, SOD in plasma and hepatic glycogen concentration were still significantly lower than the control level. No significant change was observed in trehalose concentration during hypoxia and reoxygenation periods. These results indicated that although the activities of ACP and AKP were likely increased to facilitate the hydrolysis of foreign matter, the overall strength of the immune response was decreased as LZM, PO and SOD activities were suppressed after exposure to hypoxic conditions. The energy stores of exposed crabs were reduced due to the expenditure of energy during exposure to hypoxic stress. In general, chronic hypoxia would impair the immunocompetence and increase the energy expenditure of Chinese mitten crab, further increased the risk of pathogen infection and feed coefficient, so the negative effects of hypoxia should not be ignored.     

Effects of dietary glucose and starch levels on the growth,haematological indices and hepatic hexokinase and glucokinase mRNA expression of juvenile mirror carp (Cyprinus carpio)

The effect of the different dietary carbohydrate types and levels on growth performance, haematological indices and hepatic hexokinase (HK) and glucokinase (GK) genes expression involved in control of glucose metabolism, was studied in juvenile mirror carp (Cyprinus carpio). Two carbohydrates (glucose and starch) diets with two levels (250 and 500 g kg^?1) were fed to triplicate groups of 35 fish for 60 days. The best weight gain rate and specific growth rate were observed in fish fed with 250 g kg^?1 glucose diet and 500 g kg^?1 starch diet (P < 0.05). Fish fed with 500 g kg^?1 glucose showed low feed utilization, with the highest food conversion ratio and the lowest protein efficiency ratio (P < 0.05). Hepatosomatic index was significantly higher in fish fed with glucose diets and the 500 g kg^?1 starch diet compared to 250 g kg^?1 starch. CHOL, HDL‐C and LDL‐C were significantly highest in fish fed with 500 g kg^?1 starch than all other diets (P < 0.05). Hepatic GK mRNA expression level and activity were positively related to glucose and starch levels (P < 0.05). Correlation analysis showed that hepatic glycogen concentration was increased by dietary carbohydrate content (P < 0.05). These results suggest that GK may play a major role in the postprandial glucose utilization in juvenile mirror carp.     

Effects of acute hyperglycaemia stress on indices of glucose metabolism and glucose transporter genes expression in cobia (Rachycentron canadum)

The objective of the present study is to preliminarily clarify the mechanism of carbohydrates metabolism in cobia (Rachycentron canadum) (85 ± 3 g) receiving injection of glucose solution. We examined plasma glucose (GLU), total protein (TP), triglyceride (TG), cholesterol (CHOL), insulin, liver glycogen and muscle glycogen, activities of hepatic hexokinase (HK), phosphofructokinase (PFK) and pyruvate kinase (PK), as well as relative expressions of glucose transporter 1 (GLUT1), GLUT2, GLUT3, GLUT4, GLUT5 and GLUT9 in hemocyte, liver and muscle of R. canadum when fish were injected with 200 μl of glucose solution (255 mg/ml) after 0, 1, 2, 4, 8, 12, 24 and 48 hr. Fish received injection of 0.68% saline served as control. Results indicated that the plasma GLU, TG and CHOL increased and reached peak at 1, 8 and 48 hr postinjection (hpi) respectively. The hepatic glycogen increased from 1 hpi, and reached peak at 8 hpi, plasma insulin increased at 1 hpi, and reached peak at 2 hpi, and activity of hepatic PK peaked at 8 hpi. Furthermore, the relative expressions of GLUT1, GLUT2, GLUT3, GLUT4 and GLUT5 in hemocytes reached peak at 1,4, 8, 4 and 8 hpi, respectively, relative expressions of GLUT2, GLUT3, GLUT5 and GLUT9 in liver reached peak at 24, 24, 12 and 24 hpi, respectively, and relative expressions of GLUT1 and GLUT3 in muscle were significantly higher at 2 and 2–4 hpi, respectively compared with those in controls. In conclusion, low ability of utilizing glucose in R. canadum may be attributed to insufficient insulin secretion, low activities of key glycolytic enzymes (HK, PFK and PK) regulated by glucose injection and slow increase of GLUTs.     

Effects of dietary protein sources on growth,survival and digestive capacity of Octopus maya juveniles (Mollusca: Cephalopoda)

We propose two hypotheses to explain the inexistence of adequate prepared diet for Octopus maya at this date: Hypothesis 1 is related to changes in protein structure during protein cooking, which affects the digestibility. Hypothesis 2 is related to changes on nutritional characteristics during ingredient process, which affects the nutritional composition of diet. To test hypothesis 1, experiments one and two were directed to determine if protein cooking reduces digestibility and growth of animals when compared to fresh or lyophilized protein sources. For hypothesis 2, three experiments were conducted, testing seven different dietary protein sources offered in isolation or combined in artificial diets fed to O. maya. Results demonstrated that the diets that promoted growth were the ones based on fresh crab paste, and both lyophilized crab and squid tentacles paste. In consequence hypothesis 1 was accepted. The cooking process also changed nutritional characteristics of protein sources, affecting the growth of O. maya. Results obtained when squid and crab were mixed suggest that nutritional requirements of octopuses were covered with that diet in similar forms compared to when using fresh or lyophilized crab, also confirming hypothesis 2. Based on growth rates obtained, we can conclude that nutritional requirements of O. maya must be between 80% and 86% Protein (P), 5.1–5.6% Lipids and a protein: energy ratio between (P/E) 38.9 and 42.2 g MJ^?1.     

Effects of xylan and cottonseed meal on growth performance,digestion, intestinal morphology and the expression of two peritrophin genes of Chinese mitten crab,Eriocheir sinensis

Xylan is one of the main non‐starch polysaccharides (NSPs) in cottonseed meal. This study aimed to evaluate the anti‐nutrition effect of xylan and to better understand cottonseed meal as a feed ingredient for the Chinese mitten crab, Eriocheir sinensis. A diet containing 280 g/kg fishmeal without cottonseed meal or xylan was formulated as a control (FM diet). A second diet (XYL diet) was supplemented with 53.3 g/kg xylan according to its amount in the third diet, the cottonseed meal diet (CSM diet), which was formulated to include 400 g/kg cottonseed meal. The last diet (CSM + XYLase diet) included 400 g/kg xylanase hydrolysed cottonseed meal, in which most xylan was hydrolysed. Diets were isonitrogenous (370 g/kg crude protein) and isoenergetic (17.58 KJ/g) and were randomly fed to 12 tanks of crabs for 8 weeks. Results showed that no difference was detected among groups in growth performance, serum biochemical index, or digestive and metabolism enzyme activity (p > 0.05). The apparent digestibility coefficient (ADC) of dry matter was FM > XYL > CSM + XYLase > CSM (p < 0.05). The ADC of protein in crab fed diet FM and XYL was significantly higher than CSM and CSM + XYLase (p < 0.05). Cottonseed meal decreased the fold height of the hindgut, upregulated the expression of peritrophin genes of Es‐PL44 and Es‐PP1 (p < 0.05), while xylan decreased the fold height of the hindgut and upregulated the expression of Es‐PP1 (p < 0.05). These results indicated that the negative effect of cottonseed meal and xylan on digestibility partly compensated by enhanced absorption of the hindgut innerly and by supplementation of xylanase externally, and cottonseed meal is an attractive alternative protein source in general for Chinese mitten crab.     

Evaluating the effects of dietary resistant starch on growth,digestion, metabolism,immunity and resistance to ammonia stress in Litopenaeus vannamei

Resistant starch (RS) is considered to be a good alternative to antibiotics. A 56‐day feeding trial was followed by induction of acute ammonia stress to evaluate the effects of dietary RS on growth, digestion, metabolism, immunity and resistance to ammonia stress in Litopenaeus vannamei. The four diets used differed only in RS content: 0 g/kg (Control), 10 g/kg (RS1), 30 g/kg (RS2) and 50 g/kg (RS3). The results showed that dietary RS improved the growth and the survival rates of shrimp exposed to ammonia stress. At 56 days, the activity of digestive and metabolic enzymes (amylase, lipase, pepsin, hexokinase and pyruvate kinase) was increased in the three RS groups, while trypsin activity only increased in the RS1 and RS2 groups; immune‐related parameters (the total antioxidant capacity; the activity of superoxide dismutase, total nitric oxide synthase and phenoloxidase; and the expression of heat‐shock protein 70, thioredoxin, prophenoloxidase, lysozyme and toll gene) were increased in the three RS groups. After exposure to ammonia stress, all the selected immune parameters of the three RS groups were higher than those of the control group at 24 hr. Therefore, dietary RS improved the growth, digestion, metabolism, immunity and resistance to ammonia stress in L. vannamei.     

饲料中可消化淀粉对大口黑鲈生长、体组成和非特异性免疫指标的影响

配制6种不同可消化淀粉水平(5.93%、8.71%、11.96%、15.11%、18.16%、21.74%)的等氮和等脂肪的饲料,以试验鱼的生长、饲料效率、体组成、血糖及非特异性免疫和血液学参数作指标,评定大口黑鲈饲料中可消化淀粉的适宜水平。用上述6种饲料饲喂初始体质量(28.36 ± 0.10)g 的大口黑鲈48 d,每饲料设3个重复,每重复35尾鱼。采用表观饱食投喂,每天饲喂2次(8:00和16:00)。结果显示,饲料中可消化淀粉水平为21.74%时,大口黑鲈成活率最低;可消化淀粉水平超过8.71%时,鱼体终末体质量、特定生长率和摄食量均显著下降;但饲料效率和蛋白质效率在可消化淀粉水平为11.96%时达到最高。随着饲料中可消化淀粉水平的升高,饲料的蛋白质消化率差异不显著,但脂肪和淀粉的消化率显著降低;全鱼、肌肉、内脏及肝脏的蛋白质含量均显著降低,而水分含量显著升高,脂肪含量在8.71%组达到最高后又显著降低;肝体比、脏体比、肝糖原及血清谷丙转氨酶和谷草转氨酶的活性均显著升高。饲料中可消化淀粉水平高于11.96%时,试验鱼餐后6至12 h呈现持续的高血糖症状;血清蛋白质含量和血清补体活性在可消化淀粉为8.71%时达到最高;而血清溶菌酶活性和头肾白细胞呼吸爆发活性在11.96%组达到最高。另外,红细胞数和红细胞压积未受到饲料中可消化淀粉水平增高的显著影响,但血红蛋白含量显著降低。综合大口黑鲈的生长、饲料效率、体组成、血糖和非特异性免疫指标得出,大口黑鲈对饲料中可消化淀粉的利用与耐受力有限,饲料中可消化淀粉的适宜水平为8.71% ~ 11.96%。     

Effects of dietary lipid sources on growth performance,lipid metabolism and antioxidant status of juvenile Russian sturgeon Acipenser gueldenstaedtii

Six isonitrogenous and isoenergetic diets were used to test the influence of lipid source on growth performance, antioxidant status and lipid metabolism of juvenile Russian sturgeon, Acipenser gueldenstaedtii. Each diet was supplemented with 90 g kg^?1 of lipid from each of six sources including fish oil (FO), beef tallow (BT), sunflower oil (SO), linseed oil (LO) and equal combinations of FO + SO + BT (FSB) or LO + SO + BT (LSB). After 56 days, fish fed LSB demonstrated highest weight gain, specific growth rate and lowest hepatosomatic index among all groups. The n‐6 polyunsaturated fatty acids (PUFAs) in the whole fish were highest in the SO group, and n‐3 PUFAs were highest in fish fed LO. The fish fed FO contained highest n‐3 highly unsaturated fatty acids. Triglyceride in the serum of fish fed LSB was lowest, but was not significantly different from that in the SO group. Triglyceride in the serum of fish fed FO and BT was highest among all groups. Lipase, malate dehydrogenase and lipoprotein lipase activities were highest in fish fed LSB. Serum malondialdehyde in fish fed LSB was significantly lower than in fish fed FO or SO, but no significant differences were found among fish fed LSB, BT, LO or FSB. Fish fed LSB showed higher catalase activity and total antioxidant capacity than fish fed FO or FSB. This study indicates that linseed, sunflower oil and BT mixed oil are a suitable lipid source and can benefit growth performance and antioxidation in juvenile sturgeon.     

Effects of different levels of dietary protein on the growth performance,nutrient utilization,digestive enzymes and physiological status of white shrimp,Litopenaeus vannamei juveniles reared in inland saline water

A 60‐day feeding trial was conducted to illustrate the effect of dietary protein levels on the growth and physio‐metabolic responses of juvenile Litopenaeus vannamei reared in inland saline water (ISW). Six isoenergetic (15 MJ/kg) and isolipidic (60 g/kg) diets with graded level of crude protein viz., 240 (T240), 260 (T260), 280 (T280), 300 (T300), 320 (T320) and 340 (T340) g/kg diet were formulated. Significantly higher (p < .05) weight gain (%), specific growth rate, with lower food conversion ratio were found in T320 and T340 groups. The protein utilizing efficiency and whole‐body protein content were significantly higher (p < .05) in the T320 group. Trypsin activity increased with the increasing dietary CP level but amylase activity decreased with the increasing dietary CP level. Transaminase enzymes, haemolymph protein and haemocyanin were elevated in T320 and T340 groups. The lactate dehydrogenase and malate dehydrogenase activities were significantly higher (p < .05) in the T240 group. Shrimp of T240 group had the lowest (p < .05) glycogen and total haemocyte count with highest (p < .05) haemolymph glucose and antioxidant enzymes activities than the other groups. Based on the results, feeding 320 g CP/kg is found to be optimum for supporting maximum growth and health status of L. vannamei reared in ISW at 8 g/L salinity. The finding of the present study will help in developing a low‐cost feed for L. vannamei reared in ISW.     

饲料糖水平对吉富罗非鱼幼鱼生长和肝代谢功能的影响

为研究饲料糖水平对吉富罗非鱼幼鱼生长性能和肝代谢功能的影响,实验配制等蛋白、等脂肪含量的8种不同糖水平(10％、15％、20％、25％、30％、35％、40％和45％)饲料,每个糖水平设3个重复,饲养周期49 d,结果显示:(1)饲料糖水平对吉富罗非鱼幼鱼的增重率、成活率、饲料系数和肝体比均有显著影响(P＜0.05).饲料糖水平为35％时,罗非鱼增重最快;饲料糖水平为40％时饲料系数最低.(2)随着饲料糖水平的升高,鱼体肌糖原、粗脂肪含量逐渐升高,鱼体肝糖原含量先增加后下降.(3)饲料糖水平对各组鱼血清谷草转氨酶、谷丙转氨酶、血清磷酸果糖激酶活性、总蛋白和总胆汁酸浓度均有显著影响(P＜0.05),且随着糖水平的升高,呈上升趋势;而鱼体肝酯酶和脂蛋白脂酶活性则是先上升后下降.(4)饲料糖水平35％时,肝脏组织出现少量细胞脂滴空泡状现象;饲料糖水平40％和45％时,肝脏组织切片有明显的细胞脂滴空泡状、核偏移和细胞质消失现象.肝脏脂滴空泡状面积率与组织脂肪含量具有显著的正相关,与肝脏组织的脂肪肝病变程度成正比.结果表明,吉富罗非鱼苗种饲料以29.10％～ 35.00％的糖水平较利于吉富罗非鱼幼鱼生长及后期的脂肪肝病预防.     

Effects of dietary tea polyphenols on growth,immunity and lipid metabolism of juvenile black carp Mylopharyngodon piceus

An 8‐week feeding experiment was aimed to investigate the effect of dietary tea polyphenols (TP) on growth, immunity and lipid metabolism in juvenile black carp Mylopharyngodon piceus (initial weight 5.90 ± 0.03 g). Tea polyphenols were added at different levels (0, 25, 50, 100 and 500 mg/kg; TP₀, TP₂₅, TP₅₀, TP₁₀₀ and TP₅₀₀). The results are as follows: the highest specific growth rate (SGR) and condition factor (CF) and activity of trypsin (TRS) of intestine in TP₅₀, but SGR and activities of lipase (LPS)and TRS of intestine and content of whole body crude protein in TP₅₀₀ were remarkably lower than TP₀. Compared with TP₀, content of serum superoxide dismutase (SOD) and glutamic oxalacetic transaminase (GOT) remarkably increased (p < .05), but contents of glutathione (GSH), glutathione peroxidase (GSH‐Pox), malondialdehyde (MDA), triglyceride (TG) and low‐density lipoprotein cholesterol (LDL‐C) were significantly decreased (p < .05), content of cortisol was remarkably lower in TP₅₀ and TP₁₀₀ (p < .05), expression of growth hormone (GH) and melanocortin 4 receptor (MC4R) in liver and GH in muscle were remarkably up‐regulated in TP₅₀, but expression of apolipoprotein A‐1 (ApoA1), GH and MC4R of intestine, ApoA1 of liver and MC4R of muscle in TP₅₀₀ were remarkably down‐regulated, contents of complement 3 (C3), complement 4 (C4), high‐density lipoprotein cholesterol (HDL‐C) and LDL‐C were significantly reduced in TP₅₀₀ (p < .05). In conclusion, TP could improve growth performance and oxidative capacity on juvenile black carp, and its optimal dosage was 50 mg/kg.     

Effects of dietary lipid source on fatty acid composition,expression of genes involved in lipid metabolism and antioxidant status of grass carp (Ctenopharyngodon idellus)

This study determined the effect of different lipid sources on growth, feed use, lipid metabolism and antioxidant status of grass carp (Ctenopharyngodon idellus). Juvenile fish (56.9 ± 4.7 g) were divided into four triplicate groups and fed diets containing 30 g/Kg of fish oil (FO), olive oil (OO), peanut oil (PO) and linseed oil (LO), respectively, for 60 days. Weight gain and feed conversion ratio were not significantly different between the dietary groups, but we observed changes in the fatty acid composition of muscle and intraperitoneal fat reflecting the fatty acid profile of the dietary lipid source. In the hepatopancreas, the highest mRNA level of fatty acid translocase CD36 (FAT/CD36) and carnitine palmitoyl transferase (CPT‐1A) was both observed in the FO group. In muscle, the expression of FAT/CD36 and CPT‐1A in the LO group was significantly higher than that in other groups, except for CPT‐1A in the PO group. In addition, the lowest and highest content of malondialdehyde in serum was observed in OO and FO groups, respectively. In summary, dietary lipid source altered the fatty acid composition, potential uptake (FAT/CD36) and oxidation (CPT‐1A) of fatty acids, and antioxidant status of grass carp, which should be considered when selecting a lipid source.     

饲料中不同蛋白质和淀粉水平对斜带石斑鱼生长性能和肝脏相关代谢酶活性的影响

为了探讨饲料蛋白质和碳水化合物对斜带石斑鱼的互作效应,实验采用3×3因子设计,配制蛋白质水平(P)为38%、45%和52%,淀粉水平(S)为10%、20%和30%的9种实验饲料,分别饲喂斜带石斑鱼56 d。结果显示,38%粗蛋白与10%淀粉饲料组(38P/10S饲料组)增重率显著低于其他各组,52P/10S组增重率最高,但与45P/20S、45P/30S、52P/20S组差异不显著。增加饲料蛋白质或淀粉水平显著增加饲料效率、鱼体蛋白质与脂肪含量及肝糖原肝脂含量,而降低摄食率和鱼体水分含量。增加饲料蛋白质水平降低蛋白质效率,但增加淀粉水平却增加蛋白质效率及肝体比与脏体比。饲料蛋白质水平和淀粉水平对鱼体灰分含量无明显影响。肝中肝酯酶、脂蛋白酯酶、脂肪酸合成酶、谷丙转氨酶和谷草转氨酶活性均随蛋白质或淀粉水平的升高呈显著上升趋势。增加饲料蛋白质水平显著降低肝中葡萄糖-6-磷酸酶活性,而增加肝中苹果酸酶活性,但对肝中葡萄糖激酶、丙酮酸激酶、磷酸果糖激酶、磷酸烯醇式丙酮酸羧激酶和葡萄糖-6-磷酸脱氢酶活性没有明显影响。增加饲料淀粉水平显著增加肝中葡萄糖激酶、丙酮酸激酶、磷酸果糖激酶、葡萄糖-6-磷酸脱氢酶和苹果酸酶活性,但显著降低磷酸烯醇式丙酮酸羧激酶和葡萄糖-6-磷酸酶活性。上述结果显示,斜带石斑鱼的生长和肝脏代谢明显受饲料蛋白质和淀粉水平的影响,其中,糖代谢酶活性受淀粉水平的影响较大,而受饲料蛋白质水平的影响较小,斜带石斑鱼生长适宜的饲料蛋白质和淀粉水平分别为45%和20%。