Effects of salinity acclimation on the growth performance,osmoregulation and energy metabolism of the oriental river prawn,Macrobrachium nipponense (De Haan)

In this study, we evaluated the growth, osmoregulation and energy metabolism of the oriental river prawn, Macrobrachium nipponense, reared during 6 weeks with different salinities (0, 8, 14 and 22 g/L). The results showed that the haemolymph osmolality of M. nipponense increased with an increase in ambient osmotic pressure; the isosmotic point was 490 mOs/kg H₂O. The prawns showed a higher survival rate, weight gain rate and hepatopancreas index in salinity 14 g/L. Digestive enzymes were all affected by salinity, and the highest activities were observed in the salinity 14 g/L. The mRNA expression of Na⁺‐K⁺‐ATPase in gills and p53 in hepatopancreas were the highest in salinity 22 g/L. The expressions of heat shock protein 90 and glutathione S‐transferase genes in hepatopancreas were significantly higher in the salinity 8 g/L. Lipid metabolism‐related genes in hepatopancreas were significantly expressed in the salinity 14 g/L. The glucose‐6‐phosphatase gene in hepatopancreas was highly expressed in the salinity 8 and 22 g/L, and the expression of the ecdysone receptor gene in hepatopancreas was significantly higher in the salinity 14 g/L. The results showed that salinity 14 g/L could promote the growth of M. nipponense. However, higher salinity conditions may cause physiological damage, which provides a theoretical basis for brackish water culture of M. nipponense.     

Molecular cloning,characterization and expression analysis of the fatty acid‐binding protein (MnFABP), involved in dietary lipid sources response in oriental river prawn,Macrobrachium nipponense

A fatty acid‐binding protein (FABP) gene designated as MnFABP10 was cloned and characterized from the freshwater prawn Macrobrachium nipponense. The full‐length cDNA of MnFABP10 was 646 bp encoding a 130 amino acid. Real‐time quantitative RT‐PCR showed that the MnFABP10 gene was expressed in various tissues with the highest expression in the hepatopancreas. The MnFABP10 mRNA levels in the hepatopancreas and ovary of M. nipponense were dependent on the stages of ovarian development. Western blot results revealed a single immunoreactive band with an estimated molecular mass of approximate 14 kDa in the developmental ovary. Then, M. nipponense with an initial body weight of 0.090 ± 0.0010 g were fed with four isonitrogenous and isocaloric diets with different oils, that is, beef tallow (BT), soybean oil (SO), pollack fish oil (FO) and a mixture of fish oil and soybean oil (FO/SO 2 : 1 w/w) for 52 days. The mRNA levels of MnFABP10 in the hepatopancreas were influenced by different lipid sources, with a peak expression observed in prawns fed SO. This study suggests that MnFABP10 may have a putative function in ovary maturation, and its mRNA expression in the hepatopancreas can be regulated by the source of dietary lipids in M. nipponense.     

Effects of cholesterol on growth,feed utilization,body composition and immune parameters in juvenile oriental river prawn,Macrobrachium nipponense (De Haan)

An 8‐week feeding trial was conducted to investigate the effects of dietary cholesterol levels on growth, feed utilization, body composition and immune parameters in juvenile oriental river prawn, Macrobrachium nipponense. Six isolipid (80 g kg^?1 crude lipid) and isoproteic (400 g kg^?1 crude protein) diets, supplemented with 0, 3.0, 6.0, 9.0, 12.0 and 15.0 g kg^?1 cholesterol, were evaluated. Growth performance and feed utilization of M. nipponense were improved as dietary cholesterol levels increased. Weight gain and specific growth rate were highest, and feed conversation ratio was lowest, when prawns were fed a diet supplemented with 9.0 g kg^?1 cholesterol. However, final body weights and survival rates of juvenile M. nipponense were not affected significantly by dietary cholesterol. Body composition of prawns, including moisture, crude protein and crude lipid, was not significantly affected by changes in dietary cholesterol. The immune parameters measured in hepatopancreas, including total antioxidant capacity, and glutathione, catalase, alkaline phosphatase and acid phosphatase activities, were at optimum levels in prawns fed with 9.0 g kg^?1 dietary cholesterol. In summary, the best growth performance, lowest feed conversation ratio, and the most enhanced antioxidant capacity and immunity parameters were attained in juvenile M. nipponense when fed a diet supplemented with 9.0 g kg^?1 cholesterol.     

An evaluation of increasing linolenic acid level in the diet of Macrobrachium nipponense: Lipid deposition,fatty acid composition and expression of lipid metabolism‐related genes

To determine the effects of linolenic acid (LNA, 18:3n‐3) in oriental river prawn (Macrobrachium nipponense), an 8‐week feeding experiment was conducted using six isonitrogenous and isoenergetic semi‐purified diets containing 0.07 g/kg (control), 7.3 g/kg, 16.6 g/kg, 20.2 g/kg, 27.3 g/kg and 36.3 g/kg LNA. The hepatopancreas lipid content decreased significantly when dietary LNA content was >20.2 g/kg. Fatty acid analysis revealed that the percentage of 18:3n‐3 in the hepatopancreas significantly increased with increasing dietary LNA levels, while 20:5n‐3, 22:5n‐3 and 22:6n‐3 levels in the hepatopancreas decreased in a curvilinear manner as dietary LNA increased. Additionally, qRT‐PCR results revealed that hepatopancreas mRNA expression of acetyl‐CoA carboxylase (ACC) decreased with increasing dietary LNA, while the greatest carnitine palmitoyl transferase‐1(CPT1) mRNA expression was observed in the 2.73 g/kg and 36.3 g/kg groups. Furthermore, hepatopancreas mRNA expression of acyl‐CoA delta‐9 desaturase (SCD) and fatty acyl elongase 6(elovl6) was downregulated when prawns fed the diets containing >20.2 g/kg LNA. These results indicate that dietary 18:3n‐3 could decrease lipid deposition through increased fatty acid β‐oxidation and modulated fatty acid synthesis, and alter fatty acid composition by regulating fatty acyl elongase and fatty acyl desaturase mRNA expression in the M. nipponense.     

Effect of dietary vitamin E on growth,immunity and regulation of hepatopancreas nutrition in male oriental river prawn,Macrobrachium nipponense

We evaluated the effects of dietary vitamin E on growth, immunity and regulation of the hepatopancreas in male oriental river prawn, Macrobrachium nipponense. Shrimps were fed 0, 40, 80, 160, 320 or 640 mg vitamin E/kg for 60 days. The 80 mg/kg group had the highest weight gain rate, specific growth rate and lowest feed conversion rate while there were no significant differences in survival rate and hepatosomatic index. The highest crude fat and lowest crude protein content were observed in the 160 mg/kg group. In the hepatopancreas, lysozyme, acid phosphatase and alkaline phosphatase activities were highest in the 160 mg/kg group, while superoxide dismutase, catalase and glutathione peroxidase activities decreased with increasing vitamin E levels. Malondialdehyde content initially decreased then increased with vitamin E levels, whereas the reverse was seen with total antioxidant capacity. Linoleic acid, DPA, DHA, total n‐3 polyunsaturated fatty acid and total polyunsaturated fatty acid first increased then decreased, while EPA and total saturated fatty acid rose with vitamin E levels. Total n‐6 polyunsaturated fatty acid content declined while there were no significant differences in linolenic and total monounsaturated fatty acid content. Following a toxicity test with Aeromonas hydrophila, hepatopancreas ultrastructure revealed that appropriate vitamin E levels promote an increase in mitochondria, endoplasmic reticulum and Golgi bodies, but excess vitamin E can damage cell structure. These results provide evidence that 80–160 mg/kg dietary vitamin E has a positive impact on growth, immunity and regulation of the hepatopancreas in male shrimp.     

Growth and metabolic responses of juvenile Macrobrachium nipponense to different dietary carbohydrate levels

It remains controversial whether carbohydrate can be efficiently used by crustaceans. Six isonitrogenous and isolipid diets were formulated containing 50–350 g kg^–1 corn starch and were fed to juvenile prawns (mean weight, 0.133 ± 0.003 g) for 56 days in five replicates. Prawns fed 50–150 g kg^–1 corn starch attained significantly greater weight gain. Digestive enzyme activities were significantly affected by dietary corn starch level. Hepatopancreatic and muscle glycogen levels peaked in prawns fed 350 g kg^–1 and 150 g kg^–1 corn starch content, respectively. Prawns fed 350 g kg^–1 corn starch had a significantly higher haemolymph glucose level than that in the other groups. Hepatopancreatic hexokinase (HK) activity increased significantly as corn starch level was increased. Hepatopancreatic pyruvate kinase (PK) activity of prawns fed the 150 g kg^–1 and 250 g kg^–1 corn starch was significantly higher than that of prawns fed 50 g kg^–1 corn starch. Including carbohydrate in the diet promoted increased lipogenic activities (glucose‐6‐phosphate dehydrogenase and malic enzyme) in the hepatopancreas. Hepatopancreatic HK and PK mRNA expression levels had similar trends with their activities. The 350 g kg^–1 corn starch level induced the highest glucose‐6‐phosphatase and pyruvate carboxylase mRNA expression levels. Overall, moderate metabolic adaptations for using dietary corn starch were detected in Macrobrachium nipponense; however, a high proportion (>150 g kg^–1 ) of corn starch in the diet may reduce growth.     

Effects of the dietary protein to energy ratio on growth,feed utilization and body composition in Macrobrachium nipponense

Oriental river prawn (Macrobrachium nipponense) has been widely cultured in Asian countries. However, its nutritional studies are very limited. In the present 8‐week study, we investigated the effects of dietary protein to energy ratio (P/E ratio) on the growth, feed utilization and body composition in juvenile M. nipponense (initial weight 0.302 ±0.03 g). Two‐factor experiment was designed and nine semi‐purified diets were formulated to contain three lipid levels (20, 80 and 140 g kg^?1) and three protein levels (330, 380 and 430 g kg^?1), producing P/E ratios from 16.5 to 23.4 mg KJ^?1 protein. The results indicated that the growth, survival rate and protein efficiency were dose dependently improved by the increased dietary lipid, but not dietary protein content. Increased dietary lipid content and/or protein content increased lipid accumulation in whole body, hepatopancreas and muscle, but did not change the feed intake and hepatopancreas weight. In conclusion, our present study indicated that M. nipponense is a species with relatively high‐energy requirement. It could utilize dietary lipid content up to 140 g kg^?1, while the dietary protein with more than 330 g kg^?1 would not promote growth and protein efficiency. Taken together, 330 g kg^?1 dietary protein and 140 g kg^?1 dietary lipid level with P/E ratio 16.49 could be optimum for M. nipponense.     

Conjugated linoleic acid affects growth performance,hepatic fatty acid profile and lipid metabolism in juvenile Synechogobius hasta

This study was conducted to determine the effect of dietary CLA (Conjugated linoleic acid) levels on growth performance, fatty acid profiles and lipid metabolism of liver in Synechogobius hasta. Fish were fed six diets with fish oil replaced by 0 (control), 5, 10, 15, 20 and 25 g kg^?1 CLA for 8 weeks. Weight gain, WG, and SGR (specific growth rate) tended to increase when dietary CLA levels increased from 0 to 10 g kg^?1 and then decline with further increasing dietary CLA levels to 25 g kg^?1. FCR (feed conversion ratio) showed contrary trend with WG and SGR. The reduced VSI (vicero somatic index) and increased HSI (hepatosomatic index) were observed in fish fed increasing dietary CLA levels. Whole‐body lipid content declined, but hepatic lipid content increased with increasing dietary CLA levels. Dietary CLA modified total percentages of the main groups of fatty acids in liver. Hepatic 6PGD, ME and ICDH activities increased with increasing dietary CLA levels. FAS and G6PD were very variable and not related to dietary treatments. CPT I activities showed no significant differences among the treatments. Based on second‐order polynomial regression analysis of WG and FCR against dietary CLA level, 8.7–10.1 g kg^?1 was indicated to be the optimal dietary CLA range for maximum growth and feed utilization for S. hasta.     

Effects of replacing dietary fish oil and squid liver oil with vegetable oils on the growth,tissue fatty acid profile and total carotenoids of the giant freshwater prawn, Macrobrachium rosenbergii

A feeding trial was conducted to investigate the complete substitution of either fish oil (FO) or squid liver oil (SLO) with crude palm oil (CPO), canola oil (CO) sunflower oil (SFO) or linseed oil (LO), as the sole added lipid source in diets fed to triplicate groups of giant freshwater prawn, Macrobrachium rosenbergii (initial weight = 0.42 ± 0.01 g) for 6 weeks. Prawns fed the CO or SLO diets showed significantly higher (P < 0.05) specific growth rate than those fed the FO or CPO diets. The feed conversion ratio of the prawns was significantly better when fed the CO diet, compared with the FO, CPO, SFO and LO diets. The muscle eicosapentaenoic acid content of prawns fed the vegetable oil (VO) diets were not significantly different (P > 0.05) from those fed the FO diet, although all VO‐based diets led to a significantly lower docosahexaenoic acid content compared with prawns fed the FO or SLO diet. The whole‐body total carotenoid content was significantly lower for prawns fed the SLO diet compared with prawns on the CO or CPO diets. The successful use of VO instead of marine‐based oils in prawn diets will likely reduce feeding costs associated with M. rosenbergii aquaculture.     

Effect of polyunsaturated fatty acids on the fecundity of the Amazon river prawn Macrobrachium amazonicum (Heller, 1862)

Effects of the ratio of dietary fatty acids, namely n‐3 (mainly long chain polyunsaturated – LC‐PUFA) to n‐6 PUFA on the fecundity of Macrobrachium amazonicum were evaluated. In T1, the diet had equal and low levels of dietary n‐3 and n‐6 fatty acids (6 mg g^?1). In T2, the concentration of n‐3 (6 mg g^?1) was a half of the concentration of the n‐6 (12 mg g^?1), and in T3, the diet had equal and high concentrations of n‐3 and n‐6 (12 mg g^?1). Females with ovaries in stages I, III and V were collected. Higher gonadosomatic index (GSI) (6.89%) was observed in females in ovarian stage V than at other ovarian stages; however, the hepatosomatic index (HIS) showed high values in all females with ovaries in the stage III. A ratio of 1:2 n‐3:n‐6 fatty acids increased the GSI of mature females and the number of eggs spawned. Raising the level of both n‐3 and n‐6 fatty acids from ~0.6% to ~1.2% of the diet did not produce any effect on the GSI or on fecundity, suggesting that the ratio is more important than the absolute value of these two families of fatty acids.     

Effects of dietary highly unsaturated fatty acid levels on growth,fatty acid profiles,antioxidant activities,mucus immune responses and hepatic lipid metabolism related gene expressions in loach (Misgurnus anguillicaudatus) juveniles

A 9‐week rearing trail was conducted to examine the effects of different dietary highly unsaturated fatty acid (HUFA) levels on the growth performance, fatty acid profiles, antioxidant activities, mucus immune responses and lipid metabolism‐related gene expressions of loach (Misgurnus anguillicaudatus) juveniles. Five test diets supplemented with 0%, 0.32%, 0.64%, 0.96% and 1.28% HUFA were used here. The loaches fed no HUFA diets had the lowest specific growth rate and survival rate. The loaches fed 0.32% HUFA diets had the lowest feed conversion rate and while no significant differences were found among the other four diet groups. Contents of hepatic eicosapentaenoic acid, docosahexaenoic acid and total polyunsaturated fatty acids were significantly increased with incremental dietary HUFA levels. Activities of hepatic superoxide dismutase (SOD), glutathione peroxidase (GPx) and catalase (CAT) in 0% HUFA group were lowest, while malondialdehyde was just the opposite. The lysozyme activity was significantly increased with incremental dietary HUFA levels. However, the activities of alkaline phosphatase and acid phosphatase reached a peak in 0.32% HUFA group. Loaches fed diets with HUFA significantly up‐regulated expressions of SOD, GPx, CAT and two lipid metabolism related genes. In conclusion, the optimal dietary HUFA level for loach juveniles was 0.64%–0.96%.     

Effect of dietary lipid levels on growth performance,fatty acid profile and enzymatic activity of juvenile swimming crab,Portunus trituberculatus

The main objective of this investigation was to study the lipid requirements of the early juvenile (C1) swimming crab (Portunus trituberculatus) based on growth performance, survival, moulting and fatty acid profile. Four test diets were formulated with graded lipid levels (3.63%, 6.70%, 10.72% and 13.91%). Each diet was fed to 4 replicates of crabs (30 crabs per replicate initial weight (8.4 ± 0.1 mg). In this study, crabs fed diets with 13.91% lipid had significantly (p < 0.05) higher survival than crabs fed with 3.63% lipid, but no significant (p > 0.05) improvement of survival was observed when dietary lipid increase from 6.70% to 13.91%. Crabs fed diets with 10.72% and 13.91% lipid had significant higher weight gain(WG) than crabs fed with 3.63% lipid. While crabs fed with diets containing 6.70%, 10.72% and 13.91% lipid showed no significant (p > 0.05) difference in weight gain(WG). Moreover, the lowest moulting number was observed in crabs fed diets with 3.63% lipid, but there was no significant difference (p > 0.05) among other groups. The content of LC‐PUFA and DHA in the crabs fed diets with 3.63% lipid was significant (p < 0.05) lower compared to other groups. But there was no significant (p > 0.05) difference in EPA and ARA content among all groups. The activity of lipase increased as dietary lipid level increased (from 6.70% to 10.72%). However, beyond 10.72%, a significant (p < 0.05) decreased in lipase activity was observed. The regression analysis of weight gain data indicated that crab fed diet containing 10.47% lipid level is considered as optimum lipid level for its maximum growth and moulting process.     

Effects of dietary docosahexaenoic acid on growth performance,fatty acid profile and lipogenesis of blunt snout bream (Megalobrama amblycephala)

Six diets were designed to investigate the effects of dietary docosahexaenoic acid (22:6n‐3; DHA) levels (0.5, 1.3, 2.3, 4.2, 8.1 and 15.9 g/kg diets) on growth performance, fatty acid profile and expression of some lipogenesis‐related genes of blunt snout bream (Megalobrama amblycephala). Fish (average weight: 26.40 ± 0.11 g) were randomly fed one of six diets for 8 weeks. Results indicated that the final body weight (FBW) and specific growth rate (SGR) of fish fed 1.3 g/kg DHA were significantly higher than other groups except for the 2.3 g/kg DHA (p < .05). Compared with other groups, the number of lipid droplet clusters of the liver stained with oil red O in the 2.3 g/kg DHA group was the highest, which was consistent with the lipid contents of whole body and liver. The DHA proportion in liver and muscle significantly increased with the increasing dietary DHA levels (p < .05), which reflected fatty acid profiles of diets. The highest mRNA expressions of acetyl‐CoA carboxylase α (ACCα), fatty acid synthase (FAS) and sterol regulatory element‐binding protein‐1 (SREBP‐1) occurred in the 1.3 g/kg DHA group, followed by 2.3 g/kg DHA. In summary, the supplementation of 1.3–2.3 g/kg DHA could improve growth performance and lipogenesis, and the dietary DHA could improve DHA and PUFA proportion in liver and muscle.     

Effects of dietary macroalgae meal and lipid source on growth performance and body wall fatty acid composition of sea cucumber Apostichopus japonicus

A 70‐day experiment was conducted to examine the effects of different macroalgal meals and lipid sources on growth, body wall composition and fatty acid (FA) profile of sea cucumber Apostichopus japonicus. Two macroalgal meals including Sargassum muticum (SM) and Gracilaria lemaneiformis (GL) and two lipid sources including fish oil (FO) and vegetable oil (VO) were formulated into four diets, i.e., S. muticum and fish oil (SF), S. muticum and vegetable oil (SV), G. lemaneiformis and fish oil (GF) and G. lemaneiformis and vegetable oil (GV). The results showed that the specific growth rates (SGR) of A. japonicus fed diets containing SM were significantly higher than those fed diets containing GL. No significant differences in SGR between the FO‐based and VO‐based groups were observed. Similar results were observed in the body wall lipid content. Most body wall FAs changed to resemble the dietary FA proportions because of the dietary effect. Concentrations of 20:4n‐6 of the SF and GF groups were significantly lower than the SV and GV groups, while levels of 20:5n‐3 and 22:6n‐3 were significantly higher than the SV and GV groups. The n‐3/n‐6 polyunsaturated fatty acids (PUFA) ratios of the SF and GF groups were significantly higher than the SV and GV groups. Moreover, the SF group had significantly higher 20:5n‐3 and 22:6n‐3 contents and n‐3/n‐6 PUFAs ratio than the GF group. These findings reveal that the SF diet can show beneficial effects on both growth performance and body wall n‐3 PUFAs content of A. japonicus.     

Current status and prospects of farming the giant river prawn ( Macrobrachium rosenbergii) and the oriental river prawn ( Macrobrachium nipponense) in China

The current status of the farming of Macrobrachium species in China is presented, including the scale of production and with an emphasis on its farming technology. The problems faced and research needed for the further development of freshwater prawn farming of China is also reviewed. Finally, this paper discusses the prospects and future expansion in this sector of national aquaculture.