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1.
An 8‐week feeding trial was conducted to determine the dietary leucine requirement for juvenile swimming crabs reared in cement pools. Six isonitrogenous and isolipidic practical diets (430 g/kg crude protein and 70 g/kg crude lipid) were formulated to contain graded leucine levels which ranged from 16.7 to 26.7 g/kg (dry weight). Each diet was randomly assigned to triplicate groups of 60 juvenile swimming crabs (initial average weight 3.75 ± 0.12 g) that were stocked in rectangle plastic baskets. The results of the present study indicated that dietary leucine levels significantly influenced weight gain (WG) and specific growth ratio (SGR) (p < .05), crab fed the diet containing 22.7 g/kg leucine had significantly higher WG and SGR than those fed the other diets. Feed efficiency and protein efficiency ratio were not significantly affected by the dietary leucine levels (p > .05). Total protein, cholesterol, triglyceride and glucose in serum were significantly affected by the dietary leucine levels. Aspartate aminotransferase (AST) and alanine aminotransferase activities in hemolymph, AST and superoxide dismutase activities in hepatopancreas were significantly affected by dietary leucine levels; moreover, crab fed the 16.7 g/kg leucine diet had higher malondialdehyde in hemolymph and hepatopancreas than those fed the other diets. Crab fed the diet containing 24.9 g/kg leucine had higher phenoloxidase activity in hemolymph than those fed the other diets. Based on two‐slope broken‐line model of SGR against dietary leucine levels, the optimal dietary leucine requirement for growth was estimated to be 22.1 g/kg of the dry diet (corresponding to 51.4 g/kg of dietary protein on a dry weight basis). In summary, findings of this study indicated that dietary leucine could improve growth performance and antioxidant status.  相似文献   

2.
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.  相似文献   

3.
An 8‐week feeding trial was conducted to evaluate the effects of replacement of fish oil (FO) with blending vegetable oils (VOs) on growth performance, antioxidant enzyme activities and fatty acid composition in tissue of swimming crab Portunustrituberculatus. Five isonitrogenous and isolipidic diets were formulated to contain VOs (colza oil: palm oil: linseed oil = 4:2:1) to replace 0 (the control diet), 250, 500, 750 and 1000 g/kg of FO (defined D0, D25, D50, D75, D100). Three hundred juvenile swimming crabs (initial weight 2.34 ± 0.08 g) were randomly stocked and sorted into 300 individual rectangle plastic baskets in three cement pools. Each treatment has three replicates, one replicate has 20 swimming crabs, and each diet fed 60 crabs distributed in 60 baskets. The results indicated that crabs fed the control diet showed significantly higher survival, final body weight, per cent weight gain (PWG), specific growth rate and moulting frequency, crude protein and crude lipid contents in muscles than those fed the D75 and D100 VO diets (p < .05). Crabs fed the D25 VO diet showed significantly higher concentration of triglyceride, low‐density lipoprotein cholesterol and total protein, activities of superoxide dismutase, catalase and glutathione peroxidase (GSH‐Px) in haemolymph than those fed the control diet (p < .05). Fatty acid composition in hepatopancreas was positively correlated with dietary composition. In summary, based on the PWG, the optimal replacement of FO with VOs was estimated to be 250 g/kg. These findings demonstrated that swimming crabs make better use of FO than VOs.  相似文献   

4.
One hundred and twenty crabs (initial weight: 51.32 ± 0.06 g) were fed three experimental diets with cottonseed meal protein hydrolysate (CPH) at 0, 6 and 12 g/kg for 60 days. The results showed that CPH0.6 diet significantly improved the 1‐hr feed intake, protease activity and weight gain of crabs. In thoracic ganglia, 4E‐binding protein (4E‐BP) expression level of crab fed the diets containing CPH was significantly higher than CPH0 group. In cerebral ganglia, protein kinase B and 4E‐BP expression levels of crab fed CPH0.6 diets were significantly lower than CPH0 group. In mid‐intestine, target of rapamycin (TOR) relative expression level of crabs fed the diets containing CPH was significantly lower than CPH0 group. 4E‐BP expression level showed an opposite pattern. In thoracic ganglia, cerebral ganglia and mid‐intestine, leptin receptor expression level of crabs fed CPH0.6 diet was significantly lower than CPH0 group. Neuropeptide Y and neuropeptide Y receptor expression level of crab fed CPH0.6 diet was significantly higher than CPH0 group. In conclusion, our results indicated that dietary supplementation of 6 g/kg CPH could stimulate appetite and quicken feeding rate via the TOR signalling pathway.  相似文献   

5.
The present study aims to assess the anti‐nutritional effect of pectin and to better understand rapeseed meal (RSM) as a feed ingredient for Chinese mitten crab, Eriocheir sinensis. A semipurified diet containing 280 g/kg fish meal was formulated as a control diet (DF). A second diet (DP) was supplemented with 26.7 g/kg pectin; the amount was estimated to be equal to that in the third diet (DR), which was formulated to include 400 g/kg RSM. Another diet (DRPase) was supplemented with 12 g/kg pectinase based on DR in which pectin was degraded by pectinase. The diets were randomly fed to twelve tanks of the crab for 8 weeks. Compared with the crabs fed DF, the specific growth rate, protein efficiency ratio, apparent digestibility coefficients (ADC) of dry matter and protein, activity of aspartate transaminase (AST) and trypsin (TP), and high‐density lipoprotein (HDL) in the serum decreased significantly in the crabs fed DR; the ADC of dry matter, activity of AST and serum HDL decreased significantly in the crabs fed Dp, but they were higher than in the crabs fed DR. Compared with the crabs fed DR, the ADC of dry matter, activity of AST and TP, and serum HDL increased significantly in the crabs fed DRPase. The mRNA expression activity of both Es‐pl44 and Es‐pp1 was DF < DP < DRPase < DR. These results indicate that pectin contributed to low utilization of RSM in Chinese mitten crab.  相似文献   

6.
Six purified diets were formulated to contain three lipid sources, fish oil (FO), linseed oil (LO) and soybean oil (SO), at 6% diet lipid crossing two levels of vitamin E (100 and 300 mg α‐tocopheryl acetate/kg diet) for each lipid source (FO100, FO300, LO100, LO300, SO100, SO300). The juvenile Chinese mitten crab, Eriocheir sinensis, respectively, fed on these diets with four replicates for 6 weeks. The crab weight gain (WG) and specific growth rate (SGR) were significantly affected by dietary lipid sources. No difference was found between the crabs fed two levels of vitamin E, but the WG and SGR were numerically higher in crab fed 300 mg/kg vitamin E than those fed the other level of vitamin E. The lipid source and vitamin E level could affect fatty acid composition in the hepatopancreas. The contents of saturated fatty acids (SAFA) and n‐3HUFA were significantly higher in the crab‐fed fish oil. The highest contents of n‐6PUFA and n‐3PUFA were found in the crab‐fed soybean oil and linseed oil respectively. The contents of SAFA, n‐3HUFA and n‐3PUFA were higher in the 300 mg/kg vitamin E treatment. A lower malondialdehyde (MDA) content and higher phenoloxidase (PO) activity were observed in the crab fed 300 mg/kg vitamin E. The results of this study indicate that the Chinese mitten crab fed the diet with 6% fish oil and 300 mg/kg vitamin E showed better growth, antioxidant capacity and resistance to Aeromonas hydrophila.  相似文献   

7.
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8.
Wan  Jin-Juan  Pan  Jian-lin  Shen  Mei-Fang  Xue  Hui  Sun  Meng-lin  Zhang  Mei-Qin  Zhu  Xi-He  Ma  Xing-kong 《Aquaculture International》2022,30(1):467-481

The research aimed to evaluate the effects of dietary fructooligosaccharide, probiotics and their combination on the growth performance, antioxidant enzymes and stress resistance of juvenile Eriocheir sinensis. Crabs (average weight: 9.90?±?0.07 g) were randomly assigned into 4 groups (3 tanks per group) fed experimental diets: basal diet (control group), basal diet supplemented with 5 g/kg FOS, basal diet supplemented with 2 g/kg multi-strain probiotics (each gram contains Lactobacillus acidophilus 106 CFU?+?Bacillus subtilis 107 CFU?+?Saccharomyces cerevisiae 1010 CFU) and basal diet supplemented with symbiotic (5 g/kg FOS?+?2 g/kg multi-strain probiotics) (designated as control, D1, D2 and D3, respectively). After 8 weeks of feeding trial, crabs were exposed to the transportation process (3 h). Cumulative mortality was recorded at 24 h, 48 h, 72 h and 96 h after transport stress, and pre-transport and post-transport sampling of hepatopancreas occurred for assay. The results indicated that crabs fed D3 had significantly higher weight gain (WG), specific growth rate (SGR) and lower feed conversion ratio (FCR) than crabs fed control diet. Before stress, compared to the control group, crabs fed D1 and D3 diet significantly increased catalase (CAT), superoxide dismutase (SOD) activities and decreased malondialdehyde (MDA) activities, the highest activities of pepsin, trypsin and chymotrypsin were observed in crabs fed D2 diet. After stress, there was a trend that the activities of antioxidants enzymes and proteases in all groups were significantly decreased. And compared to the control group, crabs fed D1 and D3 diet significantly improved SOD and CAT activities, the lowest MDA activity was observed in crabs fed D3 diet, no significant difference was obtained in activities of total antioxidant capacity (T-AOC) and three proteases among all groups (P?>?0.05). At 96 h after transportation process, the lowest cumulative mortality was observed in crabs fed D3 diet, the difference among all groups before and at 24 h, 48 h and 72 h after stress was not significant (P?>?0.05). In summary, a basal diet supplemented with synbiotic could improve the growth performance and protect the hepatopancreas of Eriocheir sinensis more effectively than singular supplementation with prebiotics or probiotics.

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9.
Four iso‐nitrogenous and iso‐lipidic diets were designed to investigate the effects of dietary phospholipids (PL) levels (with 0%, 1%, 2%, and 4% PL supplementation) on growth performance, lipid metabolism, and antioxidant capacity in early juvenile green mud crab (Scylla paramamosain). There were three replicates of 28 crabs (initial body weight from 42.02 to 42.44 mg) for each diet treatment, and growth trial lasted for 8 weeks. At the end of the growth trial, there was no significant difference in survival among all treatments. Crabs fed diet with 2% PL obtained highest weight gain (WG) and specific growth rate than other crabs. The molting frequency was not affected by different dietary PL addition. Besides, the contents of whole body lipid and long chain highly unsaturated fatty acids significantly increased with elevating dietary PL levels. In the hepatopancreas, crabs fed diet with 0% PL had significantly higher malondialdehyde concentration than other crabs. And crabs fed diet with 2% PL obtained significantly higher superoxide dismutase activity than crabs fed diets with 0% and 4% PL. Moreover, the mRNA expression of Na+/K+‐ATPase was significantly down‐regulated with dietary PL supplementation over 2%. Based on the second order polynomial regression analysis of WG, 2.37% dietary PL level was the optimal demand for early juvenile S. paramamosain. Moreover, we found crabs fed diet with 2% PL obtained better antioxidant capacity than other crabs.  相似文献   

10.
The objective of this study was to evaluate the effects of different phospholipids (PL) and cholesterol (CH) levels on the growth, moulting and fatty acid composition of juvenile swimming crab, Portunus trituberculatus. Six diets were designed to contain three PL levels (0, 10 and 20 g/kg) and two CH levels (2 and 8 g/kg). Juvenile swimming crabs (3.48 ± 0.02 g/crab) were reared for 8 weeks. The weight gain (WG) was significantly (p < .05) increased by supplementation of 8 g CH/kg of diet. However, no significant interaction between dietary PL and CH levels was found on the growth performance (p > .05). The moulting frequency (MF), protein efficiency ratio (PER) and feed efficiency ratio (FCR) were not significantly (p > .05) affected by the dietary treatments. The serum total cholesterol (TCH) significantly (p > .05) increased with increasing dietary PL level. The C20:4n‐6 and C20:5n‐3 content of the whole body of crabs increased with the addition of PL to the diet containing 2 g/kg CH of diet. An interaction was observed between PL and CH on certain saturated and unsaturated fatty acid concentrations of body.  相似文献   

11.
This study examined the effects of dietary cholesterol on the survival, molting pattern, and growth of early juveniles of the blue swimmer crab, Portunus pelagicus. Seven isocaloric diets were formulated to contain cholesterol at 0 (basal diet), 2.5, 5.0, 7.5, 10, 12.5, and 15 g/kg diet dry weight. Survival ranged from 20 to 47.5%, with the highest survival recorded for crabs fed the diet supplemented with 10 g/kg cholesterol, while the lowest survival was demonstrated by crabs fed the basal diet. The highest occurrence of molt death syndrome was found for crabs fed the diet with cholesterol supplementation of 15 g/kg. A general trend of decreasing development time to the crab 3 (C3) stage was observed with increasing dietary cholesterol supplementation up to a level of 10 g/kg, but this then decreased as dietary cholesterol level was increased to 12.5 and 15 g/kg. The specific growth rates of crabs, calculated for dry weight, carapace width, and carapace length, followed a similar trend. Our results suggest that, under the current feeding conditions, a dietary cholesterol level of 10 g/kg appears to be optimal for the culture of early juveniles of P. pelagicus.  相似文献   

12.
An 8‐week feeding trial was conducted to evaluate the effects of dietary lipid sources on growth performance, antioxidant enzyme activities and biochemical composition of juvenile swimming crab Portunus trituberculatus of initial weight 2.34 ± 0.08 g. Four different diets were formulated to contain fish oil (FO), soybean oil (SO), linseed oil (LO) or palm oil (PO). The highest final body weight, weight gain, specific growth rate and molting frequency were observed in crabs fed the FO diet. Crabs fed the SO diet showed higher glutathione peroxidase, superoxide dismutase (SOD) and catalase (CAT) activities in both serum and hepatopancreas than those fed the FO diet. The lowest malondialdehyde concentration in hepatopancreas and serum were occurred at crabs fed the SO diet. Crabs fed the LO diet had significantly higher SOD and CAT activities in hepatopancreas compared with those fed the FO diet. Crabs fed the PO diet had the highest activities of fatty acid synthase and carnitine palmitoyltransferase 1 activities in hepatopancreas among all treatments. Fatty acid compositions both in hepatopancreas and muscle reflected those of diets. Overall, these findings demonstrated that physiological–biochemical characteristics and lipid metabolism were significantly regulated by different dietary lipid sources. Moreover, dietary SO and LO supplementation could improve antioxidant ability.  相似文献   

13.
We conducted large‐scale production trials in Seward, Alaska, USA to investigate effects of dietary astaxanthin supplementation on survival, growth and shell colouration of recently settled juvenile (C1–C4) red king crabs (Paralithodes camtschaticus). We supplemented a control diet of commercial crustacean feeds with astaxanthin, and fed these diets to juvenile king crabs at densities of 2000 and 4000 crabs m?2 for 56 days. We assessed survival and growth by counting crabs and individually measuring carapace width and weighing crabs at the start and end of the experiment, and quantified crab colour (hue, saturation, brightness) in digital photographs. Diets containing astaxanthin had higher survival, suggesting that astaxanthin may provide nutritional or immune system benefits. Crabs had lower hue, higher saturation and lower brightness values when fed diets containing astaxanthin, suggesting that red king crab colouration is plastic and responds to diet. Astaxanthin is likely an important dietary component for hatchery or laboratory reared red king crab juveniles, and should be considered for aquaculture and other rearing of this and possibly other crustacean species.  相似文献   

14.
Two approaches (i.e. water and dry or semi‐dry transport) have been developed for the transport of swimming crabs Portunus trituberculatus in recent years. To evaluate their differential effects on physiological responses of crabs, we measured haemolymph components (metabolic substrates, metabolites and ions) and hepatopancreas glycogen level at different time intervals after exposure of crabs to thermal stresses in water and air. The immersed crabs exhibited no significant change in all metabolic substrates except the glucose level in the hypothermal stressed treatment (P > 0.05), whereas there was a great variation in haemolymph glucose and lipid level of air exposed crabs under both thermal stresses (P < 0.05). With respect to metabolites in immersed crabs, only urea concentration in hypothermal stressed crabs and lactate concentration in hyperthermal stressed crabs changed significantly during the experiment; by contrast, the air exposed crabs responded significantly in all metabolites to thermal stresses (P < 0.05). The immersed crabs decreased the concentration of Na+ and Mg2+, but increased the concentration of K+ and Ca2+. The change in Na+ and Ca2+ were not significant in the hyperthermal stressed crabs (P > 0.05). Nevertheless, all ions except K+ accumulated significantly in the air exposed crabs after thermal stresses (P < 0.05). Crabs in the two different media responded similar to thermal stresses in metabolism but differed greatly in ions regulation. The effects of thermal stresses on crabs could be magnified by exposure to air, leading to animals relying more on anaerobic metabolism and therefore limiting the usage of dry or semi‐dry transport approach especially at high temperature.  相似文献   

15.
A 10‐week feeding trial was conducted to evaluate the effects of dietary lipid sources on the growth and immune responses of Chinese mitten crab Eriocheir sinensis. Six isonitrogenous and isoenergetic diets were formulated with fish oil (FO), linseed oil (LO), soybean oil (SO), rapeseed oil (RO), coconut oil (CO) and beef tallow (BT) as the sources of lipid with five replicates each. Thirty crabs (2.35 ± 0.14 g) were stocked into each tank and fed twice daily. Weight gain and specific growth rate of crab fed the FO diet were significantly lower than those fed other diets (P < 0.05), except for crabs fed LO diet (P < 0.05). Crab fed the SO diet weighed more than those fed FO diets (P < 0.05). Serum superoxide dismutase and malondialdehyde of crab fed the FO diet were significantly higher than in other groups (P < 0.05). Crab fed the FO diet had the highest activities of serum phenoloxidase, acid phosphatase, alkaline phosphatase and lysozyme (P < 0.05). The fatty acid composition in the liver of crab reflected the change in test diets. Our results indicate that the use of dietary vegetable or animal oils can achieve similar growth performance to the use of dietary FO in Chinese mitten crab, but non‐FOs may impair crab immunity. Soybean oil is recommended as a suitable replacer for FO in Chinese mitten crab diet.  相似文献   

16.
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17.
A 12‐week feeding trial was conducted to determine the dietary phosphorus requirement of Heteropneustes fossilis fingerlings (7.7 ± 0.04 g). Fish were fed casein–gelatine‐based purified diets in triplicate groups near satiation with seven different levels of dietary phosphorus (3.2, 5.2, 7.2, 9.2, 11.2, 13.2 and 15.2 g/kg dry diet). All diets were formulated to be isoproteic (400 g/kg) and isoenergetic (17.89 kJ/g). Highest absolute weight gain (68.38 g/fish), best feed conversion ratio (1.48), protein retention efficiency (30.74%), protein gain (12.44 g/fish), haemoglobin (11.19 g/dL), RBCs (3.12 x106/mm3), haematocrit (33.44%) and serum phosphate (2.82 mg/L) were found at 9.2 g/kg phosphorus. Hepatic superoxide dismutase and catalase activity were also significantly influenced by the dietary phosphorus levels. Whole body and vertebrae phosphorus concentrations increased significantly as the amount of dietary phosphorus increased from 3.2 to 11.2 g/kg dry diet and then plateaued. More accurate information on dietary phosphorus requirement was obtained by subjecting the AWG, FCR, vertebrae phosphorus and whole body phosphorus concentrations data against various levels of dietary phosphorus to broken‐line analysis, which yielded the requirement in the range of 9.0–11.0 g/kg for optimum growth and mineralization of H. fossilis.  相似文献   

18.
This study evaluated the palygorskite inclusion effects on the pellet quality, growth, antioxidant status and mineral contents of Chinese mitten crabs. Crabs (n = 640; initial average weight, 1.36 ± 0.02 g) were allocated into four groups with eight replicates of twenty crabs. A basal diet supplemented with 0, 10, 20 and 40 g/kg palygorskite was fed to crabs for 8 weeks respectively. Results exhibited that dietary addition of palygorskite enhanced the pellet process electrical energy consumption, improved the hardness and durability (p < .05), reduced percentage of fines and dissolved weight loss of pellets (30, 60, 120, 240, 480 min; p < .05) in the water. Crabs had no differences on the weight gain, specific growth rate, feed conversion ratio, abdominal meat ratio and edible viscera index among the groups (p > .05). Palygorskite inclusion decreased the MDA contents of edible viscera and abdominal meat (p < .05) of Chinese mitten crabs. The ether extract contents of edible viscera in palygorskite inclusion groups were lower than that of the control group (p < .05) in Chinese mitten crabs. Furthermore, palygorskite addition linearly increased the Fe level in the edible viscera and reduced tissue Pb and Cr (p < .05) accumulations of Chinese mitten crabs. In conclusion, palygorskite inclusion could improve pellet quality, enhance the antioxidant capacity and Fe content of edible viscera, decrease the edible viscera ether extract level and tissue Pb and Cr accumulations without impairing the growth performance of Chinese mitten crabs, but increased the electrical energy consumption of pelleting.  相似文献   

19.
This experiment was designed to investigate the effects of dietary valine on the growth performance, feed utilization, digestive enzymes, serum antioxidant and immune indices of juvenile Trachinotus ovatus and determine its valine requirement. Six diets with different concentrations of L‐valine (15.0, 16.6, 18.6, 20.7, 23.5 and 25.4 g/kg dry diet, defined as diet Val‐1 to Val‐6.), were formulated to contain 430 g/kg crude protein with fish meal, soybean meal, peanut meal and precoated crystalline amino acids. Each diet was randomly assigned to triplicate treatments of 20 fish (the initial body weight was 5.34 ± 0.03 g) for 8 weeks. The results indicated that the final body weight and percent weight gain (PWG) increased with increasing valine concentration up to 18.6 g/kg (diet Val‐3), whereas the diets containing higher valine concentration reduced the growth performance significantly (p < .05). Moreover, the protein efficiency ratio, body protein deposition (BPD), muscle protein content, intestinal amylase and pepsin activities, serum T‐AOC, LZM activities, IgM, complement 3 and complement 4 concentration had a similar trend with PWG, and the trend of feed conversion ratio, serum AST, ALT activities, urea and MDA content was opposite. Meanwhile, the lipid contents of whole fish and muscle in diet Val‐6 were particularly lower than other diets (p < .05). The survival rate of diet Val‐1 was lowest in this study and was significantly lower than diet Val‐2 (p < .05). The results of polynomial regression based on PWG and BPD indicated that the optimal dietary valine requirement for Trachinotus ovatus reared in seawater‐floating net cages was 19.87–20.17 g/kg valine of dry diet, correspondingly 46.22–46.91 g/kg of dietary protein.  相似文献   

20.
To quantify the dietary potassium requirement of fingerling Labeo rohita (6.2 ± 0.12 cm; 1.98 ± 0.06 g), seven purified experimental diets (350 g/kg crude protein and 16.72 kJ/g gross energy) with graded levels of potassium (0.32, 1.35, 2.41, 3.46, 6.48, 9.47 and 12.39 g/kg diet) were fed to triplicate groups of fishes at 08:00, 12:00 and 16:00 hr to apparent satiation for 8 weeks. Live weight gain (LWG; 671.46%), specific growth rate (3.65%/day), protein efficiency ratio (2.16), protein gain (PG; 2.41 g/fish) and feed conversion ratio (1.32) were found to be best in fish fed diet containing 3.46 g/kg potassium. Gill Na+‐K+ ATPase activity was also highest in fish fed diet with 3.46 g/kg potassium. Potassium content of whole‐body, vertebrae and scales increased significantly with the increase in dietary potassium level up to 6.48 g/kg. Significant changes were also noted in serum malondialdehyde content, superoxide dismutase, catalase, glutathione peroxidase and alkaline phosphatase activity. Based on the maximum live weight and protein gain observed in the present study, the inclusion of 3.55 g/kg potassium is recommended for developing potassium‐balanced commercial feeds for intensive culture of fingerling L. rohita.  相似文献   

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