Cloning,characterization, expression analysis and RNAi of Retinoblastoma‐like gene from black tiger shrimp (Penaeus monodon)

Retinoblastoma (Rb) is a multifunctional regulator involved in several key cellular processes, such as cell cycle control, cell differentiation, tumorigenesis and senescence. In this study, an Rb‐like gene, PmRBL, was cloned from black tiger shrimp (Penaeus monodon). The full‐length cDNA sequence of PmRBL is 4,069 bp with an open reading frame of 3,243 bp, which encodes 1,080 amino acids. Quantitative real‐time PCR (qRT‐PCR) analysis indicated that PmRBL was highly expressed in the gills, hepatopancreas and ovaries of P. monodon. The highest PmRBL expression levels were observed in stage III of the ovarian development in P. monodon. RNA interference experiments were conducted to examine the expression profiles of PmRBL, PmCDK2 and PmCyclin E. The knockdown of PmRBL in the ovary and hepatopancreas by dsRNA‐RBL was successful. After dsRNA‐RBL was injected into the shrimp, the relative expression levels of PmCDK2 and PmCyclin E were upregulated at 12–72 hr in the ovaries and hepatopancreas. The localization and level of PmRBL expression in the ovary and hepatopancreas were investigated through in situ hybridization, which revealed consistent results with those of qRT‐PCR. Therefore, PmRBL, PmCDK2 and PmCyclin E may be involved in vitellogenin synthesis and ovarian maturation in P. monodon.     

Effects of crude extracellular protein and crude intracellular polysaccharides of Vibrio alginolyticus on the growth,energy metabolism regulation and WSSV resistance of Litopenaeus vannamei

This study aimed to investigate the effects of adding crude extracts of the extracellular protein (Ex‐Pro) and intracellular polysaccharides (In‐Poly) of Vibrio alginolyticus to diets, at a dosage of 10 g/kg, on the growth, energy metabolism and WSSV (White Spot Syndrome Virus) resistance of Litopenaeus vannamei (initial weight, 0.88 ± 0.04 g/shrimp). Growth and survival rate were not significantly affected by the crude extracts (p > 0.05). Shrimp fed Ex‐Pro crude extracts showed higher succinate dehydrogenase (SDH) activity in the hepatopancreas and muscle but lower lactate dehydrogenase (LDH) activity in the muscle (p < 0.05). The activities of hexokinase (HK), pyruvate kinase (PK), LDH and SDH in the hepatopancreas and the activity of SDH in the muscle were significantly increased by feeding In‐Poly crude extracts (p < 0.05). In contrast, the content of fatty acid synthase (FAS) in the muscle was significantly reduced by the crude extracts (p < 0.05). The contents of glucose and triglyceride and the activity of the electron transport system in the hepatopancreas were significantly increased by the crude extracts (p < 0.05), and the WSSV resistance of the shrimp was increased. These results indicated that the Ex‐Pro and In‐Poly crude extracts of V. alginolyticus could affect energy metabolism, and there was a correlation between WSSV resistance and energy metabolism in L. vannamei.     

Effects of dietary Bacillus and medicinal herbs on the growth, digestive enzyme activity, and serum biochemical parameters of the shrimp Litopenaeus vannamei

White shrimp (Litopenaeus vannamei) was fed six different formulations of medicinal herbs (MH) and Bacillus in a feeding trial conducted for 56 days. The survival, growth, digestive enzyme activity, and serum biochemical parameters were assessed. A basal diet without MH and Bacillus was served as the control. At the end of feeding trial, survival ranged from 76.19% to 84.76% with no significant differences (P > 0.05) among all groups. Growth measured as final weight, specific growth rate (SGR), protein efficiency ratio (PER), protein productive value (PPV), and feed efficiency ratio (FER) were improved with increased dietary MH and Bacillus. Shrimp fed 0.2% MH and 0.3% Bacillus (Diet 23) were found to have the best growth performance. For shrimp fed Diet 23 final weight and SGR were significantly (P < 0.05) higher than for controls. The digestive enzyme activity of protease and amylase in hepatopancreas and intestines were significantly (P < 0.05) enhanced by the feed supplements, however amylase of the hepatopancreas was not affected. Serum protein and glucose content were enhanced by the supplement of MH and Bacillus. Serum cholesterol in shrimp of high Bacillus level groups was significantly (P < 0.05) higher than in the control group. However, no significant difference (P > 0.05) in serum Triacylglycerols between supplemented groups and control was found. Results revealed that the combined MH and Bacillus in diet could enhance growth because it can improve digestive enzyme activity and digestive metabolism.     

Effects of different carbon sources addition on nutrition composition and extracellular enzymes activity of bioflocs,and digestive enzymes activity and growth performance of Litopenaeus vannamei in zero‐exchange culture tanks

A 35‐day feeding experiment was conducted to investigate the effects of different carbon sources addition on nutritional composition and extracellular enzymes activity of bioflocs, and digestive enzymes activity and growth performance of Litopenaeus vannamei juveniles (average 5.52 ± 0.21 g) in zero‐water exchange culture tanks. Molasses, corn flour and wheat bran were used as carbon sources and added into the tanks to promote the development of bioflocs during the experiment. During the entire experiment, good water quality and biofloc development were achieved under the addition of different carbon sources. At the end of the experiment, the proximate composition and extracellular enzymes activities of the collected bioflocs from seven biofloc groups were influenced by the addition of the different carbon sources. Meanwhile, the specific activities of protease, amylase, lipase and cellulase in the hepatopancreas, stomach and intestine of the shrimp showed differences among the seven biofloc groups, and most of them were significantly higher than those obtained in the control group (P < 0.05). There were differences in the performance (growth and FCR) of the shrimp among the seven biofloc groups, and all of them were significantly better than those obtained in the control group (P < 0.05). Based on the results of this study, 60% molasses + 20% corn flour + 20% wheat bran could be an appropriate formula of the addition of carbon sources for intensive culture of L. vannamei (mainly in terms of growth and FCR) in zero‐water exchange culture tanks.     

Effects of dietary supplementation with freeze‐dried powder of Ampithoe sp. on the growth performance,energy metabolism,and ammonia‐nitrogen tolerance of the Pacific white shrimp,Litopenaeus vannamei

This study evaluated the influence of dietary supplementation with freeze‐dried powder of Ampithoe sp. (FDPA) on the growth, energy metabolism, and resistance to ammonia‐nitrogen stress in Litopenaeus vannamei. There were four treatment groups: a 0% group (no FDPA addition), a 33% group, a 66% group (33% and 66% of the shrimp diet, respectively, replaced with FDPA), and a 100% group (only FDPA). The results of this study suggested a positive effect of FDPA supplementation on shrimp survival: the supplemented groups had significantly higher survival than the 0% group (p < 0.05). The body length, body weight, and specific growth rate (SGR) of the 33% group were higher than those of the other groups and were significantly higher than that of the 100% group (p < 0.05). FDPA feeding had a negative effect on carbohydrate metabolism pathways and energy consumption due to decreases in pyruvate kinase (PK), phosphofructokinase (PFK), succinate dehydrogenase (SDH), lactic dehydrogenase (LDH), and respiratory electron transport system (ETS) activity in shrimp fed FDPA during the culture period. The shrimp in the 33% group exhibited good resistance to ammonia‐nitrogen stress. Additionally, the glycolysis pathway and energy consumption of shrimp in the 33% group were enhanced during the ammonia‐nitrogen stress period. Consequently, it was inferred that FDPA supplementation could improve the resistance of shrimp to ammonia‐nitrogen stress (in the 33% group), which might be related to the effects of the supplement on energy metabolism pathways, particularly in terms of enhancing glycolysis to provide sufficient energy for the stress response.     

Effects of freeze‐dried powder of the Antarctic krill Euphausia superba on the growth performance,molting and fatty acid composition of the Pacific white shrimp Litopenaeus vannamei

This study was designed to evaluate the effect of dietary replacement fish meal supplemented with freeze‐dried powder of the Antarctic krill Euphausia superba (FDPE) on the growth performance, molting, and fatty acid composition of the Pacific white shrimp Litopenaeus vannamei (initial weight 1.27 ± 0.09 g). Four diets containing 0% (S0 group), 10% (S10 group), 20% (S20 group), and 30% (S20 group) FDPE were used in the present study. At the end of growth trial, the final body weight, weight gain rate, and specific growth rate in the S10, S20, and S30 groups were higher than those in the S0 group. The shrimp in the S10 and S20 groups exhibited better molting synchronism than those in the S0 group. The astaxanthin content in the hepatopancreas from the shrimp in the groups supplemented with FDPE was significantly higher than that in the S0 group (p < 0.05) and increased as the FDPE content in the feed increased. The shrimp in the S10, S20, and S30 groups had a higher monounsaturated fatty acid (MUFA) content in the hepatopancreas than those in the S0 group. The sum of EPA and DHA in the muscles from the shrimp in the S0 group was lower than that in the other groups. These results indicate that the dietary inclusion of 10%–20% FDPE can be used as practical diets in L. vannamei farmed under a clear water system.     

Evaluation of some haemolymph biochemical properties and F‐cell prevalence in hepatopancreas of white leg shrimp (Litopenaeus vanammei) after fed diets containing apple cider vinegar and propionic acid

The present study aimed to evaluate the effect of dietary ACV (apple cider vinegar) and PA (propionic acid) supplementation on some biochemical properties of haemolymph and fibrillar cell (F‐cell) number in the hepatopancreas of shrimp. Five different diets supplemented with 0%, 1%, 2%, 4% ACV and 0.5% PA diets were fed to Litopenaeus vanammei. Some biochemical parameters of haemolymph (cortisol, alkaline phosphatase, albumin, urea, uric acid, creatinine, phosphorus, total hemocyte count) and prevalence of F‐cell in hepatopancreas were examined after 60 days feeding trial. The albumin concentration and total hemocyte count in 2% and 4% ACV and PA groups were significantly higher than those of other groups (p < .05). Moreover, the highest phosphorus concentration was detected in shrimp fed 4% ACV and PA experimental diets (p < .05). No significant differences in haemolymph cortisol, urea, uric acid, creatinine, alkaline phosphatase and tubule area were observed among the experimental groups (p > .05). 2% ACV group showed more F‐cell number in hepatopancreas than other groups while the reduction in F‐cell number was observed in the PA group. Based on these observations, the tested ACV and PA diets remarkably exhibited positive impacts on nutritional value and they may be a potential for adding to shrimp diet.     

Dietary fulvic acid effects on survival and expression of immune‐related genes in Litopenaeus vannamei challenged with Vibrio parahaemolyticus

The effects of fulvic acid (FA) on survival and immune‐related gene expression were investigated in Litopenaeus vannamei challenged with Vibrio parahaemolyticus by immersion. Shrimp were fed with different dietary FA concentrations (1, 2, 4 and 6 g/kg feed) for 20 days (first bioassay) or 8 days (second bioassay, 2 g/kg feed of FA added every 2 days) and then challenged with V. parahaemolyticus. In a third bioassay, the expression of three immune‐related genes (translationally controlled tumour protein [TCTP], superoxide dismutase [SOD] and heat‐shock protein 70 [HSP70]) in haemocytes or hepatopancreas of experimental shrimp was measured by real‐time quantitative PCR at 0, 6, 12, 24, 48, 72 and 96 hr after FA (2 g/kg feed) administration. Fulvic acid increased survival at a concentration of 2 g/kg feed supplied every two days. Interestingly, TCTP gene expression was upregulated, whereas gene expression of SOD and HSP70 was downregulated. In conclusion, dietary fulvic acid improves survival in white shrimp challenged with V. parahaemolyticus and modulates the immune response. Therefore, FA merits further evaluation as prophylactic treatment in commercial shrimp farms.     

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.     

Dietary calcium requirement of red swamp crayfish (Procambarus clarkia)

To investigate dietary calcium requirement of red swamp crayfish (Procambarus clarkia), six semi‐purified diets were formulated to contain different concentrations of calcium (2.7(control group), 6.1, 11.9, 17.6, 23.5 and 29.1 g/kg calcium). Each diet was hand‐fed to triplicate of 15 crayfish with average initial body weight (6.22 ± 0.87) g for 8 weeks. The results showed that weight gain rate (WGR) significantly increased and feed conversion ratio (FCR) significantly decreased from 11.9 to 23.5 g/kg groups (p < .05). Protease activities in intestine and hepatopancreas and parathyroid hormone concentrations in serum significantly decreased with increasing dietary calcium levels (p < .05), while calcium and phosphorus contents in exoskeleton, calcium content in muscle and calcitonin concentrations in serum significantly increased (p < .05). The activities of lipase and amylase in intestine and hepatopancreas, serum alkaline phosphatase and total vitamin D concentrations in serum had significant increase as dietary calcium content increased up to 11.9–17.6 g/kg (p < .05). The inorganic phosphorus content in 29.1 g/kg group was significantly lower than those in other groups (p < .05). Broken‐line model analysis based on WGR and quadratic curve model analysis based on FCR showed that optimal dietary calcium requirement of red swamp crayfish ranged from 12.7 to 17.1 g/kg.     

Effect of dietary Bacillus licheniformis on growth,intestinal health,and resistance to nitrite stress in Pacific white shrimp Litopenaeus vannamei

The aim of this study was to evaluate effects of Bacillus licheniformis supplementation on growth, intestine digestive, antioxidant and metabolic capacity, intestine short-chain fatty acids content, and intestine microbiota composition of the Pacific white shrimp Litopenaeus vannamei. In total 2700 shrimp (initial weight 2.5?±?0.1 g/shrimp) were randomly distributed into six tanks (450 shrimp/500-L tank) and fed at 28?±?0.5 ℃ for 35 days (four times/day) with control diet and experimental diet supplemented with 10⁸ CFU/g B. licheniformis, followed by an acute nitrite stress for 10 days. At the end of the feeding trial, shrimp dietary B. licheniformis showed improved weight gain, specific growth rate, survival rate after nitrite stress, and decreased feed conversion rate compared to control group. And acetic acid and butyric acid content in the intestine of shrimp dietary B. licheniformis increased significantly except for propionic acid content. In addition, activities of amylase, lipase, and trypsin and activities of glutamine synthetase, hexokinase, and malate dehydrogenase increased significantly compared to control group. After shrimp were exposed to nitrite stress for 10 days, glutathione peroxidase, peroxidase, total antioxidant capacity, and superoxide dismutase levels were still higher in dietary B. licheniformis-shrimp, which showed that B. licheniformis enhanced the resistance to environmental stressor such as nitrite from the level of immune. The 16S rRNA sequencing showed that B. licheniformis increased diversity and abundance of some bacteria. In particular, the abundance of Proteobacteria and Planctomycetes decreased, and the abundance of Firmicutes and Bacteroidetes increased. These results revealed that B. licheniformis could improve the growth performance, increased intestine short-chain fatty acids (SCFA) content, change intestine digestive and metabolic enzyme activity, and regulated microbiota composition, so enhance the intestine antioxidant ability of shrimp subjected to nitrite stress, which is beneficial for shrimp aquaculture.

     

Hypoxia‐induced changes in survival,immune response and antioxidant status of the Pacific white shrimp (Litopenaeus vannamei) fed with graded levels of dietary myo‐inositol

A 3‐hr experiment was conducted to investigate the effects of dietary myo‐inositol (MI) supplementation on survival, immune response and antioxidant abilities in Litopenaeus vannamei under acute hypoxia stress. Six practical diets were formulated with supplementation of graded levels (control group 0, 0.1, 0.2, 0.4, 0.8 and 1.6 g/kg dry diet) of MI and were randomly assigned to triplicate groups of L. vannamei (mean weight 0.40 ± 0.00 g) for 8 weeks. Ten healthy shrimp (final mean weight approximately 11–14 g) randomly selected from each tank were exposed to hypoxia stress after feeding trial. After 3‐hr acute hypoxia stress, survival of shrimp fed MI‐supplemented diets (except 0.1 and 0.4 g/kg diets) was significantly increased compared with the control group. Shrimp fed control diet had lower activities of alkaline phosphatase (AKP), acid phosphatase (ACP), total antioxidant capacity (T‐AOC) and glutathione peroxidase (GPX), and higher malondialdehyde (MDA) and protein carbonyl (PC) contents in hepatopancreas than those fed the MI‐supplemented diets. In addition, mRNA expression levels of heat shock protein 70 (Hsp70), catalase (CAT) and penaeidin were significantly differentially regulated in hepatopancreas. In summary, dietary MI supplementation may have a positive effect on improving resistance to acute hypoxia stress of L. vannamei.     

Effect of vitamin E on spermatophore regeneration and quality of pond‐reared,black tiger shrimp (Penaeus monodon)

The objective of the present work was to evaluate the effects of different levels of vitamin E in feed on the spermatophore regeneration and quality of male Penaeus monodon. The experiment was carried out with the four following treatments: the basal diet no added vitamin E, the diet added 200, 600 and 1,000 mg/kg respectively. Spermatophore regeneration and quality were evaluated by spermatophore weight, sperm count and spermatophore absence rates, which male P. monodon were extruded spermatophore for feeding 20 and 40 days. In the experiment, the weight of the twice regenerated spermatophore of the males added to the vitamin E group was higher than that of the untreated control group. The weight of the first regenerated spermatophore with the addition of 1,000 mg/kg group was the highest and significantly higher than the control group (p < .05), but there was no significant difference among the three groups with different levels of vitamin E. The weight of the second regenerated spermatophore with the addition of 600 mg/kg group was the highest, followed by 1,000 mg/kg group, both of which were higher than the control group and the addition of 200 mg/kg group. Within the same group, the regeneration spermatophore weight showed overall upward trend as the feeding time, twice regenerate experiment spermatophore weight with added to the vitamin E groups were significantly higher than the initial value (p < .05), but three spermatophore weight of male shrimp at the control group had no significant difference. The sperm quantity and the percentage of normal sperm of the twice regenerated spermatophore of the males with added to the vitamin E group was higher than that of the untreated control group, and those of the addition of 200 mg/kg group was significantly higher than that of control group (p < .05). The total number of sperm and the percentage of living sperm of male shrimp in the experimental group decreased with the increase of vitamin E in the feed. Within the same group, the total number of sperm and the percentage of living sperm of male shrimp with added to the vitamin E groups showed overall upward trend as the feeding time and were significantly higher than the initial value (p < .05), but the control group was slightly down and had no significant difference. Comprehensive sperm weight, sperm quantity and living sperm percentage of three indicators, that adding 200 mg/kg of vitamin E in feed could effectively promote the spermatophore regeneration in the male P. monodon and improve the sperm quantity. The experimental results provide a scientific basis for the breeding of P. monodon.     

Effects of dietary supplementation of Astragalus membranaceus,Codonopsis pilosula,and Glycyrrhiza uralensis extract mixture on growth performance,haematological parameters and hepatopancreatic performance in juvenile Pacific white shrimp (Litopenaeus vannamei)

Pacific white shrimp is the major farmed shrimp species in the world. It is known to be very sensitive to the environmental and management changes such as intensification, which is one of the primary necessities to increase shrimp production, but represents a stressful condition, and needs to be managed properly to diminish its negative effects in aquaculture. In this study, juvenile Pacific white shrimp were fed diets supplementing with equal quantities of Astragalus membranaceus, Codonopsis pilosula and Glycyrrhiza uralensis extracts in different concentrations (0, 1.0, 2.0 and 3.0 g/kg) for 8 weeks. We subsequently estimated the effects of supplemented diets on growth performance, haematological parameters, and histological changes of hepatopancreas. Results revealed that the supplemented mixture had no benefits on growth and survival rate, but had favourable effects on haemocyte count, number of granulocytes, and hemocyanin concentration in the haemolymph (p > 0.05). We observed that R cells and B cells were increased in hepatopancreatic tubules of shrimps fed on supplemented diets. Besides, a diet containing 2.0 g/kg of extract mixture maintained the decreased levels of alanine aminotransferase (p < 0.05) and aspartate aminotransferase (p > 0.05). Among the used concentrations, 2.0 g/kg seemed to be the most suitable concentration.     

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.     

Optimal dietary alpha‐linolenic acid/linoleic acid ratio improved digestive and absorptive capacities and target of rapamycin gene expression of juvenile grass carp (Ctenopharyngodon idellus)

Growth performance, digestive and absorptive capacities and target of rapamycin (TOR), ribosomal protein S6 kinase 1 (S6K1) and eIF4E‐binding protein (4E‐BP) gene expression in the hepatopancreas and intestine of juvenile grass carp (Ctenopharyngodon idellus) fed graded ratios of dietary alpha‐linolenic acid/linoleic acid (ALA/LNA) (0.01, 0.34, 0.68, 1.03, 1.41, 1.76 and 2.15) for 60 days were investigated. The results showed that ALA/LNA ratio of 1.03 significantly improved (i) per cent weight gain (PWG) and feed efficiency, (ii) hepatopancreatic trypsin, chymotrypsin, lipase, amylase and intestinal creatine kinase (CK) activities, (iii) hepatopancreatic trypsinogen‐2 and chymotrypsinogen mRNA levels. Meanwhile, fish fed with ALA/LNA ratio of 0.68 significantly enhanced, (iv) Na⁺/K⁺‐ATPase and γ‐glutamyl transpeptidase activities in whole intestine, and alkaline phosphatase activities in the proximal intestine (PI) and distal intestine, (v) amylase, intestinal Na⁺/K⁺‐ATPase alpha‐subunit isoform 1, Na⁺/K⁺‐ATPase alpha‐subunit isoform 8 and CK mRNA abundances, (vi) TOR and S6K1 gene expression in the hepatopancreas and intestine of juvenile grass carp. Based on the quadratic regression analysis of PWG, cholecystokinin and leptin contents in the PI, optimal dietary ALA/LNA ratio of juvenile grass carp (8.78–72.00 g) was estimated to be 1.08, 1.19 and 1.05, respectively.     

Effects of dietary vitamin K levels on growth performance,enzyme activities and antioxidant status in the hepatopancreas and intestine of juvenile Jian carp (Cyprinus carpio var. Jian)

A total of 1400 juvenile Jian carp (Cyprinus carpio var. Jian) (8.93 ± 0.03 g) were fed diets containing graded levels of vitamin K at 0.027 (basal diet), 1.52, 3.02, 4.51, 6.02 and 7.52 mg kg^?1 diet for 60 days to investigate the effects of vitamin K on growth, enzyme activities and antioxidant capacity in the hepatopancreas and intestine. Percentage weight gain (PWG), feed intake and feed efficiency of fish were improved by vitamin K. Activities of trypsin, chymotrypsin, amylase and lipase in the intestine and hepatopancreas and Na⁺, K⁺‐ATPase, creatine kinase, alkaline phosphatase and gamma‐glutamyl transpeptidase in the intestine were increased by vitamin K. Malondialdehyde and protein carbonyl contents in the hepatopancreas and intestine were decreased with vitamin K supplements. Certain level of vitamin K increased antihydroxyl radical, antisuperoxide anion, superoxide dismutase, catalase, glutathione‐S‐transferase, glutathione peroxidase and glutathione reductase activities and glutathione contents in the hepatopancreas and intestine. Intestinal Lactobacillus, E. coli and Aeromonas were changed with vitamin K supplements. Together, these results indicate that vitamin K improved fish growth, digestive and absorptive ability, and anti‐oxidant capacity. The dietary vitamin K requirement of juvenile Jian carp (8.93–73.7 g) based on PWG was 3.13 mg kg^?1 diet.