Effects of graded levels of dietary myo‐inositol on non‐specific immune and specific immune parameters in juvenile Jian carp (Cyprinus carpio var. Jian)

The aim of this study was to evaluate the effects of myo‐inositol (MI) on non‐specific immune and specific immune defence in fish. A total of 1050 Jian carp (Cyprinus carpio var. Jian) (22.28±0.07 g) were randomly distributed into seven groups, of three replicates each, of feeding diets containing graded levels of MI (163.5, 232.7, 384.2, 535.8, 687.3, 838.8 and 990.3 mg MI kg^?1 diet). After a 60‐day growth trial, an infectious trial was conducted by injection of Aeromonas hydrophila for 17 days. Results showed that the red blood cell (RBC) and the white blood cell count were significantly increased with increasing MI levels up to 535.8 mg kg^?1 diet (P<0.05). The spleen index showed a tendency similar to RBC, whereas the head kidney index showed the inverse pattern (P<0.05). The phagocytic activity of leucocytes, haemagglutination titre, lysozyme activity, anti‐A. hydrophila antibody titre and immunoglobulin M, after being injected with A. hydrophila, were all improved with an increase in the MI levels up to 232.7–687.3 mg kg^?1 diet respectively (P<0.05). Myo‐inositol did not influence serum acid phosphatase activity and total iron‐binding capacity (P>0.05). These results suggested that MI could enhance non‐specific immune and specific immune responses in fish.     

Dietary phosphorus prevents oxidative damage and increases antioxidant enzyme activities in intestine and hepatopancreas of juvenile Jian carp

This study was conducted to investigate the effect of dietary phosphorus on the intestine and hepatopancreas antioxidant capacity of juvenile Jian carp (Cyprinus carpio var. Jian). Jian carp, with an average initial weight of 7.17 ± 0.01 g, were fed with diets containing graded concentrations of available phosphorus, namely 1.7 (control), 3.6, 5.5, 7.3, 9.2 and 11.0 g kg^?1 diet for 9 weeks. Results showed that, in intestine and hepatopancreas, content of malondialdehyde (MDA), protein carbonyl (PC) and glutathione (GSH), capacity of anti‐superoxide anion (ASA) and anti‐hydroxyl radical (AHR), and glutathione reductase (GR), catalase (CAT), glutathione S‐transferase (GST), superoxide dismutase (SOD) and glutathione peroxidase (GPx) activities were significantly affected by dietary phosphorus levels (P < 0.05). Regression analysis showed that significant quadratic responses occurred in MDA content and ASA, GST, GPx and AHR activities in intestine, GSH content and CAT and SOD activities in hepatopancreas (P < 0.05). These results indicate that optimal level of dietary phosphorus prevented oxidative damage and increased antioxidant enzyme activities in the intestine and hepatopancreas of juvenile Jian carp. The phosphorus requirement estimated from MDA using quadratic regression analysis was 5.7 g kg^?1 diet.     

Growth, digestive capacity and intestinal microflora of juvenile Jian carp (Cyprinus carpio var. Jian) fed graded levels of dietary inositol

A 60‐day feeding trial was carried out with juvenile Jian carp (Cyprinus carpio var. Jian) to study the effects of myo‐inositol (MI) on the growth, digestive enzyme and intestinal microbial population. Diets with seven levels of inositol (163.5, 232.7, 384.2, 535.8, 687.3, 838.8 and 990.3 mg MI kg^?1 diet) were fed to Jian carp (initial weight 22.28±0.07 g). Per cent weight gain (PWG) was improved with increasing inositol levels up to 535.8 mg MI kg^?1 diet (P<0.05), and plateaued (P>0.05). The protein production value, lipid production value and ash production value were increased with increasing dietary inositol levels up to 384.2, 838.8 and 838.8 mg MI kg^?1 diet respectively (P<0.05). Although intestinal protein content and trypsin activity were not affected by inositol levels (P>0.05), chymotrypsin, lipase and amylase activities in intestine were the lowest for fish fed the MI‐unsupplemented diet (P<0.05). Alkaline phosphatase, Na⁺, K⁺‐ATPase, γ‐glutamyl transpeptidase and creatinkinase activities in the intestine were increased with an increase in the inositol levels up to 384.2–687.3 mg MI kg^?1 diet (P<0.05). Intestinal Aeromonas hydrophila and Escherichia coli decreased with an increase in the levels of dietary inositol up to 232.7 and 687.3 mg MI kg^?1 diet respectively (P<0.05), while Lactobacillus in the intestine increased with an increase in inositol levels up to 990.3 mg MI kg^?1 diet (P<0.05). In conclusion, inositol improved growth, digestive capacity and intestinal microbial population of juvenile Jian carp, and the dietary inositol requirement for PWG of juvenile Jian carp is 518.0 mg MI kg^?1 diet.     

Influence of dietary zinc on lipid peroxidation,protein oxidation and antioxidant defence of juvenile Jian carp (Cyprinus carpio var. Jian)

This study was conducted to study the effects of dietary zinc on lipid peroxidation, protein oxidation and antioxidant defence of juvenile Jian carp (Cyprinus carpio var. Jian) by feeding fish with increasing levels of zinc (15.3, 26.9, 40.8, 58.2, 68.9 and 92.5 mg Zn kg^?1) for 6 weeks. Results indicated that malondialdehyde (MDA) content and protein carbonyls (PC) in serum were the highest in fish fed diet containing 15.3 mg zinc kg^?1 diet (P < 0.05). Serum antisuperoxide anion (ASA), superoxide dismutase (SOD), glutathione peroxidase (GSH‐Px), glutathione reductase (GR) activities and glutathione (GSH) content were improved with increasing dietary zinc levels up to 40.8 mg zinc kg^?1 diet (P < 0.05) and levelled off (P > 0.05). Serum antihydroxy radical (AHR), catalase (CAT) and glutathione‐S‐transferase (GST) activities followed the similar pattern to that observed in ASA. The MDA and PC levels, ASA, AHR, SOD, CAT, GPx, GR, GST activities and GSH content in intestine, hepatosomatic and muscle tissue followed the similar pattern to that observed in serum. The present results indicated that zinc decreased lipid peroxidation and protein oxidation and improved antioxidant defence in fish.     

Myo-inositol prevents oxidative damage, inhibits oxygen radical generation and increases antioxidant enzyme activities of juvenile Jian carp (Cyprinus carpio var. Jian)

This study was conducted to evaluate the effects of dietary myo -inositol (MI) on the antioxidant status of juvenile Jian carp ( Cyprinus carpio var. Jian). A total of 1050 Jian carp (22.28±0.07 g) were randomly distributed into seven groups of three replicates each, feeding diets containing graded levels of MI (163.5, 232.7, 384.2, 535.8, 687.3, 838.8 and 990.3 mg kg⁻¹ diet) for 60 days. Results indicated that the malondialdehyde content was the lowest for fish fed diets containing ≥384.2 mg MI kg⁻¹, and the highest for fish fed the MI-unsupplemented basal diet ( P <0.05). The protein carbonyl content was decreased with increasing dietary MI levels up to 535.8 mg kg⁻¹ diet, and no differences were found with a further increase in the MI concentration. The anti-superoxide anion capacity (ASA) and anti-hydroxyl radical capacity (AHR) were increased with increasing MI levels up to 535.8 mg kg⁻¹ diet, and plateaued thereafter. The superoxide dismutase and glutathione- S -transferase activities showed the same tendency with the ASA capacity. Catalase, glutathione peroxidase and glutathione reducase activities were improved with increasing MI levels up to 838.8, 384.2 and 687.3 mg kg⁻¹ diet, respectively, and remained nearly constant thereafter. These results suggested that MI could inhibit oxygen radical generation, increase enzymatic antioxidant capacity and prevent oxidative damage of carp. Dietary MI requirements for ASA and AHR activities of juvenile Jian carp were 567.94 and 517.22 mg MI kg⁻¹ diet respectively.     

Effects of dietary thiamin supplement on growth,body composition and intestinal enzyme activities of juvenile Jian carp (Cyprinus carpio var. Jian)

A total of 1050 juvenile Jian carp (Cyprinus carpio var. Jian) (8.20 ± 0.02 g) were fed diets containing seven graded levels of thiamin (0.25, 0.48, 0.79, 1.06, 1.37, 1.63 and 2.65 mg kg^?1) for 60 days to investigate the effects of thiamin on growth, body composition and digestive enzyme activities. Percent weight gain (PWG), feed intake and feed efficiency (FE) were the lowest in fish fed the basal diet (P < 0.05). Protein productive value and lipid productive value increased with increasing dietary thiamin levels up to 1.06 and 0.79 mg kg^?1 diet, respectively (P < 0.05). Body protein and lipid increased with increasing dietary thiamin levels (P < 0.05), while moisture and ash of fish carcasses decreased with the increase in dietary thiamin supplementation (P < 0.05). Intestinal folds height had a similar trend to PWG (P < 0.05). Activities of α‐amylase, lipase, trypsin, Na⁺, K⁺‐ATPase, alkaline phosphatase and gamma‐glutamyl transpeptidase in intestine were all affected by the dietary thiamin (P < 0.05). In conclusion, thiamin could improve growth and intestinal enzyme activities of juvenile Jian carp. The dietary thiamin requirement of juvenile Jian carp (8.0–60.2 g) based on PWG was 1.02 mg kg^?1 diet.     

Effects of pyridoxine on antioxidative parameters in juvenile Jian carp (Cyprinus carpio var. Jian)

To investigate the effects of dietary pyridoxine (PN) on antioxidant status of fish in serum, intestine and trunk kidney, 1050 juvenile Jian carp (11.7 ± 0.1 g) were used for the experiment. The carp were divided into seven groups and fed diets containing graded levels of PN (0.20, 1.71, 3.23, 4.96, 6.32, 8.58 and 12.39 mg kg^?1 of diet) for 80 days. Results of the study showed that content of malondialdehyde in serum, intestine and kidney tissues was the highest when fed the diet containing 1.71 mg PN kg^?1 diet (P < 0.05). Meanwhile, the protein carbonyl content of intestine and kidney tissue showed a downward trend to a point (P < 0.05). Conversely, activities of superoxide dismutase, catalase, glutathione peroxidase (GSH‐Px), glutathione S‐transferase, glutathione reductase and glutathione (GSH) content in serum, intestine and kidney tissue were generally higher in PN‐supplemented diets than unsupplemented diet (P < 0.05). The present results indicated that the PN decreased lipid peroxidation and protein oxidation in fish, and partly because of its improved antioxidant enzymes activities and levels of GSH.     

Effects of graded levels of dietary vitamin C on the growth,digestive capacity and intestinal microflora of juvenile Jian carp (Cyprinus carpio var. Jian)

A 60‐day experiment was carried out to study the effects of vitamin C [ascorbic acid (AA)] on the growth, digestive enzyme activities and intestinal microbial population. Diets with six levels (0.0, 21.4, 45.1, 69.5, 93.6 and 142.1 mg AA kg^?1 diet) of supplemental ascorbyl polyphosphate were fed to juvenile Jian carp (Cyprinus carpio var. Jian) (12.63±0.02 g). The specific growth rate (SGR), feed efficiency and productive protein value were significantly improved with increasing AA levels up to 45.1 mg AA kg^?1 diet (P<0.05). The hepatopancreas and muscle AA concentrations were increased with increasing dietary AA levels up to 69.5 and 45.1 mg kg^?1 diet respectively (P<0.05). The activities of intestinal trypsin, chymotrypsin, lipase, α‐amylase, Na⁺, K⁺‐ATPase, alkaline phosphatase, gamma‐glutamyl transpeptidase and creatinkinase were all positively affected by the AA supplementation (P<0.05). Intestinal Lactobacillus and Bacillus were increased with increasing AA levels up to 45.1 mg AA kg^?1 diet (P<0.05), while intestinal Escherichia coli decreased with increasing AA levels up to 45.1 mg AA kg^?1 diet (P<0.05). In conclusion, AA improve the digestive capacity and intestinal microbial population of Jian carp, and the dietary AA requirement for SGR of juvenile Jian carp was 40.9 mg AA kg^?1 diet.     

Dietary myo‐inositol requirement for juvenile gibel carp (Carassius auratus gibelio)

An 11‐week growth trial was conducted to determine dietary myo‐inositol (MI) requirement for juvenile gibel carp (Carassius auratus gibelio). Myo‐inositol was supplemented to the basal diet to formulate six purified diets containing 1, 56, 107, 146, 194 and 247 mg MI kg^?1 diet, respectively. Each diet was fed to triplicate groups of juvenile gibel carp (initial body weight 3.38 ± 0.27 g, mean ± SD) in a flow‐through system. The diets were randomly assigned to different fish tanks. Fish fed ≥ 107 mg MI kg^?1 diet had significantly higher weight gain (WG), feed efficiency (FE) and protein efficiency ratio than those fed 1 mg MI kg^?1 diet. Fish fed ≥ 56 mg MI kg^?1 diet had higher feeding rate and survival compared with fish fed 1 mg MI kg^?1 diet. Dietary supplemental inositol did not affect fish liver inositol concentration. Fish fed ≥ 56 mg MI kg^?1 diet had higher body dry matter, crude protein and gross energy and lower hepatosomatic index than fish fed 1 mg MI kg^?1 diet. Dietary inositol supplementation decreased fish body ash. Quadratic regression of weight gain indicated that the myo‐inositol requirement to maximum growth for juvenile gibel carp was 165.3 mg MI kg^?1 diet.     

Effects of exogenous xylanase supplementation in plant protein‐enriched diets on growth performance,intestinal enzyme activities and microflora of juvenile Jian carp (Cyprinus carpio var. Jian)

A total of 900 juvenile Jian carp (Cyprinus carpio var. Jian) (7.99 ± 0.02 g) were fed diets containing graded levels of xylanase at 220 (unsupplemented control), 650, 1070, 1480, 1810 and 2470 U kg^?1 diet for 10 weeks to investigate the effects of xylanase levels on growth performance, intestinal enzyme activities and microflora. The per cent weight gain, feed efficiency, protein efficiency ratio, protein production value, lipid production value, ash production value, calcium production value and phosphorus retention ratio were significantly improved with increasing levels of xylanase up to a point, and thereafter declined (P < 0.05). The activities of trypsin, chymotrypsin, lipase and amylase in the hepatopancreas and intestine, activities of alkaline phosphatase, Na⁺, K⁺‐ATPase, creatine kinase and γ‐glutamyl transpeptidase in three intestinal segments were improved by dietary xylanase (P < 0.05). The amounts of Lactobacillus, Escherichia coli and Aeromonas were significantly affected by dietary xylanase levels (P < 0.05). In conclusion, xylanase supplementation improved growth performance, enhanced intestinal enzyme activities and influenced the balance of intestinal microflora of juvenile Jian carp. The optimal level of xylanase in juvenile Jian carp (7.99–99.16 g) based on PWG was 1259 U kg^?1 diet by the quadratic regression analysis.     

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.     

Effects of glutamate in low‐phosphorus diets on growth performance,antioxidant enzyme activity,immune‐related gene expression and resistance to Aeromonas hydrophila of juvenile mirror carp (Cyprinus carpio)

This study investigated the effects of glutamate (Glu) in low‐phosphorus diets on growth performance, haematological indices, antioxidant enzyme activity, immune‐related gene expression and resistance to Aeromonas hydrophila in juvenile mirror carp (Cyprinus carpio) (5.07 ± 0.02 g). Fish were fed either graded levels of Glu (0 g/kg, 5 g/kg,  10 g/kg and 20 g/kg, named G0, G0.5, G1 and G2, respectively) in a low‐phosphorus diet (15 g/kg NaH₂PO_4, 0.49), or a normal phosphorus diet ( 20 g/kg NaH₂PO_4, 0.61) without added Glu (C), for 8 weeks. At the end of the feeding trial, the fish were challenged with A. hydrophila. Compared with G0 group, 10 g/kg and 20 g/kg Glu supplementation of the low‐phosphorus diet significantly improved the final weight, WGR, SGR and PER, and decreased FCR (p < .05). Glu supplementation of the low‐phosphorus diet significantly enhanced the T‐AOC, SOD activity and GSH content in intestine (p < .05). Glu supplementation significantly reduced MDA content in foregut and midgut and increased CAT activity in midgut and hindgut (p < .05). Regarding immune‐related gene expression, Glu supplementation significantly diminished the up‐regulation of intestinal TNF‐α, IL‐1β and IL‐8 mRNA levels induced by phosphorus deficiency (p < .05). The survival rate of the G1 group was significantly higher than that of the G0 group (p < .05). In conclusion, 10 g/kg Glu supplementation in low‐phosphorus diets can improve the growth performance, enhance the activity of intestinal antioxidant enzymes and strengthen the immune function of juvenile mirror carp.     

Effect of dietary iron levels on growth,body composition and intestinal enzyme activities of juvenile Jian carp (Cyprinus carpio var. Jian)

A 60‐day feeding trial was carried out to investigate the effect of iron on growth, body composition and digestive enzyme activities. Diets with seven levels of iron (53.9, 90.0, 115.6, 146.1, 176.0, 215.8 and 266.0 mg iron kg^?1 diet) were fed to Jian carp (initial weight 11.4 ± 0.0 g). Per cent weight gain (PWG), feed efficiency (FE) and protein efficiency ratio were the lowest in fish fed the basal diet (P < 0.05). Body protein content was increased with the increasing iron levels (P < 0.05), but moisture, lipid and ash of fish were not significantly affected by dietary iron levels (P > 0.05). Activities of trypsin, lipase, α‐amylase, Na⁺, K⁺‐ATPase, alkaline phosphatase and gamma‐glutamyl transpeptidase were improved with increasing dietary iron levels. Serum iron were significantly enhanced with dietary iron levels up to 146.1 mg iron kg^?1 diet, and plateaued. In conclusion, iron improved digestive enzyme activities of juvenile Jian carp and the dietary iron requirement for serum iron of juvenile Jian carp (11.4–64.0 g) was 147.4 mg iron kg^?1 diet with ferrous fumarate as the iron source.     

Pb~(2+)对建鲤幼鱼抗氧化酶活性和总抗氧化能力的影响

为了解铅对建鲤幼鱼(Cyprinus carpio var.Jian)的影响,将建鲤幼鱼暴露于不同水平(0、0.648、1.296、6.480 mg/L)的Pb2+水溶液中,于96 h分别测定建鲤幼鱼肝胰脏、肠、鳃、肌肉中的超氧化物歧化酶(SOD)、谷胱甘肽过氧化物酶(GSH-Px)、过氧化氢酶(CAT)活性及总抗氧化能力(T-AOC)。结果表明:随着Pb2+浓度的升高,抗氧化酶活性升高,达到极值后下降。0.648 mg/L浓度组中,肝胰脏中抗氧化酶活性及总抗氧化能力均有较明显升高;肌肉中抗氧化酶活性及总抗氧化能力变化较小;在高浓度组(6.480 mg/L),肾中的三种抗氧化酶活性及总抗氧化能力仍在升高,而在其他组织中酶的活性有所降低。上述研究结果表明,与肠、鳃、肌肉、肾相比,肝胰脏中的抗氧化酶活性及总抗氧化能力敏感,是最先启用的主要解毒器官;在高浓度胁迫时,肝胰脏解毒能力下降,抗氧化防御作用的主要器官由肝胰脏转移到肾脏。     

The effects of methionine‐enriched Artemia nauplii on growth,amino acid profiles,absorption enzyme activity and antioxidant capability of common carp (Cyprinus carpio var. Jian) larvae

The effects of methionine‐enriched Artemia nauplii on growth, amino acid profiles and activity of absorption enzymes and antioxidant capability of common carp (Cyprinus carpio var. Jian) larvae were investigated in this study. The newly hatched Artemia nauplii enriched with methionine at four levels (0, 400, 800, 1,600 mg/L) for 16 hr was used as live food for common carp larvae for 21 days. The results demonstrated that the level of methionine in nauplii enriched with methionine increased significantly as the level of supplemental methionine rose (p < 0.05). The specific growth rate (SGR) and body length growth rate (BLGR) values in all experimental groups were significantly higher than those in the control group (p < 0.05) in the trial period. With the supplement of methionine, the amino acid profiles vary depending on the type of amino acid and/or the level of methionine applied. Further examination revealed that the activity of absorption enzymes in the 800 and 1,600 mg/L groups were all significantly higher compared to the other two groups (p < 0.05). Similar results on the antioxidant capability of fish larvae were also observed among the treatments. The changes in these physiological factors allowed for the control of the content of supplemental methionine in Artemia nauplii for larvae and potentially the ability to improve the growth performance of common carp larvae.     

Methionine hydroxy analogue prevents oxidative damage and improves antioxidant status of intestine and hepatopancreas for juvenile Jian carp (Cyprinus carpio var. Jian)

Oxidative damage and antioxidant status of intestine and hepatopancreas for juvenile Jian carp (Cyprinus carpio var. Jian) fed graded levels of methionine hydroxy analogue (MHA: 0, 5.1, 7.6, 10.2, 12.7, 15.3 g kg^?1 diet) for 60 days were studied. Radical scavenging ability, antioxidant enzymes activities such as superoxide dismutase (SOD), catalase (CAT), glutathione‐S‐transferase (GST), glutathione peroxidase (GPX) and glutathione reducase (GR), as well as glutathione (GSH), protein carbonyl (PC) and malondialdehyde (MDA) contents were assayed in these tissues. Results indicated that anti‐superoxide anion capacity in intestine and anti‐hydroxyl radical capacity in hepatopancreas significantly improved with dietary MHA levels up to 7.6 and 10.2 g kg^?1 diet respectively, whereupon they decreased (P < 0.05). SOD, CAT, GST, GPX, GR activities in intestine and hepatopancreas, as well as GSH content in hepatopancreas significantly increased with optimal MHA levels which were in the range of 5.1–10.2 g kg^?1 diet, and thereafter decreased (P < 0.05). Meanwhile, MDA and PC contents in these tissues together with GOT and GPT activities in plasma significantly decreased with optimal MHA levels which were in the range of 5.1–7.6 g kg^?1 diet, and thereafter increased (P < 0.05). These results suggested that MHA improved antioxidant status and depressed lipid and protein oxidation in intestine and hepatopancreas.     

Effects of dietary zinc sources and levels on growth performance,tissue zinc retention and antioxidant response of juvenile common carp (Cyprinus carpio var. Jian) fed diets containing phytic acid

Plant protein‐based diets are widely used for common carp (Cyprinus carpio var. Jian). The plant source antagonist, such as phytate, negatively affects the bioavailability of trace minerals, but this aspect was not considered in previous studies on this species. A 10‐week growth trial was conducted to investigate the effects of inorganic Zinc (ZnSO₄·7H₂O, Zn‐S) and organic Zn (2‐hydroxy‐4‐(methylthio) butanoic Zinc, Zn‐M) on growth performance, Zn retention and antioxidant responses of common carp (initial weight 10.0 ± 0.03 g). Eleven semi‐purified diets containing 7 mg/kg phytic acid were prepared with 0, 5, 20, 35, 50 and 65 mg/kg Zn from Zn‐S and Zn‐M (12.8 mg/kg Zn in basal level), respectively. The results showed that either Zn‐S or Zn‐M inclusion improved growth performance, vertebral Zn deposition and antioxidant responses of fish. The Zn requirement based on WGR, vertebrae Zn and plasma SOD were 47.0, >77.8 and 48.5 mg/kg, and 63.3, 42.2 and 36.8 mg/kg, respectively, with Zn‐S and Zn‐M as Zn sources. The relative bioavailability of Zn‐M was 2.44‐ (vertebrae Zn deposition) and 1.74‐fold (plasma SOD activity) the availability of Zn‐S in the diet of common carp. The lower growth performance and poor bioavailability in vertebrae of Zn‐S group were related to the chelating of zinc with phytic acid.     

Effect of dietary pantothenic acid supplement on growth, body composition and intestinal enzyme activities of juvenile Jian carp (Cyprinus carpio var. Jian)

A 9-week feeding trial was carried out with juvenile Jian carp to study the effect of dietary pantothenic acid (PA) on growth, body composition and intestinal enzyme activities. Semi-purified diets with seven levels (4.0, 15.5, 25.6, 36.1, 45.9, 56.1 and 65.9 mg PA kg⁻¹) of supplemental calcium d -pantothenate were fed to Jian carp (13.0 ± 0.0 g). PA improved specific growth rate (SGR), protein productive value (PPV), protein efficiency ratio (PER) and lipid production value (LPV) ( P <  0.05). Fish fed the control diet had significantly lower feed efficiency (FE) than that in any other group ( P <  0.05). Body protein content increased with increasing PA levels ( P <  0.05), but moisture, lipid and ash of fish carcasses were negatively related to the graded PA levels ( P <  0.05). Intestine protein content (IPC), hepatopancreas protein content (HPC) and activity of α-amylase, lipase, trypsin, Na⁺,K⁺-ATPase, alkaline phosphatase (AKP) and gamma-glutamyl transpeptidase (γ-GT) were all positively affected by the dietary PA levels ( P <  0.05), while intestine index (ISI) and hepatopancreas index (HSI) decreased with the increment of supplemental levels of PA ( P <  0.05). These results suggested that PA could enhance fish growth and intestinal enzyme activities. The dietary PA requirement of juvenile Jian carp, Cyprinus carpio var . Jian (13.0–73.0 g), for optimal growth estimated by the broken-line analysis was 23.0 mg PA kg⁻¹ diet.     

Use of supplemental amino acids on the success of reducing dietary protein levels for Jian carp (Cyprinus carpio var. Jian)

A feeding trial was conducted to investigate the effects of essential amino acids (EAA) supplementation on the success of dietary protein reduction for Jian carp (Cyprinus carpio var. Jian). Five diets were formulated including a positive control (Diet 1, 378.4 g/kg protein), a negative control (Diet 5, 289.8 g/kg protein) and three test diets (Diet 2‐Diet 4, 340.4–299.0 g/kg protein supplemented with EAA). No significant decline of growth performance in fish fed decreased dietary protein with EAA supplementation, which were significantly higher than the negative control. The apparent digestibility coefficients (ADC) of protein and most EAAs were not significantly affected by the dietary treatments. Dietary treatments did not affect whole‐body composition, but influenced protein and EAAs retentions. Total ammonia nitrogen (TAN) excretion decreased with the decreasing dietary protein, and the highest plasma ammonia content was observed in fish fed Diet 5. Plasma glucose concentration increased with the decreasing dietary protein reduction, while other plasma parameters were not affected by dietary treatments. These results indicated that low‐protein diets (299.0 g/kg) supplemented with EAA can maintain protein, EAA digestibility and retention in Jian carp, and also has benefit in the reduction of TAN excretion.     

Immune response,disease resistance and intestinal microflora of juvenile Jian carp (Cyprinus carpio var. Jian) fed graded levels of pantothenic acid

This study was to investigate the effect of dietary pantothenic acid (PA) on the disease resistance, immune response and intestinal microflora on juvenile Jian carp (Cyprinus carpio var. Jian). Seven diets (4.0, 15.5, 25.6, 36.1, 45.9, 56.1 and 65.9 mg PA kg^?1) were fed to Jian carp (12.95 ± 0.03 g) for 9 weeks. After 9‐week feeding trial, the challenge experiment with Aeromonas hydrophila was conducted to determine the impact of PA on fish disease resistance. Survival rate after challenge was promoted with the increasing PA levels (P < 0.05). Blood counts also significantly increased up to the dietary PA level of 25.6 mg PA kg^?1 (P < 0.05). Leucocyte phagocytic activity, lectin potency, lysozyme and acid phosphatase activity, and total iron‐binding capacity were improved with increasing PA levels (P < 0.05). Serum immunoglobulin M level and agglutination antibody titre to A. hydrophila were increased (P < 0.05) in fish fed the diets with the dietary PA levels between 56.1 and 65.9 mg kg^?1. PA also promoted the growth and reproduction of Lactobacillus and depressed Escherichia coli and A. hydrophila (P < 0.05). These results suggested that pantothenic acid could improve disease resistance, immune response, and the balance of intestinal microflora in juvenile Jian carp.