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1.
Previously we isolated the major alginate lyase isozyme LbAly35 from a marine snail Littorina brevicula and showed that this enzyme was significantly heat stable in a broad pH range compared with other molluscan alginate lyases (Hata et al., Fish Sci 75:755?C763, 2009). LbAly35 showed practically no similarity to other molluscan alginate lyases in the N-terminal amino-acid sequence of 20 residues and no cross-reactivity with anti-abalone alginate lyase antiserum. These led us to consider that the primary structure of LbAly35 is considerably deviated from other molluscan enzymes. Thus, in the present study, we first compared the thermal stability of LbAly35 with an abalone alginate lyase, HdAly, and found that the first order inactivation rate constants for LbAly35 at 40 and 45?°C were 1/20 and 1/45 of those for HdAly, respectively. Then, we cloned cDNAs encoding LbAly35 and characterized its deduced amino-acid sequence comparing with those of other molluscan alginate lyases. The cDNAs were amplified by polymerase chain reaction (PCR) and 5??- and 3??-RACE PCRs from the L. brevicula hepatopancreas cDNA using degenerated primers synthesized on the basis of partial amino-acid sequences of LbAly35. The cDNA covering the entire translational region of LbAly35 comprised 1,093?bp and encoded an amino-acid sequence of 296 residues. The amino-acid sequence consisted of an initiation methionine, a putative signal peptide for secretion (22 residues), a propeptide-like region (10 residues), and a mature LbAly35 domain of 263 residues. Although the N-terminal region of LbAly35 was significantly deviated from those of other molluscan alginate lyases, the catalytic domain of LbAly35 showed ~45?% identity to other molluscan enzymes which had been classified under polysaccharide-lyase-family-14 (PL-14). In addition, the amino-acid residues crucially important for the catalytic actions of PL-14 enzymes were also conserved in LbAly35. Accordingly, LbAly35 was regarded as a member of PL-14 as other molluscan alginate lyases despite the significant deviation of its N-terminal region.  相似文献   

2.
This study is aimed at the isolation and screening of alginate lyase‐producing bacteria from the gastrointestinal tracts of hybrid abalone, Haliotis rubra x H. laevigata, as probiotic candidates. Six bacterial isolates were detected to produce alginate lyase. Of these, the isolate with the highest alginate‐lyase activity was identified as Enterobacter ludwigii strain EN‐119, displaying 99% similarity of 16S rDNA sequence. Further assays indicated that E. ludwigii showed good viability and stability when it was incorporated into manufactured pellets and stored at 4°C for 7 days. The isolate also had high tolerance of high salinity (35 mg/L), low pH in simulated stomach juice (5) and to simulated intestinal juice containing surfactants such as bile salts and gastric enzymes (pepsin and trypsin). Additionally, a short, preliminary study indicated that supplementation of E. ludwigii via manufactured pellets improved the total weight gain and specific growth rate of hybrid abalone. These results suggest that E. ludwigii is a potential probiont for shortening the culture period of hybrid abalone.  相似文献   

3.
Oxygen consumption and ammonia excretion rates of three abalone species, Haliotis discus discus, H. gigantea, H. madaka and their hybrids were measured at 20 °C by incubating for 3 h under dark and light (N = 9–13 for each species and hybrid). Animals were fasted before and during the experiment and measurements were made first under dark followed by light on the next day. The rates increased with the increase in body weight and were higher under light than dark. On average, H. discus discus had higher oxygen consumption (DD; dark = 0.039, light = 0.04 ml/g/h) than H. gigantea (G; D = 0.033, L = 0.036) and H. madaka (M; D = 0.034, L = 0.035); the hybrids had varied patterns with respect to their parental species [DD × M (D = 0.032, L = 0.038); M × DD (D = 0.03, L = 0.038); G × DD (D = 0.035, L = 0.04) and DD × G (D = 0.03, L = 0.034), mother first]. M (0.261, 0.298 μmol/g/h) had the highest ammonia excretion rate while G (0.162; 0.264) and DD (0.229; 0.232) had the lowest under dark and light, respectively. The hybrids had varied patterns in comparison with their parents (DD × M = 0.247, 0.32;M × DD= 0.177, 0.28; DD × G = 0.249, 0.364 and G × DD = 0.116, 0.155). The O/N ratios under both conditions in all species and hybrids indicated that they had carbohydrate dominated metabolism. Results demonstrated physiological variability among the species and hybrids indicating necessity of different strategies for their management and aquaculture.  相似文献   

4.
This study investigated the effects of sodium alginate supplementation on gut microbiota composition, health parameters, growth performances and growth‐related gene expression of Malaysian mahseer. Five test diets were formulated by supplementing 0%, 0.1%, 0.2%, 0.4% and 0.8% sodium alginate. Triplicate groups of juvenile Tor tambroides (2.19 ± 0.05 g) were stocked in 15 aquaria (20 individuals per aquarium) and fed at 3.0% body weight per day for 60 days. PCoA and UPGMA analysis showed that gut bacterial community were more convergence in higher sodium alginate‐supplemented diets. The percentage of Porphyromonadaceae, Bacteroides, Plesiomonas and Shewanella were substantially higher and Aeromonas, Entomoplasmatales and Prevotellaceae were drastically lower in higher sodium alginate (0.2%–0.8%) diets. Sodium alginate supplementation (≥0.2%) significantly improved the haematocrit value and respiratory burst activity of T. tambroides. Growth performances and feed utilization were significantly higher in 0.2%–0.4% sodium alginate‐supplemented diets. The increased growth rate of T. tambroides was governed by both hyperplastic and hypertrophic muscle growth. Real‐time PCR data demonstrated that most of the growth‐related genes were significantly upregulated in 0.2%–0.4% sodium alginate‐supplemented diet. Finally, it can be concluded that sodium alginate should be supplemented at 2 g/kg in practical fish feed formulation.  相似文献   

5.
ABSTRACT: Poly(α- L -guluronate)lyase, as one of alginate lyases, was purified from the culture medium of a marine bacterium, Pseudomonas sp. strain F6, to an electrophoretically homogeneous state. The enzyme was shown to have a molecular mass of 36 kDa by sodium dodecylsulfate–polyacrylamide gel electrophoresis (SDS-PAGE), and was most active at around pH 7.5 and was stable between pH 6.5 and pH 8.5. In the thermal stability experiments, the enzyme's activity diminished through an intermediate state with increasing incubation temperatures and was finally lost when heated at 100°C for 15 min. The addition of hen egg-white lysozyme to the enzyme decreased thermal stability dramatically. The apparent retention of enzyme activity (approximately 50%) was observed after the addition of 6 M guanidine hydrochloride and 8 M urea. Enzyme activity was lost completely with 10 mMSDS, while the ordered structure, which is considered likely to be β-structure, was markedly created. The similar conformational feature has also been created in marine bacterial and mollusc enzymes and the β-structure is commonly observed in polyuronate lyases. The divalent cation (Ca2+) promoted the activity of the calcium chelator-treated enzyme significantly, suggesting that Ca2+ is involved in the formation of the active intermediate between the acidic uronate(s) and amino acid side-chain(s) of the enzyme.  相似文献   

6.
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.  相似文献   

7.
Hybridization among abalone species has been suggested as a possible means to increase their growth rates for aquaculture. As a first step to test the usefulness of the hybrids of Japanese abalone species (Haliotis discus discus, Haliotis gigantea and Haliotis madaka) for aquaculture, we characterized the genetic background and gonad development of hybrids that were produced by artificial insemination. The hybrid status of the resulting offspring was confirmed by assaying 14 allozymes and by RFLP analysis of the 16s rRNA and cytochrome oxidase I (COI) regions of mtDNA using 13 restriction enzymes. Histological examination of the gonads of the hybrids was conducted in comparison with those of the parental species. Cross‐breeding among the three species was conducted successfully in all combinations although with lower fertilization rates (means of 1.3–60.8%) than the parental species (34.3–90%). Crosses between H. discus discus and H. madaka had higher fertilization rates (22.4–60.8%) than those involving H. gigantea (1.3–19.9%). The hybrids were ascertained by the presence of both parental genotypes at the LDH‐A, ME‐A, MDH‐A and GPI loci. The maternal origin of the hybrid mtDNA was confirmed by digestion with DdeI, TaqI, HpaII of the COI region. No polymorphism was observed in the 16S rRNA region. The hybrids had gonadal development and maturity stages similar to the parental species up to fully mature oocytes and sperm. They spawned upon stimulation and produced viable offspring with high fertilization rates and successful development to the juvenile stage in back‐ and homologous hybrid crosses.  相似文献   

8.
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9.

We evaluated the impact of a combined vitamin E (vit E), a mixture of nucleotide (mixed-NT), Haematococcus pluvialis (H. pluvialis), arachidonic acid (AA), and yeast extract powder (YEP) supplementations on the relative mRNA expression of reproduction and antioxidant-related genes in red claw crayfish Cherax quadricarinatus using an orthogonal design (L16 45) plus control diet for 70 days feeding trial. Five factors with four levels: A, vit E 40, 160, 240, and 320 mg/kg diet; B, mixed-NT 2, 4, 6, and 8 g/kg diet; C, H. pluvialis 2, 4, 6, and 8 g/kg diet; D, AA 5, 10, 15, and 20 g/kg diet; E, YEP 2.5, 5, 10, and 15 g/kg diet were studied. The relative mRNA expression of reproduction-related genes (vitellogenin (vtg) and fatty acid-binding protein (fabp)), and antioxidant-related genes (heat shock protein 70 (hsp70), glutathione peroxidase (gpx), glutathione S-transferase (gst), mitochondrial manganese superoxide dismutase (mmnsod), and ferritin) in hemocyte, hepatopancreas, and ovary tissues were measured. There was a major depression in gene expression levels throughout the experimental diet at high vit E 320 mg/kg level with other factors. Expression of antioxidant enzyme genes significantly increased in treatments of T9, T10, T11, and T12, while significantly decreasing in treatment of T13 and other treatment groups with high vit E 320 mg/kg levels with the other factors. Gene expression of vtg and fabp demonstrated similar patterns to those of antioxidant genes. These results provide evidence that combined supplementations of vit E, mixed-NT, H. pluvialis, AA, and YEP with vit E 240 mg/kg, mixed-NT 8 g/kg, H. pluvialis 4 g/kg, AA 5 g/kg, and YEP 10 g/kg may present a novel strategy for improving reproduction performance and antioxidant activities in RC-crayfish, C. quadricarinatus by the positive impact on the molecular level of reproduction and antioxidant genes.

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10.
The number of growth rings was counted on broken and burnt otoliths of eight Lethrinus spp. from two local populations: Lethrinus atkinsoni, L. harak, L. miniatus, L. nebulosus, L. obsoletus, L. ornatus, L. ravus, and L. rubrioperculatus, collected from 1985 to 1996 in waters off the Ryukyu Islands. Growth rings were revealed to be formed annually from about October to June by marginal analysis. In addition to obtaining the three parameters in von Bertalanffy growth equation and the maximum age in specimens, the relationship between age and both ovarian maturity rate and sex ratio (percentage female) was analyzed. The age at 50% of ovarian maturity was the lowest at 1–2 years old in L. harak, L. ravus, and L. rubrioperculatus and was the highest at approximately 4 years old in L. nebulosus. The age at which the sex ratio decreased to 50% due to sexual transition from female in protogynous hermaphrodite species was the lowest at 3–4 years old in the L. atkinsoni Okinawa population and was the highest at 7–8 years old in L. miniatus. The oldest maximum age for specimens was 26 years in L. nebulosus and the youngest maximum age was 12 years in L. ornatus.  相似文献   

11.
Differences in survival and growth rates in seahorse Hippocampus guttulatus juveniles feeding on Artemia sp. or copepods have been related to specific digestive capacities of seahorse newborn, which are capable of actively forage on available prey from the first day of live. Other seahorse species, such as H. abdominalis and H. hippocampus, show high success feeding on Artemia nauplii suggesting species-specific differences in the digestibility of prey among seahorses. In this study, the profiles of digestive enzyme activity during the initial 15 days after release (DAR) were very low for trypsin, chitinase and α-amylase. In contrast, higher activities towards any of the assayed substrates for lipase (butyrate, octanoate and oleate) were evident from 0 DAR onwards. From 15 DAR onwards, the effect of diet composition became evident in juveniles previously fed on a mixed diet (Artemia + copepods), which showed a clear increase in all the assayed enzymes when compared with juveniles fed on Artemia as a sole prey. As a practical applicability of this study, a feeding schedule ensuring an adequate digestibility of the prey is proposed based on ontogenetic enzymatic activities of seahorse juveniles fed on different prey.  相似文献   

12.
The main goal of this research was to analyse in vitro compatibility of Nile tilapia (Oreochromis niloticus) digestive proteinases and enzymes recovered from species comprising fishery waste as Pleoticus muelleri, Artemesia longinaris and Patagonotothen ramsayi. It evaluated the use of exogenous enzymes as feed supplements to increase digestion efficiency in tilapia fingerlings and juveniles (3.5 ± 0.11 g and 11.6 ± 1.5 g, respectively). We successfully have obtained proteinases from fishery waste as source of exogenous enzymes. P. muelleri and A. longinaris enzymes had more activity of acid and alkaline proteinases than P. ramsayi. SDS‐PAGE gels demonstrated that Nile tilapia digestive proteinases keep their activity when combined with each exogenous proteinase. Exogenous enzymes varied in their ability to enhance hydrolysis of different feed ingredients. P. muelleri by‐products are the best candidates to be employed as feed supplements for tilapia juveniles. Enzymes from this by‐product did not affect the activity and integrity of fish digestive enzymes, improved the hydrolysis of different protein sources (fish meal, squid meal, shrimp meal and soybean meal), and maintained its activity after being exposed to high temperatures and acid pHs. Our findings are applicable to other places where O. niloticus is raised utilizing local fishery waste, and also to different cultured species.  相似文献   

13.
Psorospermium haeckeli is a thick-walled, unicellular organism widely reported in European astacid crayfish. Its taxonomic status and life cycle have not been elucidated. It is often referred to as a “parasite”, but conclusive evidence has yet to be found. Recent examination of two North American crayfish species, Procambarus clarkii and Procambarus zonangulus, confirmed its presence in the south-central USA (Louisiana) with morphologies that differ from that of P. haeckeli. This form had been previously reported from Orconectes virilis in southern Canada. We report here the presence of this North American form of Psorospermium in additional North American crayfish including Orconectes immunis and Orconectes rusticus from the northern USA (Minnesota and Wisconsin), Procambarus alleni and Procambarus fallax from the southern USA (Florida), and Pacifastacus leniusculus from the western USA. We also confirm this Psorospermium in O. rusticus from eastern Canada (Ontario). It was not, however, confirmed in several additional southern crayfish species including Cambarus diogenes, Cambarellus puer, Fallicambarus fodiens, and Orconectes palmeri. We describe the morphological forms of this Psorospermium and conclude that it is present in many crayfish species in North America.  相似文献   

14.
The goal of this study was to compare conventional soybean meal (SBM) with modified SBM (MSBM) after chemical and enzyme pretreatment to potentially reduce the antinutritional factors (ANF), as a fishmeal (FM) replacer at 50% or 100% in the diets of yellow perch (Perca flavescens). Half of the SBM and MSBM diets contained an enzyme cocktail (of phytase and carbohydrate‐degrading enzyme), and the other half received no enzyme supplementations. Fingerlings (297; initial weight, 11.01 ± 0.19 g) were randomly distributed over nine treatments, in triplicate, and fed these isonitrogenous diets (crude protein 410 g/kg) that included replacing FM with SBM at 50% or 100% without or with enzyme supplementations (S50, S100, S50+E or S100+E, respectively), MSMB at 50% or 100% without or with enzyme supplementations (MS50, MS100, MS50+E or MS100+E, respectively) or a control FM‐based diet. After 10 weeks, the growth performance, feeding efficiencies, proximate composition, intestinal/pyloric caeca digestive enzymes and liver metabolic/antioxidant enzymes in P. flavescens were measured. The highest (p < 0.05) growth performance and nutrient utilization parameters (protein efficiency ratio and protein productive value, PPV) were observed for the MS50+E group, which was not statistically different to parameters for the control and MS50 groups, and significantly (p < 0.05) higher than all other groups. The lowest and highest growth performance and feed conversion ratios, respectively, were observed in the S100, S100+E and MS100 groups. The highest protease activity (in both intestine and pyloric caeca) was observed for the control group, but was significantly similar to MS50, MS50+E and S50+E groups. The lowest value was observed for 100% replacement of FM protein by SBM and MSBM fed groups. However, inclusion of exogenous enzymes in feed showed positive effects in MS50+E (compared to MS50) for PPV, lipid productive value and amylase activity in the intestine. Activity of protein metabolism enzymes (i.e., alanine transaminase and aspartate aminotransferase) in the liver was the highest in the control group, which was similar (p < 0.05) to the MS50+E and MS50 groups. Antioxidant enzymes (catalase, superoxide dismutase and glutathione peroxidase) in the liver were the lowest in the control group, which was significantly similar (p < 0.05) to the group given the feed with 50% replacement of FM protein. Complete (100%) replacement of FM protein exhibited the highest antioxidant enzyme activity. Conclusively, performance of the MS50 and MS50+E groups was similar to the FM group and better than SBM group; therefore, MSBM with high protein and low ANFs has considerable potential as an alternative to FM in aquafeed.  相似文献   

15.
The effect of six different binding agents (agar, sodium alginate, cassava starch, gelatin, wheat gluten and kelp meal) in two concentrations (30 g kg−1 and 50 g kg−1) were evaluated with respect to physical quality of Litopenaeus vannamei broodstock pelleted feed, after 15, 30, 60, 90, 120, 150 and 180 min of water immersion. The best treatments in terms of water stability, water absorption and protein leaching were obtained with sodium alginate and wheat gluten at 50 g kg−1. In a second experiment, the feed ingestion and diet digestibility with these two binders and their combination (1 : 1) were compared against a control diet containing 50 g kg−1 wheat flour. There were no significant differences (P > 0.05) in the daily feed ingestion rate 2.39–3.33% of the biomass. The most representative values of apparent digestibility of protein (ADP) and apparent dry matter digestibility (ADMD) were achieved with diets containing wheat gluten and alginate + gluten mixture as binder. Based on these results, combinations with 50 g kg−1 wheat gluten is recommended as binder in pelleted feed for broodstock L. vannamei.  相似文献   

16.
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17.
This study determined the minimum inhibitory concentrations (MICs) for oxytetracycline hydrochloride (OTC) and erythromycin (Em), along with the α-glucosidase (α-glu) activities in 110 Nocardia seriolae strains isolated in Miyazaki and Kagoshima prefectures in 2008–2009. The strains were examined for the presence of the tet(K), tet(L), tet(M), tet(O), tet(S), erm(A), erm(B), mph(A), mef(A), and msr(D) genes. All the α-glu-positive strains (n = 15) were OTC resistant and Em sensitive, with MICs of 32–64 and <0.125 μg/ml, respectively. All the α-glu-negative strains (n = 95) were OTC sensitive, with MICs of 2–4 μg/ml, and most of them (93 of 95) were Em resistant, with MICs of >128 μg/ml. The MICs for Em in the remaining 2 α-glu-negative strains were <0.125 μg/ml. The 15 OTC-resistant strains possessed the tet(K) and/or tet(L) gene(s), and all of the 93 Em-resistant strains possessed both the mef(A) and msr(D) genes. The relationship between α-glu activity and drug sensitivity of the N. seriolae strains may explain the difference in prevalence of each phenotype. Nevertheless, the relationship should be further explored using N. seriolae isolates collected from more prefectures and farms.  相似文献   

18.
Five experimental diets with different carbohydrates/lipid ratio (CHO:L, 0.75, 1.28, 2.10, 2.52, 4.63) were formulated. Fish were randomly assigned by triplicate (10 fish per tank, 0.50 ± 0.01 g). Growth was registered every 15 days until end of the experiment (45 days). Samples were taken for analysis of chemical carcass composition, blood chemistry, glycogen and lipid liver content, digestive and metabolic enzyme activities. Results showed that survival, growth performance parameters and plasma glucose were not affected by treatments (p > 0.05). Lipids of carcass and liver, as well as triglycerides and plasma cholesterol increase significantly as CHO:L ratio decreased. While an inversely proportional tendency was observed for carcass protein and liver glycogen (p < 0.05). Digestive enzymes did not show significant differences among treatments (p > 0.05). Finally, Hexokinase (HK), glucokinase (GK), phosphoenol pyruvate carboxykinase (PEPCK) and fructose‐1,6‐biphosphase (FBPase) showed high regulation by carbohydrates up to the CHO:L ratio of 2.10 (p < 0.05), while pyruvate kinase (PK) activity was not significantly affected by the CHO:L ratio. By the other side, glucose‐6‐phosphate dehydrogenase (G6PD) tends to significantly increase as the CHO:L ratio increases. We conclude that A. tropicus fry have a high capacity to utilize carbohydrates substituting lipids as energy source in balanced diets.  相似文献   

19.
The influence of dietary supplementation of Lactobacillus acidophilus, on growth performance, digestive enzyme activities, gut histomorphology and gut microflora were evaluated in juveniles striped catfish (Pangasianodon hypophthalmus). Five experimental diets were formulated by supplementing 0, 103, 105, 107 and 109 CFU/g L. acidophilus in fishmeal and casein‐based semi‐purified diet. Triplicate groups of striped catfish (21.69 ± 0.18 g) were stocked in 15 fiberglass tanks with stocking density of 25 individuals per tank and fed twice daily at 2.5% of the fish body weight for 12 weeks. Weight gain, specific growth rate, feed conversion ratio and the protein efficiency ratio were significantly higher in fish fed with 105 and 107CFU/g L. acidophilussupplemented diets compared with the other treatment groups. Compared with the control and fish fed low (103 CFU/g) L. acidophilus supplementation, those fed with 105 and 107 CFU/g had significantly higher (p < 0.05) apparent protein digestibility. Inclusion of L. acidophilus at 107 CFU/g diet significantly increased amylase, protease and lipase activities. Microscopic analysis showed that the villi length in both the anterior and posterior gut and microvilli length in the posterior gut increased significantly in fish fed L. acidophilus supplementation at 105 and 107 CFU/g of diet. The fish fed L. acidophilus supplemented diets significantly increased the total lactic acid bacteria counts in the gut of striped catfish compared with the control‐fed group. Based on gut histomorphology and growth performance, inclusion of L. acidophilus at 105 CFU/g appears to have the most positive effect on striped catfish farming.  相似文献   

20.
The present study aimed to investigate the effects of dietary supplementation of Lactobacillus delbrueckii (L. delbrueckii) on growth performance, body composition, intestinal enzyme activities and gene expression of Cyprinus carpio Huanghe var. Fish (mean 1.05 ± 0.03 g in triplicate) were conducted for 8 weeks with five treatments in triplicate. The fish in the control were fed a basal diet, and those in D2, D3, D4 and D5 were fed basal diet containing L. delbrueckii at 1 × 10 CFU/g, 1 × 10 CFU/g, 1 × 10 CFU/g and 1 × 10 CFU/g. The growth performance and the hepatic IGF‐I expression of fish increased significantly as L. delbrueckii level increased from 0 to 1 × 10 CFU/g, but decreased significantly with further increasing L. delbrueckii levels. The whole body protein, lipid contents, intestinal digestive and absorptive enzyme activities were significantly affected by dietary L. delbrueckii levels with the highest values observed in fish fed diet containing 1 × 106 CFU/g L. delbrueckii. The carbohydrate content showed the opposite trend. The results suggest that supplementation of L. delbrueckii as probiotic in the diet at approximately 1 × 10 CFU/g can improve growth performance, intestinal enzyme activities and the growth‐related gene expression in Cyprinus carpio Huanghe var.  相似文献   

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