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1.
Used as a traditional Chinese medicine, the high mortality rate and slow growth of Whitmania pigra larvae are the most serious bottlenecks for the scale development of artificial breeding. Firstly, five light colour treatments (white, blue, green, red and yellow) were tested to determine effects of light spectrum on the growth of larval W. pigra at the same intensity of 70.00 μmol m?2 s?1. The experiment lasted for 45 days. Under our experimental conditions, the weight gain (WG) and the specific growth rate (SGR) under blue light condition were significantly higher compared with the other treatments (P ≤ 0.05). It is reasonable to conclude that blue light can promote the leech growth. In addition, reared at five blue light intensity treatments (20.00 ± 3.84, 40.78 ± 4.18, 53.67 ± 5.98, 70.00 ± 7.26 and 87.33 ± 5.77 μmol m?2 s?1), the WG and SGR increased with increasing intensity. Meanwhile, they were significantly higher in the 70.00 and 87.33 μmol m?2 s?1 treatments (P ≤ 0.05). In the higher intensity light treatments, the digestive enzymes were higher and antioxidant enzymes were lower. These results suggest that the optimal light spectrum for the culture of W. pigra during the early life stage was blue and the optimal light intensity was higher light intensity (70.00–87.33 μmol m?2 s?1).  相似文献   

2.
To evaluate the possible dietary application of live and heat‐inactivated probiotic Bacillus pumilus SE5 in grouper Epinephelus coioides, juveniles (14.6 ± 0.2 g) were fed either a basal control diet (without probiotic) or the basal diet supplemented with 1.0 × 108 CFU g?1 live (T1) and heat‐inactivated B. pumilus SE5 (T2). The heat‐inactivated probiotic significantly improved the final weight, weight gain (WG) and specific growth rate (SGR) at day 60 and significantly decreased the feed conversion ratio (FCR) at day 30 and 60, while the viable probiotic significantly decreased the FCR at day 60 (P < 0.05). Phagocytic activity, serum complement C3 and IgM levels as well as SOD activity elevated significantly in fish fed the heat‐inactivated probiotic for 60 days (P < 0.05). Furthermore, the heat‐inactivated probiotic remarkably up‐regulated expression of TLR2 and pro‐inflammatory cytokines (IL‐8 and IL‐1β) in head kidney (P < 0.05), but the viable probiotic failed to do so. These results indicated that heat‐inactivated B. pumilus SE5 can effectively improve the growth performance and immune responses of E. coioides.  相似文献   

3.
Effects of light intensities on growth, survival, reproductive and life span traits of Artemia urmiana were investigated under laboratory conditions. Nauplii of A. urmiana were hatched and raised in 100 g L?1 at four illuminations including 0, 100, 2000 and 5000 lx with 14:10 (light:dark) photoperiod. Mating pairs of mature animals were randomly isolated and reared continuously under similar conditions. The mode and potential of reproduction as well as adult survival shown by each pair were determined throughout their life span. Results showed that percentages of nauplii survival were significantly (P ≤ 0.05) different at 5000 and 0 lx (76.50% compared with 26.25%) respectively. Total number of offspring was highly correlated with the light intensities showing increased numbers at higher light intensities compared with darkness or 100 lx. Reproduction mode was relatively affected by various light intensities. Significant (P ≤ 0.05) differences were found both in reproductive period and life span at different illuminations. Maximum and minimum offspring productions per reproductive day were found at 5000 and 100 lx respectively. The relative degree of oviparity increased as the illumination decreased (57.92% compared with 22.65% at 0 and 5000 lx respectively). The optimum light intensities appear to be between 2000 lx and 5000 lx in this study. These findings could probably be useful for mass culture of A. urmiana in indoor or recirculating systems as well as in outdoor systems for intensive cyst and biomass production.  相似文献   

4.
A feeding trial was conducted to determine the optimum dietary protein level of sea cucumber Apostichopus japonicus juvenile focusing on growth performance and non‐specific immune response. Diets with seven crude protein levels (42.0, 108.9, 155.2, 216.7, 258.0, 313.3 and 357.5 g kg?1) were fed to sea cucumber juveniles (1.05 ±0.01 g) once a day for 100 days. More than 70% survival was observed, and there was no significant difference among all treatments. The sea cucumbers fed diets containing 108.9 g kg?1 crude protein showed significantly (P < 0.05) higher body weight gain than those of the sea cucumbers fed diets containing 42.0, 216.7, 258.0, 313.3 and 357.5 g kg?1 crude protein. No significantly differences (P > 0.05) were observed in moisture, crude protein, crude lipid, ash and carbohydrate content of the body wall among all treatments. The coelomic fluid catalase activity of the sea cucumbers generally increased with increasing dietary protein levels. Therefore, the acid phosphatase, superoxide dismutase and lysozyme activity increased with increasing dietary protein levels at first and decreased subsequently. The relationship between dietary protein levels and body weight gain was analysed by a second‐order polynomial regression analysis model. The result indicates that the optimum dietary protein level for sea cucumber juveniles is 135.4 g kg?1.  相似文献   

5.
A nutrition trial with striped catfish (Pangasianodon hypophthalmus) juveniles was undertaken to evaluate the effect of replacing dietary fishmeal (FM) protein with corn gluten meal (CGM). A diet with FM as the main protein source was used as the control diet (FM). Five experimental diets (approximately 320 g kg?1 crude protein) were formulated to progressively replace 20% (CGM20), 40% (CGM40), 60% (CGM60), 80% (CGM80) and 100% (CGM100) of FM protein. Fifteen fish per tank (initial weight 11.2 ± 0.6 g) were randomly distributed into 18 80‐litre fibreglass tanks connected to a closed recirculation system (temperature 30.3 ± 1.0 °C). The diets were tested in triplicate for 12 weeks. The final weight and specific growth rate (SGR) of fish fed diets CGM20, CGM40 and CGM60 were not significantly different compared to fish fed the FM diet. Feed intake (FI) tended to decrease with increasing dietary CGM level. Striped catfish fed FM, CGM20 and CGM40 had significantly lower feed conversion ratio (FCR) compared with fish fed CGM80 and CGM100 (P < 0.05). The protein efficiency ratio (PER) of fish fed the CGM80 and CGM100 diets was significantly lower than those of all other treatments (P < 0.05). Total ammonia‐nitrogen (TAN) excretion increased with elevated dietary CGM inclusion. The viscerosomatic index (VSI) of fish fed the CGM80 and CGM100 diets were significantly higher (P < 0.05) than those of fish fed the other treatments. The crude lipid content in the final body composition of the striped catfish was elevated significantly with increasing dietary CGM levels. Fish fed the CGM80 and CGM100 diets displayed haematocrit levels significantly lower (P < 0.05) than those fed the other diets. The haemoglobin content in fish was significantly higher in fish fed CGM20 and lower at CGM100 compared to fish fed the FM diet. The results of the present trial indicated that the optimum level of FM protein replacement with CGM determined by quadratic regression analysis was 25.1% on the basis of maximum SGR.  相似文献   

6.
A 49‐days feeding trial was conducted to study the effects of sodium butyrate on growth performance, gut morphology of juvenile grass carp. Five isoenergetic and isonitrogenous experimental diets were compounded by the supplementation in the basal diet with gradient sodium butyrate at 0, 500, 1000, 2000, 3000 mg kg?1 respectively. A total of 375 juvenile grass carp (with initial body weight of 3.8 g) were randomly allocated into five diet treatments, and each treatment has three replicates. The results showed that the specific growth rate (SGR) of SB1000 and SB2000 group was significantly higher (P < 0.05) than that of the other groups. Moreover, the lowest SGR was observed in SB3000 group. Feeding rate and the whole‐body proximate composition including moisture, crude lipid, crude protein and crude ash were not affected by sodium butyrate (P > 0.05). Total superoxide dismutase activities in hepatopancreas in the experimental groups were significantly higher than those in the control group (P < 0.05). Glutathione peroxidase activity in hepatopancreas was significantly upregulated by dietary sodium butyrate level (P < 0.05). However, the activity of total antioxidant capacity and the contents of malondialdehyde were not significantly different among groups. The expression levels of mRNA encoding PepT1 and LAT2 in the foregut both showed a first increasing and then decreasing tendency as dietary sodium butyrate level increased (P < 0.05), and peaked in SB1000 and SB2000 groups respectively. The results indicated that appropriate dietary supplementation of sodium butyrate at 2000 mg kg?1 could improve the growth, antioxidant ability and intestinal absorption capacity of the juvenile grass carp.  相似文献   

7.
South African juvenile dusky kob Argyrosomus japonicus are more abundant in turbid estuaries than in clear marine‐dominated estuaries. Turbidity can reduce light penetration into the water and create an environment different from that experienced by fish under culture conditions in mechanically filtered clear water. In order to optimize rearing conditions of this species, the effects of light intensity (23–315 lx) and feeding method (restricted ration vs. feeding to apparent satiation) on growth and food conversion ratio (FCR) of juvenile A. japonicus were assessed in a 56‐day growth trial. Fish weight increased from 7.2±1.6 to 41.9±10.2 g fish?1 at a growth rate of 3.25% body weight day?1. Light intensity did not significantly affect growth or FCR. Feeding method did not significantly affect growth rate, but average FCR was significantly better in treatments fed a ration of 3.6% body weight day?1 than in treatments fed to apparent satiation. Therefore, a light intensity range of 23–315 lx can be used to culture dusky kob juveniles. The better FCR in fish fed a restricted ration suggests that a ration of 3.6% body mass day?1 allowed good growth of juvenile dusky kob.  相似文献   

8.
A study was conducted to estimate the optimum requirement of dietary phosphorus (P) for Channa argus × Channa maculata. Effects of dietary P levels on the tissue composition, serum biochemical parameters and antioxidant status were also examined. Five practical diets were formulated to contain graded levels (4.8 g kg?1, 6.4 g kg?1, 7.9 g kg?1, 9.4 g kg?1 and 11.0 g kg?1) of available P from dietary ingredients and monocalcium phosphate (MCP). Each diet was randomly assigned to triplicate groups of 30 juvenile fish (initial body weight, 20.50 ± 0.53 g) for 8 weeks. The results showed that the specific growth rate (SGR) and weight gain (WG) were all significantly improved by dietary P up to 9.4 g kg?1 (P < 0.05) and then levelled off beyond this level. Broken‐line analysis showed maximum weight gain (WG) was obtained at dietary available P concentrations of 9.6 g kg?1. With the increase in dietary P level, protein efficiency rate (PER) increased significantly and reached a plateau, while the feed conversion ratio (FCR), the mesenteric lipid somatic index (MSI) and the whole‐body lipid content significantly reduced (P < 0.05). Dietary P levels also affected the mineralization (ash and P) of whole body, vertebrae and scale (P < 0.05). Quadratic analysis based on P contents in whole body, vertebrae, scale and ash content in vertebra indicated that the available P requirements were 10.4, 9.8, 10.0 and 10.3 g kg?1, respectively. However, no differences were found in the whole‐body moisture, crude protein, serum calcium (Ca) contents or Ca/P value, as well as the viscerosomatic index (VSI) and hepatosomatic index (HSI) among all the treatments (P > 0.05). Triglyceride (TG), total cholesterol (TC), high‐density lipoprotein cholesterol (HDL‐C) and low‐density lipoprotein cholesterol (LDL‐C) decreased significantly, while serum P content, HDL‐C/TC and HDL‐C/LDL‐C value increased significantly with dietary available P levels (P < 0.05). No significant changes in superoxide dismutase activity and malondialdehyde (MDA) content were observed (P > 0.05), but serum catalase (CAT) and glutathione peroxidase (GPx) activities and the ratio of CAT/SOD and GPx/SOD increased significantly with increasing dietary P levels (P < 0.05). In conclusion, the optimal P requirement of juvenile snakehead in practical feed was 9.6 g kg?1. Signs of P deficiency were characterized by poor growth, slightly reduced mineralization and the antioxidant capacity and an increase in body lipid content.  相似文献   

9.
Present experiment was conducted to determine the effect of different feeds with varying protein levels on the growth, survival and reproductive performance of zebrafish, Danio rerio. The control diet (T1) was wild‐collected zooplankton from local fish ponds, while test diets with 350 g kg?1 protein (T2), 400 g kg?1 protein (T3) and 450 g kg?1 protein (T4) were formulated and fed to fish for a period of 210 days. The significantly (P < 0.05) highest mean weight gain and specific growth rate were observed in T1, which were similar with T3 and T4. The significantly (P < 0.05) highest number of egg production per female and relative fecundity were found in T1, followed by T4 and T3 while T2 produced lowest number of eggs. No significant (P > 0.05) differences were observed in brood survival rate, fertilization and hatching rate among the dietary treatments. The highest (P < 0.05) fry survival rate was recorded in T1, followed by T3 and T4. Thus, it is suggested that control diet i.e. mixed zooplankton exhibited better growth, reproductive performance and fry survival rate. However, diet containing 400 g kg?1 crude protein also gave comparable results in terms of growth, survival and reproductive performance of zebrafish.  相似文献   

10.
Two 8‐week growth trials were conducted in indoor recirculation system to evaluate the protein requirements for juvenile (3.70 ± 0.20 g) and pre‐adult (85.2 ± 0.70 g) gibel carp, Carassius auratus gibelio var. CAS III. Six isoenergetic diets were formulated for each trial using fish meal and casein as protein sources, and protein level was 250–450 g kg?1 in Trial 1 and 200–450 g kg?1 in Trial 2. With the increasing dietary protein, feeding rate (FR) and feed conversion ratio (FCR) significantly decreased (P < 0.05). Weight gain (WG) increased first and then reached a plateau in 330–450 g kg?1 in Trial 1 (P > 0.05), while decreased after the maximum value in 350 g kg?1 in Trial 2 (P < 0.05). Productive protein values (PPVs) were lower in 370–450 g kg?1 in Trial 1 and 400–450 g kg?1 in Trial 2 (P < 0.05). Increasing dietary protein level increased protein content and decreased lipid content in whole fish body and white muscle (P < 0.05). Apparent digestibility coefficient of dry matters (ADCd) decreased, while apparent digestibility coefficient of protein (ADCp) increased in 370–450 g kg?1 in Trial 1 and 250–450 g kg?1 in Trial 2 (P < 0.05). Trypsin activity significantly increased in 370–450 g kg?1 in Trial 1 (P < 0.05) and was not affected in Trial 2 (P > 0.05). Hepatic alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activities in both trials increased when dietary protein was above 400 g kg?1 (P < 0.05). Based on quadratic regression of WG, it was estimated that dietary protein requirement for maximum growth was 414 g kg?1 (digestible protein of 376 g kg?1) and 365 g kg?1 (digestible protein of 324 g kg?1) for juvenile (3.70 g) and pre‐adult gibel carp (85.2 g).  相似文献   

11.
Light is a key environmental factor that influences the growth, culture and survival of aquatic organisms. This study examined the effects of different light qualities (red, orange, white, blue and green light) and intensities (5 μmol m?2 s?1, 15 μmol m?2 s?1 and 40 μmol m?2 s?1) on the hatching and metamorphosis of larva of Haliotis discus hannai Ino and the growth and survival of juveniles. It was found that under blue and green light, the hatching success rate and metamorphosis of larva were significantly higher than those for any other light quality (P < 0.05), and there was a decreasing trend with an increase in light intensity. Under red and orange light, the abnormality rate of trochophores in each light intensity treatment and the time required for the metamorphosis of larva were significantly higher than those for any other light group (P < 0.05). Both the abnormality and metamorphosis rates significantly increased with light intensity. Under white light, at an intensity of 40 μmol m?2 s?1, the settlement and size of larva at metamorphosis were significantly smaller than those for any other light intensity (P < 0.05). Under red and orange light, the SGR of juvenile abalone in each light intensity treatment was significantly lower than that in any other light group (P < 0.05), but no significant difference was identified (P > 0.05). Therefore, selecting blue and green light and controlling the light intensity to 5–15 μmol m?2 s?1 during fingerling reproduction of abalone should increase the hatching success rate of larva and the yield per water body.  相似文献   

12.
The experiment was conducted to determine the effect of dietary DL‐methionine addition in fish meal reduction diet for juvenile golden pompano (Trachinotus ovatus). The trial comprises the following of 11 diet treatments. (i) D1 diet as the standard was formulated with fish meal as the main protein source. (ii) D2–D5 diets were formulated to replace fish meal with soybean meal at 60, 120, 180 and 300 g kg?1, respectively, and the amino acid profiles (including methionine and lysine) of D2–D5 were referred to the amino acid profile of D1. (iii) D6‐D9 diets were the same as D2–D5, respectively, but without methionine supplementation. (iv) D10 and D11 diets were the same as D3 and D5 diets, respectively, but without lysine supplementation. Each diet was randomly fed to groups of 20 fish (initial average weight about 18 g) per net cage (1.0 × 1.0 × 1.5 m) in triplicate and the feeding experiment lasted for 56 days. Weight gain (WG, %) and final body weight (FBW, g) of fish fed D3 diet were significantly higher than those of fish fed D8 and D9 diets (P < 0.05), but without significant differences with fish fed other diets (P > 0.05). Feed conversion ratio (FCR) of D3, D4 and D5 diet treatments were significantly lower than that of D11 diet treatment (P < 0.05), but without significant difference with other diet treatments (P > 0.05). Whole‐body protein contents of fish fed D3–D5 were significantly higher than those of fish fed D7–D9 (P < 0.05), but without significant differences with fish fed other diets (P > 0.05). In conclusion, the replacement of fish meal by soybean meal could reach 300 g kg?1 without detrimental but profitable effect on growth and survival when enough methionine and lysine were supplemented in the diet; moreover, lysine is not the first‐limiting amino acid relative to methionine for juvenile T. ovatus from the present growth and proximate composition results.  相似文献   

13.
A 10‐day experiment was performed to examine different mono, binary and ternary dietary combinations on survival and growth of D‐shaped and umbone black‐lip pearl oyster, Pinctada margaritifera, larvae. The three tropical microalgae species were the flagellate Isochrysis galbana clone T. Iso (CS‐177) and diatoms Chaetoceros calcitrans (CS‐178) and Chaetoceros muelleri (CS‐176) which were fed to D‐shaped and umbone larvae at a density of 7000 and 14 000 cells mL?1, respectively. A second experiment was performed to investigate the feasibility of replacing T. Iso with a lipid emulsion for both D‐shaped and umbone larvae for 10 and 12 days, respectively. The treatments included only T. Iso, unfed and lipid emulsion to substitute T. Iso at levels of 10% (LIP10), 30% (LIP30) and 100% (LIP100). In the first experiment, results showed that a monospecific diet of T. Iso led to significantly higher (P < 0.05) survival and growth of D‐shaped larvae than all the other treatments. Meanwhile, D‐shaped larval survival was significantly lower when only fed C. calcitrans as well as growth for those fed C. calcitrans or in combination with C. muelleri. However, for umbone larvae, survival and growth were significantly higher when fed a binary combination of T. Iso and C. muelleri or the ternary combination of T. Iso, C. muelleri and C. calcitrans compared with all other treatments. For the second experiment, results showed that with increasing lipid emulsion replacement, survival of both D‐shaped and umbone larvae significantly decreased (P < 0.05); however, the LIP100 treatment was not significantly different (P > 0.05) from the unfed treatment. For D‐shaped larvae, no significant growth difference was detected (P > 0.05) between the T. Iso and LIP10 fed treatments while for umbone larvae, the T. Iso, LIP10 and LIP30 were not significantly different (P > 005). These results indicate that microalgae combinations appear more necessary for later staged P. margaritifera larvae. In addition, the use of a lipid emulsion appeared to provide some nutrition to the larvae, although more research should be conducted to improve the use of such replacements.  相似文献   

14.
To investigate the effect of dietary sodium chloride (NaCl) on meat quality of white shrimp (Litopenaeus vannamei) reared in low‐salinity (2 g L?1) water, shrimp were distributed into four groups (treatments T‐1, T‐2, T‐3 and control) with three replicates. All shrimps were completely randomised stocked into 12 tanks at an initial density of 40 shrimps per tank. Diets for the control, T‐1, T‐2 and T‐3 groups consisted of the basal diet supplemented with 0 g kg?1, 10 g kg?1, 20 g kg?1 and 40 g kg?1 of NaCl respectively. After 50 days, shrimps in T‐3 showed significantly better (P < 0.05) moisture, crude protein and ash than those of the control and T‐1. Higher muscle Na content was observed (P < 0.05) in T‐3 than that of the control. Significant increases (P < 0.05) in contents of inosinic acid, total free amino acid (TFAA) and essential free amino acid (EFAA) were also found in T‐3. Texture assays showed significant differences (P < 0.05) in hardness, adhesiveness and springiness between group T‐3 as compared with those of T‐1 and control. It indicated that dietary supplementation of NaCl appeared to be a promising practice to improve meat quality of white shrimp reared in low‐salinity waters.  相似文献   

15.
Ethoxyquin (EQ) is the most common synthetic antioxidant used for preventing rancidity in fish foodstuffs. However, literature related to the effects of dietary EQ on performance of fish was limited. The present study was conducted to investigate the effects of EQ on performance and EQ residue in muscle of juvenile Japanese seabass Lateolabrax japonicus and to estimate the optimal EQ concentration in the diet. Graded levels [0 (control), 50, 150, 450 and 1350 mg EQ kg?1 diet] of EQ were added to the basal diet, resulting in five dietary treatments in the experiment. Each diet was fed to triplicate groups of seabass (initial body weight 8.01 ± 0.76 g) for 12 weeks in floating sea cages (1.5 × 1.5 × 2.0 m, 30 fish per cage). Survival ranged from 78.9 to 86.7%, and was irrespective of dietary EQ levels. The specific growth rate (SGR) of fish fed diets supplemented with ≤50 mg kg?1 EQ had significantly (P < 0.05) higher SGR than fish fed diets supplemented with ≥150 mg kg?1 EQ, the highest SGR was observed in fish fed diet with 50 mg kg?1 EQ supplementation. Feed intake (FI) and feed efficiency (FE) were not significantly (P > 0.05) different among dietary treatments. Fish fed diets with 50 and 1350 mg kg?1 EQ had a significant (P < 0.05) lower body lipid content than fish in the control group. Muscle EQ level significantly increased when dietary EQ increased. Optimal EQ concentration estimated by polynomial regression based on maximum growth of juvenile Japanese seabass was 13.78 mg kg?1 diet.  相似文献   

16.
The growth rate, survival rate, development and setting rate of larval sea cucumber Apostichopus japonicus were measured under four light intensities (0, 50, 500 and 2,000 lx), and the growth rate and metabolism of the juvenile sea cucumbers were investigated under four light intensity treatments (0, 100, 1,000 and 2,500 lx). The light requirements (i.e. intensity) of the sea cucumber changed as they grew. Better growth performance, development and survival rate were observed in embryos and larvae under 500 lx treatment. However, reduced light intensity (50 lx) increased the settlement rate of the larvae. The highest specific growth rate occurred in juvenile sea cucumbers under 1,000 lx. The sea cucumbers in this group also had the lowest oxygen consumption rate and ammonia excretion rate, but the highest O:N ratio, indicating that the optimal light intensity for the juvenile sea cucumber culture was 1,000 lx. Therefore, appropriate light intensities were suggested to provide larval and juvenile sea cucumbers with better growth and development conditions.  相似文献   

17.
The aim of this study was to evaluate different replacement levels of fish meal (FM) by poultry by‐product meal (PBM) on survival, growth performance and body composition of juvenile tench (Tinca tinca). A 90‐day experiment was conducted with 5 month‐old juveniles (31.95 mm total length, 0.396 g weight). Eight practical diets (50% crude protein) differing in the level of replacement of FM protein by PMB protein were tested: 0% (control), 25%, 31%, 37%, 43%, 49%, 55% and 61% corresponding to 0, 184.8, 229.2, 273.5, 317.8, 362.1, 406.5 or 450.8 g PBM kg?1 diet respectively. Significant differences were not found (P > 0.05) between 25% replacement of FM protein by PBM protein (184.8 g kg?1 PBM in diet) and control diet. At higher replacement levels, fish had significantly lower growth, higher feed conversion ratio and lower protein productive value (P < 0.05). Fish with externally visible deformities ranged from 1.1% to 3.3%. The relation among amino acid profiles of the diets, body composition, growth performance of juveniles and amino acid requirements of other fish species is discussed. Up to 184.8 g PBM kg?1 diet can be included in diets for juvenile tench without impairing growth performance.  相似文献   

18.
An 8‐week feeding trial was conducted to determine the optimum dietary methionine (Met) requirement of juvenile Pseudobagrus ussuriensis with an initial average weight of 0.60 g reared in indoor flow‐through and aerated aquaria. Six isonitrogenous (430 g kg?1 protein) and isolipidic (50 g kg?1 lipid) test diets were formulated to contain graded levels of crystalline L‐methionine (4.9, 9.0, 11.8, 14.2, 18.1 and 20.8 g kg?1 dry diets, respectively) at a constant dietary cystine level of 2.5 g kg?1 dry diets. Equal amino acid nitrogen was maintained by replacing methionine with non‐essential amino acid mixture. Fish were randomly allotted to 18 aquaria (1.0 × 0.5 × 0.8 m) with 50 fish to each glass aquarium. Fish were fed twice daily (08:00 and 16:00) to apparent satiation. No significant difference was observed in survival of fish (84.67–91.33%). Specific growth rate (SGR), weight gain (WG), feed conversion ratio (FCR), protein productive value (PPV) and protein efficiency ratio (PER) were significantly affected by different dietary methionine levels (P < 0.05). WG, SGR PPV and PER increased, while FCR decreased with increasing dietary methionine level from 4.9 to 11.8 g kg?1 (P < 0.05). However, with further increase from 11.8 to 20.8 g kg?1, WG, SGR PPV and PER significantly decreased, FCR increased (P < 0.05). The whole body and muscle composition were affected by different dietary methionine levels (P < 0.05). Condition factor (CF) increased with increasing dietary methionine levels up to 11.8 g kg?1 (P < 0.05) and after 11.8 g kg?1 methionine diet, but not significant, declines were observed (P > 0.05). Hepatosomatic index (HSI) of the 4.9, 9.0, 11.8 and 14.2 g kg?1 Met diets was significantly higher than that of fish fed diets 18.1 and 20.8 g kg?1 Met diets (P < 0.05). Viscerosomatic index (VSI) of the 4.9, 9.0 and 11.8 g kg?1 Met diets was significantly higher than that of fish fed diets 14.2, 18.1 and 20.8 g kg?1 Met diets (P < 0.05). Quadratic regression analysis of WG and PER against dietary methionine levels indicated that the optimal dietary methionine requirement for maximum growth and feed utilization of juvenile Pseudobagrus ussuriensis was 14.3 and 14.1 g kg?1 dry diet (35.3 and 34.8 g kg?1 dietary protein), respectively, in the presence of 2.5 g kg?1 dry diets cystine.  相似文献   

19.
A total of 630 juvenile Chinese sucker, with an average initial weight of 1.72 ± 0.05 g, were fed seven diets for 56 days to study the effect of dietary methionine levels on growth, feed utilization, body composition and haematological parameters on juvenile Chinese sucker. Diet 1 using fish meal as the sole protein source and diets 2–7 using fish meal and fermented soybean meal as intact protein sources supplemented with crystalline amino acids contained six levels of l ‐methionine ranging from 6.4 to 18.9 g kg?1 of dry diet at a constant dietary cystine level of 3.7 g kg?1. Each diet was randomly assigned to three aquaria. Results indicated that the highest weight gain, specific growth rate (SGR), feed efficiency ratio, protein efficiency ratio and protein productive value occurred at 13.9 g methionine kg?1 diet among the methionine supplemented dietary groups, beyond which they showed declining tendency. The whole body and muscle protein contents of juvenile Chinese sucker were positively correlated with dietary methionine level, while muscle lipid content was negatively correlated with it. The total essential amino acids content of muscle was increased significantly with increasing dietary methionine level from 6.4 to 13.9 g kg?1 (P < 0.05). Apparent digestibility coefficients of dietary protein were significantly affected by dietary treatments. Serum protein, cholesterol and triacylglycerol increased with increasing dietary methionine levels, but showed a relatively lower value for fish fed the 18.9 g methionine kg?1 diet. Quadratic regression analysis of SGR against dietary methionine level indicated that optimal dietary methionine requirement for juvenile Chinese sucker was 14.1 g kg?1 of the diet in the presence of 3.7 g kg?1 cystine (corresponding to 32.0 g kg?1 of dietary protein on a dry‐weight basis).  相似文献   

20.
To assess the effects of A3α‐peptidoglycan (A3α‐PG) extracted from Bifidobacterium sp. on the immune response and disease resistance of sea cucumber, different concentrations (0, 0.5, 5 and 50 mg mL?1) of A3α‐PG suspensions were used to perform hypodermic injection on Apostichopus japonicus, followed by a Vibrio splendidus challenge. Total coelomocyte count (TCC), phagocytosis activity and activities of four immunological enzymes in both cell‐free coelomic fluid (extra‐cellular, EC) and coelomocyte lysate supernatant (intracellular, IC), including acid phosphatase (ACP), alkaline phosphatase (ALP), superoxide dismutase (SOD) and peroxidase (POD), were measured at 2, 6, 14 and 24 h post injection (hpi). The TCC was not significantly affected (P > 0.05) by A3α‐PG, ranging from 1.84 × 106 to 3.53 × 106 cells mL?1. The coelomocyte phagocytosis activity was significantly activated (P < 0.05) in all the A3α‐PG treatments, whereas no significant difference was observed between them except 24 hpi (P > 0.05). The EC‐ACP activity in the 5.0 mg mL?1 treatment increased significantly (P < 0.05) at all sampling times, while the IC‐ACP activity in the 50 mg mL?1 treatment increased significantly (P < 0.05) at 2 hpi. Also, the 5.0 mg mL?1 treatment had significant (P < 0.05) increase in the EC‐ALP activity within 14 hpi and the EC‐POD activity at 2 hpi, respectively, while significantly (P < 0.05) enhanced IC‐ALP and IC‐POD activities were observed in the 50 mg mL?1 treatment within 6 hpi and at 2 hpi, respectively. Only the 5.0 mg mL?1 treatment showed significant (P < 0.05) increase in the EC‐SOD activity at 2 hpi and IC‐SOD activity within 14 hpi, respectively. The challenge test showed that the animals treated with 50 mg mL?1 of A3α‐PG had notably lower cumulative mortality after 14 days following V. splendidus exposure. All together, these results suggest that A3α‐PG could positively enhance immune response that effectively promotes the health status of A. japonicus against V. splendidus infection.  相似文献   

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