首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 453 毫秒
1.
An 8‐week feeding trial was conducted to investigate the optimum dietary protein and lipid levels for growth, feed utilization and body composition of Pseudobagrus ussuriensis fingerlings (initial weight: 3.40 ± 0.01 g). Twelve diets containing four protein levels (350, 400, 450 and 500 g kg?1 crude protein) and three lipid levels (50, 100 and 150 g kg?1 crude lipid) were formulated. Fish were randomly allotted to 36 aquaria (1.0 × 0.5 × 0.8 m) with 25 fish to each glass aquarium. Fish were fed twice daily (08:00 and 16:00) to apparent satiation. The results showed that weight gain and specific growth rate (SGR) decreased with increasing dietary lipid level from 50 to 150 g kg?1 at the same dietary protein level. Fish fed the diets containing 150 g kg?1 lipid exhibited higher feed conversion ratio (P < 0.05), lower protein efficiency ratio (PER) and nitrogen retention efficiency (NRE) relative to fish fed the diet containing 50 and 100 g kg?1 lipid. Weight gain and SGR significantly increased with increasing dietary protein from 350 to 450 g kg?1 at the same dietary lipid level, and even a little decline in growth with the further increase in dietary protein to 500 g kg?1. Daily feed intake, NRE and PER were significantly affected by both dietary protein and lipid levels (P < 0.05) and tended to decrease with increasing dietary protein and lipid levels. Whole‐body protein content increased as protein levels increased and lipid levels decreased. Whole‐body lipid and muscle lipid content increased with increasing dietary lipid level, and decreased with increasing dietary protein at each lipid level. There was no significant difference in condition factor and viscerosomatic index among fish fed the diets. Hepatosomatic index was affected by dietary lipid level (P < 0.05), and increased with increasing dietary lipid level at the same protein level. These results suggest that the diet containing 450 g kg?1 protein and 50 g kg?1 lipid with a P/E ratio of 29.1 mg protein kJ?1 is optimal for growth and feed utilization of P. ussuriensis fingerlings under the experimental conditions used in the study.  相似文献   

2.
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   

3.
Six isonitrogenous (320 g kg?1) and isolipidic (60 g kg?1) diets were formulated with graded levels (0, 5, 10 and 15 g kg?1) of dicalcium phosphate (DCP) and fungal phytase (750 and 1500 FTU kg?1 diet). Tra catfish (Pangasianodon hypophthalmus), 9.6 g, were fed the diets for 12 weeks. Each experimental diet was fed to eight replicates of fish to apparent satiation. At the end of the trial, fish fed the diets containing 15 g kg?1 DCP, 750 and 1500 FTU kg?1 phytase had higher growth performances, protein efficiency ratio and phosphorus retention than those fed the control diet, 5 g kg?1 DCP and 10 g kg?1 DCP diets (P < 0.05). Whole body ash and phosphorus concentration of fish fed the 10 g kg?1 DCP and 15 g kg?1 DCP diets were significantly higher than those of fish fed the control diet. Higher apparent digestibility coefficient of phosphorus was observed in fish fed the phytase supplemented diets. The present results indicate that supplementation of phytase at 750 FTU kg?1 and 1500 FTU kg?1 improves growth performances, feed and phosphorus utilization. The supplementation can completely replace dicalcium phosphate or other phosphorus sources in tra catfish feed and reduce the phosphorus discharge into environment.  相似文献   

4.
Six isonitrogenous and isocaloric semi‐purified diets were prepared with different levels of microbial levan: control (Basal), T1 (Basal + 2.5 g kg?1 diet), T2 (Basal + 5 g kg?1 diet), T3 (Basal + 7.5 g kg?1 diet), T4 (Basal + 10 g kg?1 diet) and T5 (Basal + 12.5 g kg?1 diet), fed to six groups of fish in triplicate tanks. The results of the 60 days feeding trail showed that supplementation of dietary levan significantly affected the weight gain percentage and specific growth rate of the treatment groups fed at 10 g kg?1 or more levan. Lowest feed conversion ratio (FCR) value and highest survival percentage among levan fed groups were observed with 12.5 g kg?1 incorporation (T5) and was comparable with (T4) group. Significant increase in muscle RNA level and RNA/DNA ratio was observed with the increasing dietary levan. Fish fed 12.5 g kg?1 levan had significantly higher protease, amylase and lipase activities compare with the control group. Lowest Aspartate aminotransferase (AST) activity in the liver and muscle was observed in the T5 group fed with highest level of dietary levan. Overall results conclude that dietary microbial levan incorporation at 12.5 g kg?1 could be used as potent dietary prebiotic for the culture of L. rohita juveniles.  相似文献   

5.
The study was to evaluate the effects of dietary fish meal (FM) partially replaced by housefly maggot meal (HMM) on growth, fillet composition and physiological responses of juvenile barramundi, Lates calcarifera. HMM at 100, 150, 200 and 300 g kg?1 was supplemented in the basal diet to replace dietary FM protein. Basal diet without HMM supplementation was used as control. Total of five experimental diets were fed to triplicate groups of juvenile barramundi (initial weight: 9.66 ± 0.22 g) in a flow‐through rearing system for 8 weeks. Fish fed all experimental diets showed no effects (P > 0.05) on weight gain and whole body protein, lipid and moisture content. Fish fed control diet and 100 g kg?1 HMM diet had the highest (P < 0.05) hepatic superoxide dismutase (SOD) activity, followed by 150 g kg?1 HMM group, the lowest in 200 and 200 g kg?1 HMM groups. Hepatic thiobarbituric acid reactive substance (TBARS) value was the highest in fish fed 150–300 g kg?1 HMM diets, followed by 100 g kg?1 HMM group and the lowest in fish fed the control diet. Fish fed the 300 g kg?1 HMM diet had lower plasma lysozyme activity than fish fed other diets. The results indicated that up to 300 g kg?1 HMM can be used to substitute dietary FM protein without negative effect on growth. Although physiological responses were also considered, up to 100 g kg?1 HMM in barramundi diet was recommended.  相似文献   

6.
A 10‐week feeding trial with four dietary protein levels (400, 450, 500 and 550 g kg?1 crude protein) and two dietary lipid levels (80 and 160 g kg?1 crude lipid) was conducted to assess optimum dietary protein and lipid levels for the growth, feed utilization and body composition of juvenile Manchurian trout (initial weight 11.80 ± 0.15 g). Fish were fed twice daily (08:30 and 16:30 h) to apparent satiation. The results showed that fish fed the diet with 500 g kg?1 protein and 80 g kg?1 lipid had the highest growth and feed efficiency. However, fish fed the diet with 450 g kg?1 protein and 160 g kg?1 lipid showed comparable growth to that of the fish fed diet 5 (500/80) and had higher protein efficiency ratio (PER), nitrogen retention (NR) and energy retention (ER) than other groups (P < 0.05). Growth, PER, NR and ER of fish fed the 160 g kg?1 lipid diet was significantly higher (P < 0.05) than that of fish fed the 80 g kg?1 lipid diet at 400 and 450 g kg?1 protein diet, whereas these values showed an opposite trend at 500 and 550 g kg?1 protein diet, and the lowest PER, NR and ER was found by fish fed the 400 g kg?1 protein diet with 80 g kg?1 lipid. Fish fed diets with 400 g kg?1 protein had lower feed intake (FI) than that of other groups. Feed intake of fish fed 80 g kg?1 lipid level was significantly lower than that of fish fed 160 g kg?1 lipid diet at 400 g kg?1 protein (P < 0.05), while no significant differences were observed at 450, 500 and 550 g kg?1 protein‐based diets. Contrary to moisture content, lipid content of whole body and muscle increased significantly (P < 0.05) with increasing lipid levels. The results of this study indicated that the diet containing 450 g kg?1 protein and 160 g kg?1 lipid, with a P/E ratio of 23.68 g protein MJ?1 would be suitable for better growth and feed utilization of juvenile Manchurian trout under the experimental conditions and design level used in this study.  相似文献   

7.
A feeding trial was conducted to evaluate the effect of replacing fish meal protein with fermented soybean meal (FSM) on the growth performance, feed utilization, amino acid profile, body composition, morphological parameters, activity of antioxidant and digestive enzymes of black sea bream (Acanthopagrus schlegeli) juvenile. Five isonitrogenic and isolipidic diets were prepared with levels of 0 (control), 80, 160, 240 and 320 g kg?1 FSM. Triplicate groups (40 fish per tank) of juvenile black sea bream with initial weight of 1.17 ± 0.04 g were hand‐fed to visual satiation at three meals per day for 8 weeks. The fish fed diets containing different levels of FSM had no significant differences regarding survival and specific growth rate compared with control group. Feed and protein efficiency ratios of fish fed diet containing 320 g kg?1 FSM were significantly lower than those of control group. Daily feed intake and daily protein intake of fish fed diet containing 240–320 g kg?1 were significantly higher than those of control group. Hepatosomatic index and condition factor of fish were not affected by different dietary FSM level. Fish fed diets containing 240–320 g kg?1 FSM had significantly higher visceral somatic index than control group. Whole body proximate and amino acid compositions of fish were not affected by dietary FSM level. The activity of digestive enzymes in the intestine was not affected by dietary FSM level. The activity of glutathione peroxidase in liver was significantly higher for fish fed the diet containing 160 g kg?1 FSM compared with control group. This study showed that up to 40% fish meal in the diets of juvenile black sea bream could be replaced by fermented soybean meal with supplementation of methionine, lysine and taurine.  相似文献   

8.
A 63‐day growth trial was undertaken to estimate the effects of supplemented lysine and methionine with different dietary protein levels on growth performance and feed utilization in Grass Carp (Ctenopharyngodon idella). Six plant‐based practical diets were prepared, and 32CP, 30CP and 28CP diets were formulated to contain 320 g kg?1, 300 g kg?1 and 280 g kg?1 crude protein without lysine and methionine supplementation. In the supplementary group, lysine and methionine were added to formulate 32AA, 30AA and 28AA diets with 320 g kg?1, 300 g kg?1 and 280 g kg?1 dietary crude protein, respectively, according to the whole body amino acid composition of Grass Carp. In the groups without lysine and methionine supplementation, weight gain (WG, %) and specific growth rate (SGR, % day?1) of the fish fed 32CP diet were significantly higher than that of fish fed 30CP and 28CP diets, but no significant differences were found between 30CP‐ and 28CP‐diet treatments. WG and SGR of the fish fed 32AA and 30AA diets were significantly higher than that of fish fed 28AA diets, and the performance of grass carp was also significantly improved when fed diets with lysine and methionine supplementation (P < 0.05), and the interaction between dietary protein level and amino acid supplementation was noted between WG and SGR (P < 0.05). Feed intake (FI) was significantly increased with the increase in dietary protein level and the supplementation of lysine and methionine (P < 0.05), but feed conversion ratio (FCR) showed a significant decreasing trend (P < 0.05). Two days after total ammonia nitrogen (TAN) concentration test, the values of TAN discharged by the fish 8 h after feeding were 207.1, 187.5, 170.6, 157.3, 141.3 and 128.9 mg kg?1 body weight for fish fed 32CP, 32AA, 30CP, 30AA, 28CP and 28AA diets, respectively. TAN excretion by grass carp was reduced in plant‐based practical diets with the increase in dietary protein level and the supplementation of lysine and methionine (P < 0.05). The results indicated that lysine and methionine supplementation to the plant protein sources‐based practical diets can improve growth performance and feed utilization of grass carp, and the dietary crude protein can be reduced from 320 g kg?1 to 300 g kg?1 through balancing amino acids profile. The positive effect was not observed at 280 g kg?1 crude protein level.  相似文献   

9.
A feeding trial was conducted in a recycling water system during 10 weeks to determine the optimal protein to lipid ratio in Asian red‐tailed catfish (Hemibagrus wyckioides). Six diets of two protein levels (390 and 440 g kg?1) with three lipid levels (60, 90 and 120 g kg?1) were formulated. Fish (1.96 g) were fed six diets with four replicates to apparent satiation at a stocking density of 50 fish per tank (500 L). Faeces were collected in cultured tanks at the end of the feeding trial for digestibility measurement. Significantly, improved growth performances (P < 0.01) and higher feed utilization (P < 0.001) were observed in fish fed with higher lipid diets. However, higher protein diets did not significantly improve fish growth but they reduced FCR (P < 0.001) and protein efficiency ratio (P < 0.01). Higher lipid diets also resulted in significantly increased adipose‐somatic index, carcass fat and reduced moisture of the fish. The study revealed the protein sparing effect of dietary lipid in the catfish and highest growth performance was found by fish fed 390 g kg?1 protein and 120 g kg?1 lipid diet with P/E ratio of 20.48 mg protein kJ?1. DP/DE ratio for maximal growth rate in diets was 21.48 mg protein kJ?1.  相似文献   

10.
Two experiments were conducted to quantify the dietary thiamin (experiment I) and pyridoxine (experiment II) requirements of fingerling Cirrhinus mrigala for 16 weeks. In experiment I, dietary thiamin requirement was determined by feeding seven casein–gelatin‐based diets (400 g kg?1 CP; 18.69 kJ g?1 GE) with graded levels of thiamin (0, 0.5, 1, 2, 4, 8 and 16 mg kg?1 diet) to triplicate groups of fish (6.15 ± 0.37 cm; 1.89 ± 0.12 g). Fish fed diet with 2 mg kg?1 thiamin had highest specific growth rate (SGR), protein retention (PR), RNA/DNA ratio, haemoglobin (Hb), haematocrit (Hct), RBCs and best feed conversion ratio (FCR). However, highest liver thiamin concentration was recorded in fish fed 4 mg thiamin kg?1 diet. Broken‐line analysis of SGR, PR and liver thiamin concentrations exhibited the thiamin requirement in the range of 1.79–3.34 mg kg?1 diet (0.096–0.179 μg thiamin kJ?1 gross energy). In experiment II, six casein–gelatin‐based diets (400 g kg?1 CP; 18.69 kJ g?1 GE) containing graded levels of pyridoxine (0, 2, 4, 6, 8 and 10 mg kg?1 diet) were fed to triplicate groups of fish (6.35 ± 0.37 cm; 1.97 ± 0.12 g). Fish fed diet containing 6 mg kg?1 pyridoxine showed best SGR, FCR, PR, RNA/DNA ratio, Hb, Hct and RBCs, whereas maximum liver pyridoxine concentration was recorded in fish fed 8 mg kg?1 dietary pyridoxine. Broken‐line analysis of SGR, PR and liver pyridoxine concentrations reflected the pyridoxine requirement from 5.63 to 8.61 mg kg?1 diet. Data generated during this study would be useful in formulating thiamin‐ and pyridoxine‐balanced feeds for the intensive culture of this fish.  相似文献   

11.
This study investigated the effects of phenylalanine on growth, digestive and absorptive ability and antioxidant status of young grass carp (Ctenopharyngodon idella). Young grass carp were fed diets containing 3.4 (basal diet), 6.1, 9.1, 11.5, 14.0 and 16.8 g phenylalanine kg?1 diet with a fixed of 10.7 g tyrosine kg?1 diet for 8 weeks. Percent weight gain (PWG), feed efficiency and feed intake of fish were the lowest in fish fed the basal diet (P < 0.05). Trypsin, lipase and amylase activities in the hepatopancreas, and antioxidants including glutathione contents and glutathione reducase activities in the hepatopancreas and intestine were all the highest in fish fed 11.5 g phenylalanine kg?1 diet (P < 0.05). Trypsin, chymotrypsin and amylase activities in whole intestine, and creatine kinase, Na+, K+‐ATPase and alkaline phosphatase activities in the proximal intestine, and superoxide dismutase activities in the hepatopancreas and intestine were all the highest when phenylalanine at level of 9.1 g kg?1 diet (P < 0.05). In conclusion, phenylalanine improved growth, digestive and absorptive ability, and antioxidant capacity of young grass carp. The phenylalanine requirement of young grass carp (256–629 g) based on PWG was 10.4 g kg?1 diet or 3.44 g 100 g?1 protein.  相似文献   

12.
A 12‐week feeding trial was conducted to evaluate the effects of dietary vitamin C on growth performance, antioxidant status and innate immune responses in juvenile yellow catfish, Pelteobagrus fulvidraco. Six isonitrogenous and isolipidic diets (44% crude protein and 7% lipid) were formulated to contain six graded dietary vitamin C (ascorbate‐2‐poly‐ phosphate, ROVIMIX® STAY‐C® 35) levels ranging from 1.9 to 316.0 mg kg?1 diet. The results of present study indicated that fish fed the lowest vitamin C diet had lower weight gain (WG) and specific growth rate (SGR) than those fed the diets supplemented vitamin C. WG and SGR did significantly increase with dietary vitamin C levels increasing from 1.9 to 156.5 mg kg?1. However, no significant increase was observed with further dietary vitamin C levels increasing from 156.5 to 316 mg kg?1. Survival, protein efficiency ratio and feed efficiency were not significantly affected by the dietary vitamin C levels. The activities of serum superoxide dismutase, catalase and glutathione peroxidase significantly increased when dietary vitamin C levels increased from 1.9 to 156.5 mg kg?1, fish fed the lowest vitamin C diet had higher serum malondialdehyde content than those fed the diets supplemented with vitamin C. Fish fed the diet containing 156.5 mg kg?1 vitamin C had the highest lysozyme, total complement activity, phagocytosis index and respiratory burst of head kidney among all treatments. The challenge test with Aeromonas hydrophila indicated that lower cumulative survival was observed in fish fed the lowest vitamin C diet. Analysis by broken‐line regression of SGR and lysozyme activity indicated that the dietary vitamin C requirement of juvenile yellow catfish was estimated to be 114.5 and 102.5 mg kg?1 diet, respectively.  相似文献   

13.
A feeding trial was conducted to study the effect of dietary lipid on growth performance and heat‐shock protein (HSP70 and HSP60) response of white seabass (WSB), Atractoscion nobilis. Five diets were formulated to contain 440 g kg?1 protein from 300 g kg?1 fish meal, 240 g kg?1 soybean meal and 100 g kg?1 soy protein concentrate with different levels of lipid: 100, 120, 140, 160 or 180 g kg?1. At the end of the trial, heat shock response based on HSP70 and HSP60 was measured in liver and white muscle from fish at ambient temperature and temperature shock conditions. Final weight and percent gain were significantly higher for fish fed the 100 g kg?1 lipid diet than for fish fed the rest of the diets (P ≤ 0.05). Feed conversion ratio was lowest for fish fed the 100 g kg?1 lipid diet. The HSP70 and HSP60 responses were positively correlated to dietary lipid levels following temperature shock. At ambient temperature, HSP60 and HSP70 responses in muscle and HSP60 response in liver increased with dietary lipid level. Temperature shock significantly increased the HSP response of fish in all treatments. Results of this study demonstrated that a moderate (110–120 g kg?1) level of dietary lipids would be recommended for production diets but a higher dietary lipid level may be required for optimal stress tolerance.  相似文献   

14.
An 8‐week feeding trial was conducted to determine the effect of dietary l ‐methionine supplementation on growth performance, serum immune and antioxidative responses of juvenile Nile tilapia Oreochromis niloticus. Six iso‐nitrogenous (282 g kg?1 crude protein) diets were formulated to contain graded levels of methionine (0.32%, 0.54%, 0.75%, 0.93%, 1.14% and 1.33% of dry weight) at a constant dietary cysteine level of 0.83 g kg?1. Each diet was randomly assigned to triplicate groups of 25 juvenile fish (2.3 ± 0.0 g), which were fed three times daily (8:30, 12:30 and 17:00 hours). The results showed that growth performance and feed utilization significantly improved when dietary methionine levels increased (P < 0.05). Using quadratic regression analysis of weight gain against dietary methionine levels indicated that, the optimal dietary methionine requirement for maximum growth of juvenile tilapia was 9.12 g kg?1 of the dry diet in the presence of 0.83 g kg?1 cystine. In addition, maximum C4 content and lysozyme activity were observed in fish fed 7.50 g kg?1 methionine diet; maximum C3 content and superoxide dismutase activity were obtained in fish fed 9.30 g kg?1 dietary methionine level. While there was no significant difference in serum glutathione peroxidase activity among all methionine supplemented treatments (P > 0.05). Methionine supplementation decreased malondialdehyde content in serum significantly (P < 0.05) when compared with the control diet, while there was no significant difference among supplemented treatments. These data suggested that l ‐methionine affected antioxidant status and promoted serum immune response in juvenile Nile tilapia, and at non‐stressed status, the requirement of dietary methionine in maintaining normal immunity and physiology is lower than that for maximum growth.  相似文献   

15.
An 8‐week feeding trial was conducted to investigate the effects of dietary cholesterol levels on growth, feed utilization, body composition and immune parameters in juvenile oriental river prawn, Macrobrachium nipponense. Six isolipid (80 g kg?1 crude lipid) and isoproteic (400 g kg?1 crude protein) diets, supplemented with 0, 3.0, 6.0, 9.0, 12.0 and 15.0 g kg?1 cholesterol, were evaluated. Growth performance and feed utilization of M. nipponense were improved as dietary cholesterol levels increased. Weight gain and specific growth rate were highest, and feed conversation ratio was lowest, when prawns were fed a diet supplemented with 9.0 g kg?1 cholesterol. However, final body weights and survival rates of juvenile M. nipponense were not affected significantly by dietary cholesterol. Body composition of prawns, including moisture, crude protein and crude lipid, was not significantly affected by changes in dietary cholesterol. The immune parameters measured in hepatopancreas, including total antioxidant capacity, and glutathione, catalase, alkaline phosphatase and acid phosphatase activities, were at optimum levels in prawns fed with 9.0 g kg?1 dietary cholesterol. In summary, the best growth performance, lowest feed conversation ratio, and the most enhanced antioxidant capacity and immunity parameters were attained in juvenile M. nipponense when fed a diet supplemented with 9.0 g kg?1 cholesterol.  相似文献   

16.
A 14 weeks growth trial was performed to estimate the protein requirement for growth and maintenance of zebra sea bream (Diplodus cervinus) juveniles. For that purpose, nine isolipidic diets were formulated to contain increasing protein levels (from 50 to 550 g kg?1) at the expense of carbohydrate. Each diet was assigned to duplicate groups of 20 fish, with an average body weight of 7.7 g. Feed efficiency improved with dietary protein up to 400 g kg?1, no further differences being noticed at higher protein levels. Fish fed the 50 g kg?1 protein diet lost weight during the trial. In the other groups, weight gain improved as dietary protein increased up to 350–400 g kg?1. Fish fed diets with 250 g kg?1 protein or lower had lower whole‐body protein content than the other groups. A curvilinear‐plateau model was used to adjust weight gain and protein gain (g kg ABW?1 day?1) to dietary protein levels. Based on that model, the optimum dietary protein requirement for maximum weight gain was estimated to be 437.6 g kg?1 and for maximum protein gain 461.9 g kg?1, corresponding to a protein intake of 7.63 g kg ABW?1 day?1. Protein requirement for maintenance was estimated to be 1.01 g kg ABW?1 day?1.  相似文献   

17.
The aim of this study was to examine the effects of the immunostimulant combination (IC) containing β‐glucan, A3α‐peptidoglycan, vitamin C and vitamin E on the growth performance, non‐specific immunity and protection against Vibrio harveyi infection in cobia (Rachycentron canadum). Fish were fed diets containing six graded levels of IC (0, 1, 2, 3, 4 and 5 g kg?1 diet) for 8 weeks. The results showed that the survival rate ranged from 81.1 to 84.4% with no significant difference among all the groups (P > 0.05) after the feeding experiment. Dietary IC significantly increased the specific growth rate (SGR), serum lysozyme, alternative complement pathway (ACH50) activity, phagocytosis percentage (PP) and respiratory burst activity of head kidney macrophages of cobia. Moreover, feeding of supplemented diets containing 3.0 g kg?1 IC resulted in significantly lower mortality against the pathogens, V. harveyi compared with the control group. To elevate the growth and immune resistance ability of cobia, the optimal dose of dietary IC administration, determined by second‐order polynomial regression analysis was 3.43 and 2.71 g kg?1 diet, respectively, on the basis of the SGR and mortality after challenge with V. harveyi.  相似文献   

18.
A growth trial was conducted to examine the effect of dietary digestible energy (DE) content on methionine (Met) utilization and requirement in juvenile Nile tilapia (Oreochromis niloticus). Ten iso‐nitrogenous (288 g kg?1 protein) practical diets, with two DE levels (10.9 MJ kg?1; 12.4 MJ kg?1) and five methionine supplementation levels (0, 1, 2, 4 and 6 g kg?1), were hand‐fed twice daily to triplicate groups of Nile tilapia (initial body weight 8.95 ± 0.06 g) for 8 weeks. Weight gain (WG) and specific growth rate (SGR) increased significantly with increasing dietary methionine concentration at the same DE content (P < 0.001). At the same dietary methionine level, WG and SGR of fish fed high‐DE diets were significantly higher than that of fish fed low‐DE diets (P = 0.0001), although no interaction was found between dietary DE and methionine supplementation. Based on quadratic regression analysis between dietary methionine concentration and weight gain, optimal methionine requirement for maximum growth, expressed as g Met required kg?1 diet (low‐ versus high‐DE diets), increased as diet DE concentration increased (7.34 versus 9.90 g kg?1 diet, respectively; with cysteine 4.70 g kg?1 diet). The results indicated that diet DE content affects methionine utilization and requirement in juvenile Nile tilapia, fish fed high‐DE diets required more methionine for maximum growth.  相似文献   

19.
The aim of this experiment was to determine the effects of dietary inclusion with mannan oligosaccharide (Bio‐Mos, Alltech, Nicholasville, KY, USA) on growth, survival, physiological and immunological conditions and gut morphology of the black tiger prawn (Penaeus monodon). Five diets supplemented with MOS at 0 g kg?1 (control diet), 1, 2, 4 and 8 g kg?1 were fed to the prawn juveniles (0.4 ± 0.06 g, total weight) for the duration of 63 days. Growth was the highest (P < 0.05) when the prawns were fed the 1 g kg?1 MOS included diet. Wet tail muscle index (Tw/B), dry tail muscle index (Td/B) and tail muscle protein (Tmp) were higher (P < 0.05) in the prawns fed MOS included diets MOS compared with the prawns fed the control diet. Total haemocyte counts (THCs) of the prawns fed MOS included diets were higher (P < 0.05) than THCs of the prawns fed the control diet. Epithelium layer and epidermal cell density of the gut of the prawns fed 1 g kg?1 and 2 g kg?1 MOS diets were better than the prawns fed the control and other MOS diets. The results imply a positive effect of dietary supplementation of 1–2 g kg?1 MOS in the culture of black tiger prawns.  相似文献   

20.
A feeding experiment was conducted to determine the dietary zinc (Zn) requirement of hybrid tilapia fed on a diet with soya bean meal as the sole protein source. The quantity of phytic acid in the experimental diet was 15.5 g kg?1. Juvenile hybrid tilapia were fed on diets containing 31–227 mg Zn kg?1 in triplicates for 6 weeks. Haematology of the fish was not affected by various dietary Zn levels. Fish fed on a diet containing 31 mg kg?1 endogenous Zn showed the lowest growth rates, feed utilization, and body and plasma Zn levels. Weight gain (WG), plasma Zn level and superoxide dismutase (SOD) activity increased when a higher quantity of dietary Zn of 127 mg kg?1 was administered to the experimental fish. Beyond this level, the values of these parameters were relatively stable. On the other hand, within the dietary Zn range tested, whole‐body Zn and ash increased with higher dietary Zn levels. Analysis using a broken‐line model showed that the dietary Zn requirements of hybrid tilapia fed on soya bean meal‐based diets containing 15.5 g kg?1 endogenous phytic acid were 115, 115 and 105 mg kg?1 based on WG, whole‐body Zn retention and plasma Zn level, respectively.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号