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 500 毫秒
1.
A feeding trial was conducted for 60 days to study the effects of exogenous microbial phytase supplementation on the growth and nutrient digestibility of Pangasius pangasius fingerlings. Eight isocaloric and isoprotein experimental diets (35.67% crude protein and 3870 kcal kg?1) were prepared with graded levels of phytase, e.g., 0 (T1), 150 (T2), 250 (T3), 350 (T4), 500 (T5), 1000 (T6) and 2000 (T7) FTU (phytase units) kg?1. Three hundred and fifteen fingerlings of P. pangasius (1.97–2.05 g) were randomly distributed in seven treatments with three replicates each. Maximum weight gain (350.72%), specific growth rate (2.51%), protein efficiency ratio (2.1), apparent net protein utilization (27.85%), energy retention value (88.47%) and feed conversion efficiency were observed in T5 group supplemented with 500 FTU phytase kg?1 diet. Apparent dry matter and protein digestibility in phytase‐supplemented groups were significantly (P<0.01) higher at a minimum supplement of 500 FTU kg?1 or higher. Liver alkaline phosphatase activity increased significantly in treatment groups. Supplementation at 500 FTU kg?1 of phytase is optimum in the diet of P. pangasius fingerlings.  相似文献   

2.
African catfish Clarias gariepinus (Burchell) fingerlings (3.16–3.92 g initial body weight) were investigated for 30 days in four different groups using different amounts of l ‐ascorbic acid (AA) and iron (supplied as FeC6H5O7) in their feedings. Diet 1 (control): no addition of AA or iron; diet 2 (H‐AA/FE): high (600 mg kg?1) AA and low (218 mg kg?1) iron; diet 3 (H‐HE/AA): high (364 mg kg?1) iron and low (200 mg kg?1) AA; and an unfed group, which was investigated only for 15 days due to high mortality. The live weight gain, feed intake, specific growth rate (SGR; % body weight day?1) and feed conversion rate (FCR) were measured or calculated. At the end of the experimental period, the whole body content of AA, iron, reduced glutathione (GSH), glutathione disulphide (GSSG) and malondialdehyde (MDA), as well as the glutathione peroxidase (GSHPx) activity, were measured. The production traits did not differ significantly as a result of the different AA and iron contents of the feed. AA content increased significantly in all the groups as compared with the initial value, except in the unfed group. The difference between the treated groups as compared with the control, with regard to the two AA/iron treated groups, was also significant. The iron content in the fish body increased significantly compared with the initial value, except in the unfed group. The difference compared with the control was significant only in the H‐FE/AA group. The difference between the groups that consumed low and high iron content diets was also significant. The GSH and GSSG content, as well as the GSH/GSSG ratio and GSHPx activity of the fish body, did not differ significantly as compared with the initial value or with the control. The lipid peroxide status, as measured by the MDA content, did not differ significantly either as an effect of the AA and iron supplementation, but decreased as an effect of ageing and starvation. It may be concluded that, under the present experimental conditions, the C. gariepinus fingerling tissue stores of AA and/or iron increased as a result of feed supplementation, but without altering the actual lipid peroxide status and the amount/activity of the glutathione redox system.  相似文献   

3.
A 60‐day feeding trial was conducted to quantify the effects of microbial phytase supplementation on apparent absorption, whole body and bone contents of minerals in Pangasius pangasius fingerlings. Seven isoprotein (35.67%) and isocaloric (3870 kcal kg?1) diets were prepared with graded levels of supplemental phytase at 0 (T1), 150 (T2), 250 (T3), 350 (T4), 500 (T5), 1000 (T6) and 2000 (T7) FTU (Phytase Units) kg?1. Three hundred and fifteen fingerlings of P. pangasius (1.97–2.05 g) were randomly distributed in seven treatments with three replicates each. There was significant increase (P<0.05) in tissue protein content in phytase‐supplemented groups compared with the control. Apparent absorptions of calcium (Ca), phosphorus (P), magnesium (Mg), manganese (Mn), zinc (Zn), iron (Fe), potassium (K), copper (Cu) and cobalt (Co) were significantly (P<0.05) higher in the phytase‐supplemented groups than the control group. Faecal ash and P contents were significantly (P<0.05) higher in the control (T1) than the phytase‐supplemented groups. Whole‐body contents of Ca, P, Zn, Fe, Cu and Co were significantly (P<0.05) improved by the dietary supplementation of phytase‐barring Mg and Mn. Concentrations of bone Ca, P, K, Cu and Co were significantly (P<0.05) higher in phytase‐supplemented groups. Bone ash contents (40.77–44.85%) were increased concomitantly with the increased level of phytase inclusion upto 500 FTU kg?1 diet. It was observed that a minimum dose of 250 FTU phytase kg?1 diet improved the mineral absorption and utilization in P. pangasius fingerlings.  相似文献   

4.
An experiment was conducted to investigate the effects of Lactobacillus plantarum on the production of African catfish (Clarias gariepinus). Five experimental diets containing 0, 103, 105, 107, and 109 CFU of Lactobacillus plantarum g?1 diet (T1–T5 treatments respectively) were fed to African catfish (Clarias gariepinus) (9.20 ± 0.1 g initial body mass), for 70 days. Results indicated significantly lower growth performance in the fish fed diet without probiotics and in those fed diet with the least probiotic level. Treatments with probiotics significantly improved the blood profile and carcass protein but significantly reduced the carcass fat (P < 0.05); these treatments also marginally improved the carcass minerals in comparison with the treatment without probiotic (P < 0.05). Challenging the fish fed the experimental diets with Salmonella typhi showed higher immunity of fish fed the probiotic diets than those fed the nonprobiotic diet. Duncan’s multiple range test showed that the best fish performance was observed with 103 CFU g?1 L. plantarum for very parameter measured. However, regression analyses showed the optimum level of the bacteria to be 104.13–105 CFU g?1  相似文献   

5.
The purpose of this study was to verify the effect of dietary Ca2+ on the growth and survival of silver catfish fingerlings (Rhamdia quelen) exposed to different water pH (5.5, 7.5 and 9.0). Silver catfish fingerlings were randomly placed in a thermoregulated water re‐use system with twelve 250 L‐tanks, two 1000 L‐biofilters and a 2000 L‐reservoir with a medium flow of 3.84 L min?1 tank. Stocking density was 0.16 fingerlings L?1. To prepare the treatment diets, the control diet (0.8 g kg?1 Ca2+) was supplemented with CaCO3 to yield experimental diets with 6.4, 9.5 and 23.9 g kg?1 Ca2+. There were three replicates/treatments. Survival was more than 93.9% in all treatments. Exposure of silver catfish fingerlings to alkaline or acid water reduced growth, and this effect was not ameliorated by dietary Ca2+ supplementation. Moreover, when fingerlings were maintained in water with pH 7.5, the best dietary Ca2+ range for silver catfish fingerling growth was 0.8–6.4 g kg?1.  相似文献   

6.
A feeding trial was conducted for 60 days to delineate the effect of both gelatinized and non‐gelatinized corn with or without supplementation of exogenous α‐amylase at two level of protein 35% (optimum) and 27% (sub‐optimum) on growth, tissue composition and protein sparing effect of carbohydrate in the diet of Labeo rohita fingerlings. Three hundred and sixty fingerlings (average weight 10.00±0.15 g) were randomly distributed in 12 treatment groups with two replicates for each. Twelve semi‐purified diets containing either 35% or 27% CP were prepared with different levels of α‐amylase (0, 50, 100 and 150 mg kg?1) and starch type [gelatinized (G)/non‐gelatinized, (NG)] viz. T1 (NG, 35% CP, 0 mg kg?1α‐amylase), T2 (G, 35% CP, 0 mg kg?1α‐amylase), T3 (NG, 27% CP, 50 mg kg?1α‐amylase), T4 (NG, 35% CP, 50 mg kg?1α‐amylase), T5 (G, 27% CP, 50 mg kg?1α‐amylase), T6 (G, 35% CP, 50 mg kg?1α‐amylase), T7 (NG, 27% CP, 100 mg kg?1α‐amylase), T8 (NG, 35% CP, 100 mg kg?1α‐amylase), T9 (G, 27% CP, 100 mg kg?1α‐amylase), T10 (G, 35% CP, 100 mg kg?1α‐amylase), T11 (NG, 27% CP, 150 mg kg?1α‐amylase) and T12 (NG, 35% CP, 150 mg kg?1α‐amylase). The fish were acclimatized to the experimental condition for 24 days during which control diet (NG, 35% CP) was fed. Weight gain percentage, specific growth rate, protein efficiency ratio and apparent net protein utilization of NG corn‐fed groups at 42.43% were significantly higher (P<0.05) than the same level of G corn‐fed groups. We conclude that 42.43% NG corn supplemented with 50 mg α‐amylase kg?1 feed at sub‐optimum level of CP (27%) significantly enhanced the growth and protein in L. rohita fingerling. Addition of dietary α‐amylase to G corn had no added advantage on growth of L. rohita fingerling.  相似文献   

7.
Six oxidized fish oil contained diets were formulated to investigate the effect of graded levels of vitamin E (VE) (α-tocopherol acetate: 160, 280, and 400 mg kg?1) associated with either 1.2 or 1.8 mg kg?1 selenium (Se) on growth, body composition, and antioxidant defense mechanism of juvenile largemouth bass. Another control diet containing fresh fish oil with 160 mg kg?1 VE and 1.2 mg kg?1 Se was also prepared. Over a 12-week feeding trial, about 5 % of Micropterus salmoide fed diet OxSe1.2/VE160 showed inflammation and hemorrhage symptoms at the base of dorsal, pectoral, and tail fin. Fish in all treatments survived well (above 90 %). Feed intakes (88.42?89.58 g fish?1) of all treatments were comparable. Growth performances (weight gain and specific growth rate) and feed utilization (feed and protein efficiency ratio) were significantly impaired by dietary oil oxidation, and they did not benefit from neither VE nor Se supplementation. Regardless of dietary VE and Se supplementation, oxidized oil ingestion resulted in markedly decreased hepatosomatic index and intraperitoneal fat ratio. Oxidized oil ingestion also induced markedly lower liver and muscle lipid contents, and these effects could be alleviated by dietary Se supplementation. Dietary oil oxidation stimulated hepatic catalase activities relative to the control, and supplementation of VE abrogated this effect. Hepatic reduced glutathione content in the control was markedly higher than that of treatment OxSe1.2/VE160, without any significant differences comparing with the other oxidized oil receiving groups. Hepatic glutathione peroxidase activity and liver Se concentration reflected dietary Se profile, whereas liver VE level reflected dietary VE profile. Compared with the control, fish fed diet OxSe1.2/VE160 obtained markedly higher serum, liver and muscle malondialdehyde contents, which droppe significantly with increasing either VE or Se supplementation. In conclusion, the overall results in this study suggested that both VE and Se inclusion could protect largemouth bass from the oxidative damage challenged by dietary oil oxidation.  相似文献   

8.
Six iso‐nitrogenous (350 g protein kg?1) and iso‐caloric (4100 kcal kg?1) diets with or without probiotics supplementation namely T1 (Basal feed (BF) without probiotics; control), T2 (BF + Bacillus subtilis and Lactococcus lactis), T3 (BF + L. lactis and Saccharomyces cerevisiae), T4 (BF + B. subtilis and S. cerevisiae), T5 (BF + B. subtilis, L. lactis and S. cerevisiae) and T6 (BF + heat‐killed bacteria of B. subtilis, L. lactis and S. cerevisiae) were fed to Labeo rohita fingerlings (6.0 ± 0.06 g) for 60 days in triplicate tanks (30 fish per tank). In all probiotic‐supplemented diets, the probiotic concentration was maintained at 1011 cfu kg?1 feed. After 60 days of culture, the fish fed combination of three probiotics at equal proportion (T5) had higher (P < 0.05) growth, protein efficiency ratio, nutrient retention and digestibility and lower (P > 0.05) feed conversion ratio over other treatment groups. Total heterotrophic bacterial population in intestine was drastically reduced on 15th and 30th days of sampling than the initial value (0 day of sampling) for T3, T4 and T5 groups. Except T6, the gut colonization of respective probiotics, which were supplemented through the diets, was also increased up to 30 days of culture of fish and thereafter remained constant.  相似文献   

9.
A combination of probiotics and prebiotics as synbiotics allows assessing their synergistic effects. This study evaluated the effects of a synbiotic supplement on growth performance, haematological parameters and resistance to Saprolegnia parasitica in rainbow trout, Oncorhynchus mykiss (Walbaum) fingerlings. Fish fed a dietary synbiotic in three levels of 0.5, 1.0 and 1.5 g kg?1 thrice a day. The fingerlings were challenged with Saprolegnia parasitica after 60 days post feeding and their mortalities recorded up to 15 days. The fingerlings at all three experimental treatments showed significant (P < 0.05) increases in final mean weights and specific growth rates (SGR). The best feed conversion ratio (FCR), feed conversion efficiency (FCE) and maximum survival rate were also obtained by the fish fed 1.0 g synbiotic kg?1 diet. Furthermore, supplementation with synbiotic significantly increased blood factors at all treatments. After challenges with Saprolegnia parasitica, the synbiotic‐fed groups showed significantly higher survival rates compared with the control group. These results reveal that a dietary synbiotic of 1.0 g kg?1 fed for 60 days leads to increased growth performance and survival rate as well as improved feeding efficiency in rainbow trout fingerling, rendering them more resistant against infection by Saprolegnia parasitica.  相似文献   

10.
The fingerling‐rearing experiment of the threatened catfish, Mystus cavasius was carried out at different stocking densities in earthen nursery ponds. Twelve‐day‐old fry were stocked at 200 000 ha?1 in treatment‐1 (T1), 250 000 ha?1 in treatment‐2 (T2) and 300 000 ha?1 in treatment‐3 (T3) respectively. The mean length and weight of fry at stocking was 1.24 ± 0.25 cm and 0.11 ± 0.04 g respectively. Fry in all the experimental ponds were supplemented with SABINCO nursery feed for the first 14 days and starter‐I feed for days 15–56. The physico‐chemical parameters and plankton population of pond water were within the suitable level for fish culture. Growth in terms of final weight, final length, weight gain, length gain and specific growth rate and survival of fingerlings were significantly higher in T1 than those in T2 and T3. Feed conversion rate was significantly lower in T1 followed by T2 and T3 in that order. Significantly higher number of fingerlings was produced in T3 than that in T2 and T1. Even then, consistently higher net benefits were obtained from T1 than those from T3 and T2. Among the treatments evaluated, 200 000 fry ha?1 was the best stocking density considering the highest growth, production and net benefits of fingerlings of M. cavasius in nursery ponds.  相似文献   

11.
This study was conducted to investigate the effects of dietary chitosan on growth performance, hematological parameters, intestinal histology, stress resistance and body composition in the Caspian kutum (Rutilus frisii kutum, Kamenskii, 1901) fingerlings. Fish (1.7 ± 0.15 g) were fed diets containing chitosan at different levels (0, 0.25, 0.5, 1 and 2 g kg?1 diet) for a period of 60 days. Results showed that the feed conversion ratio significantly decreased in fish fed diet containing 1 g kg?1 of chitosan compared to the other groups (P < 0.05), but there were no significant differences between treatments in terms of specific growth rate and condition factor (P > 0.05). Leukocyte increased in fish fed diet containing 2 g kg?1 of chitosan compared to the other groups (P < 0.05). Lymphocytes, eosinophils and neutrophils did not significantly change among dietary treatments (P > 0.05). Also, the chitosan supplementation did not affect the whole-fish body composition (P > 0.05). Light microscopy demonstrated that the intestinal villus length increased in fish fed diet containing 1 g kg?1 of chitosan compared to control group (P < 0.05). While 11 and 13 ‰ salinity and 30 °C thermal stress had no effect, 1 g kg?1 of chitosan (P < 0.05) showed highest survival rate (70 %) in 34 °C thermal stress. The results showed that chitosan in the diet of the Caspian kutum fingerlings could improve feed conversion ratio, the nonspecific defense mechanisms and resistance to some of the environmental stresses.  相似文献   

12.
A 10-week feeding experiment was performed in hybrid catfish (Clarias macrocephalus (Gunther) × C. gariepinus (Burchell, 1822) with initial average weight of 1.17 g, in glass aquaria of 200-L capacity. The experiment comprised seven treatments with three replicates each. Ascorbyl phosphate calcium (APCa) was included at 30, 75, 150, 300 and 1000 mg kg−1 feed and compared with one with ascorbyl polyphosphate (APP) at 36 mg kg−1 feed and one without vitamin C supplementation. Fish fed APCa-supplemented feed showed better growth, feed conversion ratio, survival rate and protein utilization compared with those without such supplementation. Ascorbate concentrations in liver and head kidneys were correlated closely with dietary APCa levels. Vertebral collagen and hydroxyproline contents were significantly lower in the fish group without ascorbate supplementation. Red blood cell and white blood cell counts showed no correlation with vitamin C supplementation. Serum protein level was lowest in the group fed feed without vitamin C supplementation and this was lower than those fed feed with APCa and APP supplementation. The fish fed APCa- and APP-supplemented feed showed no difference in serum protein levels. External scorbutic symptoms and histopathological changes of gill tissue were noted in fish fed feed without APCa supplementation. The study indicates that 12.6 mg kg−1 of ascorbic acid molar equivalent supplied as APCa (30 mg kg−1) provided maximum growth and no gross signs as well as histological changes resulting from vitamin C deficiency.  相似文献   

13.
An 84‐day feeding trial was conducted to study the effect of different levels of dietary protein, 250 (P25), 300 (P30), 350 (P35), 400 (P40) and 450 g (P45) kg?1 dry matter (DM) on growth, feed intake, feed utilization and carcass composition of bagrid catfish Horabagrus brachysoma fingerlings. Triplicate groups of fingerlings with mean initial body weight of 2.2 g were fed the experimental diets twice daily, till satiation, in 150‐L tanks supplied with flow‐through freshwater. Daily dry matter intake by the fingerlings decreased significantly (P < 0.05) when fed P25 diet, containing 250 g protein kg?1. The highest body weight gain, specific growth rate (SGR) and protein efficiency ratio (PER), and the lowest feed conversion ratio (FCR) were observed in fish fed 350 g protein kg?1 diet. The fish fed with P45 diet had the lowest (P < 0.05) carcass lipid content. The polynomial regression analysis indicates that H. brachysoma fingerlings require 391 g dietary crude protein kg?1 diet.  相似文献   

14.
A study was designed to investigate the possible positive prebiotic effects of mannan oligosaccharides (MOS) on growth and reduction of anxiety behaviors in zebrafish (Danio rerio). The experimental diets were supplemented with 0, 2, 4, 6, or 8 g MOS kg?1 and were fed to juvenile fish (0.47 ± 0.017 g) in triplicates for six weeks. Significant differences were found in the final body weight, body weight intake, percent body weight intake, and specific growth rate among treatments. The regression analyses showed that the optimum MOS level was 4–4.1 g MOS kg?1 diet. Fish fed 4 g MOS kg?1 feed showed higher survival than the other treatments. Also, using the novel tank test, fish fed with 4 g MOS kg?1 diet showed lower anxiety by swimming in the upper portion of the tank. The other behavior parameters remained unaffected by the prebiotic. The results indicated the beneficial effect of the prebiotic MOS on growth and partly on welfare of zebrafish juveniles.  相似文献   

15.
The present study was conducted to evaluate the effect of dietary supplementation of probiotic bacterium Bacillus licheniformis on the gut microbiota, growth and immune response in Macrobrachium rosenbergii juveniles (4.0 ± 0.02 g). Five isocaloric experimental diets supplemented with different concentrations of B. licheniformis, viz. Control (without probiotic supplementation), T1 (1.0 × 106 cfu g?1feed), T2 (1.0 × 107 cfu g?1feed), T3 (1.0 × 108 cfu g?1 feed) and T4 (1.0 × 109 cfu g?1 feed) were used for the experiment. After 60 days of feeding trial, the growth performance increases significantly in all the experimental groups compared with control, and highest weight gain, specific growth rate and lowest feed conversion ratio were recorded from T4 (P > 0.05). However, juvenile survival was not found to be significantly affected by probiotic supplementation (P > 0.05). The total bacterial count and Bacillus spp. count in the gut were significantly increased with concurrent decrease in pathogenic Aeromonas spp. and Pseudomonas spp. in all the experimental groups compared with control (P < 0.05). Compared with control, immune parameters were increased significantly in all the experimental groups (P < 0.05). Highest haemocyte count, phenol oxidase, superoxide dismutase and antibacterial activity in haemolymph were recorded from T4 (P < 0.05). When prawns were challenged with Vibrio alginolyticus, the cumulative mortality was significantly lower in T4 (P < 0.05). These results indicate that dietary supplementation of B. licheniformis can manipulate the gut microbiota and increase the growth and immune response of M. rosenbergii. In the present study, concentration response on the probiotic effect of B. licheniformis was observed which showed higher effects at a concentration of 1.0 × 109 cfu g?1 feed in the laboratory condition.  相似文献   

16.
A feeding trial was conducted for 60 days to study the effect of dietary protein, microbial phytase and citric acid on intestinal digesta pH, bone ash and bone mineral contents in Labeo rohita juveniles. Eight experimental diets were prepared in 2 × 2 × 2 factorial arrangement with crude protein levels (25% and 35%), microbial phytase (0 and 500 U kg?1), and citric acid (0 and 3%). The 25% crude protein level feed was supplemented with phytase (U kg?1) and citric acid (%) at the level of 0,0 (C25); 500,0 (T1); 0,3 (T2); 500,3 (T3), and 35% crude protein level feed at 0.0 (C35); 500,0 (T4); 0,3 (T5) and 500,3(T6) respectively. One hundred and twenty juveniles of L. rohita (av. wt. 12.61–13.72 g) were distributed randomly in eight treatments, each of with three replicates. Addition of citric acid in the 25% crude protein feed significantly decreased (P<0.001) feed pH with concurrent decrease in intestinal digesta pH (P<0.001) and increased the bone ash content (P<0.05) by 4.6%. An interaction between citric acid and phytase (P<0.05) was also observed for bone ash content. Increasing the dietary protein content from 25% to 35% significantly decreased (P<0.01) bone Zn content by 14.9%, which was more prominent with the addition of citric acid, resulting in significant interaction between protein and citric acid (P<0.05), but the bone Cu content was significantly increased (P<0.01) with increasing dietary protein content. Dietary supplementation of microbial phytase (500 U kg?1) significantly increased (P<0.05) bone Na, Ca, K, P and Fe contents by 15%, 12.1%, 17.4%, 9.2% and 40.7%, respectively, whereas bone P and Mn content was significantly increased (P<0.05) by addition of citric acid (3%). Addition of phytase to plant‐based diets increased the bioavailability of minerals, thereby increasing bone mineralization. The effect of phytase was increased because of addition of citric acid (3%).  相似文献   

17.
Three approximately isoenergetic (17 kJ g?1) diets were formulated with dietary protein levels of 270, 360 and 480 g kg?1 (DM basis) providing protein-to-energy ratios of 15.69, 20.48 and 27.16 mg crude protein (CP) kJ?1, respectively. The effects of these diets on several growth and nutritional parameters were evaluated for the fry (2.50 ± 0.184 g) and fingerlings (11.53 ± 0.023 g) of Siganus canaliculatus (Park). Maximum growth and best feed utilization efficiency of fry were obtained using the diet containing 480 g kg?1 protein and P:E ratio of 27.16 mg CP kJ?1. For fingerlings the best results were obtained with the diet containing 360 g kg?1 protein and P:E ratio of 20.48 mg CP kJ. Body composition of the fry was not affected by the feeding regime whilst the effect was evident in the fingerling groups. The carcass protein content of the fingerling was observed to increase with increasing P:E ratios while lipid content decreased as P:E increased.  相似文献   

18.
Results are reported of the growth and yield of the Malawi chambo, Oreochromis karongae (Trewavas, 1941) association, and Oreochromis shiranus (Boulenger. 1896) in polyculture with Clarias gariepinus (Burchell. 1822). Six ponds of 150 m2 were assigned to two replicates of three treatments: C. gariepinus and O. shiranus; C. gariepinus and chambo spawned on station; C. gariepinus and chambo collected from the lake. Total fish stocking density was 3 m?2, and stocking ratio 1:2 (C. gariepinus: titapias). Initial mean body weights were 10.9 g for O. shiranus. 13.2 g for C. gariepinus and 13.3 g for chambo. The ponds were fertilized with chicken manure at the rate of 13.5 kg dry matter ha?1 day?1, representing the daily NPK loading of 0.618.0.186 and 0.191 kg ha?1, respectively. Maize bran was applied at 3% body weight day?1 for 168 days. Fish growth rate for C. gariepinus was significantly higher (P < 0.05) than that of the tilapias. Weight gains were 0.48-0.57 g day?1 for C. gariepinus, 0.30-0.31 g day?1 for chambo and 0.24 g day?1 for O shiranus. There was no difference (P > 0.05) in the growth of chambo despite the source of fingerlings. More fish biomass came from C. gariepinus stocked at 1 m?2 than from the tilapias stocked at 2 m?2. Extrapolated fish yields in the range of 4.37-4.75 t ha?1 year?1 were obtained from the polyculture of chambo and C. gariepinus. Oreochromis shiranus and C. gariepinus gave 3.95 t ha?1 year?1. Low water temperatures for 112 days slowed the growth of tilapias but did not seem to inhibit the growth of C. gariepinus. Chicken manure and maize bran, applied at smallholder farmer's level, has produced higher yields than by using O. shiranus in monoculture at optimal temperatures. The yields obtained show that the polyculture system is feasible during the cold season and may justify investment in aquaculture at semi-intensive level in Malawi.  相似文献   

19.
The value of toasted Mucuna utilis seed meals was investigated in this study by evaluating the nutritional profile and the utilization of the processed seeds in isonitrogenous (35% CP) and isocaloric diets (17 kJ g?1) for African catfish Clarias gariepinus (Burchell 1822). Toasting the M. utilis seed significantly reduced the levels of tannins, phytate, trypsin, and hemagglutinin in the seeds. However, protein, gross energy, arginine, histidine, and valine were increased (P ≤ 0.05). The processed seed was then used to formulate five experimental diets by progressively increasing its inclusion (by 50 g kg?1) from zero up to 200 g kg?1. A sixth diet was also formulated with raw M. utilis included at 200 g kg?1 to determine the efficacy of the processing method applied in this study. Fifty fingerlings of C. gariepinus (2.02 g ± 0.08) stocked in 18 hapas measuring 1 × 1 × 1 m3 were then fed the diets for 56 days. The growth of C. gariepinus fingerlings was significantly improved by the addition of the toasted M. utilis seed meal. However, fish fed the diet containing 200 g kg?1 of raw M. utilis had poor growth with higher mortality (35%). Estimation of the feeding cost using the diets revealed reduction in production cost of fish with the inclusion of toasted M. utilis seed meal. It was concluded that toasting significantly improved the nutritional quality of this unconventional feedstuff, allowing better utilization at up to 200 g kg?1 inclusion level in the diet of African catfish C. gariepinus.  相似文献   

20.
This study was conducted to evaluate the effects of dietary taurine on growth performance and feed utilization of Nile tilapia (Oreochromis niloticus) larvae. Four plant protein‐based, isonitrogenous (400 g kg?1 protein), isoenergetic (19 MJ kg?1) diets supplemented with four taurine concentrations (0.0, 5.0, 10.0 and 15.0 g kg?1; designated as T0, T0.5, T1 and T1.5, respectively) were prepared. The diets were fed to triplicate groups of fish larvae (0.024 g average body weight), to apparent satiation, three times per day for 60 days. Larval growth rates and feed utilization efficiency were significantly improved with increasing supplemental taurine up to 10 g kg?1 and decreased with further taurine supplementation. The quadratic regression analyses indicated that the maximum larval performance occurred at about 9.7 g kg?1 of total dietary taurine. Fish survival was significantly lower at 15 g kg?1 dietary taurine than at other taurine levels. Body protein significantly increased, while body moisture and ash decreased, with increasing dietary taurine up to 10 g kg?1 and decreased with further taurine supplementation to 15 g kg?1. Body lipid was not significantly affected by dietary taurine concentration. A number of body amino acids (tryptophan, arginine, histidine, leucine, isoleucine, valine, alanine, glycine, threonine and taurine) significantly increased with increasing supplemental taurine up to 10 g kg?1 and then decreased with further increase in dietary taurine levels. The rest of body amino acids were not significantly affected by dietary taurine. The present results suggest that about 9.7 g kg?1 dietary taurine is required for optimum performance of Nile tilapia larvae fed soybean meal‐based diets.  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