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1.
The use of antibiotics to control fish disease is one of the constraints in tilapia farming. Hence, the use of probiotic and live organisms as alternative strategies has received much more attention. This study was undertaken to evaluate the use of Spirulina (Arthrospir platensis) as a growth and immunity promoter for Nile tilapia, Oreochromis niloticus (L.). Fish (1.88 g) were randomly distributed at 20 fish per 100 L aquarium and fed a diet containing either 0.0, 1.25, 2.5, 5.0, 7.5 or 10.0 g Spirulina kg?1 diet for 12 weeks. After the feeding trial, fish of each treatment were challenged by pathogenic Aeromonas hydrophila, which was given by an interperitoneal injection, and they were kept under observation for 10 days to record any abnormal clinical signs and the daily mortality rate. The growth‐promoting influence of Spirulina was observed with fish, and the optimum growth and feed utilization were obtained at 5.0 g Spirulina kg?1 diet. No significant changes were observed in fish survival among the different treatments. Spirulina supplementation improved the protein and lipid contents in fish bodies without significant differences among them, especially when fed 2.5–10.0 g kg?1 diet, but no significant differences in the moisture and ash contents were observed among different treatments. The physiological parameters were improved when fish were fed a Spirulina‐enriched diet. However, the highest red blood cells, white blood cells and nitro blue tetrazolium values were obtained at 5.0–10.0 g Spirulina kg?1 diet; meanwhile, the lowest value was obtained in the control. Total fish mortality due to A. hydrophila infection decreased with an increase in the Spirulina level in fish diets. These results indicate that Spirulina supplement is promising as an alternative method to antibiotics for disease prevention in tilapia aquaculture, and the optimum level of Spirulina in the fish diet should be 5.0–10.0 g kg?1 diet.  相似文献   

2.
ABSTRACT

Fish cage culture is an intensive, continuous-flow fish farming system, allowing intensive exploitation of water bodies with relatively low capital investment. This study aimed to determine the production function of Nile tilapia, Oreochromis niloticus, in cages; the profit-maximizing biomass at 300–400 and 500–600 fish per m3 for cages of different volumes; and the influence of water body conditions in fish performance. Feed intake, survival rate, and water temperature were monitored daily; dissolved oxygen, pH, and transparency of water were monitored each 15 days. Caged tilapia were fed daily on commercial, floating pellets (32% crude protein) at 0900, 1300, and 1700, and feeding rate was adjusted based on weight gain and survival rate. Data were analyzed statistically by ANOVA (P = 0.05) and regression analysis; the Mitscherlich function was chosen to represent the production function. Carrying capacity of both stocking densities reached 200 kg/m3 and no differences were found (P > 0.05) regarding accumulated biomass and individual average weight over time. The larger stocking density yielded larger accumulated biomass and had better feeding efficiency and no differences between individual average weights of fish at both densities were observed (P > 0.05). Profit-maximizing biomass at 500–600 fish/m3 was 145 kg/m3 and at 300–400 fish/m3 was 121 kg/m3. Cage farming of Nile tilapia at 500–600 fish/m3, individual average weight 283 g, presented many advantages: optimization of space and production time, better feed efficiency, higher fish production per unit volume of cages, and increased profitability.  相似文献   

3.
For the sustainable farming of tilapia, proper maintenance of their health and adequate treatment for infections at appropriate time are inevitable. The indiscriminate use of antibiotics in aquaculture, as a part of treatment and as growth promoters, accelerates antimicrobial resistance (AMR) among the fish pathogens. In the present study, we have isolated diverse aeromonads from Nile tilapia and studied their antibiogram and plasmid profiling. Aeromonas hydrophila, Aeromonas veronii, Aeromonas sobria, Aeromonas dhakensis, Aeromonas caviae, Aeromonas jandaei and Aeromonas aquatica were isolated from infected tilapia (n = 150), and their Shannon wiener diversity index was calculated as 1.926. A. veronii was found to be the most multiple antibiotic‐resistant pathogen with the MAR index of 0.46, and A. aquatica was noticed as the least resistant isolate. The minimum inhibitory concentration of resistant antibiotics was shown as >256 mcg/ml for most of the isolates. The virulent genes such as aerolysin and hemolysin were identified in all the isolates except A. aquatica. The detection of class 1 integrons, plasmid profiling and plasmid curing studies confirmed that AMR exhibited by most of the Aeromonas species is of plasmid mediated. This challenges the risk of wide spread of AMR among the pathogens and subsequent treatment of the infection.  相似文献   

4.
In this study, the use of Lactobacillus acidophilus as a probiotic for Nile tilapia (Oreochromis niloticus) culture was studied. Fish survival and the expression of some genes involved in the immune response were assessed. Diet supplementation with L. acidophilus for 15 days caused a significant increase in fish survival during a challenge with Aeromonas hydrophila and variations in immune response related to IL‐1β and transferrin expression in Nile tilapia spleen and kidney. Moreover, extracellular products (ECPs) of L. acidophilus showed high antibacterial activity against fish pathogens such as A. hydrophila and Streptococcus agalactiae in vitro. It was also observed that viable L. acidophilus was able to disrupt quorum sensing activity in Chromobacterium violaceum.  相似文献   

5.
Tilapia, Oreochromis niloticus, is among the fish species with high potential for aquaculture in intensive farming, and Brazil is among the largest producers worldwide. Some of the amino acid requirements in practical diets for tilapia are still unknown. Thus, this study determined the dietary arginine requirements for Nile tilapia juveniles based on growth performance, hematological and biochemical responses, and muscle growth. Three hundred Nile tilapia juveniles (2.95 ± 0.79 g) were distributed into 20–500 L fiberglass aquaria and fed five extruded isoproteic (28% crude protein) and isoenergetic (3160 kcal/kg) diets formulated to contain 0.95, 1.10, 1.25, 1.40, and 1.55% arginine. Based on the quadratic regression analysis, the best results in weight gain, feed conversion, protein efficiency ratio, and protein retention were estimated in fish fed diets containing 1.36, 1.34, 1.36, and 1.37% arginine, respectively. The best amino acid body retention values were estimated in fish fed diets containing 1.31–1.37% arginine. Muscle growth occurred mainly by hyperplasia in fish fed 0.95% arginine, whereas reduction in the hyperplasia time and signs of hypertrophy occurred in fish fed 1.10–1.55% arginine diets. It was concluded that a diet with 1.36% of arginine (with 1.53% lysine in diet) meets the requirements of Nile tilapia juveniles.  相似文献   

6.
Streptococcosis cause severe losses for global tilapia farming, especially in developing countries. The aim of this study was to identify and characterize streptococci recovered from Nile tilapia farmed in the Philippines. Moribund and apparently healthy fish were sampled from grow-out cages, ponds and hatcheries. Clinical signs observed included exophthalmia, eye opacity, ascites, lethargy, erratic swimming and haemorrhages. Results showed that both Streptococcus iniae and Streptococcus agalactiae were associated with disease in these sites. Consistent with global reports, including those from South-East Asia, S. agalactiae was more widespread than S. iniae. Molecular serotyping of the S. agalactiae isolates identified the serotype Ia and serotype Ib. Histopathological findings were meningitis, meningoencephalitis and septicaemia. Identical virulence profiles were found for all strains of S. iniae, while S. agalactiae strains were separated into virulence profile I and profile II. All strains were susceptible to the tested antibiotics and resistant to oxolinic acid. Only S. agalactiae serotype Ib showed resistance to sulphamethoxazole–trimethoprim. This is the first study from the Philippines to characterize the streptococci involved in disease outbreaks in tilapia aquaculture. Outputs from this study will promote the development of efficacious disease control strategies in tilapia farming for the Philippines and South-East Asia.  相似文献   

7.
Mass mortality has occurred among cultured Nile tilapia, Oreochromis niloticus, on fish farms in Manzala, Dakahlia province, Egypt, in the summer season, 2019. Moribund fish were reported with deep ulcers, septicaemic lesions and sampled for bacterial isolation. In this study, most isolates were subjected to bacteriological examination, antibiotic sensitivity test, 16S rRNA gene sequencing and histopathological examination. Following isolate identification, intraperitoneal challenge of Nile tilapia with a bacterial suspension 2 × 106 CFU/ml was performed. Samples from liver, spleen and kidney were collected for histological and biochemical analysis. The results showed a high similarity (99%) to Photobacterium damselae strains using phylogenetic analysis of 16S rRNA. P. damselae exhibited resistance to amoxicillin and erythromycin, as well it was highly sensitive to chloramphenicol and doxycycline. Moreover, haemorrhage, oedema, hemosiderosis and melanomacrophage activation in the liver and head kidney of infected fish were detected by light and electron microscopy. Also, significant higher levels of CAT and SOD in the spleen and head kidney, as well as the serum levels of NO were observed in experimentally challenged O. niloticus, compared to the control fish. Our data identified P. damselae for the first time from infected Nile tilapia, describing its sensitivity to a variety of antibiotics, histopathological alterations and oxidative stress impact, and it could be useful indicators for understanding P. damselae pathogenesis, which might provide a preventive efficacy for P. damselae.  相似文献   

8.

以‘吉富’、‘新吉富’、‘埃及尼罗’3种不同品系尼罗罗非鱼(Oreochromis niloticus)为研究对象, 通过不同品系之间生长与高密度胁迫反应的比较, 探讨3种尼罗罗非鱼的生长特点与应激后生理响应的变化规律。将初始规格基本一致的3种品系尼罗罗非鱼饲养100 d后, 吉富罗非鱼特定生长率最高, 新吉富其次, 两者间无显著差异(P>0.05), 埃及尼罗罗非鱼特定生长率显著低于吉富罗非鱼(P<0.05)。吉富与新吉富罗非鱼的内脏比显著高于埃及尼罗(P<0.05); 3种尼罗罗非鱼的肥满度之间无显著差异(P>0.05)。养殖实验结束后, 进行48 h的急性高密度(100 g/L)应激实验。应激48 h内, 吉富与新吉富罗非鱼血清总蛋白、葡萄糖、谷草转氨酶、胆固醇与溶菌酶活力/水平以及肝HSP70mRNA水平呈先上升后下降的变化。应激48 h后, 埃及尼罗罗非鱼血清皮质醇水平与应激前相比无显著差异(P>0.05), 吉富与新吉富罗非鱼的皮质醇水平显著高于应激前(P<0.05); 埃及尼罗罗非鱼血清溶菌酶活力与肝HSP70 mRNA水平在应激后48 h内始终高于应激前(P<0.05)。研究结果表明, 短期高密度胁迫可提高3种尼罗罗非鱼血清葡萄糖与甘油三酯的利用, 并诱发肝损伤。埃及尼罗罗非鱼的抗高密度应激能力高于吉富和新吉富罗非鱼。

  相似文献   

9.
通过在饲料中分别添加2×107 CFU/g的芽孢杆菌制剂、中草药芽孢杆菌制剂、复合微生态制剂和中草药复合微生态制剂,研究4种微生态制剂对吉富罗非鱼(Oreochromis niloticus)生长、肠道菌群及抗病力等的影响。结果显示：(1)饲料中添加4种微生态制剂均可显著提高罗非鱼的增重率(P<0.05),对成活率和饲料利用率也有一定程度的提高(P>0.05),而中草药复合微生态制剂对罗非鱼促进生长效果最佳。(2)饲料中添加4种微生态制剂可以显著提高罗非鱼肠道中的细菌总数、芽孢杆菌、乳酸杆菌和双歧杆菌数量(P<0.05),大肠杆菌数量显著低于对照组(P<0.05),说明饲料中添加一定量的4种微生态制均可改善罗非鱼的肠道菌群结构,以中草药复合微生态制剂的改善效果最佳。(3)经人工感染无乳链球菌后,罗非鱼对照组全部死亡,4个实验组只有部分死亡。鉴定发现,吉富罗非鱼的死亡均由感染无乳链球菌所致,试验组罗非鱼的免疫保护率分别为51.42%(B组)、58.62%(C组)、58.62%(D组)和68.93%(E组),以中草药复合微生态制剂组的免疫保护率最高。综上所述,在饲料中添加一定比例的中草药复合微生态制剂可以提高吉富罗非鱼生长指标、改善其肠道菌群结构和增加抗病力。  相似文献   

10.
Abstract

Because Saudi Arabia is a substantial importer of fish and its capture fishery is operating beyond maximum sustainable limits, it has a special interest in developing fish farming. It has been encouraging tilapia production. This study examines the costs of tilapia farming in the Central Region of Saudi Arabia using cross sectional data from 23 intensive fish farms. It provides information about the relative importance of different cost items such as variable costs and feed costs in total costs. Also, cost functions are estimated by ordinary least squares and a cubic cost function is found to provide the best fit to the available data. Minimum average cost of production occurs for 201 tonnes of tilapia per year per farm and profit is maximised for a production of 300 tonnes annually per farm. All farms operate at less than profit‐maximising scale and most operate at less than minimum efficient scale. The reasons could be low quality fry, low levels of management expertise in culturing tilapia and the secondary nature of tilapia farming. Lack of water is likely to limit future expansion of tilapia farming in Saudi Arabia.  相似文献   

11.
A 8‐week feeding trial was conducted to determine the effect of substituting fish oil with palm oil‐laden spent bleaching clay (SBC), a by‐product from crude palm oil (CPO) refining, on growth, feed utilization, fatty acid composition and heavy metal accumulation in the muscle of Nile tilapia, Oreochromis niloticus. Four isonitrogenous and isolipidic practical diets were formulated to contain 0, 100, 200 or 300 g kg?1 SBC. Growth performance of Nile tilapia was significantly better in fish fed the 100 g kg?1 SBC diet compared with fish fed the 0, 200 or 300 g kg?1 SBC diet. Growth and feed utilization efficiency of fish fed 200 or 300 g kg?1 SBC were similar to fish fed the control diet without added SBC. Whole‐body composition, body‐organ indices and haematocrit of tilapia were not affected by dietary treatments. Fatty acid compositions in the muscle lipid of Nile tilapia were strongly influenced by dietary treatments with progressively elevated levels of total saturates and n‐6 PUFA because of the dietary influence of these fatty acids from residual CPO adsorbed onto SBC. A gradual decrease in total n‐3 PUFA concentrations were also observed with the ratio of n‐3 to n‐6 fatty acids in muscle lipids decreasing from 4.75 to 4.41, 3.23 or 2.37 after 8 weeks on the 0, 100, 200 or 300 g kg?1 SBC diet, respectively. The arsenic, cadmium and lead concentrations in the experimental diets increased with increasing dietary levels of SBC but the concentrations of these heavy metals in the whole body and bone of Nile tilapia were not significantly different among fish fed the various diets. The present 8‐week study showed that in fishmeal‐based diets for Nile tilapia, palm oil‐laden SBC can totally replace added fish oil. The use of this presently discarded waste product from palm oil refining in tilapia diets will greatly contribute to reducing the impact of rising feed costs in the culture of tilapia in many tropical countries. Other potential benefits may include acting as a feed binder, removal of mycotoxins in fish feeds as well as adsorbing toxic substances present in the culture water.  相似文献   

12.
In support of developing sustainable aquafeeds, production performance and fillet fatty acid profile were assessed in juvenile Nile tilapia (0.61 ± 0.0 g/fish mean ± SE) raised for 16 weeks on diets containing fish oil or 50:50 blends of fish and plant-derived lipids. Standard, low 18:3n-3, or saturated fatty acid (SFA)-enriched soybean oils, palm oil, or low 18:3n-3 canola oil may be used to partially spare fish oil in feeds for Nile tilapia without impairing production performance, though use of hydrogenated soybean oil appears to impair growth and conversion efficiency. Of the plant lipids evaluated, palm and SFA-enriched soybean oil appear to be the best alternatives in terms of maintaining fillet long-chain polyunsaturated fatty acid content and the nutritional value of tilapia fillets.  相似文献   

13.
ABSTRACT

A 120-day feeding trial was conducted in floating cages to evaluate growth performance and digestibility of Nile tilapia (Oreochromis niloticus) juveniles fed diets containing different levels of poultry by-product meal (PBM) as a replacement for fishmeal. Nile Tilapia with an average body weight of 56.6 ± 0.28 g were used in this experiment. Five diets were formulated to contain graded levels of PBM at 0%, 5%, 10%, 20%, and 30% poultry by-product meal (PBM) and are referred as PBM0, PBM5, PBM10, PBM20, and PBM30, respectively. Groups of 25 Nile tilapia were fed close to the apparent satiation, three times a day. The results showed that growth performance, survival and whole-body composition for fish fed the experimental diets were not significantly different (P > .05) than fish fed the control diet. Apparent digestibility of dry matter, protein, lipid and amino acids of fish fed the PBM20 and PBM30 were lower compared to the other treatments (P < .05). The PBM dietary levels significantly lowered total protein, high-density-lipoprotein (HDL) and cholesterol concentration. The results of this study indicated that good quality PBM can be used up to 30% in commercial diets for Nile tilapia without any adverse effect.  相似文献   

14.
The photosynthetic activity of cyanobacteria (predominantly Microcystis spp.) after passage through the digestive tract of Nile tilapia (Oreochromis niloticus) and silver carp (Hypophthalmichthys molitrix) was determined by CCD fluorescence imaging, using slow complementary area approach, during a 4‐day cultivation of fish faeces in algal ZBB medium. The cyanobacteria colonies exhibited a 92–95% reduction in of activity (P<0.001) after passage through Nile tilapia, whereas there was a significant (P<0.01) stimulation of photosynthetic activity after passage through the silver carp gut.  相似文献   

15.
Two different colours (red and green) of visible implant elastomer (VIE) were used in Nile tilapia (Oreochromis niloticus). The visibility, location and retention of the VIE tags was investigated and any adverse effects on fish survival and growth determined. The use of VIE tags for monitoring individual fish during a bacterial challenge with either Streptococcus agalactiae or S. iniae was also studied. The results showed that VIE treated fish were lighter but not shorter than the non‐tagged control fish and that tagging caused no mortality. The retention of tags was better at the base of pectoral fin followed by the nasal area, lower abdomen, upper abdomen and branchiostegal rays inside the operculum. During the bacterial challenge experiment individual animals could be easily identified using the VIE tags. In this preliminary study, VIE tagging appears suitable for Nile tilapia research, as with other fish species, and could be a novel method to identify individual animals during microbial pathogenesis studies.  相似文献   

16.
Mushroom stalk waste (MSW) generated from the oyster mushroom industry is drastically increasing and safe disposal of MSW is becoming a critical issue worldwide. Mushrooms are an established, excellent source of nutraceuticals and antioxidants, and therefore MSW may confer similar effects when consumed. The severe deterioration of aquatic habitat may compromise the homoeostasis of antioxidative metabolism of Nile tilapia, Oreochromis niloticus, which resulted in a reduced total production. Based on this paradigm, hot water extracts (HWE, 2‐ and 5‐h) of MSW were evaluated as a supplement in fish feed and determined the effect on growth performance and the antioxidant status of Nile tilapia, O. niloticus, in vivo. The HWE 5‐h contained significantly higher amounts of nutrient and β‐glucan than HWE 2‐h (P < 0.05). Four standardized in vitro antioxidant assays showed that HWE 5‐h was a better antioxidant agent than HWE 2‐h (P < 0.05). Tilapia fingerlings fed 5 g kg?1 HWE supplemented feed produced better (P < 0.05) growth and higher antioxidant enzyme activities than 10 g kg?1 HWE, CD and BD. Thus, HWE of MSW included at 5 g kg?1 may be beneficial to tilapia farming and may also provide a way of disposing the waste created by mushroom farming.  相似文献   

17.
Nile tilapia, Oreochromis niloticus (L.), and channel catfish, Ictalurus punctatus (Rafinesque), were experimentally infected by immersion with three isolates (Lake, DL8O5 and MS91452) of Streptococcus sp. from diseased fish. To enhance infection, the lateral body surface of each fish was scraped prior to bacterial exposure. The Lake and DL8O5 isolates caused exophthalmia, ocular opacity and ocular haemorrhage in some tilapia. Histopathology of these fish revealed; meningitis; polyserositis of heart, liver, spleen, ovary and kidney; splenitis; ovaritis; and myocarditis. Isolate MS91452 induced only mild granulomas in spleen, kidney and ovary of tilapia. The Lake and DL8O5 isolates induced endophthalitis, Channel catfish infected with the Lake and DL805 isolates developed similar eye lesions to tilapia. Histologic lesions caused by all three isolates in channel catfish consisted of meningoencephalitis, mild myocarditis, splenitis and ovaritis, but these lesions were not as severe as in Nile tilapia.  相似文献   

18.
The main goal of this research was to analyse in vitro compatibility of Nile tilapia (Oreochromis niloticus) digestive proteinases and enzymes recovered from species comprising fishery waste as Pleoticus muelleri, Artemesia longinaris and Patagonotothen ramsayi. It evaluated the use of exogenous enzymes as feed supplements to increase digestion efficiency in tilapia fingerlings and juveniles (3.5 ± 0.11 g and 11.6 ± 1.5 g, respectively). We successfully have obtained proteinases from fishery waste as source of exogenous enzymes. P. muelleri and A. longinaris enzymes had more activity of acid and alkaline proteinases than P. ramsayi. SDS‐PAGE gels demonstrated that Nile tilapia digestive proteinases keep their activity when combined with each exogenous proteinase. Exogenous enzymes varied in their ability to enhance hydrolysis of different feed ingredients. P. muelleri by‐products are the best candidates to be employed as feed supplements for tilapia juveniles. Enzymes from this by‐product did not affect the activity and integrity of fish digestive enzymes, improved the hydrolysis of different protein sources (fish meal, squid meal, shrimp meal and soybean meal), and maintained its activity after being exposed to high temperatures and acid pHs. Our findings are applicable to other places where O. niloticus is raised utilizing local fishery waste, and also to different cultured species.  相似文献   

19.
Francisella orientalis is a highly virulent, emerging bacterium that causes mass mortalities in tilapia. This pathogen also affects numerous other warm-water fish species, including three-line grunt, hybrid striped bass and various ornamental fish. This study sheds light on two new species of fish that are susceptible to F. orientalis. Asian seabass and largemouth bass showed variable levels of susceptibility in a bacterial challenge experiment. After intraperitoneally injected with a dose of 106 CFU/fish, a total of 64.28% and 21.42% mortalities were obtained in Asian seabass and largemouth bass, respectively. Meanwhile, Nile tilapia showed acute mortality of 100%. All fish showed typical lesions of francisellosis, including multifocal granulomas in the spleen and head kidney. Immunohistochemical analysis revealed strong positive signals inside the granulomas of all fish. The bacterial recovery in solid media from infected fish was highest in Nile tilapia (85.71%), followed by Asian seabass (35.71%) and largemouth bass (21.42%). PCR results tested 100% positive for Nile tilapia, and 78.57% and 21.42% for Asian seabass and largemouth bass, respectively. In conclusion, Asian seabass and largemouth bass are susceptible to this pathogen, which warrants new management strategies when employing predation polyculture systems of these species with tilapia.  相似文献   

20.
The aim of this study was to evaluate Lactobacillus acidophilus, Streptococcus thermophilus, Bifidobacterium bifidum, and yeast Saccharomyces cerevisiae singly and in combination as probiotic supplements in Nile tilapia (Oreochromis niloticus) fingerling diets. All the probiotic-supplemented diets resulted in growth higher than the control. Best growth rate, food consumption, and food conversion (P < 0.05) were in the group fed a cocktail of the three bacteria. Feed cost, return on weight gain, and profit margin increased in fish groups fed diets inoculated with probiotics. Supplementation with Lactobacillus acidophilus, Bifidobacterium bifiduim, and the three-bacteria cocktail were most effective in eliminating mortality in an A. hydrophila challenge.  相似文献   

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