Haematological response and growth performance of Nile tilapia (Oreochromis niloticus L.) fed diets containing folic acid     

Margarida Maria Barros  Maria José Tavares Ranzani-Paiva  Luiz Edivaldo Pezzato  Dario Rocha Falcon  & Igo Gomes Guimarães 《Aquaculture Research》2009,40(8):895-903

Haematological response and growth performance over 150 days, and resistance to a low-temperature stress of Nile tilapia fed diets with increasing folic acid (FA) levels were evaluated. The experiment was conducted in a completely randomized design with eight FA levels (0.0, 0.5, 1.0, 2.0, 3.0, 4.0, 5.0 and 6.0 mg kg⁻¹ feed) supplemented in purified diets (32.0% CP and 13 398 kj DE kg⁻¹). One hundred and ninety-two fingerlings were randomly assigned to 32 net cages distributed in eight 1000 L aquaria with a physical and biological filter and a temperature control system (26.0 ± 1.0 °C). For cold-induced stress, fish were transferred to 24 30 L-aquaria with individual biofilters and aeration. The water temperature was gradually reduced until it reached 13 °C. Haematological parameters evaluated before and after cold stress were total erythrocytes and leucocytes count, differential leucocyte, haemoglobin, haematocrit, total plasmatic protein and haematometric indices. Growth performance parameters were mean weight gain, feed conversion ratio and survival. Dietary FA supplementation did not influence erythropoiesis under normal temperature conditions; cold stress impaired erythropoiesis, causing hypochromic microcytic anaemia and leucopoiesis, and also neutrophilia. Growth performance is influenced by folate and supplementation between 0.5 and 1.0 mg FA kg⁻¹ diet, which makes up for nutritional demands, guaranteeing production and health under appropriate temperature conditions.  相似文献   

Streptococcosis in red hybrid tilapia (Oreochromis niloticus) commercial farms in Malaysia     

Najiah Musa  Lee Seong Wei  Nadirah Musa  Ruhil H Hamdan  Lee Kok Leong  Wendy Wee  Mohd Nur Amal  Basiriah M Kutty  & Siti Zahrah Abdullah 《Aquaculture Research》2009,40(5):630-632

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Effect of potential probiotic bacteria on growth and survival of tilapia Oreochromis niloticus L., cultured in the laboratory under high density and suboptimum temperature     

Juan Pablo Apún-Molina  Apolinar Santamaría- Miranda  Antonio Luna-González  Sergio F. Martínez-Díaz  & Maurilia Rojas-Contreras 《Aquaculture Research》2009,40(8):887-894

This study examined the effect of potential probiotic bacteria on growth and survival of the tilapia Oreochromis niloticus , under high density and suboptimum temperature. Presumptive Bacillus and lactic acid bacteria (LAB) were isolated from tilapia and from their culture system and were characterized for haemolytic and enzymatic activity, and antagonism against Vibrio . Selected strains were included in the diet of juvenile tilapia and evaluated during a 134-day assay. The experiment was conducted with four treatments: (1) fish fed with commercial feed plus Dry Oil^®; (2) fish fed with commercial feed plus LAB; (3) fish with bacilli in water; (4) fish with a mixture of treatments 2 and 3. Tilapias in all treatments, including bacteria, grew significantly better than fish fed with commercial feed plus Dry Oil^® (control group). Survival was similar in all treatments. The physicochemical parameters of the culture system were maintained within the optimal ranges for the species, with the exception of temperature (19.9–24.82 °C). Animals fed diet supplemented with bacilli and LAB had good survival and the best growth performance, suggesting that bacteria are appropriate growth-stimulating additives in tilapia cultivation.  相似文献   

Overall performances of Nile tilapia (Oreochromis niloticus) associated with using vegetable oil sources under suboptimal temperature     

Amel M. El Asely  Rasha M. Reda  Ayman S. Salah  Mohamed A. Mahmoud  Mahmoud A. O. Dawood 《Aquaculture Nutrition》2020,26(4):1154-1163

The optimum water temperature required for the normal growth of Nile tilapia is 25–30°C. In this study, tilapia was reared under suboptimal temperature (21.50 ± 1.50°C) and fed four diets with fish oil (FO), corn oil (CO), sunflower oil (SFO) and linseed oil (LnO) for 8 weeks. The results revealed improved final weight, average daily gain and intestinal amylase activity in the LnO group compared to FO and SFO groups (p < .05). The feed intake was increased significantly in FO and LnO groups compared to CO and SFO groups, while the feed conversion ratio was increased in the FO group (p < .05). The CO, SFO and LnO diets resulted in higher carcass lipids than fish fed FO, while CO decreased the ash content (p < .05). The growth hormone was significantly lowered by LnO, followed by SFO, while CO improved the serum alkaline phosphatase activity (p < .05). Glutathione peroxidase enhanced in fish fed SFO, while the lowest activities were recorded in fish fed FO (p < .05). Total superoxide dismutase was significantly elevated by CO and LnO when compared with fish fed FO and SFO (p < .05). Substituting FO with vegetable oils had normal intestinal and liver histological appearance. It could be concluded that substituting FO with either CO or LnO for Nile tilapia could maintain the normal growth performance and feed utilization with enhanced antioxidant capacity under suboptimal temperature.  相似文献   

Effect of experimental arginine supplementation on the growth,immunity and resistance of tilapia fingerlings to Streptococcus agalactiae     

Rafael Alves Vianna  Roberta Torres Chideroli  Arthur Roberto da Costa  Oswaldo Pinto Ribeiro Filho  Leandro Licursi de Oliveira  Juarez Lopes Donzele  Eduardo Arruda Teixeira Lanna  Daniela Dib Gonalves  Ulisses de Padua Pereira 《Aquaculture Research》2020,51(3):1276-1283

Streptococcosis causes serious economic losses to fish farms every year. A four‐week feeding trial was carried out to evaluate arginine (ARG) supplementation in the diet of Nile tilapia (Oreochromis niloticus) fingerlings challenged by Streptococcus agalactiae. Fish were fed with experimental diets containing five levels of supplementation with 1.39%, 1.76%, 1.97%, 2.18% or 2.39% analysed level of ARG. Each diet was randomly distributed in 30 tanks containing 20 fish/tank. After 30 days, no differences were observed in performance parameters, weight gain, daily weight gain, specific growth rate, feed intake or food conversion. After the performance assay, fingerlings were infected with 1.95 × 10⁸ CFU/fish of Streptococcus agalactiae. Mortality was verified daily, and the respiratory burst of leucocytes and nitric oxide production were measured at 0 hr, 24 hr, 7 days and 15 days after infection. The survival rate of the fish is compared using the Kaplan–Meier method, with values of 4.29%, 14.8%, 10.8%, 17.2% and 33.3% for the 1.39, 1.76, 1.97, 2.18 and 2.39 treatments respectively. A reduction in the mortality rate and a boost in the immune responses was observed in all the supplementations of ARG in the diet; however, the best survival rates were obtained in the treatments with 2.39% ARG as well as the most efficient immune responses.  相似文献   

Comparison between the intestinal microbiome of healthy fish and fish experimentally infected with Streptococcus agalactiae     

Bruna Rafaela dos Santos Silva  Mariana Silveira Derami  Douglas Alvaredo Paixo  Gabriela Felix Persinoti  Wanderley Dias da Silveira  Renato Pariz Maluta 《Aquaculture Research》2020,51(8):3412-3420

Nile tilapia (Oreochromis niloticus) farming is an economic activity that is soaring in the whole world. Septicemia due to Streptococcus agalactiae is the main disease impacting fish farming. The aim of this study was to compare the gut microbiome of healthy animals and animals experimentally infected with S. agalactiae strain 21171A. The microbiome was established with 16S ribosomal DNA next‐generation sequencing (NGS). One hundred Nile tilapias, with an average weight of 35 g, were distributed into two groups. Fifty fish from the challenged group were orally inoculated with 100 μl of a bacterial solution containing 1.98 × 10³ CFU/ml of S. agalactiae strain 21171A, while 50 controls were orally inoculated with sterile saline. After the experiment, 24 fish from the challenged group and 27 fish from the control group were analysed. For both groups, bacteria attached to the mucosa (M) and present in faeces (F) were analysed. The mean of the number of taxa identified in the infected group (M + F) (45.87 ± 30.13) was lower than in the control (M + F) (67.70 ± 21.10) (p < .01). Nineteen bacterial taxa were more abundant in faecal samples from the infected group when compared with the control group (p < .01). Thirty‐nine taxa were associated with mucosa samples from the challenged group when compared to the control samples (p < .01). No OTU was associated with healthy samples. The results demonstrate that the infection with S. agalactiae reduces the variability of the gut microbiota. Moreover, some bacteria proliferate during the infection.  相似文献   

盐度、碱度对尼罗罗非鱼生长和肌肉品质的影响     

程亚美  赵金良  宋凌元  吴红岩  周昊天 《水产科学》2020,39(3):341-349

在水温(24±1)℃下,将初始体质量(50.00±4.12)g的尼罗罗非鱼放入150 cm×60 cm×40 cm循环可控水族缸内,每箱15尾,每组设置3个平行。将尼罗罗非鱼在盐度(12 g/L)、碱度(23.8 mmol/L NaHCO3)、盐碱(12 g/L和23.8 mmol/L NaHCO3)以及淡水(对照组)水体中分别饲养56 d,比较和测量各组鱼体生长性能指标、肌肉常规营养成分、结合氨基酸和游离氨基酸含量,研究盐度、碱度对罗非鱼生长性能和肌肉品质的影响。试验结果显示,与淡水组相比,改变水体盐度、碱度对鱼体质量增加率、特定生长率和饲料系数均无显著影响(P>0.05)。盐碱组鱼肌肉灰分含量升高,粗蛋白含量下降;粗蛋白含量显著低于其他组(P<0.05);各组水分和粗脂肪含量差异不显著(P>0.05)。各组必需氨基酸量与氨基酸总量比值和必需氨基酸与非必需氨基酸比值分别为40%~41%和66%~69%,各组间差异不显著(P>0.05);处理组中必需氨基酸指数为47.06~59.66,盐碱组>碱度组>盐度组,盐碱组显著高于盐度组和碱度组(P<0.05)。碱度组、盐碱组和盐度组鲜味氨基酸总量分别为淡水组的1.78倍、1.74倍和1.63倍,且碱度组和盐碱组显著高于盐度组(P<0.05);盐碱组甜味氨基酸和游离氨基酸总量显著高于盐度和碱度组(P<0.05)。水体盐度、碱度均可有效改善罗非鱼肌肉营养价值和呈味特征,而碱度对肌肉呈味的影响效果更加明显。  相似文献   

Capsular polysaccharide of Streptococcus agalactiae is an essential virulence factor for infection in Nile tilapia (Oreochromis niloticus Linn.)     

Defeng Zhang  Xiaoli Ke  Zhigang Liu  Jianmeng Cao  Youlu Su  Maixin Lu  Fengying Gao  Miao Wang  Mengmeng Yi  Fengling Qin 《Journal of fish diseases》2019,42(2):293-302

Streptococcus agalactiae (Group B Streptococcus, GBS) is associated with diverse diseases in aquatic animals. The capsule polysaccharide (CPS) encoded by the cps gene cluster is the major virulence factor of S. agalactiae; however, limited information is available regarding the pathogenic role of the CPS of serotype Ia piscine GBS strains in fish. Here, a non‐encapsulated mutant (Δcps) was constructed by insertional mutagenesis of the cps gene cluster. Mutant pathogenicity was evaluated in vitro based on the killing of whole blood from tilapia, in vivo infections, measuring mutant survival in tilapia spleen tissues and pathological analysis. Compared to wild‐type (WT) GBS strain, the Δcps mutant had lower resistance to fresh tilapia whole blood in vitro (p < 0.01), and more easily cleared in tilapia spleen tissue, and was highly attenuated in tilapia and zebrafish. Additionally, compared to the Δcps mutant, numerous GBS strains and severe tissue necrosis were observed in the tilapia spleen tissue infected with WT strains. These results indicated that the CPS is essential for GBS pathogenicity and may serve as a target for attenuation in vaccine development. Gaining a better understanding of the role, the GBS pathogenicity in fish will provide insight into related pathogenesis and host–pathogen interactions.  相似文献   

Evidence of potential vertical transmission of tilapia lake virus     

Jidapa Yamkasem  Puntanat Tattiyapong  Attapon Kamlangdee  Win Surachetpong 《Journal of fish diseases》2019,42(9):1293-1300

Tilapia lake virus disease (TiLVD) is an emerging viral disease in tilapia with worldwide distribution. Although the horizontal transmission of TiLV has been demonstrated through the cohabitation of infected fish with susceptible fish, no direct experiment showed the potential of vertical transmission from broodstock to progeny. In this study, natural outbreaks of TiLV in broodstock and fry in two tilapia hatcheries were confirmed. The TiLV genomic RNA was detected in liver and reproductive organs of infected broodstock, while infective virus was isolated in susceptible cell line. In situ hybridization assay confirmed the presence of TiLV in the ovary and testis of naturally infected fish and experimentally challenged fish. Moreover, early detection of TiLV in 2‐day‐old fry and the presence of TiLV genomic RNA and viable virus in the testis and ovary suggested the possible transfer of this virus from infected broodstock to progenies. As infective virus was present in gonads and fry in natural outbreak and experimental fish, the importance of biosecurity and prevention of the virus to establish in the hatchery should be emphasized. Hence, the development of TiLV‐free broodstock and the maintenance of high biosecurity standards in the hatcheries are essential for any attempt of virus eradication.  相似文献   

Virucidal effects of common disinfectants against tilapia lake virus     

Phitchaya Jaemwimol  Kwanrawee Sirikanchana  Puntanat Tattiyapong  Skorn Mongkolsuk  Win Surachetpong 《Journal of fish diseases》2019,42(10):1383-1389

Tilapia lake virus (TiLV) is an emerging virus associated with high fish mortality and economic losses. This study investigates the virucidal effects of the following disinfectants (active ingredients) on TiLV: 2.5 ppm iodine, 10 ppm sodium hypochlorite (NaOCl), 300 ppm hydrogen peroxide (H₂O₂), 80 ppm formalin and 5,000 ppm (0.5%) Virkon^®. Factors that affect the disinfectants’ efficacy, including temperature, contact time and soiling (organic matter) interference, were examined under conditions mimicking natural aquaculture practices. TiLV inactivation of higher than 5 log₁₀ TCID₅₀ ml^?1 was achieved after 10 min and at 28°C for all disinfectants except formalin; similar inactivation levels were reached by NaOCl and Virkon^® at 10 min and 4°C. Extended exposure to formalin from 10 to 60 min at 28°C rendered more than 5 log₁₀ inactivation. Increasing synthetic organic matter in the water to mimic soiling interference reduced the efficacy of NaOCl, iodine and H₂O₂ when tested at 10 min and 28°C; however, Virkon^® still achieved more than 5 log₁₀ inactivation. This study demonstrates that most common disinfectants effectively reduced viral loads to minimum levels. To limit the spread of TiLV in aquaculture farms and related facilities, the appropriate use of such disinfectants should therefore be promoted and implemented.  相似文献