Effect of dietary probiotic Biogen® supplementation as a growth promoter on growth performance and feed utilization of Nile tilapia Oreochromis niloticus (L.)

Probiotic microbial feed supplements are gaining wide acceptance in livestock production, and may be applicable to aquaculture production systems. The present study was conducted to examine probiotic treatment in the fingerling diet of Nile tilapia Oreochromis niloticus (L.). A total of 240 of Nile tilapia fingerlings (weight ranged from 22.96 to 26.40 g) were divided into five experimental groups. The experiment was conducted for 120 days. Experimental diets were identical in all, except for the variation in probiotic levels. A probiotic (Biogen^®) was used at 0% (diet 1), 0.5% (diet 2), 1.5% (diet 3), 2.0% (diet 4) and 2.5% (diet 5) inclusion rates in the experimental diets. The growth performance and nutrient utilization of Nile tilapia including weight gain, specific growth rate, protein efficiency ratio, protein productive value and energy retention were significantly (P≤0.01) higher in the treatment receiving probiotic (Biogen^®) than the control diet. No differences were observed for moisture, ash and protein content (P≤0.01) among the experimental diets. The lowest gross energy and lipid contents were recorded for fish fed the diet containing 0.5% Biogen^® (P≤0.01). The production performance and subsequent cost–benefit analyses clearly indicated that the diets containing probiotic biogen recorded the highest net return and the lowest total cost compared with the control diet.     

高温诱导对尼罗罗非鱼性别分化及生长的影响

采用自雌鱼口腔中取出受精卵人工孵化的方法建立了尼罗罗非鱼家系20个。受精后9d,将各家系鱼苗分成两份,分别在28℃(对照组)和36℃(高温诱导组)下养殖,诱导处理12d后,统计高温诱导期成活率并将实验鱼转入自然水温下培育,养殖60～120d后对各实验组的雄性率及生长情况进行测定。结果表明,高温处理对仔鱼的成活率没有影响,但能显著提高某些家系的雄性率,如F27(诱导组88%,对照组49%)、F37(诱导组90%,对照组53%)和F41(诱导组91%,对照组53%);高温处理后多数家系的雄性率略有升高,但不显著;有两个家系高温诱导组雄性率低于对照组,分别是F8(诱导组43%,对照组46%)和F35(诱导组29%,对照组38%),这显示了尼罗罗非鱼性别分化受遗传和环境因子共同作用。生长情况测定结果表明,高温诱导对发育初期罗非鱼的生长没有显著影响。本研究结果说明,高温处理能显著提高某些家系的雄性率,高温诱导和家系选择有望成为高雄性率尼罗罗非鱼新品种培育的新的技术手段。     

Spontaneous diploidization of the maternal chromosome set in Nile tilapia (Oreochromis niloticus L.) eggs

Spontaneous diploidization of the maternal chromosome set (SDM) in Oreochromis niloticus is described here for the first time. The SDM phenomenon was observed in progeny of only one XY neofemale out of 11 such neofemales from which eggs had been fertilized with UV‐irradiated sperm: this treatment produced only the expected haploid embryos from the other females. SDM progeny were produced from three different batches of eggs from this female. No significant differences in survival at different stages of embryonic development were observed between the SDM and the diploid control group. The maternal inheritance of SDM progeny was verified using multilocus DNA fingerprinting. Only diploid karyotypes were observed in these fish and diploid control groups. In both the SDM and control groups, sex ratios were significantly skewed towards males (93.3% and 65.0% males respectively). The actual mechanism of SDM in eggs from this particular female remains unknown.     

Fisheries by-catch and processing waste meals as ingredients in diets for Nile tilapia, Oreochromis niloticus

Digestibility, feeding and growth studies were conducted with Nile tilapia using diets containing fishery by‐catch and processing waste meals. Three meals manufactured from sorted fisheries by‐catch (MBM, from mixed benthic species, SPM, from small pelagic species, CAM, from mixed catfish species) one from tuna cannery waste (TCW) and one commercial anchovy meal (COM) were tested. By‐catch and processing waste meals had lower protein, lower lipid and higher ash contents than anchovy meal. The meals were all highly digestible and no significant differences (P≥0.05) were observed between apparent protein digestibility measurements. Five feeds, containing fish meal as the major protein ingredient, were formulated and fed to triplicate groups of 30 juvenile tilapias for 9 weeks. Survival, weight gain, specific growth rate (SGR), feed conversion ratio, protein efficiency ratio, phosphorus retention and whole body proximate composition were compared. Weight gain and SGRs were similar for each treatment group and compared favourably with the results obtained from juvenile tilapia elsewhere. Growth was the highest for CAM (P≤0.05), which contained both the highest essential amino acid levels and the highest ash content. Phosphorus retention was significantly lower in fish fed with high ash meals, MBM, CAM and TCW (P≤0.05) than in fish fed with the lower ash meals COM and SPM. Overall, the fisheries by‐catch and processing waste meals evaluated in this study are suitable protein ingredients for juvenile tilapia feeds.     

Time related alterations in digestibility and faecal characteristics as affected by dietary composition in the Nile tilapia (Oreochromis niloticus L.)

After being shifted to a new diet, time related alterations in digestibility, faecal waste production and faeces recovery in Nile tilapia were assessed in relation with dietary ingredient composition. Four experimental diets were formulated according to a 2 by 2 factorial design: two starch inclusion levels (20 or 40%) and two maize starch types (native versus gelatinized). After introduction to the experimental diets, faeces were collected weekly from Week 2 till 6 using settling tanks. Digestibility of ash, organic matter and dry matter increased with time (P < 0.001). For organic and dry matter the time related alteration in digestibility were different between both starch types (P < 0.05). All faecal waste characteristics altered with time (P < 0.01). The incline in faeces recovery with time was affected by starch type (P < 0.01); being the largest at the 40% gelatinized maize diet. In conclusion, the minimal length of the adaptation period in digestibility studies for obtaining unbiased digestibility estimates is dependent on diet composition, in this study with Nile tilapia 4 weeks for diets with gelatinized starch and 6 weeks with native starch.     

尼罗罗非鱼淀粉酶性质的初步研究

研究了尼罗罗非鱼(Oreochromis niloticus)肝脏淀粉酶的基本性质及金属离子对该鱼淀粉酶活性的影响。结果表明:罗非鱼淀粉酶活力的最适pH是6.5,最适底物浓度是2%。研究金属离子对该鱼淀粉酶活力影响,一价金属离子K+、Li+、Na+对酶活力影响较小;二价金属离子Cu2+对酶活力具有抑制作用,Zn2+对酶活力无明显影响;三价金属离子Al3+对酶活力具有抑制作用,但效果不是很强烈,Fe3+对酶活力具有明显的激活作用;碱土金属Mg2+、Ca2+对淀粉酶活性有激活作用,而Ba2+对酶具有抑制作用;重金属离子Cd2+、Pb2+有明显的抑制作用。     

Effect of phytic acid on growth and nitrogen retention in tilapia Oreochromis niloticus L.

Two experiments were conducted to determine the effect of phytic acid on nitrogen retention in tilapia (Oreochromis niloticus). The first experiment utilized graded levels of soybean meal (SBM) with or without hydrolysis of phytic acid. The second experiment utilized diets containing graded levels of purified phytic acid. In the first experiment, weight gain was inversely related to SBM inclusion beyond 250 g kg^?1 of the crude protein (CP). Broken‐line and quadratic models were applied to the growth data. The models suggest limiting inclusion to 380 and 170 g kg^?1 CP for untreated and phytase treated SBM, respectively. The two SBM treatments exhibited similar trends in efficiency parameters. However, significant differences (P < 0.05) within treatments appeared when phytase treated SBM surpassed 250 g kg^?1 CP, but not until 750 g kg^?1 CP with untreated SBM. At similar rates of SBM incorporation, apparent net protein utilizations with untreated SBM were significantly higher beyond 250 g kg^?1 CP (P < 0.05). In the second experiment, phytic acid did not affect efficiency parameters until the concentration was twice that in diets incorporating SBM as 1000 g kg^?1 CP in a 330 g kg^?1 CP diet. Phytic acid does not reduce nitrogen retention in tilapia, and its removal from SBM may decrease nitrogen retention.     

Evaluation of visible implant elastomer tags for pathogenesis research in Nile tilapia (Oreochromis niloticus)

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.     

猪油对罗非鱼生长及餐后脂质代谢的影响

在实用饲料配方的基础上分别添加0%、5%、10%猪油组成试验饲料饲喂罗非鱼(Oreochromis niloticus)(初重43 g)8周,比较研究猪油不同添加水平对罗非鱼生长及餐后脂质代谢的影响。结果表明,罗非鱼的末重(FBW)、特定生长率(SGR)、增重率(WGR)和饲料效率(FE)随着饲料中猪油水平的增加而显著升高。而摄食量(FI)表现出相反的变化趋势,即高水平猪油组显著低于对照组。随猪油添加水平增加,罗非鱼肝胰脏超氧化物歧化酶(SOD)、谷丙转氨酶(ALT)和谷草转氨酶(AST)活力显著降低,而肝脏丙二醛(MDA)含量显著增加。血清中甘油三酯(TG)、胆固醇(CHO)、高密度脂蛋白胆固醇(HDL-C)、低密度脂蛋白胆固醇(LDL-C)和极低密度脂蛋白胆固醇(VLDL-C)含量均随饲料中猪油水平增加而显著升高。各试验组罗非鱼血清中CHO、TG、LDL-C和VLDL-C含量随时间推移均表现出先升高后降低的变化趋势,TG和VLDL-C的峰值出现在餐后6h,而CHO和LDL-C峰值在餐后9 h。但HDL-C表现出相反的变化趋势,即先降低后升高,在餐后6 h达到最低值。总之,饲料中添加不同水平猪油会促进罗非鱼生长,但会影响罗非鱼的肝功能以及餐后脂质代谢,罗非鱼抗氧化能力也相应受到影响。     

Cortisol Response of Nile Tilapia,Oreochromis niloticus (L.), to Temperature Changes

Abstract

Nile tilapia, Oreochromis niloticus (L.), is a commercially-valuable fish species with high nutritional value. As a result of the intensive aquaculture of this species, handling, transport, and environmental changes that causes stress on these fish are unavoidable. The objective of this study was to determine the effects of gradual and acute temperature changes on juvenile tilapia. No significant difference (P > 0.05) was found among serum cortisol levels in juvenile tilapia when the water temperature was gradually increased from 27°C to 32°C, or 40°C, and maintained for 1 hour, although the levels were five times pretreat-ment levels. When tilapia acclimated to 27°C were subjected to 18°, 27°, 30°, 32°, 34°, 36°, 38°, or 40°C water for 10 minutes in a water bath, followed by a recovery period of 10 minutes at 27°C in the original aquaria, no significant difference (P > 0.05) in cortisol levels was observed among treatments except for significantly elevated levels at 38°C and 40°C. When tilapia acclimated to 27°C were subjected to the same temperature exposures but given a recovery period of 60 minutes at 27°C in the original aquaria, there was no significant (P > 0.05) increase in cortisol levels in tilapia among treatments from 18° to 36°C; but there was a significant (P > 0.05) increase between values from those treatments at 38° and 40°C. Acute temperature changes initiated the cortisol response as early as 10 minutes in fish following exposure to 38°C or 40°C and resulted in significant increases in the 38°C and 40°C treatments following 1 hour of recovery at 27°C. These results have implications for the management of tilapia during bacterial challenge, vaccination, and handling and transport during aquacultural activities.     

Characterization and comparison of variations in reproductive performance of Chitralada strain Nile tilapia, Oreochromis niloticus (L.)

In an attempt to better understand and characterize the variability in the female reproduction of individual Thai‐Chitralada strains of Nile tilapia, Oreochromis niloticus (L.), tagged mature females (n=68) from a single population were monitored in a hapa‐in‐pond system over a 12‐month experimental period. Spawn female⁻¹, eggs female⁻¹ day⁻¹, eggs kg female⁻¹ day⁻¹, day spawn⁻¹ and weight (g) at first spawning of individual females were determined from the regular weekly sampling of weight (g) and eggs per spawn. For analysis, the females were grouped into two, high spawning (HSF) and low spawning frequency (LSF) classes based on their spawning frequency (SF) record. Moreover, nested under these two classes were two groups each based on growth rate, i.e., high frequency – large size (HL), high frequency – small size (HS), low frequency – large size (LL) and low frequency – small size (LS). There was no difference in eggs spawn⁻¹ among all females. The HSF group produced 68% and 361% more eggs female⁻¹ day⁻¹ than the population mean and LSF group respectively. Eggs female⁻¹ day⁻¹ and spawn female⁻¹ remained high in the HSF group and low in the LSF group throughout the 12‐month experimental period. This suggests that individual female spawning activity is consistent within a population in a common environment. The inter‐spawn interval increased with age in all four groups, and day spawn⁻¹ was shorter by 130% in HSF females compared with day spawn⁻¹ in LSF. The HSF group also spawned more successively (≥3), while the LSF group of females had fewer successive spawns (≤2). Body weight (g) had no influence on the number of eggs produced. The study indicates that separating frequently spawning females could be used as an important strategy to improve commercial seed production of Nile tilapia.     

三种生态环境下尼罗罗非鱼免疫因子的比较

随机选取海水池塘(盐度28)和淡水池塘养殖及水库天然增殖的3种不同生态环境下、体质量为200~500g的尼罗罗非鱼为研究材料,采用生物化学方法测定3种生态环境尼罗罗非鱼血清中碱性磷酸酶、酸性磷酸酶、过氧化物酶、谷胱甘肽还原酶的活性和蛋白质量浓度。结果显示,3种生态环境中罗非鱼血清中碱性磷酸酶和酸性磷酸酶活力差异不显著(P0.05),其余各组间罗非鱼血清中过氧化物酶和谷胱甘肽还原酶的活性及血清蛋白质量浓度差异显著(P0.05),酶活力和蛋白质量浓度依次为:水库海水池塘淡水池塘。试验结果表明,水库天然增殖的尼罗罗非鱼具有较高的磷酸酶活性。     

Response of Nile tilapia (Oreochromis niloticus) to diet acidification: Effect on growth performance and feed utilization

A 12-week feeding trial was undertaken to assess growth, nutrient utilization, some hematological parameters, and proximate composition of Nile tilapia (Oreochromis niloticus) fed diets supplemented with graded levels (0.5%, 1.0%, and 1.5%) of two blends of organic acids or organic salts. Seven isonitrogenous (300 g CP kg^?1) and isocaloric (19.0 MJ gross energy kg^?1) diets were formulated. The control diet (D1) contained neither added blend of organic acids nor organic salts. Three diets (D2, D3, and D4) were supplemented with 0.5%, 1.0%, and 1.5% of malic acid + oxalic acid blend (OAB), respectively. The other three diets (D5, D6, and D7) were supplemented with 0.5%, 1.5%, and 1.5% of calcium lactate + sodium acetate blend (OSB), respectively. Fingerlings (7.05 ± 0.02 g) were randomly distributed into 21 glass aquaria (160 liter), with each aquarium holding 15 fish. At the end of the feeding trial, O. niloticus offered the control diet showed lower growth and feed utilization than all those fed the organic acids or organic salts blends supplemented diets. Fish fed the diet D3 showed the highest body weight (BW), body length (BL), weight gain (WG), specific growth rate (SGR), feed intake (FI), and the best feed conversion ratio (FCR) and protein efficiency ratio (PER). Fish fed diet supplemented by 1.5% OAB (D4) showed the highest serum protein content, while control group (D1) showed the lower level of total lipids compared with the other treatments. Fish group fed the diet supplemented with 0.5% of OSB (D5) showed the highest protein and ash contents and the lowest lipid content of the whole fish body, while the control group showed the lowest protein and the highest fat content. The present observations suggest that the growth, feed utilization, and health status of juvenile O. niloticus can be enhanced with a supplementation of 1% of OAB or OSB in the diet.     

Effect of three natural phytochemicals supplementation on growth performance,testosterone level and feed utilization of Nile tilapia (Oreochromis niloticus)

An 84‐day feeding experiment was conducted to determine the effects of dietary ginseng extract (GE), tribulus extract (TE) and date palm pollen grains (DPPG) on growth, testosterone level and nutrient utilization of Nile tilapia, Oreochromis niloticus, fingerlings. Seven experimental treatments were conducted in three replicates: control fed basal diets without any supplementations, GE_0.2 (supplemented with 0.2 g GE/kg diet), GE_0.4 (supplemented with 0.4 g GE/kg diet), TE_0.6 (supplemented with 0.6 g TE/kg diet), TE_1.2 (supplemented with 1.2 g TE/kg diet), DPPG₃ (supplemented with 3 g DPPG/kg diet) and DPPG₆ (supplemented with 6 g DPPG/kg diet). The results indicated that all dietary phytochemicals significantly increased growth compared to the control. Plasma testosterone levels were improved by 86.27%, 64.58%, 57.35% and 24.58% with TE_1.2, GE_0.4, TE_0.6 and DPPG₆, respectively, more than the control. The relationship between testosterone and final body weight showed a significant simple linear regression with a positive correlation. The nutrient utilization imprxoved with higher doses of phytochemical supplementations. Moreover, protein content increased and ether extract decreased with phytochemical supplementation. The present results concluded that higher doses of GE, TE and DPPG could be used as growth promoters and testosterone boosters for Nile tilapia fingerlings.     

Comparative digestion efficiencies in conventional, genetically improved and genetically male Nile tilapia, Oreochromis niloticus (L.)

Apparent digestibility of dry matter, protein, lipid and energy of a fishmeal‐based feed (41% crude protein, 9% crude lipid and 19 kJ g⁻¹ gross energy) was compared in genetically improved farmed tilapia (GIFT), genetically male Nile tilapia (GMNT) and conventional Nile tilapia (CNT) (Oreochromis niloticus). The experimental fish were reared individually under standardized conditions in a recirculation system at 27±0.1°C for 10 weeks. Titanium dioxide (TiO₂) was used as a marker. Faeces of individual fish were collected daily by siphoning and stored at −18°C before analysis. No significant differences (P<0.05) were observed in the digestibility coefficients of feed dry matter (78.2±3.4%, 77.7±4.4% and 76.4±3.7%), protein (87.9±3.0%, 88.4±2.8% and 88.0±3.3%), lipid (90.0±2.5%, 91.0±2.1% and 89.4±3.0%) and energy (90.4±1.9%, 90.7±2.0% and 89.4±2.3%) in GIFT, GMNT and CNT respectively. At the end of the experiment, there were no significant differences (P<0.05) in average percentage growth (82.2±7.2, 87.3±7.7 and 74.7±4.1 respectively for GIFT, GMNT and CNT), growth rates or feed utilization efficiencies between the three tilapia groups. We conclude that the higher growth claimed for improved GIFT and GMNT as compared with CNT, if ever existing, cannot be attributed to higher nutrients or energy digestibility.     

Evaluation and Nutrient Quality of Detoxified Jackbean Seeds,Cooked in Distilled Water or Trona Solution,as a Substitute for Soybean Meal in Nile Tilapia,Oreochromis niloticus,Diets

ABSTRACT

Jackbean, Canavalia ensiformis, seeds were detoxified using eight different wet thermal detoxification methods in either distilled water (5% w/v) or trona (NaCO₂.NaHCO₃.2H₂O) solution. The effects of the detoxification methods on hemagglutinating, antitryptic and urease activities, and on the digestibility coefficient of crude protein and gross energy in the jackbean seeds were investigated. Cracked jackbean seeds cooked (100°C) in trona solution for one hour proved to be more effective as a method of inactivating the antinutritional factors in jackbean seeds. Dried detoxified jackbean seed meals were incorporated in dry practical diets providing 20% or 30% of total protein and fed to Nile tilapia, Oreochromis niloticus, fingerlings (mean weight, 6.7 g) twice daily to apparent satiation for 70 days. Mortality was low and no abnormal fish behavior was noted even when the detoxified jackbean meals provided 30% of total protein in diet. Growth and feed utilization indices, were similar (P > 0.05) between the diet in which cracked jackbean seeds cooked in water provided 20% of total protein and in diets in which cracked jackbean seeds cooked in trona solution provided 20% or 30% of total protein. Carcass composition and hepatosomatic index showed no definite trend among O. niloticus fingerlings fed the experimental diets.     

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

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.     

低温胁迫对尼罗罗非鱼水通道蛋白(Aquaporin 1，AQP1)基因(AQP1)表达的影响

以经过连续多代抗寒选育获得的尼罗罗非鱼(Oreochromis niloticus)耐寒品系为实验材料, 克隆了尼罗罗非鱼水通道蛋白基因(AQP1)的cDNA序列, 并采用实时荧光定量PCR分析方法探讨了低温胁迫对罗非鱼AQP1基因表达水平的影响。序列分析结果显示, 尼罗罗非鱼AQP1 cDNA长度为1 098 bp, 包含36 bp的5′端非翻译区序列、783 bp开放阅读框(ORF)和279 bp的3′非翻译区序列, 编码261个氨基酸。氨基酸序列比对表明, 各物种间AQP1序列的同源性较高(96%~59%)。聚类分析表明, 尼罗罗非鱼首先与同属鲈形目丽鱼科的斑马拟丽鱼(Maylandia zebra)聚在一起, 再与其他硬骨鱼类聚为一类。实时荧光定量PCR 结果表明: 在水温从30℃逐渐降到10℃过程中, 肌肉和肝组织AQP1基因的表达量从20℃开始均逐渐下调。其中肌肉组织中, 与30℃时的表达量相比, 耐寒品系在20℃时表达量大幅度下调, 当水温为15℃时, 其表达量下调幅度为22.16倍。当水温降到10℃时, 其表达量下调了107.73倍。而对照组AQP1基因的表达量在15℃时, 下调幅度为5.38倍。当水温达到10℃时, 其表达量下调幅度为11.30倍。结果分析显示, 耐寒品系与对照组AQP1基因在低温条件下的表达量存在显著性差异(P<0.05)。而在肝组织中, 当水温降到15℃时, 耐寒品系和对照组的表达量下调幅度分别为3.38倍、1.42倍。水温降到10℃时, 其表达量上调幅度分别为18.85倍、9.01倍。结果分析表明, 低温条件下耐寒品系与对照组AQP1基因在肝组织中的表达差异不显著(P>0.05)。结果表明, AQP1表达对温度敏感, 耐寒品系较高的耐寒能力与其在低温条件下的肌肉组织大幅上调表达有关。由此可见, AQP1基因在罗非鱼低温适应过程中发挥重要作用, 是潜在的研究罗非鱼耐寒机制的候选基因之一, 本研究为进一步研究罗非鱼的耐寒分子机制和开展鱼类抗逆育种提供参考。