Offspring Growth in a Diallel Crossbreeding with Three Strains of Nile Tilapia Oreochromis niloticus

Abstract— A complete diallel crossing of three strains, Stirling, Korean and Local, was used to evaluate heterosis of intraspecific crossbreeding on early growth of Nile tilapia Oreochromis niloticus . All possible F-1 hybrid offspring were obtained and their growth rates to 90 d were compared. The specific heterosis for F-1 hybrids in Stirling × Korean, Stirling × Local and Korean × Local crosses were 7.61, 5.63 and 7.70 for weight, and 0.47, 0.26 and 0.55 for length, respectively. The purebred Stirling strain showed better growth than the other two strains (P < 0.05). When growth of F-1 hybrids was compared between sexes, males grew more rapidly than females (P < 0.05). However, no differences were observed in growth of male or female between hybrid groups. Purebred males in the Stirling strain were slightly heavier than those in the Korean and Local strains, and Local × Stirling, Korean × Local and Local × Korean crosses. However, in purebred females Stirling was superior to Korean, but not the Local strain and all F-1 hybrid crosses. Implications to choose the appropriate strains for developing a breeding program of tilapia are also discussed.     

Thiamin Requirement of Nile Tilapia,Oreochromis niloticus

Juvenile Nile tilapia, Oreochromis niloticus, were fed to apparent satiation twice daily with purified diets containing 0, 1.0, 2.0, 4.0, 8.0, and 16.0 mg/kg and 0, 2.0, 4.0, 8.0, 16.0, and 32.0 mg/kg of thiamin in separate 14‐ and 8‐wk trials (Experiments 1 and 2, respectively). Fish fed the diet devoid of thiamin developed neurological disorders, anorexia, reduced growth, and feed efficiency and increased mortality (Experiment 2 only) within 4–6 and 8–10 wk for Experiments 2 and 1, respectively. Low red blood cell count (RBC) and hematocrit (Ht) were observed in fish fed the thiamin‐deficient diet. Serum pyruvate was elevated in fish fed the thiamin unsupplemented diet. Serum lactate was not affected by dietary thiamin levels. Whole body protein was unaffected by dietary levels of thiamin. Body moisture and ash increased whereas body lipid decreased in fish fed the thiamin unsupplemented diets. None of these abnormalities were observed in fish fed the thiamin‐supplemented diets. Using the response curves determined by PROC NLMIXED to estimate dietary thiamin levels required for various response variables, a dietary thiamin level of 3.5 mg/kg diet was adequate for optimum growth, feed intake and efficiency, survival, prevention of neurological symptoms, and maintaining normal levels of RBC, Ht, serum pyruvate, and proximate body composition.     

Fillet Yields from Four Strains of Nile Tilapia (Oreochromis niloticus) and a Red Variety

Tilapia (Oreochromis, spp.) have been introduced globally and domesticated, resulting in a number of different strains. This diversity offers the potential for difference in body morphology and, in turn, fillet yields. A trial was conducted at Auburn University, Auburn, Alabama, to compare processing characteristics of four populations of Oreochromis niloticus using two domesticated strains (Egypt and Ivory Coast), two less domesticated strains (Sagana and Lake Victoria), and a red variety (Santa Fe). Male tilapia (N?=?25/strain) were manually processed and the dress-out percentage and visceral fat calculated. Mean individual weights of pre-processed fish were similar (range = 403.8 ± 27.6 g to 413.8 ± 24.5 g) with the exception of the larger Sagana strain (434.2 ± 15.4 g). The Ivory Coast strain had the highest percent dress out (33.1% ± 2.1%), while the Sagana strain had the lowest (29.6% ± 1.5%). The Red strain had the greatest percent visceral fat (2.3% ± 1.0%) and the Sagana had the lowest (0.2% ± 0.4%).     

吉富等品系尼罗罗非鱼的起捕率差异

在常规土质鱼池中进行了吉富“８８”、“７８”和埃及等四品系尼罗罗非鱼的起捕率比较试验。结果表明吉富品系的三网累计起捕率显著地高于其他品系（Ｐ〈０．０１）。１９９５年的试验中，吉富的三网累计起捕率为６７％、“８８”为３８％，“７８”为２３％，埃及为２２％。１９９６年的试验中，吉富的三网累计起捕率为８１．５％，“８８”为６２％，试验结果表明吉富品系尼罗罗非鱼的起捕率较高。     

Comparative Performance of Four Strains of Nile Tilapia (Oreochromis niloticus) in Brackish Water Ponds in Indonesia

Four selectively bred strains of Nile tilapia (Oreochromis niloticus) were evaluated for production in brackish water ponds in Indonesia. Survival to 124 days was relatively low for all four strains (39%–48%), and growth during the later stages of the trial was poor (SGR < 1.5 %/day) due to water quality deterioration in the pond. Although the ‘Red’ tilapia strain demonstrated the best production parameters, red-colored tilapia bring lower prices in both our test markets (South Sulawesi and Aceh provinces). Of the four strains, the genetically enhanced supermale Indonesian tilapia?×?genetic improvement of farmed tilapia (GESIT×GIFT) cross provided the best economic return.     

Geosmin and Off-Flavor in Nile Tilapia (Oreochromis niloticus)

Abstract

The concentration of geosmin (1,10-trans-dimethyl-trans-9-decaol) in fresh tilapia were analyzed by applying high-vacuum distillation, extraction and gas chromatography techniques. The distribution of geosmin in the fish was determined by examining tissues from various parts of tilapia, along with the rates of geosmin absorption and purging. Analysis showed that when geosmin was added to fish flesh at concentrations ranging from 2.8 to 390 μg per kg of flesh, the rate of recovery was 51 to 89%. Sensory evaluation detected muddy flavor in freshwater tilapia with geosmin content ranging from 7.55 to 9.85 μg/kg of fish flesh. However, panelists failed to detect muddy flavor in brackish water tilapia that contained geosmin only in the range of 1.5 to 2.6 μg/kg. Among various tissues of the fish, the intestines contained the highest geosmin concentration, and appeared in descending order in the abdominal, skin and muscle tissues. After holding for 2 h in water with 5 and 50 μg/l geosmin, tilapia absorbed 17.6 and 42.2 μg/kg geosmin in the flesh, respectively. Holding the fish over longer periods in water with higher geosmin content resulted in a greater amount of absorption. In contrast, transferring muddy-flavored fish to static clean water purged geosmin from the fish but it required at least 16 days to eliminate the muddy flavor.     

Dynamic Viscoelastic Properties of Tilapia (Oreochromis niloticus) Skin Gelatin

ABSTRACT

The viscoelastic properties of gelatin extracted from tilapia skin (protein yield: 21.2%) were evaluated using dynamic rheology tests. The flow curves of tilapia gelatin sols (1.0–6.6% w/w, 40°C; 0.5%, 2–40°C) complied with the Herschel-Bulkley model (R² = 0.92–0.99), indicating the presence of yield stress, while the gelling and melting temperature of gelatin dispersions (1.0–6.6%) fit well with the Eldridge-Ferry model (R² = 0.97). Tilapia skin gelatin displayed good thermo-stability and strong gel-forming properties, showing great potential as an alternative for mammal-based gelatin applied in various food products.     

苯甲酸雌二醇诱导新吉富罗非鱼雌性化的研究

2009年7月12日至10月21日和2010年5月1日至11月6日,水温23～31℃范围下,在3口2.72m×1.55m×0.72m、水深0.62m的水泥育苗池和3口1.2m×1.0 m×1.0 m、网目20目/英寸的小网箱中,分别放养100尾体长0.7～1.9㎝的新吉富尼罗罗非鱼(Oreochromis niloticus)苗,投喂含不同剂量的苯甲酸雌二醇(EB)激素的饲料,以获得用于生产YY超雄鱼的XY转化雌鱼。结果显示,用100 mg.kg-1EB饲料投喂26d、36d、46d、59d和饲养102d后,实验鱼的雌性率分别为80.0%、93.4%、93.9%和94.0%,分别比对照鱼(54.8%)高25.2%、38.6%、39.1%和39.2%;用200 mg.kg-1EB饲料投喂24d和饲养188d后,实验鱼的雌性率为83.1%,比对照鱼(46.9%)高出36.2%。经Χ2检验,两次试验的雌性转化率差异均极显著(P<0.001)。实验鱼和对照鱼的成活率差异不显著,未见畸形现象。实验结束时两批实验鱼的体质量和全长均显著小于对照鱼(P<0.01和P<0.05),未转化的实验雄鱼与对照雄鱼的全长、体质量差异不显著(P>0.50)。综合分析认为,用EB诱导新吉富罗非鱼苗雌性化的适宜剂量为200 mg.kg-1饲料,投喂35d左右较为适宜。     

吉富罗非鱼成鱼脏器系数的研究

为研究罗非鱼(Oreochrowis niloticus)组织脏器重量与体重的关系,获得脏器系数.本研究随机选取40尾体重为600～900 g雄性吉富罗非鱼(GIFT)成鱼,进行体重、心脏、肝脏、肾脏、脾脏、肠、鳃、皮肤、胆囊、鳞片、肌肉及其他组织(鱼头、鱼鳍和鱼骨等)重量的测定,对体重与各组织脏器重量进行相关性分析,...     

Ultrasound Enhanced Immersion Protocols for Masculinization of Nile Tilapia, Oreochromis niloticus

Androgen immersion protocols have been unsuccessful in consistently producing all-male tilapia at a high enough ratio for them to be commercially viable. This study explored the use of ultrasound to improve on the results of previous immersion studies. Variables tested include two hormones (trenbolone acetate-TBA and 17α-methyldihydrotestoterone-MDHT) at two concentrations (100 and 250 μg/L) and with or without ultrasound (cavitation level). All hormone treatments with ultrasound and non-ultrasound resulted in significantly higher masculinization than the appropriate controls ( P < 0.05). Among pairs of treatments of the same hormone at the same dose, all ultrasound treatments resulted in significantly higher number of males compared with non-ultrasound treatments with the exception of MDHT 250 μg/L ( P 0.05). Comparing across all ultrasound treatments, TBA 250 μg/L with ultrasound had higher masculinization than all the other ultrasound treatments ( P 0.05). Comparing across all non-ultrasound treatments, TBA 250 μg/L had higher ( P 0.05) masculinization than MDHT 100 μg/L and TBA 100 μg/L with non-ultrasound. Two of the three replicates of TBA 250 μg/L ultrasound treatment resulted in 100% males and the highest mean percentage (98%) of males. This study thus demonstrated the potential of a short-term immersion protocol using ultrasound to more predictably produce all-male, commercially viable tilapia seed.     

Methionine Requirement in Practical Diets of Juvenile Nile Tilapia,Oreochromis niloticus

Two feeding experiments were conducted to confirm methionine requirement in practical diets of juvenile Nile tilapia, Oreochromis niloticus. Test diets used in both experiments contained 414 kcal gross energy, 28 g protein, and 5 g lipid per 100 g diet. In the first experiment, seven diets were made using cottonseed meal (CSM), dehulled solvent‐extracted soybean meal (DSESM), and gelatin as intact protein sources. Methionine was added to five of these diets at 0.03 or 0.06% increments to produce methionine levels ranging from 0.33 to 0.57% of the diet. Each diet was fed to four replicate groups of male juvenile Nile tilapia (5.62 ± 0.13 g) in a recirculation system for 8 wk. Broken‐line regression analysis of weight gain indicated that methionine requirement of juvenile Nile tilapia was 0.49% of the diet or 1.75% of dietary protein at cystine level of 0.45% of the diet. The second experiment was designed based on methionine requirement determined in the first experiment and also contained seven test diets. The first six diets contained CSM and DSESM as protein sources. Methionine was added to five of these diets at an increasing rate of 0.06% to produce methionine levels ranging from 0.49 to 0.79% of the diet. In the last diet (Diet 7), a portion of DSESM was replaced by gelatin to reduce methionine level to 0.33% of the diet in order to test whether methionine is limited. Each diet was also fed to four replicate groups of male juvenile Nile tilapia (2.32 ± 0.06 g) in a recirculation system for 9 wk. At the termination of the second experiment, there were no significant differences in terms of weight gain, survival, and feed efficiency ratio (FER) among the fish fed the first six diets. However, weight gain and FER of the fish fed these diets were significantly better than those fed Diet 7, confirming the methionine requirement value as has been determined in the first experiment.     

Economic Analysis of Nile Tilapia (Oreochromis niloticus) Production in Tanzania

In Tanzania, Nile tilapia culture is a promising aquaculture enterprise. Information on production costs could assist fish farmers in economic and financial planning. Economic profitability of small‐scale Nile tilapia production in Tanzania is analyzed using a model that simulates individual fish growth and takes into account fish population dynamics in the pond. The results suggest that the current practiced mixed‐sex tilapia culture without predation is not economically sustainable. Extension efforts should be geared toward developing a Nile tilapia production system that is based on a hand‐sexed all‐male tilapia. Meanwhile catfish can be introduced in ponds to control overcrowding in mixed‐sex tilapia culture without predation. Studies to determine optimal pond sizes, availability of feed, and a quality fingerling supply chain are also fundamental for developing a sustainable Nile tilapia production system in Tanzania. Under improved Nile tilapia production systems, returns are high enough to justify investment through borrowed capital from formal institutions.     

Streptococcus iniae Infection of Tilapia Oreochromis niloticus in a Recirculation Production Facility

Abstract— Streptococcus iniae was isolated from moribund pure strain Nile tilapia Oreochromis niloticus in a water recirculation aquaculture facility. The extent of the infection was determined in a number of separate culture systems at the facility. A pilot study was also conducted to gain information on potential stressors that may play a role in spread of the infection within such a water reuse facility. The conditions employed in the pilot stress test did not have any apparent impact on spread of S. iniae infection to fish in additional tanks within the facility.     

棉酚对罗非鱼（Oreochromisniloticus）离体精子毒性作用的研究

新鲜采取的尼罗罗非鱼精液在加入棉酚的精子保存液中28℃下培养。高达10mM 的乙酸棉酚也不影响精子在一小时内的存活率。罗非鱼精子的存活率在培养三小时后存活率显下降，而低浓度棉酚（25－100μM）显提高罗非鱼精子的 存活率。 本对上述实验结果进行了讨论。     

木薯粉在罗非鱼饵料中的适口性研究

选择健康的吉富罗非鱼为试验鱼,比较不同水平木薯粉之间的诱食效果以及木薯粉与豆粕、次粉的适口性,评价木薯粉在罗非鱼饵料中的应用效果。结果表明,(1)40%、30%木薯粉组的诱食活性显著高于10%、20%木薯粉组(p0.01),40%与30%木薯粉之间没有显著差异(p0.05)。(2)罗非鱼对木薯粉与豆粕、次粉的适口性依次为豆粕木薯次粉。     

罗非鱼类立克次氏体病的组织病理学观察

本文主要研究感染类立克次氏体(Rickettsia-like organism,RLO)的养殖罗非鱼(Oreochromis aureus♂×Oreochromis niloticus♀)肝、脾、肾、肠、鳃和心脏的组织病理变化。感染类立克次氏体的罗非鱼各器官广布粗糙不圆整的白色小结节,这些结节为肉芽肿坏死灶,分层不典型,与周围健康组织的界限不甚明显;严重病变的组织坏死区域较大,与周围明显增生的细胞形成清晰的巨大肉瘤状肿物。经吉姆萨-瑞氏染色后,在病变组织内,尤其是脾肾组织的巨噬细胞胞质内可见蓝紫色球状或颗粒样、成簇分布的类立克次氏体。这些发现可为罗非鱼类立克次氏体病的病理学诊断提供依据。     

Comprehensive Investigation of Streptococcosis Outbreaks in Cultured Nile Tilapia,Oreochromis niloticus,and Red Tilapia,Oreochromis sp., of Thailand

Streptococcosis causes economic losses due to mass mortality at all culturing stages in Nile tilapia, Oreochromis niloticus, and red tilapia, Oreochromis sp., farming throughout Thailand. Diseased tilapia collected from outbreak areas during 2003–2012 were examined using histopathological, biochemical, and molecular tools. Infected fish showed clinical signs of septicemia, and bacteria were found in visceral organs. All gram‐positive cocci isolates were negative to catalase and oxidase, and exhibited β‐hemolysis; however, they possessed various biochemical profiles. PCR amplification of the 16S rRNA gene was used for 165 samples, and resulted in identification of 143 (86.67%) with Streptococcus agalactiae and 14 (8.48%) with Streptococcus iniae, and 8 (4.85%) with mixed infection. High similarity (≥98%) of 16S rRNA gene sequences to the reference strain S. agalactiae (accession no. EF092913) and S. iniae ATCC29178 type strain was observed in the typing of S. agalactiae and S. iniae from Thai farmed tilapia. This investigation documented that at least two species of streptococcal bacteria, S. agalactiae and S. iniae, were involved in tilapia streptococcal infection in Thailand. The molecular recognition of the etiologic agents showed that S. agalactiae was the dominant species that cause disease in all culture areas, whereas S. iniae were discovered only in cases from the northeastern and central regions.     

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。