Complete Replacement of Fish Meal by Soybean Meal with Dietary L-Lysine Supplementation for Nile Tilapia Oreochromis niloticus (L.) Fingerlings

The effect of complete replacement of fish meal by soybean meal (SBM) with the dietary L-lysine supplementation in prepared diet was studied in Nile tilapia fingerlings. Five isonitrogenous (33.2% crude protein) and isocaloric (4.8 kcal gross energy/g of diet) diets were formulated. Diet 1 was similar to a high quality commercial tilapia diet, containing 20% fish meal and 30% SBM. Diets 2–5 contained 55%, 54%, 53%, and 52% SBM and 0.5%, 1.0%, 1.5%, and 2.0% L-lysine supplementation, respectively. After 10 wk, there was a significant difference in the final individual weight, final body length (cm), weight gain (%), specific growth rate (SGR), feed conversion ratio (FCR), protein effkiency ratio (PER), and food intake among flsh groups ( P ≤ 0.05). The best bal individual weight, final individual length (cm), weight gain (%), specific growth rate, feed conversion ratio, protein efficiency ratio (PER), and food intake were recorded in fish fed diet 2, which contained 55% SBM and 0.5% L-lysine. There was a significant difference between it and diet 1 (control). Moisture in fish flesh was not significantly different ( P > 0.05) among treatments and averaged 75.13%, while percentage protein was significantly dltrerent ( P ≤ 0.0% and the best result was achieved in flsh fed diet 2 and diet 1 (control). The highest values of digestibility coefficients of protein, fat and energy were recorded in groups of fish fed diet 2. These suggest that a diet with 55% SBM supplemented with 0.5% L-lysine can totally replace fish meal in a diet for Nile tilapia fingerlings, without adverse effect on fish performance.     

Effect of Dietary Fish Meal Replacement by Canola Meal on Growth Performance and Hepatic Intermediary Metabolism of Genetically Improved Farmed Tilapia Strain of Nile Tilapia,Oreochromis niloticus,Reared in Fresh Water

An 8‐wk feeding trial was conducted to evaluate the potential of replacing fish meal with canola meal in experimental diets for genetically improved farmed tilapia (GIFT) strain of Nile tilapia, Oreochromis niloticus (mean initial weight: 20.0 ± 0.62 g, means ± SD), reared in fresh water. Six isonitrogenous (30% crude protein) and isolipidic (10%) diets were formulated with canola meal included at six levels of 0 (control), 11, 22, 33, 44, and 55%, replacing 0, 15, 30, 45, 60, and 75% fish meal, respectively. Growth performance and feed utilization showed no significant differences among the treatments. In general, dietary canola meal supplementation showed significant effect on hepatic composition of tilapia, but not muscle composition. Viscerosomatic index tended to increase with increasing dietary canola meal levels from 0 to 44%, and then declined when dietary canola meal levels further increased from 44 to 55%. Dietary fish meal replacement by canola meal significantly influenced several hepatic enzymatic activities, including succinate dehydrogenase, lactate dehydrogenase, malic dehydrogenase, lipoprotein lipase, and hepatic lipase, suggesting that dietary fish meal replacement by canola meal had significant effects on nutrient metabolism in the liver. Based on the information above, 75% of dietary fish meal could be replaced by canola meal with no effect on growth performance of GIFT strain of Nile tilapia. Use of canola meal in practical diets for GIFT stain of Nile tilapia may allow producers and feed mills to formulate more economical diets.     

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.     

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.     

Production of Australian Red Claw Cherax quudricarinatus in Polyculture with Nile Tilapia Oreochromis niloticus

Abstract— Australian red claw crayfish Cherax quudricarinurus were cultured in monoculture and in polyculture with male Nile tilapia Oreochromis niloricus in nine 0.02-ha earthen ponds. Red claw with an average weight of 7 g were stocked in all ponds at 2/ m². Tilapia with an average weight of 19 g were stocked in six ponds at either 0.5 or 1/m². A sinking 32% fish diet and dry alfalfa hay was provided to all ponds as feed and forage. After 135 d, red claw survival was similar (19–24%) in all treatments while average weights were 76 g in monoculture and 48 g in both polyculture treatments. Lower than expected survival was a result of stress caused by poor shipping conditions. Tilapia survivals were similar (84–90%) in all ponds and had an average weight of 403 g when stocked at 1/m² and 444 g when stocked at 0.5/m². Red claws are generally considered non-aggressive, especially when compared with other clawed crustaceans. This lack of aggressiveness is suggested as a cause for decreased growth in polyculture with tilapia.     

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.     

Oxytetracycline-Induced Blood Disorder in Juvenile Nile Tilapia Oreochromis niloticus (Trewavas)

Abstract.— This study examined the long-term effect of a common aquaculture antibiotic, oxytetracycline, on several blood parameters of the Nile tilapia Oreochromis niloticus under laboratory conditions. The fish were fed daily on isocaloric (24.56 ± 0.96 J/mg gross energy) and isonitrogenous (38.89 ± 0.08% crude protein) diets incorporated with varying concentrations of the drug (5.00, 2.50, 1.25 and 0.63%) for 8 wk. A control diet with no oxytetracycline was fed to another group of fish. Significant reductions in leukocyte, erythrocyte, thrombocyte, hematocrit, and hemoglobin values were observed, the reductions being directly proportional to the concentrations of the drug in the diet, indicating an anemic response. Though the use of oxytetracycline in aquaculture can be beneficial, the results from this investigation suggest that the drug may have some level of interference with the blood chemistry of the fish at therapeutic dosage.     

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。     

Apparent Protein and Energy Digestibility and Amino Acid Availability of Commercial Meat and Bone Meal for Nile Tilapia,Oreochromis niloticus

Meat and bone meal (MBM) is an excellent source of amino acids (AAs) for fish but its proximate composition varies according to its origin and processing. Apparent digestibility coefficients (ADC) of dry matter, crude protein, and gross energy, and apparent availability coefficients (AAC) of essential and nonessential AAs (EAA and NEAA, respectively) in MBM containing various levels of crude protein (MBM‐340, 370, 400, 430, and 460 g/kg) were determined for juvenile Nile tilapia (Oreochromis niloticus, 32.7 ± 4.5 g). A reference diet containing 351.9 g/kg crude protein and 4541.1 kcal/kg of gross energy and test diets containing a 70:30 mixture of the reference diet and MBM were used with 5 g/kg Cr₂O₃ as an external indicator. ADC of dry matter, gross energy, and crude protein in MBM samples were 42.9–76.2%, 71.6–89.1%, and 49.4–86.9%, respectively. MBM‐400, 430, and 460 showed higher dry matter, gross energy, and crude protein ADC than that by MBM‐340 and 370. All AAs in MBM‐460 showed AAC of EAA > 90%, while the value for MBM‐430 was >85%, except arginine (82.1%) and lysine (84.8%). High ADC of energy, crude protein, and AAC in MBM‐430 and 460 indicate good potential as quantitative AA sources. Besides the low AA quality of MBM‐340, 370, and 400, their utilization is limited by low digestible energy and high ash, which should be considered in the production of least‐cost, well‐balanced, and sustainable diets for tilapia.     

Replacement of Fish Meal by Plant Proteins in the Diet of Nile Tilapia: Digestibility and Growth Performance

Apparent digestibility coefficient (ADC) values for a number of ingredients of plant or animal origin were obtained in order to formulate diets based on such values and to evaluate growth performance of Nile tilapia Oreochromis niloticus fed four experimental diets in which fish meal was gradually replaced by a mixture of other ingredients.The digestibility of various diet components was measured by using an inert marker in the feed and by using the Guelph faeces collecting system. ADC values of the ingredients tested were generally high, especially for fish meal. It was found that extruded pea seed meal (92.6%), defatted soybean meal (94.4%), full-fat toasted soybean (90.0%) and micronized wheat (88.6%) were the best vegetable proteins tested. Lupin seed meal and faba bean meal had similar ADC values for protein and energy.Groups of tilapia, initial mean body weight (SD) 6.7 (0.1) g, were fed experimental diets with the same digestible protein (DP) and digestible energy (DE) containing graded levels of a mixture of vegetable ingredients as partial or total replacement of fish meal protein. A growth trial was conducted over 12 weeks as partial or total replacement of fish meal protein. A growth trial was conducted over 12 weeks at a water temperature of 25 °C. Significant differences were observed for weight gain among tilapia fed diets D0, D33, D66 and D100 (containing only animal protein, 33, 66, and 100% of plant protein, respectively). No significant differences were observed for voluntary intake among tilapia fed diets D0, D33 and D66. These values were significantly lower than those observed for tilapia fed plant protein based diet (D100) and suggest the possibility of partial replacement of fish meal by vegetable proteins without negative effects.     

Induction of Triploidy and Tetraploidy in Nile Tilapia, Oreochromis niloticus (L.)

Abstract.— Induction of triploidy and tetraploidy in Nile tilapia, Oreochromis niloticus , was investigated by heat shock, cold shock, hydrostatic pressure, and/or chemicals (cytochalasin A, B, and D). Additionally, efficacy of combined protocols was determined. Heat shock 10 min after fertilization induced triploidy when incubation temperature was 24 C but not when incubation temperature was 31 C. Heat shock of 40–41 C at 4–6 min after fertilization was effective in inducing up to 100% triploidy with hatchability similar to controls. Cold shock at 13 C for 45 min five min after fertilization induced 85–100% triploids. Heat shock and multiple heat shocking were the most effective treatments for the induction of tetraploidy. Two heat treatments of 41 C applied at 65 and 80 min after fertilization for 5 min each produced approximately 80% tetraploidy in hatched fry. Immersion of fertilized eggs in cytochalasin A, B, or D at concentrations up to 10 μg/L applied at various times and durations was ineffective in inducing triploidy or tetraploidy.     

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.     

Physicochemical Properties of Pepsin-Solubilized Collagen Extracted from Nile Tilapia (Oreochromis niloticus) Scale

ABSTRACT

The aim was to investigate the physicochemical properties of pepsin-solubilized collagen (PSC) extracted from fish scales of Nile tilapia. The results indicated that Nile tilapia scales are rich in collagen. Therefore, the scales are a promising cost-effective collagen source. The conversion of hydroxyproline to collagen was 12.9. Based on the patterns of sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), PSC comprised at least two different α chains, α1 and α2, and was classified to be type I with no disulfide. Fourier transform infrared spectroscopy spectrum showed that the bands of amide A, I, and II of PSC were found at 3,301, 1,631, and 1,239 cm^?1 wavelength. The content of imino acids was 187 residues per 1,000 total amino acid residues. Maximum solubility was observed at pH 4, and minimum was at pH 7. Almost no change in solubility was observed in the presence of NaCl up to 2% (w/v), and the decrease was more pronounced with increasing NaCl concentration. The temperature of denaturation was 35.4°C. Results show that PSC has physicochemical properties that can be applied in the cosmetics, biomedical, pharmaceutical, and food industries.     

沸石强化活性污泥法在尼罗罗非鱼养殖中的应用

试验结果表明,养殖系统出水水质较进水水质有明显改善.经过100 d的循环水养殖,尼罗罗非鱼的平均体质量由30.34 g增加至120.08 g,平均生长速度为0.89 g/d,存活率为85.6%.     

Effects of Preservation Methods On Geosmin Content and Off-Flavor in Nile Tilapia (Oreochromis niloticus)

Abstract

In this study, the masking or reduction of off-flavor in tilapia due to various preservation methods such as salting, drying, frying, smoking, microwave heating, marinating and fermentation with carbohydrate mixture (som fak preparation) was investigated by subjecting the processed tilapia to sensory evaluation and analyzing the concentrations of geosmin (1,10-trans -dimethyl-trans -9-decaol) in the processed samples. Dry salting or brining muddy-flavored fish and then drying either by hot air at 50°C or sun-drying resulted to only a slight reduction in the geosmin content of the product. Deep-frying reduced the muddy flavor intensity and geosmin content in salted-dried tilapia. Pretreatment of tilapia fillets with acidified brine before smoking reduced geosmin content and masked the muddy flavor in the smoked product. Microwave cooking of fresh muddy-flavored tilapia showed no effect on its geosmin content nor its off-flavor. Marinating tilapia in acetic acid solution resulted in decreased muddy flavor, and longer marinating period led to lower geosmin content in the product. The geosmin content of som fak made from muddy-flavor and non-muddy-flavor tilapia differed significantly, although sensory evaluation yielded no significant differences between the two types of som fak, and the taste panelists preferred the product fermented for 3 days.     

Organic Solvent and Laundry Detergent Stable Crude Protease from Nile Tilapia (Oreochromis niloticus) Viscera

The objective of this study was to explore the characteristic activity of crude protease extracted from Nile tilapia viscera. The optimal temperature and pH of the crude protease from Nile tilapia viscera were 60°C and 8.0, respectively. The enzyme was stable to heat treatment up to 45°C and over a pH range of 7–11 for 30–120 min. The protease was effectively inhibited by phenylmethylsulfonyl fluoride (PMSF) and soybean trypsin inhibitor (SBTI). It was activated by Ca²⁺ and Fe²⁺, while inhibited in order by Hg²⁺ > Fe³⁺ > Cu²⁺ > Mn²⁺. The protease showed great stability toward Tween 20, Tween 80, and Triton X-100 and moderate stability toward sodium dodecyl sulfate (SDS) and hydrogen peroxide (H₂O₂)_. Nevertheless, it showed excellent stability and compatibility with various solid and liquid laundry detergents at temperatures from 30 to 50°C. The protease showed not only an improved activity but also a satisfied stability in 25% (v/v) organic solvents for 7 days at 37°C. At higher concentrations (50–75%), the protease activity was decreased by hydrophilic solvents, except dimethyl sulfoxide (DMSO), whereas it was enhanced by hydrophobic solvents. Thus, the crude protease is an excellent candidate as a biocatalyst for detergents, foods, pharmaceuticals, and environmental applications.     

Incorporating Date Pits Phoenix dactylifera and their Sprouts in Semi-purified Diets for Nile Tilapia Oreochromis niloticus (L.)

The expansion in date processing has produced a large quantity of date pits Phoenix dactylifera L.: var. ruzeiz that could be used in animal feeds. To evaluate the nutritional value of date pits and their sprouts, two growth trials were conducted using semi-purified diets and fingerling tilapia Oreochromis niloticus (L.). In the first trial, four isocaloric-isonitrogenous diets containing different levels (0, 15, 30, and 45%) of date pits as a replacement for corn starch were fed to three replicate groups of fingerlings with a mean initial weight of 3.09 ± 0.10 g/fish. At the conclusion of the 9-wk growth trial, final weight gain, feed conversion, specific growth rate and PER were significantly reduced in fish fed diets with all levels of date pits as compared to those fed the control diet (without date pits). However, there were no significant differences in these parameters for fish fed diets contained 15%, 30%, or 45% date pits. Body crude fat was gradually reduced as the level of date pits in the test diets was increased. Consequently, body moisture, crude protein and total ash were proportionally increased. In second trial, three isocaloric-isonitrogenous diets containing 0% date pits (control diet), 15% date pits sprouted for 15 d, and 15% date pits sprouted for 30 d were fed to triplicate groups of tilapia with mean initial weight 2.60 t 0.09 g/ fish) for 9 wk. Growth rates and body composition of fish fed diets containing date pits that were sprouted for 15 or 30 d were similar to that of those fed the control diet. Under the reported conditions the inclusion of sprouted date pits did not affect growth and body composition, whereas nonsprouted date pits negatively influenced fish performance.