二倍体和三倍体虹鳟精液低温保存寿命的研究

与二倍体（2n组）精原液做比较,以不同密度为组别,研究了4℃下两组（3n-HD和3n-LD）三倍体虹鳟（Oncorhynchus mykiss）精原液的保存时限。结果发现,随着保存时间的延长,精液中精子的活力和寿命逐渐降低。2n组、3n-HD组和3n-LD组虹鳟精原液中精子分别在保存5d、4.5d和12.5d后失去活力;在7d、15d和14.5 d后死亡,即三倍体虹鳟精原液4℃保存时间约为二倍体的2倍,说明低温短期保存三倍体虹鳟精原液可以取得较好效果。     

二倍体和三倍体虹鳟精液低温保存寿命的研究

与二倍体(2n组)精原液做比较,以不同密度为组别,研究了4℃下两组(3n-HD和3n-LD)三倍体虹鳟(Oncorhynchus mykiss)精原液的保存时限。结果发现,随着保存时间的延长,精液中精子的活力和寿命逐渐降低。2n组、3n-HD组和3n-LD组虹鳟精原液中精子分别在保存5d、4.5d和12.5d后失去活力;在7d、15d和14.5 d后死亡,即三倍体虹鳟精原液4℃保存时间约为二倍体的2倍,说明低温短期保存三倍体虹鳟精原液可以取得较好效果。     

Performance of plastic biofilter media with different configuration in a water recirculation system for the culture of Nile tilapia (Oreochromis niloticus)

Three kinds of locally available plastic biofilter media with different configurations (plastic rolls, PVC pipes and scrub pads) were evaluated for their efficiency in organic waste removal from the effluents of an intensive recirculating tilapia culture system. A set of three types of solid-removing filters consisting of screened sedimentation; upflow sand as well as plastic bead filtration accomplished the mechanical filtration. Values of critical metabolic wastes like total ammonia nitrogen (TAN) (0.92 ppm) and nitrite-nitrogen (NO₂-N) (0.22 ppm) were found to be well within the acceptable limits, while other water quality parameters in the culture water were also maintained within the normal range by the filtration system. Removal rates of 3.46 g TAN/m³ per day and 0.77 g NO₂-N/m³ per day, as well as TAN and NO₂-N removal efficiencies of 29.37 and 27.3% respectively, were established to be the best for the plastic-roll biofilter medium as compared to PVC-pipe and scrub-pad media. Percent removal of TAN and NO₂-N per pass of the biofilter (25.49 and 26.3% respectively) and the specific TAN and NO₂-N removal rates (43 and 9.6 mg/m² per day) of plastic rolls were also found to be superior to the other two biofilter media. Pieces of PVC pipes as biofilter medium is recommended to be used in the biofilters in view of their cheaper cost.     

Effects of Oxygen Supplementation on Lake Trout Brood Stock

This study was conducted to determine the effects of oxygen supplementation and nitrogen supersaturation on the fecundity and performance of Lewis Lake strain lake trout, Salvelinus namaycush, brood stock. Performance of brood fish held in water supersaturated with oxygen was compared to that of controls raised at or below 100% saturation for 334 days. Incoming water averaged 78.4% saturation in the morning; the addition of oxygen increased saturation to 104.6%. As a result, average morning nitrogen saturation was reduced from 105.7% to 100.9%. In oxygen-supplemented water, peak daily oxygen saturation averged 129.0% in the afternoon. At this saturation level, average nitrogen gas was reduced to 98.4% saturation. Total gas pressure never exceeded 109.1% with oxygen supplementation; however, nitrogen supersaturation reached 110% in raceways with no oxygen supplementation. Weight gain, feed conversion, egg survival, egg size, and number of eggs per female were not affected by increasing oxygen saturation.     

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.     

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.     

诺氟沙星在金鳟体内的药物代谢动力学研究

实验水温为15±2℃,金鳟（Oncorhynchus mykiss）（平均体质量100±10g）单剂量肌肉注射30.0 mg/kg诺氟沙星后,应用高效液相色谱（HPCL）法于0.15,0.25,0.5,0.75,1,1.5,2,4,6,8,12,24,48,72 h测定了鱼血浆、肝脏和肾脏组织中药物的浓度,研究了诺氟沙...     

诺氟沙星在金鳟体内的药物代谢动力学研究

实验水温为15±2℃,金鳟（Oncorhynchus mykiss）（平均体质量100±10g）单剂量肌肉注射30.0 mg/kg诺氟沙星后,应用高效液相色谱（HPCL）法于0.15,0.25,0.5,0.75,1,1.5,2,4,6,8,12,24,48,72 h测定了鱼血浆、肝脏和肾脏组织中药物的浓度,研究了诺氟沙星在金鳟组织中的分布及药物动力学规律。结果表明,诺氟沙星在金鳟体内吸收分布迅速,符合药物动力学一级吸收二室开放模型,但消除缓慢。诺氟沙星在金鳟血浆、肝脏和肾脏中的主要动力学参数如下：分布半衰期（T1/2α）分别为0.866、1.985、0.388h;消除半衰期（T1/2β）分别为31.369、36.402、30.975h;药时曲线下面积（AUC）分别为：308.005μg/mL.h、622.721μg/g.h、794.362μg/g.h。     

Fly Prepupae as a Feedstuff for Rainbow Trout, Oncorhynchus mykiss

Fly larvae may provide an effective method to mitigate two large and growing global concerns: the use of fish meal derived from capture fisheries in aquaculture diets and manure management in livestock and poultry facilities. A 9‐wk feed trial was conducted to determine whether fly larvae could be used as a partial fish meal and fish oil replacement in rainbow trout, Oncorhynchus mykiss, diets. A trout diet was formulated to contain 40% crude protein and 15% fat. Sixty‐seven percent of the protein in the control diet was derived from fish meal, and all the fat was derived from fish oil. Two of the test diets included using the black soldier fly, Hermetia illucens, prepupae, which are 40% protein and 30% fat, as 25 and 50% replacement for the fish meal component of the control diet. The total protein derived from black soldier fly prepupae in these two test diets was 15 and 34%, respectively. A third test diet included using housefly, Musca domestica, pupae, which is 70% protein and 16% fat, as 25% replacement for the fish meal component of the control diet. Data suggest that a rainbow trout diet where black soldier fly prepupae or housefly pupae constitute 15% of the total protein has no adverse effect on the feed conversion ratio of fish over a 9‐wk feeding period. In addition, the diet with black soldier fly prepupae permitted a 38% reduction in fish oil (i.e., from 13 to 8%); however, fish fed black soldier fly diets low in fish oil had reduced levels of omega‐3 fatty acids in their muscle fillets. The findings from this study suggest that either the black soldier fly or the housefly may be a suitable feedstuff for rainbow trout diets.     

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.     

Determination of Salt Diffusion Coefficient in Rainbow Trout (Oncorhynchus mykiss)

ABSTRACT

The diffusion properties of sodium chloride in rainbow trout muscle during dry salting at 10°C were investigated. The average initial dry matter content of the samples increased from 27.80 ± 0.10 to 36.01 ± 0.16%, and the average salt content increased to 17.98 ± 0.38 g NaCl/100 g dry matter at the end of the 10-h dry salting process. The analytical solution of Fick’s second law considering one-dimensional diffusion through an infinite slab was used to calculate effective salt diffusion coefficients (D_eff). The D_eff values in rainbow trout fillets decreased with increasing salting time and ranged from 6.64 × 10^?10 to 16.45 × 10^?10 m²/s.     

Physiological Responses of Rainbow Trout Oncorhynchus mykiss to Crowding and Anesthesia with AQUI-S™

Abstract.— Following exposure to the anesthetic AQUI-S™, plasma cortisol concentration in immature rainbow trout was measured as (mean) 293 ± 48 ng/ mL, which was significantly ( P > 0.05) higher than the mean concentration in resting fish. Cortisol concentrations remained significantly ( P > 0.05) elevated for at least 24 h after treatment. This was accompanied by a significant increase and decrease in hematocrit and plasma potassium, respectively. These perturbations continued for at least 48 h following recovery from anesthesia. Plasma concentrations of total protein and sodium remained unchanged following anesthesia with AQUI-S™. Crowding stress is commonly encountered by fish during manipulation in aquaculture situations. Anesthetising fish prior to, and during, manipulation may reduce the associated stress. Changes in cortisol values resulting from crowding (30 min; 0.1 kg/L) during anesthesia with AQUI-S™ were not appreciably different from those in fish crowded without anesthesia. Thus, anesthesia with AQUI-S™ at the recommended dose of 17 mg/L did not appear to be effective for alleviating the stress of crowding under the conditions of our experiments.     

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.     

Use of Underground Brackish Water for Reproduction and Larviculture of Rainbow Trout,Oncorhynchus mykiss

Broodfish were reared for 6 months in underground brackish water (11 ppt), and the quality of eggs and semen was evaluated in comparison to broodfish held in fresh water. Fry produced by the broodfish in brackish water (S) and freshwater (F) were then reared in different salinities (1, 4, 7, and 10 ppt). Broodfish successfully matured and spawned in underground brackish water, and gonad quality was better than of the broodfish in fresh water (p < 0.01). Growth indices of fry produced by both groups decreased with increasing salinity (p < 0.01). Survival was not affected by the salinities tested. Underground brackish water can be used as a source to induce successful sexual maturation and to produce high-quality gonads.     

虹鳟鱼对挤压膨化饲料的养分消化率

膨化技术已在食品工业中应用了将近100年。挤压膨化造成物料的物理和化学变化，如粒度减小、淀粉糊化及酶的失活。温和的挤压加工通常会提高动物对植物蛋白的消化率，但对虹鳟鱼是否如此，尚有待研究。     

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.     

Use of ideal protein concept for precision formulation of amino acid levels in fish-meal-free diets for juvenile Nile tilapia (Oreochromis niloticus L.)

This study was undertaken in a closed system with Nile tilapia (Oreochromis niloticus) to examine the effects of total replacement of fish meal (FM) by soybean meal. Nile tilapia fingerlings with an average weight of 5.34±0.08 g were hand‐fed one of the five isoenergetic (≈13.5 MJ digestible energy kg^?1) and isoproteic (≈31% of digestible protein) experimental diets to satiation, six times a day during 85 days in eight replicate fibreglass tanks (six fish per tank). The control diet containing FM was substituted by soybean meal, with and without essential amino acids (lysine, methionine and threonine) or dicalcium phosphate supplementation. The supplemental amino acids were added at levels to simulate the reference amino acid profile of Nile tilapia carcass protein, based on the ideal protein concept. The results showed that soybean meal diet supplemented only with dicalcium phosphate was inferior to the control diet with FM and soybean meal diets supplemented with dicalcium phosphate and essential amino acids. Multiple essential amino acids and dicalcium phosphate incorporation in soybean meal diets was associated with performance, whole‐body composition and carcass yield equal to that of the fish fed with the control diet containing FM. These data suggest that a diet with all plant protein source, supplemented with essential amino acids, based on tissue amino acid profile, can totally replace FM in a diet for Nile tilapia, without adverse effects on the growth performance, carcass yield and composition.     

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。     

金鳟养殖试验

在辽宁省凤城市四门子镇新农水产养殖场进行金鳟鱼的养殖试验。养殖用水为当地山涧冷泉水,养殖水面为100m2,共投放单重20g的鱼种12000尾。试验期间,金鳟生长良好,成活率为99%,利润为12万元。试验结果表明,金鳟作为良好水环境的指示生物,具有极高的生态附加值,可以为进一步开发辽东山区的生态资源和冷水资源提供有效途径,为促进生态经济的协调发展奠定良好基础。     

Production Characteristics of Rainbow Trout,Oncorhynchus mykiss and Brook Trout,Salvelinus fontinalis Under Seasonal Pond Conditions

Abstract

The production characteristics of juvenile rainbow trout, Oncorhynchus mykiss and brook trout, Salvelinus fontinalis were compared under winter pond conditions. Juvenile rainbow trout (55.1 ±1.5 g) and brook trout (28.9 ±0.4 g) were stocked at a density of 8,750 fish/ha into six 0.04-ha ponds. After 163 days, survival, growth, and feed conversion were similar (P >0.05). The results of this study suggest that brook trout may attain growth rates similar to rainbow trout under winter pond conditions in temperate regions of North America.