Effects of additive iron on growth,tissue distribution,haematology and immunology of gilthead sea bream, <Emphasis Type="Italic">Sparus aurata</Emphasis>

The comparative effects of iron-supplemented levels on growth, tissue distribution, haematology and immunology of gilthead sea bream, Sparus aurata (2 g) were investigated, using four organic (50, 100, 200, 300 mg ORG/kg diet) and one inorganic iron source (200 INOR mg/kg diet). Fish were treated for 12 weeks with the experimental diets and maintained at a water temperature of 19–22°C. Growth (final weight and specific growth rate), tissue distribution (spleen, liver and muscle), haematological parameters (red blood cells, haematocrit, haemoglobin and mean corpuscular haemoglobin concentration) and non-specific immune indexes (respiratory burst activity and antibacterial activity of serum) were analysed. No significant differences were found in growth and iron tissue distribution among the tested groups. Red blood cell counting was statistically higher in fish given 50 ORG, 100 ORG, 200 ORG and 200 INOR feeds. However, haematocrit, haemoglobin and mean corpuscular haemoglobin concentration were not significantly affected by increasing dietary iron. Fish receiving the 100 ORG diet had the best performance with respect to the respiratory burst activity and significantly higher values for antibacterial activity of serum were obtained in fish fed with the 300 ORG diet. The present findings provided no clear evidence of the optimum iron concentration. However, there was adequate indication that iron supplementation enhanced the performance of gilthead sea bream, mainly from a haematological and immunological point of view.     

Effects of capture,loading density and transport stress on the mortality,physiological responses,bacterial density and growth of rohu <Emphasis Type="Italic">Labeo</Emphasis><Emphasis Type="Italic"> rohita</Emphasis> fingerlings

This study evaluated the effects of three levels of loading density (200, 300 and 400 g L⁻¹) and four levels of duration (1, 3, 6 and 9 h) on the mortality, plasma cortisol and chloride levels and growth of rohu Labeo rohita fingerlings in a transport simulation. While total immediate mortality was low (4–12%), delayed mortality was high (27–49%). Initial capture and handling were found to constitute the most stressful phase as indicated by elevated plasma cortisol. The levels of cortisol continued to rise at 6 and 9 h after transport, with the highest level observed at 9 h after transport. The level of plasma chloride fell after transport across all density levels and treatment durations. Specific growth rate (SGR, %/day) and total bacterial density (cfu/g) were not different between and within treatments, and between treatments and the controls. This study demonstrates that transport has a profound effect on the stress responses of rohu fingerlings. Although the level of immediate mortality was low, the higher level of delayed mortality has serious implications in terms of production inefficiency for grow-out farmers.     

Evaluation of Growth and Disease Resistance of USDA103, USDA303, USDA102, and USDA102 × USDA103 Strains of Channel Catfish, Ictalurus punctatus

USDA103, USDA303, USDA102, and USDA102 × USDA103 strains of channel catfish (27.7 ± 0.7 g/fish) were fed daily for 6 wk. Feed consumption and weight gain were highest (P < 0.001) in USDA103, USDA303, and USDA102 × USDA103 fish. USDA102 fish exhibited the poorest (P < 0.01) feed conversion ratio. Fillet and whole‐body content were similar (P > 0.05) among strains when final weight was used as a covariate. USDA103, USDA303, and USDA102 × USDA103 strains had higher (P < 0.01) protein efficiency ratios compared to USDA102. In a second study, the four groups of catfish (22.2 ± 1.9 g/fish) were challenged with Edwardsiella ictaluri and mortality was recorded for 3 wk postchallenge. Survival was higher (P < 0.02) for USDA303 and USDA102 × USDA103 fish. Results of these studies demonstrate that the USDA103 and USDA303 strains of catfish were superior in growth performance. Results of the bacterial challenge show that the USDA303 and USDA102 × USDA103 strains of fish exhibited increased survival. Continued selection of the USDA103 line and crossing this line of fish with lines of fish such as the USDA102 strain may produce fish with desirable growth and disease characteristics.     

Effects of temperature and feed processing on protease activity and dietary protease on growths of white shrimp,Litopenaeus vannamei,and tilapia,Oreochromis niloticus × O. aureus

Effects of temperature and processing on the stability of a commercial protease were assessed in an in vitro trial followed by growth trials with white shrimp and tilapia. Results showed that the protease has a high heat stability against pelleting, and it could hydrolyse dietary proteins during feed processing. In Exp. 2, white shrimp (3.3 g) fed low fish meal (FM) diet (LFD) with protease addition had similar growth to that fed high fish meal diet, and both had higher weight gain (WG) and lower feed conversion ratio (FCR) than that fed LFD without protease addition (P < 0.05). In Exp. 3, compressed (CD) or extruded (ED) diets containing 30 g kg^?1 or 90 g kg^?1 FM were supplemented with or without protease and then fed to tilapia (1.7 g) for 8 weeks. WG was improved and FCR decreased (P < 0.05) by the supplementation of protease in 30 g kg^?1 FMCD, but not in 90 g kg^?1 FMCD and ED diets when compared to those diets without protease supplementation. The digestibility trial with CD indicated the improved apparent digestibilities of dry matter and crude protein by dietary protease in 30 g kg^?1 FMCD, but not in 90 g kg^?1 FMCD. Results above showed that the protease has a high heat stability and the supplementation of protease in CD with low FM level can improve the growth of shrimp and tilapia.     

草鱼不同混养模式下围隔底泥反硝化、硝化和氨化速率

应用乙炔抑制法测定了草鱼(Ctenopharyngodon idellus)不同混养模式围隔底泥的硝化、反硝化和氨化速率,以探究草鱼不同混养模式对池塘底泥－水界面N元素动态变化的影响,并为草鱼养殖模式的优化提供必要的参考依据.混养组合分别为一元组（草鱼）、二元组（草鱼+鲢、草鱼+凡纳滨对虾）、三元组（草鱼+鲢+凡纳滨对虾,设2种放养比例）.结果显示:1）草鱼不同混养模式中底泥的反硝化速率范围为0～734.15 μmol/(m2·d),硝化速范围为0～1 209.20 mmol/(m2·d),化速率范围为0～41.25 mmol/(m2·d).2)草鱼不同混养模式底泥的反硝化速率较高,与很多河口和湖泊数值接近;在养殖中期,底泥的硝化速率很小甚至检测不到;底泥的氨化速率呈逐月递增趋势,以三元混养组最高.3）混养组中凡纳滨对虾(Litopenaeus vannamei)的放养密度越大,草鱼的放养密度越小,反硝化作用出现得越早,但反硝化速率很难保持开始的水平;反之,反硝化作用出现得较晚,并会随着养殖周期的推移迅速升高;放养种类越单一,底泥的硝化速率越低,且鲢(Hypophthalmichthys molitrix)放养密度越高,硝化速率越高.从养殖模式优化的角度来看,草鱼三元混养组要优于单养和二元混养组,但三元混养组中两种放养密度各有优劣,有待进一步优化以确定最佳放养比例.     

充气培养对半叶马尾藻生长﹑营养盐吸收和生化组成的影响

将半叶马尾藻(Sargassum hemiphyllum)置于实验室球形培养瓶内培养15 d,设置5个充气速率(50 m L/min、100 m L/min、200 m L/min、400 m L/min和800 m L/min)为实验组,静水培养(0)为对照组。每隔5 d测定藻体的生长速率和营养盐吸收速率,培养实验结束时,测定藻体的色素含量、可溶性蛋白和可溶性糖含量。结果表明:充气速率和培养时间均对半叶马尾藻的生长和PO34--P的吸收具有显著影响,而对NO3--N来说,仅培养时间对其吸收影响显著。培养第1天时,充气可显著促进营养盐吸收,最大充气速率(800 m L/min)培养的半叶马尾藻对NO3--N和PO34--P的吸收速率分别比静水培养的马尾藻高133.77%和89.51%,生长速率也比静水培养的马尾藻高95.04%。随着培养时间的延长,充气速率对半叶马尾藻的生长和营养盐吸收的促进作用逐渐减弱。在培养第15天时,充气速率为800 m L/min条件下的半叶马尾藻对NO3--N的吸收速率比静水培养的马尾藻低24.87%,对PO34--P的吸收速率仅高出静水培养下的46.03%,而生长比静水培养的马尾藻高出75.16%。同时,除了可溶性蛋白含量,高充气速率可抑制叶绿素a(Chla)、类胡萝卜素(Car)和可溶性糖合成。因此,水体运动是通过对营养盐吸收及其他生理过程产生的作用间接影响半叶马尾藻的生长,而不是直接影响半叶马尾藻生长和产量的最重要因素。     

Reproductive cycle,age, and body size at maturity and fecundity of female willowy flounder <Emphasis Type="Italic">Tanakius kitaharai</Emphasis>

Annual reproductive cycle, age and body size at maturity, and potential and relative fecundity were examined in female willowy flounder in the North Pacific off Japan. Vitellogenesis became active from September, followed by the beginning of spawning in December. The spawning season continued until May with its peak in January. Estimated maturation rate was 50% at a standard length of 16 cm, 30% in 2-year-olds, and almost 100% in ≥3-year-old fish. Potential fecundity increased with age, while relative fecundity decreased in older fish. The results clarify some aspects of the detailed reproductive biology of female willowy flounder and emphasize the importance of age-composition data in estimating reproductive potential within a population.     

Effect of ration size on growth,body composition,and energy and protein maintenance requirement of fingerling Indian major carp, <Emphasis Type="Italic">Labeo rohita</Emphasis> (Hamilton)

An eight-week feeding trial has been conducted to determine the optimum ration for Indian major carp, Labeo rohita, fingerling (4.10 ± 0.30 cm, 0.55 ± 0.16 g) by feeding a purified diet (40% CP; 3.61 kcal g⁻¹ GE) at six levels, 2, 4, 6, 8, 10, and 12% of body weight per day, at 0800 and 1600 h, in triplicate, to 20 fish per trough fitted with a water flow-through system. Highest weight gain, best feed conversion ratio (FCR), best specific growth rate (SGR%), and highest protein efficiency ratio (PER) were evident for rations of 6–8% body weight. Second-degree polynomial regression analysis for FCR, PER, protein, and energy retention data indicated the break-points occurred at 6.55, 6.75, 6.80, and 6.95% bw per day, respectively. Significant (P < 0.05) differences between body composition were observed for fish fed different rations. Maximum body protein content was recorded for 6% and 8% rations. A linear increase in body fat content was evident with increasing ration. Body moisture and ash content remained non-significantly (P > 0.05) low for higher rations, however. On the basis of these results it is recommended that feeding in the range 6.5–7.0% bw per day corresponding to 2.6–2.8 g protein and 23.49–25.31 kcal energy per 100 g of the diet per day is optimum for growth and efficient feed utilization of Labeo rohita. Results for 2–4% rations (0.8–1.6 g protein and 7.23–14.46 kcal energy) suggest these amounts approximate to the maintenance requirement of this fish.     

Comparative Susceptibility of Channel Catfish,Ictalurus punctatus; Blue Catfish,Ictalurus furcatus; and Channel (♀) × Blue (♂) Hybrid Catfish to Edwardsiella piscicida,Edwardsiella tarda,and Edwardsiella anguillarum

Members of the genus Edwardsiella are important pathogens of cultured and wild fish globally. Recent investigations into the phenotypic and genotypic variation of Edwardsiella tarda have led to the segregation of E. tarda into three distinct taxa: E. tarda, Edwardsiella piscicida, and Edwardsiella anguillarum. In catfish aquaculture in the southeastern USA, E. piscicida has been more commonly associated with disease than E. tarda or E. anguillarum, and recent research has demonstrated E. piscicida to be more pathogenic in channel catfish than E. tarda or E. anguillarum. Anecdotal reports from industry suggest an increased prevalence of E. piscicida associated with the culture of channel (♀) × blue (♂) hybrid catfish. This work investigated the comparative susceptibility of channel catfish, blue catfish, and their hybrid cross to molecularly confirmed isolates of E. tarda, E. piscicida, and E. anguillarum. There was significantly higher mortality in hybrid catfish compared to channel catfish following intracoelomic injection of E. piscicida. To our knowledge, E. piscicida is the first bacterial pathogen to demonstrate increased pathogenicity in hybrid catfish compared to channel catfish.     

投喂卤虫无节幼体条件下黄颡鱼仔稚鱼生长、存活率、摄食力和体成分的变化

试验分析了投喂卤虫无节幼体条件下黄颡鱼(Pseudogrus fulvidraco)仔稚鱼生长、存活率、摄食力和体成分的变化。随着仔稚鱼的生长和发育,摄食率和胃充塞度逐渐加大,体长大于10 mm的仔鱼,摄食率都在93.3%以上,大多数个体胃充塞度都在3～5级。投喂卤虫无节幼体的黄颡鱼仔稚鱼生长较传统育苗方式生长快,存活率高。体内粗养分、氨基酸与脂肪酸含量都发生相应变化。黄颡鱼淀粉酶、蛋白酶与脂肪酶活性均在1日龄时即可检测到,开口期即5日龄时,3种消化酶比活力均达到较高值,15日龄后消化酶比活力又都降低到较低水平。卤虫无节幼体体内营养物质含量丰富,大小适口,是黄颡鱼仔稚鱼开口摄食的优质生物饵料。     

Retained levels of dietary α-, γ- and δ-tocopherol in tissues and body fluids of Atlantic salmon, Salmo salar, L.

The purpose of this study was to describe the relationship between dietary supplementation and concentration of γ- and δ-tocopherol (TOH) in tissues of Atlantic salmon, Salmo salar , L., when α-TOH was fed at a constant level. Post-smolt Atlantic salmon (230 g) in duplicate tanks were fed a fish-meal-based diet with 250 g kg⁻¹ lipid. Different combinations of RRR -tocopherylacetate preparations were added to give the following levels of TOH (mg kg⁻¹) in diets 1–4, respectively: 150α; 150α+ 100δ; 150α+ 50γ+ 50δ; 150α+ 100γ+ 100δ. The concentrations of γ- and δ-TOH in most tissues were directly proportional to the feed concentrations. Exceptions were γ-TOH in erythrocytes, spleen and kidney and δ-TOH in heart muscle, where the intercept with the y -axis was significantly different from zero. The relative retained levels of α-, γ- and δ-TOH in most tissues were similar to their biological activities in mammals. An exception was muscle and adipose tissue, where γ- and δ-TOH were retained at rates of 70–90% and 20–35% compared with α-TOH, respectively. α-TOH was retained to a greater extent when α-TOH was fed alone than when γ- and δ-TOH were added to the diet. Fish growth was significantly correlated to total dietary TOH concentration. The data suggest that turnover of tocopherols in Atlantic salmon is similar to that in mammals, i.e. that discrimination between the tocopherols is mediated through competition for a tocopherol-binding protein in the liver, and consequently that α-TOH is preferentially secreted in very low density lipoprotein. Muscle and adipose tissue appear to be supplied with tocopherols from chylomicrons that have not yet been exposed to the hepatic discrimination mechanism.     

Influence of Vitamin E Source and Dietary Supplementation Level on Production Performance of Sunshine Bass, Morone chrysops ♀ × Morone saxatilis ♂, Fillet Tocopherol Content, and Immunocompetency during Stress and Bacterial Challenge

We evaluated the effects of dietary vitamin E concentration and source on production performance and immunocompetency of sunshine bass, Morone chrysops  ×  Morone saxatilis , following stress and disease challenge. Four diets were formulated to contain requisite levels (1×) or five times (5×) the vitamin E requirement of sunshine bass as met by synthetic vitamin E (SYNE) or natural source vitamin E (NSVE). Each diet was fed to juvenile sunshine bass for 8 wk prior to experimental challenges. Replicate tanks within each dietary treatment were challenged with stressor exposure (chasing with dip net), incidental Flavobacterium columnare exposure, or both; control groups were not challenged. Pathogen and/or stressor exposure largely resulted in significant reductions in immunological performance. Although significant independent dietary effects were not observed among immunological parameters, suppression of complement and macrophage respiratory burst activities was numerically lower within the 5× NSVE treatment. Production performance was largely unaffected by dietary vitamin E source or level. Fillet α-tocopherol concentration was significantly higher among fish fed the 5× diets (40.7/41.6 vs. 12.2/14.5 μg/g dry tissue for 1× diets); however, the dietary concentration required to achieve these levels was lower for NSVE. Although super-requirement levels of either source of vitamin E were apparently beneficial, NSVE was effective at ∼50% lower supplementation levels.     

Artificial spawning of European catfish, Silurus glanis L.: stimulation of ovulation using LHRH-a,Ovaprim and carp pituitary extract

Ovulation was stimulated in four groups of European catfish, Silurus glanis L., using injections of des-Gly¹⁰, [D-Ala⁶]-LHRH Ethylamide (20 μg kg^–1) and pimozide (10 mg kg^–1), Ovaprim (0.33 mL kg^–1), and carp pituitary extract (4 mg kg^–1, in one or two doses). A higher percentage of ovulating females (producing eggs of sufficient quality) was found after the LHRH-a and Ovaprim treatments (100% and 80%) in relation to fish treated with the pituitary extract (60% and 66.67%). The greatest weight of eggs was obtained in the case of repeated hypophysation and LHRH-a (1299.69 and 1298.57 g, respectively), and the smallest after single hypophysation (1144.08 g). After 60 h of incubation, the best quality of eggs was found in the group treated with Ovaprim (62.9% of live embryos) and the poorest in the two groups which underwent hypophysation (50.41% and 50.75%). No statistically significant effect by the ovulation stimulators on the characteristic qualitative and quantitative traits of obtained eggs was ascertained.     

Anaesthetic efficacy of MS‐222 and AQUI‐S® in advanced size fry of rohu,Labeo rohita, (Hamilton‐Buchanan)

Anaesthetic agents are very useful for reducing the stress caused by handling, sorting, transportation, artificial reproduction, tagging, administration of vaccines and surgical procedures in fish. The efficacy of two anaesthetics: MS‐222 and AQUI‐S^® were tested on rohu, Labeo rohita advanced size fry. The lowest effective doses that produced induction in 3 min or less and recovery times 5 min or less and meet the most criteria of good anaesthetic characteristics were 125 mg L^?1 of MS‐222, and 30 mg L^?1 of AQUI‐S^® in rohu, Labeo rohita advanced size fry. Induction times were significantly decreased with increased in the concentrations of any of the two tested anaesthetic agents. The lowest doses suitable for transportation of rohu advanced size fry observed were: 10–15 mg L^?1 of MS‐222 and 2.5 mg L^?1 AQUI‐S^®. Both anaesthetics showed promising to be used as anaesthetics for handling and transportation in rohu (Labeo rohita) advanced fry.     

Effect of dietary encapsulated organic salts (Na‐acetate,Na‐butyrate,Na‐lactate and Na‐propionate) on growth performance,haemolymph, antioxidant and digestive enzyme activities and gut microbiota of juvenile narrow clawed crayfish,Astacus leptodactylus leptodactylus Eschscholtz, 1823

A 63‐day experiment was done to study the effects of four levels (5, 10, 20 and 50 g/kg) of encapsulated organic salts (Na‐acetate, Na‐butyrate, Na‐lactate and Na‐propionate) on the growth indices and haemato‐immunological responses of crayfish Astacus leptodactylus leptodactylus (4.38 ± 0.08 g). Crayfish were distributed at 51 1,000‐L tanks (17 treatments at triplicate). The highest values of final weight (27.86 g), specific growth rate (2.94% body weight per day) and survival rate (96%) were observed in the crayfish fed the 20 g/kg of encapsulated Na‐propionate diet (p < .05). The highest activities of phenoloxidase (7.4 U/min), superoxide dismutase (7.80 U/min) and lysozyme (9.40 U/min) were observed in the gut of crayfish fed the 20 g/kg of encapsulated Na‐propionate diet (p < .05), as well as the highest activities of alkaline protease (10.70 U/mg), lipase (9.10 U/mg), amylase (9.60 U/mg) and the lactobacillus count (p < .05). Broken line regression model of SGR and phenoloxidase activity suggested that the optimum dietary levels of encapsulated Na‐acetate, Na‐butyrate, Na‐lactate and Na‐propionate could be 30.7, 31.8, 31.4 and 33.5 g/kg, respectively, in crayfish reared in culture conditions.