放养密度和投饲量对沟篮子鱼生长和饲料利用率的影响

探索了不同放养密度和投饲量水平下沟篮子鱼的生长情况和饲料利用率。     

密度、饲料配比和投饲频率对菲牛蛭成活和生长的影响

采用湿土网箱法,在内铺土层厚度约6．0cm,规格35．0cm×14．5cm×11．5cm的网箱中层,饲养体质量≥1．5 g的菲牛蛭,以存活率和个体体质量增长率为考察指标,采用L9（34）正交试验法,对养殖密度、饲料配比和投饲频率三个因素进行考察,以确定合理的养殖密度、饲料配比和投饲频率。采用层次分析法统计正交试验结果,分析各因素各水平对试验结果的影响权重。试验结果表明,以存活率为考察指标时,三种因素对成活率的影响依次为养殖密度＞投饲频率＞饲料配比,以50尾／箱的养殖密度,饲料配方Ⅱ和每15 d投喂一次的投饲频率组合为最佳;以菲牛蛭个体体质量增长率为考察指标时,三种因素对个体体质量增长率的影响依次为饲料配比＞投饲频率＞养殖密度,投喂以密度为50尾／箱、饲料配方为Ⅰ、投喂频率为每10 d投喂一次组合为最优。层次分析表明,各因素对正交试验的指标值影响的主次顺序为养殖密度、投饲频率和饲料配比,正交试验的最优方案为50尾／箱的养殖密度、配方Ⅰ和每10 d投喂一次的投饲频率。     

养殖密度对厚颌鲂幼鱼生长、饲料利用及肠道抗氧化应激性能的影响

本研究拟通过养殖实验确定厚颌鲂(Megalobrama pellegrini)幼鱼最适养殖密度;同时,利用酶学和分子生物学手段分析养殖密度对厚颌鲂幼鱼肠道抗氧化酶活性及氧化应激相关基因表达的影响。实验设计5个密度处理组,分别为0.15 kg/m³ (50尾/桶)、0.24 kg/m³ (80尾/桶)、0.34 kg/m³ (110尾/桶)、0.42 kg/m³ (140尾/桶)和0.50 kg/m³ (170尾/桶),每组设置3个平行,实验周期为42 d。结果显示,当养殖密度从0.15 kg/m³ 逐渐升高到0.50 kg/m³ 时,厚颌鲂幼鱼生长(增重率和特定生长率)呈先上升后下降的趋势,且在最大密度时(0.50 kg/m³ )增重率和特定生长率显著低于0.34 kg/m³ 密度实验组(P<0.05)。同时,最高养殖密度处理组(0.50 kg/m³ )饲料系数显著高于中低密度实验组(0.15、0.24和0.34 kg/m³ )(P<0.05),说明过高养殖密度不利于厚颌鲂幼鱼的生长和饲料利用。实验表明,提高养殖密度并未影响厚颌鲂幼鱼成活率(P>0.05),各组存活率均较高(>97%)。当养殖密度为0.34 kg/m³ 时,厚颌鲂幼鱼全鱼粗蛋白和粗脂肪含量显著高于其他各密度实验组(P<0.05)。厚颌鲂幼鱼肠道抗氧化应激相关指标受到养殖密度的显著影响,其中,0.24和0.34 kg/m³ 密度处理组鱼体肠道总抗氧化能力显著高于最低密度组(0.15 kg/m³ )和高密度组(0.42、0.50 kg/m³ )(P<0.05);最高密度实验组(0.50 kg/m³ )肠道超氧化物歧化酶(SOD)和过氧化氢酶(CAT)活性最低,而丙二醛(MDA)含量最高(P<0.05);谷胱甘肽(GSH)含量最高值出现在0.34 kg/m³ 处理组,显著高于其他各实验组(P<0.05)。最低密度实验组(0.15 kg/m³ )厚颌鲂幼鱼肠道细胞色素P450(CYP1 A)基因相对表达量显著低于较高密度实验组(0.42 kg/m³ )(P<0.05);最高养殖密度组(0.50 kg/m³ )鱼体肠道转录因子NF-E2相关因子2(Nrf2)基因相对表达量最高,而锰超氧化物歧化酶基因(MnSOD)相对表达量最低,与0.34 kg/m³ 密度处理组间有显著性差异(P<0.05),说明养殖密度过高时能引起鱼体的氧化应激反应。研究表明,体重为0.45~1.36 g的厚颌鲂幼鱼最适养殖密度为0.34 kg/m³ ,该结果可为提高厚颌鲂苗种培育效率,促进其种质资源恢复提供理论基础。     

海水网箱养殖长鳍篮子鱼的摄食与生长特性

于2005年10月至2006年5月对海水网箱养殖长鳍篮子鱼(Siganus canaliculatus)的摄食与生长特性进行了研究。结果表明,长鳍篮子鱼主要栖息于水体中下层,喜结群,易受惊,活动能力较强,具有争抢食物的习性,喜摄食网衣上附着的藻类。初始体重17.8±3.2 g的长鳍篮子鱼经187 d养殖,平均体重达68.4 g,日均增重0.27 g,平均瞬时增重率为0.72%。长鳍篮子鱼的生长速度受水温影响明显,采样阶段平均水温23.0℃时瞬时增重率达到最高值2.10%,当水温降到16.0℃以下时,瞬时增重率出现最低值0.22%。长鳍篮子鱼的全长与体长呈线性关系,相关方程式为:LT=0.7228LB+5.6424;体长与体重呈幂函数关系,相关方程式为:W=0.00002L3.0559,其生长属于等速生长类型。     

Dissolved Oxygen Level and Stocking Density Effects on Growth,Feed Utilization,Physiology, and Innate Immunity of Nile Tilapia,Oreochromis niloticus

A factorial design with three levels of dissolved oxygen (DO)—low 1.0–1.5 mg/l (LDO), medium 2.5–3.0 mg/l (MDO), and normal 6.0–6.5 mg/l (NDO)—and two stocking densities—0.2 g/l (SD1) and 0.4 g/l (SD2)—tested the interaction between oxygen and stocking density on juvenile tilapia performance. After the feeding trial, fish were intraperitoneally injected by pathogenic bacteria, Aeromonas hydrophila, and fish mortality was observed for 10 days post challenge. Highest growth was observed in the NDO-SD1 group. Reduction in DO concentration from 6.5 to 3.0 or 1.5 mg/L caused a reduction in fish growth and feed intake, which increased significantly by increasing fish density. Crude protein and total lipid in whole-fish body decreased significantly at LDO, while total lipid content decreased also at high SD. Glucose, activities of aspartate amninotransferase and alanine aminotransferase, creatinine, and uric acid in fish sera increased significantly, while total protein and total lipid decreased significantly at LDO and/or high density. Lowest fish immunity was observed in the LDO-SD2 group, suggesting that stress was maximized under LDO conditions and/or at high density.     

Effects of Population Density and Feeding Rate on Growth and Feed Consumption of Red Swamp Crawfish Procambarns clarkii

Wire-mesh enclosures were used in production ponds to conduct growth trials in which population density and feeding rate were evaluated in a 2 × 2 factorial arrangement for their effects on crawfish growth. Juvenile Procambarus clarkii of uniform size (0.5 g) were stocked at 2 or 20 animals/m² in experiment 1 and weighed biweekly for 12 wk. Rice forage served as the detrital base, and supplemental feed (25% crude protein) was provided at either a low (26–52 kg/ha per week) or high (104–418 kg/ha per week) rate. In experiment 2, mixed sizes of crawfish were stocked at 10/m² or 20/m² and fed the formulated feed at either 52 or 312 kg/ha per week. Feed consumption was estimated for each treatment combination. Only population density significantly affected crawfish growth. Mean weight gain and final weights were inversely proportional to density but only when total crawfish biomass exceeded 1,235 kg/ha. Growth was not significantly influenced by feeding rate, but the high feeding rate resulted in a significantly greater ratio of hepatopancreas weight to body weight and tended to decrease hepatopancreas moisture levels, indicating improved condition. Population density, feeding rate, and their interaction had significant effects on estimated feed consumption. From the simple linear regression of mean feed consumption on crawfish standing crop, it was estimated that crawfish consume about 0.1 kg of dry feed per ha per week per kg of crawfish biomass on a 5 d per week feeding schedule at mean water temperatures, ranging from 14 to 30 C.     

Effects of Diffused Aeration and Stocking Density on Growth, Feed Conversion, and Production of Florida Red Tilapia in Cages

The effects of four levels of diffused aeration (0, 6, 12, and 24 hours/day) and two stocking densities (400 and 600 fish/m³) on the culture performance of caged Florida red tilapia were evaluated in 1 m³ cages in a 2 ha watershed pond on St. Croix, U.S. Virgin Islands. Fish obtained a nutritionally-complete (36% protein), floating feed from demand feeders for 143 to 146 days. Diffused aeration had no significant ( P > 0.05) effect on fish growth, survival, feed conversion, and production in cages. Combined across all levels of diffused aeration, fish stocked at 400/cage had a greater growth rate (2.21 vs. 1.97 g/day), larger final body weight (370 vs. 335 g), and a lower feed conversion ratio (1.69 vs. 1.80) than fish stocked at 600/cage ( P < 0.05). The final biomass of fish stocked at the higher density (181 kg/m³) was greater than at the lower density (140 kg/m³). The enhancement of water exchange rates by diffused aeration did not increase tilapia growth rate or production in cages.     

Effects of Restricted Feeding Regimes on Growth and Feed Utilization of Juvenile Gilthead Sea Bream, Sparus aurata

The effect of restricted feeding on growth, feed efficiency, and body composition was studied in juveniles of gilthead sea bream, Sparus aurata. Juveniles (6.4 g) were stocked into 12 tanks at a density of 16 fish per tank. Four different feeding schedules were tested on triplicate groups of juvenile fish: (1) control fed for 48 d without deprivation, (2) starvation for 1 d and then refed for 2 d (S1), (3) 50% satiation for 2 d and then refed to apparent satiation for 2 d (R2), and (4) 50% satiation for 6 d and then refed to apparent satiation for another 6 d (R6). Results indicated that all fish subjected to cycled restricted feeding regimes were unable to achieve catching up with control group. The specific growth rate of fish in the control was significantly higher than those in S1, R2, and R6, which were not significantly different from each other. Protein efficiency and protein productive value were significantly higher in R2 compared to control, S1, and R6. Fish in R2 had lowest feed conversion ratio (1.12) compared to the control (1.17). Body protein composition in R6 was less than that of the control, S1, and R2, while moisture, lipid, and ash content were not significantly different compared to the control.     

Effects of Feeding Levels on Growth Performance, Feed Utilization, Body Composition, and Apparent Digestibility Coefficients of Nutrients for Grouper Epinephelus coioides Juveniles

An experiment was conducted to determine effects of feeding levels on growth performance, feed utilization, body composition, and apparent digestibility coefficients (ADCs) of nutrients for juvenile grouper Epinephelus coioides (initial weight, 10.31 ± 0.36 g). Grouper were fed a practical diet from 0 (starvation) to 3.5% (at 0.5% increments) body weight per day (bw/d) for 8 wk. ANOVA indicated that growth performance, feed utilization, body composition, and ADCs of dry matter, protein, and energy were significantly (P < 0.05) affected by feeding levels. Survival was the lowest for the starvation group and for fish fed a ration of 0.5% bw/d. Final mean body weight, weight gain (WG), specific growth rate, and metabolic growth rate increased with feeding rate from 0 to 2.5% bw/d (P < 0.05) and showed no significant differences above the level (P > 0.05). Feed conversion rate was significantly lower at a feeding level of 2.0% bw/d than above and below the level (P < 0.05). Protein efficiency ratio was markedly highest at the 2.0% bw/d ration level (P < 0.05). Lipid contents of whole body, muscle, and liver increased with increasing feeding rates from 0 to 3% bw/d and showed a slight decline at the feeding level of 3.5% bw/d. Protein contents of whole‐body composition, muscle, and liver remained relatively stable with the different ration amount with the exception of fish fed a ration of 0.5% bw/d, at which grouper possessed significantly lower body protein concentration (P < 0.05). Condition factor, viscerosomatic index, and hepatosomatic index were the lowest for fish fed 0.5% bw/d and tended to increase with the increasing feeding levels. ADCs of dry matter, protein, and energy decreased with increasing feeding levels from 0 to 2.5% bw/d and then remained relatively constant over the level. Based on the broken‐line regression analysis using WG data, the optimum and maintenance feeding levels for grouper were 2.5% bw/d and 0.25% bw/d, respectively.     

菲律宾蛤仔稚贝期不同培育密度对生长、成活率的影响

2001年～2002年在大连普兰店市进行了菲律宾蛤仔稚贝期在大水体培育条件下,培育密度为260万～400万枚/m2对稚贝的日生长速度、成活率的影响试验,2001年试验中总平均日生长速度为44 7μm,出苗量为12 168亿枚,成活率为85 4%;2002年试验中总平均日生长速度为39 2μm,出苗量为15 47亿枚,成活率为90 7%。试验表明,菲律宾哈仔稚贝培育密度为260万～400万枚/m2在实际生产中是可行的,对稚贝的日生长速度、成活率影响不显著。     

养殖密度对豹纹鳃棘鲈生长和血液生化指标的影响

为探究养殖密度对湿体质量为(132.75±0.51)g的豹纹鳃棘鲈生长和血液生化指标的影响,设计了低(9.34kg/m3)、中(19.23kg/m3)、高(37.22kg/m3)3个养殖密度,每个密度设3个重复,连续饱食投喂56d后取样,测定相关指标。试验结果表明,37.22kg/m3组的终末体质量、平均质量增加率和特定生长率均显著低于其他两组(P0.05),而9.34kg/m3、19.23kg/m3组间差异不显著(P0.05);养殖密度对饲料系数、摄食率、瞬时生长率和热量单位生长系数无显著影响(P0.05)。血清总超氧化物歧化酶的活力在37.22kg/m3组最高,19.23kg/m3组最低,且各密度组间差异显著(P0.05);37.22kg/m3组血清总抗氧化能力显著低于其他两组(P0.05),19.23kg/m3组高于9.34kg/m3组,但差异不显著(P0.05);37.22kg/m3组血清丙二醛显著高于其他两组(P0.05),而其他两组间差异不显著(P0.05);乳酸脱氢酶随养殖密度的升高显著增加,且各密度组间差异显著(P0.05);37.22kg/m3组谷丙转氨酶、谷草转氨酶显著高于其他两组(P0.05),而37.22kg/m3组的溶菌酶活性显著低于其他两组(P0.05),其他两组间差异不显著(P0.05);养殖密度对血浆葡萄糖、胆固醇、C反应蛋白、总蛋白、乳酸无显著影响。     

Effects of Stocking Density on Growth of Juvenile Channel Catfish Overwintered in Ponds

Channel catfish, Ictalurus punctatus, juveniles (mean weight 78.0 ± 3.5 g) were stocked into nine 0.04-ha earthen ponds at three rates (4,940 fish/ha, 12,350 fish/ha, and 24,700 fish/ha) and fed a prepared diet (32% protein) according to a fish size/water temperature-dependant feeding chart for 160 days during the winter. Morning water temperatures averaged 5.8°c during the study. No significant differences (P > 0.05) were found in individual fish length, survival, and percentage weight gain among treatments and averaged 19.4 cm, 96.2%, and -13.0%, respectively. No significant differences (P > 0.05) in whole-body composition were found among treatments. Percentage moisture, protein, and fat averaged 12.4, 50.8, and 28.4%, repectively. Stocking juvenile channel catfish at the lower rate, 4,940 fish/ha, did not significantly increase winter growth compared to growth of fish stocked at higher rates (12,350) and 24,700 fish/ha).     

长鳍篮子鱼繁殖季节性腺的组织学研究

采用常规组织切片法研究了长鳍篮子鱼繁殖季节各期卵巢和精巢的组织学结构特征。在所获得样本中,未发现Ⅰ期、Ⅱ期的卵巢和精巢。Ⅲ期卵巢以第Ⅲ时相卵母细胞为主,这时期液泡、卵黄颗粒出现,同时含有少量Ⅰ时相和Ⅱ时相的卵母细胞;Ⅳ期卵巢以第Ⅳ时相卵母细胞为主,Ⅳ时相晚期卵母细胞开始出现油球,细胞核偏移和变形,放射带明显;Ⅴ期卵巢的卵细胞游离,卵细胞的外层分别有胶膜、放射带和质膜;Ⅵ期卵巢主要由Ⅲ时相卵母细胞和大量的空滤泡外膜组成。长鳍篮子鱼精巢为辐射型,精巢内生殖细胞分为初级精母细胞、次级精母细胞、精子细胞和精子,各期生殖细胞和支持细胞组成了精小管,同一精小管中的生精细胞发育不同步。精子成熟后,充满整个精小管,完成发育过程。     

Effects of Stocking Density on Growth of Tilapia nilotica Cultured in Cages in Ponds

Reported maximum carrying capacities of Tilapia nilotica reared in cages are Iow ranging from 10 to 70 kg/m³. This may be related to total numbers of caged fish reared in a body of water and not simply density per cage volume. An experiment was conducted to demonstrate such effects.
Sixteen cages in a 0.77 ha pond were stocked with T. nilotica at either 250, 500, 750, or 1,000 fish/cage for a total of 12,987 fish/ha. One cage in each of four 0.13 ha ponds was stocked with either 250 or 1,000 fish/cage for a total of 1,923 or 7,692 fish/hectare, respectively. Fish were fed a 32% protein diet at equal rates for 169 days. In the 0.77 ha pond, yield per cage was positively correlated with stocking density, while individual mean weights were negatively correlated with stocking density. However, among equal densities per cage between ponds, fish in the 0.13 ha ponds gained about 26% more than in the 0.77 ha pond. An interaction of the effects of density per cage volume and per pond area may have occurred.     

培育密度对菲律宾蛤仔浮游幼虫生长与成活的影响

试验结果表明:菲律宾蛤仔浮游幼虫试验密度为5,10,15,20个/ml,各组幼体的平均日生长速度依次为18 7,12 1,11 2,8 3μm,成活率依次为88 0%,82 0%,79 8%,50 4%。综合分析认为,菲律宾蛤仔浮游幼虫在生产中育苗密度以10个/ml,15个/ml较为适宜。     

放养密度对虹鳟稚鱼生长的影响

虹鳟稚鱼伞长、体重生长速度随着放养密度的增大而降低,而这种差异随着生长时问的延长,表现更为显著稚鱼体重持定生长率随着放养密度的增大而降低,两者间存在着显著的负相关关系;Y=-5．0979X＋36．727（R2=0．9844）,Y代表体重特定生长率,X代表放养密度.日增重、饵料转化丰随着放养密度的增大而降低．净增重随着放养密度的增大而增加.     

Growth and Feed Conversion of Sub-Yearling Atlantic Sturgeon,Acipenser oxyrinchus,at Three Feeding Rates

Abstract

Growth and survival of fingerling Atlantic sturgeon, Aci-penser oxyrinchus, were examined at three different feed rates. Sturgeon (mean initial weight±SD of 28±12 g) were offered a closed-formula, commercially-available sturgeon diet (48.5% protein, 16.2% fat, 9.9% moisture, 7.6% ash, 0.5% fiber and 17.4% nitrogen free extract) via 24-hour, time-controlled feeders at rates of 1.5, 3.0, and 4.5% body weight per day (BW/day). Mean water temperature was 16.8°C. After 49 days of feeding, final length, final weight and feed conversion were all significantly affected by feeding rate (P ≤ 0.05). Peak feed conversion occurred at a ration of 1.5%, while maximum increase of both length and weight occurred at approximately 3.0%. No mortality occurred during the seven-week trial. The choice of feeding rates will ultimately depend upon production requirements and the culturist. Offering diet at a rate of 3.0% BW/day will result in significantly greater growth accompanied by high survival. Delivering diet at a rate of 1.5% BW/day will result in equally high survival and require approximately 50% less diet. It will, however, yield lower growth rates.     

养殖密度对地图鱼幼鱼生长发育的影响

在室内水族箱中养殖地图鱼的幼鱼,密度分别为50、100、200、400尾/m2,共养殖28d。试验结果表明,各密度组地图鱼幼鱼的生长速度存在明显差异,增重率、增长率、特定生长率和平均日增重都随养殖密度的增加而降低;高密度组(400、200尾/m2)地图鱼的幼鱼个体生长速度离散度明显加大。     

Effects of Feed Application Rates on Growth, Survival, and Feed Conversion of Juvenile Snakehead Channa striatus

Growth, survival and feed conversion ratio of juvenile snakehead Channa striatus were evaluated when fed a dry, formulated feed (50% crude protein) at 24 ± 1 C. Six daily feed application rates were used (0%, 5%, 10%, 15%, 20%, and 30%), as a percentage of fish body weight, with three replicates per treatment. After 29 d, final weights were all significantly greater ( P < 0.01) than initial weights, except for the 0% application. Feed applications higher than 5% did not result in increased growth ( P > 0.05). Feed conversion ratio was 0.99 at 5% feed application, and 6.3 at 30% feed application. Fish survival was increased by providing formulated diet, but no further improvement was found when feed applications exceeded 5%. Cannibalism was reduced by providing formulated feed, but it was unavoidable when substantial differences in fish size existed, even when feeding ad libitum . Our results indicate that the optimal feed application rate is close to 5% body weight/d for juvenile snakehead.     

Effect of Feeding Frequency, Water Temperature, and Stocking Density on the Growth of Tiger Puffer, Takifugu rubripes

Effects of daily feeding frequency, water temperature, and stocking density on the growth of tiger puffer, Takifugu rubripes, fry were examined to develop effective techniques to produce tiger puffer in a closed recirculation system. Fish of 4, 14, and 180 g in initial body weight were fed commercial pellet diets once to five times a day to apparent satiation each by hand for 8 or 12 wk at 20 C. Daily feeding frequency did not affect the growth of 14‐ and 180‐g‐size fish. However, the daily feed consumption and weight gain of the 4‐g‐size fish fed three and five times daily were significantly higher than those of fish fed once daily (P < 0.05). Fish of 4 and 50 g in initial body weight were reared with the pellet diet at 15–30 C for 8 wk. The weight gain of fish increased with increasing water temperature up to 25 C and decreased drastically at 30 C for both sizes. Similar trends were observed for feed efficiency, although 4‐g fish had highest efficiency at 20 C. Effects of stocking density on growth were examined with fish of 8, 13, and 100 g in initial body weight. Fish were reared with the pellet diet for 8 or 16 wk at 20 C. Fish were placed in floating net cages in the culture tank, and the stocking density was determined based on the total weight of fish and volume of the net cage. Fish of 8 g in body weight grew up to 35–36 g during the 8‐wk rearing period independent of the stocking density of 8, 15, and 31 kg/m³ at the end of rearing. Final biomass per cage reached 32, 60, and 115 kg/m³ for 13‐g‐size fish, and 10, 18, and 35 kg/m³ for 100‐g‐size fish, and the growth of the fish tended to decrease with increasing stocking density for both sizes.