牙鲜幼鱼能量代谢的初步研究

对个体重２．５～８７．６ｇ的牙鲆幼鱼的代谢进行测试。结果表明：温度和体重对牙鲆幼鱼的耗氧率及二氧化碳排出率有明显的影响;牙鲆幼鱼的呼吸商为０．８２±０．０８,氧氮比为２３．８±６．６,其能源物质以蛋白质和脂肪为主;牙鲆在盐度为３０、２５、２０和１５的水中,平均代谢率分别为３．０８、３．０７、３．８７和３．２８Ｊ／ｇ·ｈ,说明牙鲆幼鱼适盐较广,在本实验盐度阈值内,对鱼体代谢基本没影响。     

鱼类能量需要量研究进展

综述了鱼类能量需要量的研究进展。不同鱼类的基础代谢值差别不大，２０℃左右的３５～４５ｋｇ／ｋｇ＾－０．８．ｄ；鱼类维持能量需要低，为摄放总代谢能的１５％～２４％；鱼类合成Ｉｇ蛋白质和Ｉｇ脂肪代谢能需要分别主５３．９和４１．７ｋＪ。鱼类能量总需要可以用适宜能量浓度，单位体重和单位代谢体重能量需要表示，鱼类消化能需要在１３～１９ＭＪ／ｋｇ饵料，适宜能蛋比为３３．５～４６．１ＫＪＤＥ／ｇ蛋白质左右；单位     

鱼类氨氮排泄率及其毒害

氨是海洋和淡水鱼类的主要排泄产物，在水产养殖中，非离子态氨的聚积会对鱼类等养殖生物造成毒害，严重的会造成死亡。水体中氨氮含量的测定是水质分析的重要组成部分。 ｌ.鱼类的排泄率 鱼类的氮排泄物主要有氨、尿素和尿酸，对海水和淡水鱼类来说，氨都是最主要的排泄物，硬骨鱼类排泄的氨占总氮排泄物的７０％～９０％，尿素仅占５％～１５％。至于氮的排泄部位，一般氨氮主要通过鳃排出，仅一小部分通过尿液排出，尿氮则通过尿液排出体外。 氨从鳃部排出的方式主要有简单扩散和离子交换。氨主要以两种形态从鳃部排出，即离子态和非离子…     

氮的循环及氨氮、亚硝酸盐对鱼体健康的影响

正鱼类进食、呼吸、粪便排泄、繁殖、吸收和排泄盐类等行为全部都发生在水中,因此水质的好坏直接影响着鱼类的健康程度和水产品的安全性。1氮的循环氮的循环是水产养殖生态系统中物质循环的重要环节,养殖水体中氮的多少关系到水产养殖生态系统中物质能量的转化。氮是浮游植物生长所必需的,是组成蛋白质的重要成     

池塘养鱼慎防氨氮中毒

一、氨氮的来源 水中的氨氮是指以非离子氨（NH3）和离子氨（NH4＋）形式存在的氮。投入池塘中未完全消化利用的饲料，施入池塘的含氮有机肥料，池塘中死亡的动植物，在分解代谢的过程中，都会产生大量氨氮，鱼类排出的代谢废物也含有大量的氨氮，包括氨、尿素、尿酸等。氨氮的产生，与蛋白质密切相关，饲料中蛋白质含量越高，最终产生的氨氮也越多。水中的氨氮可通过硝化作用转化为硝态氮，     

褐牙鲆水中阻力的初步研究

鱼类在水中游泳时,需要克服水的阻力从而需要消耗一定的能量.鱼类依鱼种、大小以及形态特征的差异,在同样的水流条件或游泳速度下,其水中阻力也不相同.本研究通过对褐牙鲆(Paralichthys olivaceus)在垂直循环水槽中进行游泳阻力测试实验,分别用3种特征面积(横截面积、湿表面积和鱼体体积的2/3次方),获得褐牙鲆3种不同的阻力系数.经比较分析发现,在雷诺数Re为2.7×104～1.91×105时,采用湿表面积作为褐牙鲆的特征面积获得的阻力系数的平均值为0.020,此时标准差最小,仅为0.000 76.而分别用横截面积和鱼体体积的2/3次方时获得的阻力系数的标准差相对较大.因此,用褐牙鲆的湿表面积计算得到的阻力系数更适合于该种鱼类个体水中阻力的研究.     

泥鳅幼鱼对饲料中脂肪的营养需求量研究

脂肪除了提供鱼类生长所必需的脂肪酸外，还是鱼类的重要能量物质和脂溶性维生素（A、D、E、K）的溶解介质。高水平蛋白饲料一方面消耗宝贵的蛋白源，另一方面，动物对蛋白源分解代谢产生的氮、磷排泄物造成水域环境污染。因此，从营养、环境和生态学角度考虑，高效、经济、环保的配合饲料应尽量由脂肪和碳水化合物提供能量，以降低蛋白质的消耗并降低成本。     

牙鲆蛋白质感染因子蛋白基因的克隆和结构分析

采用RT-PCR方法分离牙鲆（Paralichthys olivaceus）蛋白质感染因子蛋白编码基因序列。推测的牙鲆蛋白质感染因子蛋白由472个氨基酸组成，分子量约49．6kD，具有信号肽、短肽顺接重复、疏水区、糖基化位点、二硫键、糖基缩醛磷肌醇锚定位点等蛋白质感染因子蛋白特征结构域，与红鳍东方纯（Fugu Rubripes）和大西洋鲑（Atlantic salmon）蛋白质感染因子蛋白的相似性分别为71．9％和66．4％。牙鲆蛋白质感染因子蛋白编码基因序列的获得为蛋白质感染因子进化与功能研究以及可能存在的鱼类传染性海绵样脑病研究奠定了基础。     

基于心电图法(ECG)的牙鲆听觉特性研究

牙鲆(Paralichthys olivacues)为底栖无鳔鱼类,是中国北方重要的海水经济鱼种。本研究通过自主构建的鱼类听觉测量系统,使用心电图法(electrocardiogram,ECG)分别以声刺激频率为60 Hz、100 Hz、150 Hz、200 Hz、300 Hz、400 Hz、500 Hz、700 Hz的正弦波纯音,对20尾牙鲆的听觉阈值进行测定,并绘制出牙鲆的听觉阈值曲线,研究了牙鲆的听觉特性。结果表明,20尾牙鲆均记录到声刺激诱发心率信号,牙鲆对60~200 Hz的低频音较敏感;最敏感频率为100 Hz,其听觉阈值为(94±1.5)d B。本研究可以帮助了解牙鲆的听觉特性,一方面可为鱼类听觉特性的基础研究提供参考,另一方面为今后我国牙鲆的增养殖工作,以及海洋牧场建设提供数据支撑。     

低蛋白日粮对生长猪养分消化和氮排放的影响

用体重60 kg左右的长×大杂交猪20头,分为4个处理,每个处理5个重复,各处理日粮蛋白水平在NRC(1998)标准基础上依次下降3、4和5个百分点,并添加合成氨基酸,使各处理可消化赖氨酸、蛋+胱氨酸、苏氨酸、色氨酸和异亮氨酸水平不低于NRC标准和理想蛋白质氨基酸比例,研究低蛋白氨基酸平衡日粮对生长猪养分消化代谢和氮减排的影响。结果表明,低蛋白氨基酸平衡日粮在蛋白质适度情况下对生长猪采食量、排粪量、粪蛋白量影响不明显(p0.05);蛋白质降低4个百分点以上时显著降低蛋白质消化率(p0.05);日粮氮利用率随蛋白质水平降低而升高(p0.05);有减少猪粪便中臭味物质(如吲哚等)含量,改善猪舍环境的作用。结论认为,低蛋白质氨基酸平衡日粮的减排作用主要是通过氮摄取和排出减少,而且主要是通过减少尿量和尿氮的方式实现的。     

Energy and nitrogen partitioning in 250 g Atlantic cod (Gadus morhua L.) given graded levels of feed with different protein and lipid content

The effects of feed intake level on energy and nitrogen partitioning were studied in juvenile Atlantic cod (250 g) fed two fish meal based diets differing in protein and lipid content (54:31 and 65:16) at 10 °C. Replicate groups of cod were feed deprived for 32 days or fed one of the two diets at 25, 50, 75 or 100% of group satiation for 60 days. Feed intake and oxygen consumption were measured daily and weights and chemical composition of carcass, liver, viscera and whole body were measured at start and end. Diet digestibilities were assessed in a separate experiment.

The whole body and carcass growth rates at a given feed intake did not differ between dietary groups, but the liver grew faster in the fish fed the low protein diet, resulting in higher hepatosomatic indices at the end of the experiment in the groups fed this diet.

The efficiency of utilisation of digestible nitrogen for growth (k_DNg) was higher for the low protein diet (0.73 ± 0.02) than for the high protein diet (0.53 ± 0.05), resulting in higher nitrogen retention at a given nitrogen intake. No difference in percentage nitrogen retention was seen in full-fed fish however (31.2 ± 2.5 and 28.4 ± 1.6% for the low protein and high protein diets, respectively). This can be explained by higher nitrogen intake in the fish fed the high protein diet, resulting in a smaller proportion of the intake being used for maintenance.

There was no difference in energy utilisation between dietary groups. The digestible energy requirement for maintenance (DE_maint) was 53.8 ± 0.9 kJ kg^− 1 d^− 1 (42.3 ± 0.7 kJ kg^− 0.8 d^− 1) and the utilisation efficiency for growth (k_DEg) was 0.80 ± 0.02. The energy retention in full-fed fish was 31.3 ± 3.5 and 31.7 ± 1.0% for the low protein and high protein diets, respectively. The deposited energy was distributed in approximately equal proportions in the liver and carcass, whereas viscera accounted for a minor proportion. At a given energy intake, the fish fed the high protein diet deposited more energy in the carcass and less in the liver than did those fed the low protein diet.     

Growth, feed and nutrient utilisation and gastrointestinal evacuation time in Atlantic salmon (Salmo salar L.): the effect of dietary fish meal particle size and protein concentration

Growth, nutrient utilisation and gastrointestinal evacuation time using different fish meal particle sizes and dietary protein concentration was examined in Atlantic salmon. Salmon were given micro, standard or coarse grounded fish meals at two dietary protein concentrations (30 or 45%) in isolipid diets. Gastric evacuation time was influenced by fish meal particle size. Coarse ground fish meal gave a slower gastric evacuation time compared to finer ground fish meal. Specific growth rate was not influenced by the protein concentration, but there was an adverse effect of coarse ground particles. This effect may be explained by the reduced feed intake of fish fed diets containing coarse ground fish meal. Feed conversion ratio (FCR) or energy conversion ratio (ECR) was reduced with increasing dietary protein concentration. This effect was mainly caused by different energy levels in the diets and not protein/carbohydrate levels. Standard coarse fish meal gave a reduction in ECR, but there was no effect of fish meal particle size on FCR. A protein sparing effect of starch was demonstrated. Productive protein value (PPV) and productive energy value (PEV) was not affected by dietary protein concentration or fish meal particle size. Dietary protein concentration had no effect on nitrogen or fat digestibility but there was a reduction in fat digestibility when coarse ground fishmeal was used in the diets. There were only minor effects on the dressing out percentage, condition factor and fat in cutlet.     

Low-protein supplement increases protein retention and reduces the amounts of nitrogen and phosphorus wasted by rainbow trout fed on low-fat herring

The growth, food utilization and amounts of nitrogen and phosphorus lost into the water by rainbow trout (initial size 485 g) fed on low-fat Baltic herring and supplemented with a low-protein dry diet fed separately were studied in an 18-week net cage trial. Similarly to balancing protein and nonprotein energy in full diets, giving nonprotein energy in different feeds several hours apart improved the protein retention of low-fat herring to a level comparable to a commercially available dry diet control. The amounts of nitrogen and phosphorus lost into the water were also reduced to the same extent. The losses from the plain herring-feeding were twice as high. The improved protein retention and reduced nutrient losses were accompanied by 15–25% reductions in growth of the fish compared with the control dry diet. The growth of the fish fed on plain herring was 14% lower than the growth on the dry diet control.     

Almost total replacement of fish meal by plant protein sources in the diet of a marine teleost, the European seabass, Dicentrarchus labrax

Five practical diets in which the supply of protein from fish meal was decreased gradually from 100% to about 2% and replaced by plant protein sources were formulated. European seabass weighing about 190 g were fed these diets for 12 weeks at a water temperature of 22 °C. Feed was dispensed using automatic self-feeders and voluntary feed intake (VFI) was closely monitored. We did not find any significant difference among diets in the apparent digestibility coefficients (ADC) of dry matter (80–82%), protein (94–96%), energy (88–92%) or phosphorus (49–58%). Replacement of fish meal by plant protein ingredients did not influence VFI. All groups had very good growth rates (DGI above 1.3%/day) and there were no significant differences in growth rate, feed efficiency or in daily nitrogen gains among groups. There was, however, a slight increase in fat deposition in fish fed diets with plant protein sources. Ammonia nitrogen and soluble phosphorus excretion rates were measured. Nitrogen and phosphorus balance studies indicated that fish meal replacement by plant ingredients led to a slight increase in nitrogen losses (from 83 to 103 g N/kg weight gain) but led to a significant reduction in total phosphorus losses (from 13 to 5 g P/kg weight gain). These results combined with the remarkable acceptability of diets containing high levels of plant protein ingredients with identical growth performances of European seabass show clearly that dietary fish meal levels can be considerably reduced without any adverse consequence in terms of somatic growth or nitrogen utilisation.     

Substitution of fish meal by sesame oil cake (Sesamum indicum L.) in the diet of rainbow trout (Oncorhynchus mykiss W.)

The present study evaluated the nutritional value of sesame oil cake (SOC) in rainbow trout fry (initial body weight of 1.42 g) in a growth trial performed for 45 feeding days at 15 ± 1 °C. A series of five isonitrogenous (380 g digestible protein kg^?1 dry matter (DM)) and isoenergetic (18.1 MJ digestible energy kg^?1 DM) diets were formulated in which the digestible SOC protein progressively replaced 0%, 13%, 26%, 39% and 52% of the digestible protein of a high quality fish meal (D0‐D52). Growth rate of fry significantly improved in fish fed SOC diets compared to the fishmeal control diet (D0) whatever the SOC inclusion level. This positive effect on growth was mainly related to a marked improvement of voluntary feed intake. The decrease of feed efficiency observed with increasing SOC was entirely explained by the reduction of DM and energy digestibilities with SOC incorporation. Nitrogen retention efficiency (nitrogen gain/nitrogen intake) was high (40–41%) and significantly reduced only in fish fed D52 (37%). Our results suggest that SOC can be a suitable protein source for a carnivorous fish and replace at least half of the fishmeal protein (without amino acid supplementation) without growth reduction in rainbow trout fry.     

Nitrogen balance in trout : II. Nitrogen excretion and retention after feeding diets with varying protein and carbohydrate levels

The utilization of dietary protein in rainbow trout was investigated by determining the nitrogen balance. The fish were fed on three experimental diets containing different ratios of protein and carbohydrate (74% protein/9% carbohydrate; 58%/26%; 32%/53%). Nitrogen retention was determined by measuring the nitrogen intake and nitrogen losses of the fish. In this paper we report upon nitrogen excretion, nitrogen retention, gross protein efficiency and also feed conversion. Nitrogen excretion increased with increasing protein and decreasing carbohydrate content in the diet. Similarly, nitrogen retention increased when the fish were fed a diet richer in protein. Gross protein efficiency was highest (and nearly the same) with the two diets containing higher levels of protein, while the diet low in protein but rich in carbohydrate tended to cause poorer protein efficiency. Feed conversion was also highest with the two diets with higher protein levels but lower with the diet poorest in protein. The results obtained from the study of different fish groups each fed one diet were nearly identical to results of one fish group fed different diets.     

Effects of steam pelleting or extrusion on digestibility and performance of silver perch Bidyanus bidyanus

The effects of different processing techniques on apparent digestibility coefficients (ADCs) and performance of silver perch Bidyanus bidyanus were evaluated. Results of a factorial digestibility trial, in which three diets (SP35, 95LC1 and 95LC2) and three processing methods (cold pelleted, steam pelleted and extruded) were evaluated, indicated that extrusion, but not steam conditioning, significantly improved ADCs of dry matter (DM) and energy. ADCs of DM and energy of cold‐pelleted diets were statistically similar to steam‐pelleted diets, and ADCs of nitrogen were unaffected by processing method. No interaction was found between diet type and processing method for DM, energy or nitrogen ADCs. A performance trial indicated that feed intake, weight gain and specific growth rate of fish fed steam‐pelleted diets was greater than those of fish fed extruded diets. Feed conversion and digestible protein efficiency was better in fish fed extruded diets. The results indicated that extruded diets were better utilized than steam‐pelleted diets; however, voluntary intake of extruded diets may have been limited. Fish fed cold‐pelleted SP35 exhibited inferior performance compared with fish fed steam‐pelleted or extruded SP35. Reduced performance of fish fed this diet may relate to poor utilization of digestible protein or reduced palatability. Diets for silver perch with similar formulations to SP35 and 95LC2 should be steam pelleted.     

The effect of dietary ribonucleic acid incorporation in performance of European sea bass (Dicentrarchus labrax) juveniles

The aim of this study was to evaluate the effect of dietary ribonucleic acid (RNA) on the performance of European sea bass juveniles. Two diets containing fish meal as the only nitrogen source were formulated with 39% or 50% of crude protein (LP and HP diet, respectively). Two other diets were formulated similarly to LP diet, but included yeast-RNA extract at 6.2% and 12.4% levels (LP6 and LP12 diets, respectively) by replacing dextrin. Total nitrogen content of the LP12 diet was equivalent to that of the HP diet. The four experimental diets were isoenergetic (22 kJ GE g⁻¹ DM). Triplicate groups of 25 fish (IBW=13 g) were fed the test diets for 10 weeks. The reduction of dietary protein level did not significantly affect growth rate but significantly increased feed intake and decreased feed efficiency. However, nitrogen retention (%N intake) was significantly improved with the decrease in dietary protein level. Dietary RNA incorporation did not affect feed intake or feed efficiency, although it reduced growth rate of fish fed the highest dietary RNA level. Nitrogen retention (%N intake) significantly decreased with the dietary supplementation of RNA. Dry matter, nitrogen and energy digestibilities were not significantly affected by dietary treatments. Final whole-body composition was also unaffected by dietary treatments, except for ash content which was significantly higher in the LP12 group. Hepatosomatic index was significantly increased by the dietary incorporation of RNA. The dietary supplementation of RNA had no protein sparing effect and significantly reduced energy retention. It may be concluded that dietary RNA supplementation had no nutritive value for European sea bass.     

Protein and Energy Metabolism of European Seabass (<Emphasis Type="Italic">Dicentrarchus labrax</Emphasis>) Juveniles and Estimation of Maintenance Requirements

The present work aimed to study metabolic utilization of energy and protein by juvenile European seabass reared at 25 °C and to estimate maintenance requirements, based on indirect calorimetry and nitrogen excretion measurements. Duplicate groups of fish (IBW = 22 g) were fed a practical diet, for 28 days, at ration levels of 0, 0.25, 0.5, 1 and 1.5% of body weight. At the end of this period, oxygen consumption and ammonia nitrogen excretion were measured in fed and unfed fish. Weight gain linearly increased with ration level. Feed efficiency significantly increased with nitrogen intake up to 0.68 g N/kg/day. Nitrogen retention (% N intake) was positive at all feeding levels, being maximum at 0.5% BW and then decreased with increasing ration levels. There was negative energy balance at the lowest ration level and significantly increased at higher ration levels. Daily oxygen consumption (g/kg body mass) and ammonia excretion (mg N–NH₄/kg body mass) significantly increased with ration level. Heat production and heat increment of feeding (kJ/kg/day) remained low at low ration levels and significantly increased as ration level increased from 0.5 to 1.5% BW. Below maintenance, protein energy represented 34% of total energy expenditure and significantly increased to 49–56% above maintenance. Based on indirect calorimetry and ammonia excretion data, maintenance energy and protein requirements were estimated to be 56.8 kJ DE/kg/day and 1.15 g DP/kg/day, respectively. The efficiencies of energy and protein utilization were estimated to be 0.83 and 0.66, respectively.     

瓦氏黄颡鱼幼鱼标准代谢的初步研究

研究了平均体质量为6.231、1.32 g和21.21 g瓦氏黄颡鱼幼鱼的标准代谢,并分析了幼鱼利用蛋白质、脂肪和糖类作为能源物的供能情况。通过测定幼鱼在禁食和静息状态下的耗氧率、排氨率和二氧化碳排出率,计算出幼鱼的呼吸熵、氧氮比和能耗率。试验结果表明,瓦氏黄颡鱼幼鱼的耗氧率、排氨率和能耗率均随幼鱼体质量的增加而显著下降(P<0.01),且耗氧率、排氨率和能耗率与体质量呈负相关关系,而呼吸熵与体质量则呈正相关关系。不同体质量幼鱼的二氧化碳排出率和氧氮比差异不显著;根据氧氮比的分析结果可知,瓦氏黄颡鱼幼鱼主要利用脂肪和蛋白质供能,且随着体质量的增长,脂肪供能的比例逐渐增大。结果显示,瓦氏黄颡鱼幼鱼对糖类的利用能力较为有限,有必要对该鱼的糖需求和利用率进行进一步的研究。