饲料中蛋白质和醣的含量对青鱼鱼种生长的影响

本文讨论了饲料中蛋白质和醣含量对青鱼鱼种生长的影响。试验饲料由酪蛋白、糊精、鱼肝油、羧甲基纤维素粉(CMC)、无机盐混合剂和适量的维生素组成。用于试验的青鱼鱼种的平均体重为37．12—48．32克，试验期间的水温为24—34℃，试验得到的数据，经统计分析表明，青鱼鱼种饲料的最适蛋白质含量为29．54—40．85％。饲料中蛋白质和醣含量之间存在着明显的交互作用，当蛋白质含量为37—43．3％，醣含量为9．5—18．6％时，青鱼鱼种生长最快。饲料的蛋白质含量对鱼体的蛋白质、脂肪和醣含量有一定影响，肝脏中蛋白质含量也受到饲料蛋白质含量的影响，肝醣含量则随饲料醣含量的增加而增加。饲料中蛋白质和醣的含量会影响青鱼鱼种的消化率，当饲料中蛋白质处于最适量而醣含量在30％以下时，鱼的蛋白质消化率大致为92％左右，醣含量过高将对蛋白质的消化率产生影响。饲料的组成对青鱼鱼种的血红蛋白含量影响不大。     

中国对虾对维生素B2、B5、B6营养需要的研究

研究了三种水溶性维生素Ｂ２，Ｂ５和Ｂ６在以酪蛋白为蛋白源的饲料中的不同含量对中国对虾的存活率，体重增重率，体长增长率，蛋白质消化率及实验维生素在体内的累积量等方面的影响。结果表明，在每１００ｇ饲料中维生素Ｂ２、Ｂ５和Ｂ６的含量分别在１０（体重１．５３ｇ）－２０ｍｇ（体重６．００ｇ）、４０ｍｇ、１４ｍｇ时，上述指标均达最佳，维生素缺乏或过量都会阻碍对虾生长，在适宜添加量范围中，随着饲料中维生素Ｂ６的     

红螯螯虾人工繁殖技术研究：II.红螯螯虾人工繁殖技术的探讨

红螯螯虾在厦门地区可以生长繁殖，其繁殖期为５－１０月份，盛期出现在６－８月份。每年自然水温上升至２６．３－２９．３℃时，受精卵孵化至稚虾需４２－４７天。用塑料编织网作为幼苗隐蔽栖息材料，投喂对虾苗在用１－２号配合饲料育效果理想。平均水温为２８℃时，由离开母体的稚虾（体长８ｍｍ）培育至体长为２－２．５ｃｍ的规格种苗，约需２５天。在正常情况下，每平方米育苗池，可生产出种苗１２３４－１９１０尾。     

黄海北部中国对虾放流虾生长的研究

本文报告了黄海北部中国对放流虾的生长特征。研究结果表明，在放流后到开捕时的时间间隔为，可用Ｌ＝ａ＋ｂ描绘放流虾的生长。１ｃｍ放流虾的时间为６月２日，体长１．１１ｃｍ，开捕时体长为 ２．５ｃｍ；２ｃｍ放流虾的时间是６月７日，体长为２．０ｃｍ，开捕时体长为１２．６ｃｍ。     

暗纹东方鲀对配合饲料表观消化率的初步研究

作者于1998年初步研究了暗纹东方对配合饲料的表现消化率。结果表明：在水温22℃－23℃时，东方对饲料的消化率较28℃－30℃时高；东方对配合饲料中的脂肪的消化率最高，其次为蛋白质、碳水化合物。     

蛋白能量比对中华绒螯蟹蛋白酶活力和饲料消化率的影响

于１９９９年６～７月收集中华绒螯蟹（Ｅｒｉｏｃｈｅｉｒ ｓｉｎｅｎｓｉｓ）粪便，用酸不溶灰分法测定中华绒螯蟹对饲料的消化率，同时测定其胃、肠、肝胰脏蛋白酶活力。结果表明，蛋白质能量比（Ｐ／Ｅ）２８．９３ｍｇ／ｋＪ水平对中华绒螯蟹胃、肝胰脏蛋白酶活性明显高于Ｐ／Ｅ２７．３０ｍｇ／ＫＪ和３０．３１ｍｇ／ＫＪ水平饲料蛋白南、脂肪、能量和总表观消化率分别为８２．５７％、７７．５９％、８３．９４％和９６．９     

青鱼对十四种饲料的消化率

以三氧化二铬(Cr_2O_3)为指示剂测定了青鱼(Mylophayngodon piceus)鱼种对饲料酵母、糊精、酪蛋白、豆饼粉、脱脂蚕蛹粉、玉米粉、麸皮、大麦粉、药用鱼粉、花生饼粉、棉仁饼粉、菜饼粉、苜蓿粉、青草粉共14种饲料的表观总消化率以及营养物质的消化率,并测算了总能量、能量蛋白比(C/P)以及可消化能。在水温25～28℃试验条件下,青鱼对酪蛋白的消化率最高,达93.8%;其次是饲料酵母、糊精、豆饼粉、脱脂蚕蛹粉、玉米、麸皮、消化率在82.1%～69.5%间;再次为大麦粉、棉仁粉饼、药用鱼粉、花生饼粉和菜饼粉,消化率在66.9%～45.9%间;苜蓿和草粉的消化率最差,为36.3%和22%。青鱼对营养物质的消化率有以下特点: 1.饲料中粗纤维含量与总消化率呈明显的负相关。2.粗蛋白含量与蛋白质消化率呈抛物线相关,当蛋白质在35%～40%时,蛋白质消化率最高。3.青鱼对脂肪的消化率很高,达90%以上。4.青鱼对碳水化合物具一定的消化能力。     

蛤蟆通水库乌鳢的生物学及其渔业利用

本文报道了蛤蟆通水库的乌鳢生物学特性和讨论了乌鳢在渔业生产发展中的作用。捕捞群体中平均体长２１．４—６６ｃｍ，体重１１８—３５１０ｇ，体重体长关系式为ｌｏｇＷ＝３．０４６６ｌｏｎｓＬ１．９６６６。３＋龄达到性成熟，雌雄性比为１：０．９７；个体繁殖力Ｙ（千粒鱼卵）与体长Ｌ（ｃｍ）相关关系式为Ｙ＝２．５９７４Ｌ－７８．９１８３。５月下旬一６月下旬在水库岸边有水草处筑巢产卵，卵为浮性。水温２３—２５℃时，受精卵约３天孵出仔鱼。     

长吻Wei,南方大口鲶鲤鱼对九种蛋白质饲料的离体消化率测定

采用离体消化法，测定了长吻Ｗｅｉ，南方大口鲶，鲤鱼的胃，肝胰脏，小肠三个部位对鱼粉，蚕蛹，肉粉，卫饼等九种蛋白饲料原料的离体相对消化率，结果表明，三种鱼的同种饲料干物质和蛋白质消化率，个体差异不显著，干物质消化率和蛋白质消化率无相关性，同种鱼不同部位对同一饲料的消化有差异，其中对干物质率差异不显著，对蛋白质消化率差异显著，同种鱼同种部位不同饲料的消化有差异，对干物质和蛋白质消化率差异均显著，从总体     

中国对虾晚放苗养殖试验

中国对虾晚放苗养殖试验对虾流行病的暴发，除取决于病原、寄主、环境因素外，还与对虾体长、季节、水温有一定的关系。从近几年虾病发生时的一些因素看，水温２３—２５℃，对虾体长６—８ｃｍ，时间在６月上中旬前后。而同样是“白斑病”（头胸甲上有白斑），在养成期传...     

黄颡鱼幼鱼对蛋白质和脂肪的需要量

在水温23±5℃下,将平均体质量10．32g的黄颡鱼（Pelteobagrus fulvidraco）放养在27个60cm×60cm×120cm的微流水网箱中,饲喂3个蛋白质水平（32．0％、40．0％、48．0％）,每个蛋白质水平设3个脂肪水平（3．0％、10．0％和17．0％）的饲料,饲养100d。结果表明：在3．0％脂肪水平下,黄颡鱼摄食含40．0％蛋白质的饲料时,平均末体质量、特定生长率和蛋白质效率显著提高,饲料系数降低（P〈0．05）。在10．0％脂肪水平下,黄颡鱼摄食含48．0％蛋白质饲料时,饲料系数显著降低（P〈0．05）,摄食含40．0％的蛋白质饲料次之。黄颡鱼摄食含48．0％蛋白质与3．0％脂肪饲料组和40．0％蛋白质与10．0％脂肪组的干物质消化率最高（P〈0．01）;蛋白质消化率在48．0％蛋白质与3．0％脂肪达到最高（P〈0．01）,脂肪消化率均在40．0％蛋白质与10．0％脂肪达到最高（P〈0．01）。实验表明,黄颡鱼幼鱼较为适宜的蛋白质和脂肪需要量分别为40．0％和10．0％。     

Effect of diet composition on nutrient digestibility and digestive enzyme levels of gilthead sea bream (Sparus aurata L.)

An experiment was conducted to evaluate the effects of dietary composition on apparent digestibility coefficients of protein, fat and carbohydrate of gilthead sea bream. In addition α‐amylase and proteolytic activities were measured in the digestive tract of fish, held at 20±1°C. Six experimental diets were formulated containing approximately 40%, 45% and 50% protein, 11% and 21% fat and a starch level which fluctuated from 14% to 36%. Fish having an average weight of 100–130 g were used, fed at 1.5% of their body weight daily, and digestibility was measured using an indirect method. Enzyme activities were measured in the digestive tract of fish, fed diets containing a combination of 40%, 50% protein with 11%, 21% fat at 0.5, 5, 10, 24 h after a single meal. Starch digestibility was reduced with its level in the diet. It also negatively affected fat digestibility as well as protein digestibility, the last only at the high fat level. Dietary fat level had a negative effect on starch and protein digestibility. Fat affected also strongly α‐amylase levels in the digestive tract, while its effect on protease activity was of smaller magnitude. These results indicate that digestive enzyme activities and nutrient digestibility values are affected by dietary composition, carbohydrates and fat indicating the strongest effect.     

Seasonal changes in proteolytic enzymes of yellowtail Seriola quinqueradiata (Temminck & Schlegel; Carangidae) fed extruded diets containing different protein and energy levels

Seasonal variations in pepsin, trypsin and chymotrypsin activities and protein digestibility were studied in yellowtails (Seriola quinqueradiata) reared for 1 year with extruded diets containing different levels of protein. Trypsin and chymotrypsin storage levels in the digestive tissues of starved fish were affected by seasonal changes in water temperature. Actual digestion activities of trypsin and chymotrypsin were low at lower water temperatures, but pepsin activity in the stomach tissue was not affected by low temperatures. On the other hand, trypsin and chymotrypsin activities in the intestinal contents were higher during lower water temperature months, while pepsin activity in the stomach contents was low at lower water temperatures. Apparent protein digestibility (APD) did not differ among the dietary treatments in the higher water temperature months, while in colder months it was higher in fish fed diet 1 than in fish fed diets 2 and 3. The APD values reflected pepsin activity in the stomach contents in all sampling months. Therefore, lower APD in colder months seems to be attributed to lower protease activity in the gastric digesta, implying that enhanced pepsin secretion from the stomach tissue might improve protein digestibility and growth performance in yellowtails during winter.     

The influence of environmental temperature on the apparent nutrient and fatty acid digestibility in Atlantic salmon (Salmo salar L.) fed finishing diets containing different blends of fish oil, rapeseed oil and palm oil

A 12‐week feeding trial was conducted to investigate the interactive effects between water temperature and diets supplemented with different blends of fish oil, rapeseed oil and crude palm oil (CPO) on the apparent nutrient and fatty acid digestibility in Atlantic salmon. Two isolipidic extruded diets with added fish oil fixed at 50% and CPO supplemented at 10% or 25% of total added oil, at the expense of rapeseed oil, were formulated and fed to groups of Atlantic salmon (about 3.4 kg) maintained in floating cages. There were no significant effects (P>0.05) of diet on growth, feed utilization efficiency, muscle total lipid or pigment concentrations. Fatty acid compositions of muscle and liver lipids were mostly not significantly different in salmon fed the two experimental diets but showed elevated concentrations of 18:1n‐9 and 18:2n‐6 compared with initial values. Decreasing water temperatures (11–6°C) did not significantly affect protein, lipid or energy apparent digestibilities of the diets with different oil blends. However, dry matter digestibility decreased significantly in fish fed the diet with CPO at 25% of added oil. Increasing dietary CPO levels and decreasing water temperature significantly reduced the apparent digestibility (AD) of saturated fatty acids. The AD of the saturates decreased with increasing chain length within each temperature regimen irrespective of CPO level fed to the fish. The AD of monoenes and polyunsaturated fatty acids was not affected by dietary CPO levels or water temperature. No significant interaction between diet and water temperature effects was detected on the AD of all nutrients and fatty acids. The results of this study showed that the inclusion of CPO up to about 10% (wt/wt) in Atlantic salmon feeds resulted in negligible differences in nutrient and fatty acid digestibility that did not affect growth performance of fish at the range of water temperatures generally encountered in the grow‐out phase.     

The Effect of Dietary Lipid and Long-chain n-3 PUFA Levels on Growth, Energy Utilization, Carcass Quality, and Immune Function of Rainbow Trout, Oncorhynchus mykiss

The effect of varying dietary lipid and n‐3 polyunsaturated fatty acids (PUFAs) on growth, feed efficiency, protein and energy utilization, carcass quality, and nonspecific immune functions was investigated in rainbow trout reared at two different water temperatures (7.5 and 15 C). Six diets were formulated to contain 47% digestible protein and 21 MJ/kg digestible energy. Three of the diets were formulated to contain increasing lipid levels (10, 16, and 18%) and three additional diets formulated to 18% lipid with different lipid sources. Varying dietary lipid and n‐3 PUFA levels had little effect on growth and on protein and energy utilization. Diet composition only had limited effect on susceptibility of the flesh to rancidity and on the nonspecific immunity of the fish. Increasing lipid levels did not affect fish carcass or fillet proximate composition. Replacing half of fish oil with beef tallow resulted in lower n‐3 PUFAs in fish fillet but did not affect nutrient digestibility or growth performance of fish even at 7.5 C. Increasing dietary n‐3 levels using a fish oil concentrate resulted in significant enrichment of n‐3 PUFAs and elevated n‐3 : n‐6 ratio of the whole body and carcass. Water temperature significantly affected apparent digestibility coefficient (ADC) of protein and energy but did not affect the ADC of lipid, nor did it affect nitrogen and energy retention efficiencies. The study suggests that highly saturated fats, such as beef tallow, can be used to partially replace fish oil without negative effect on digestibility and growth even at low water temperature. High dietary n‐3 PUFAs levels can be used to enrich n‐3 PUFAs of the flesh without negative effect on the immune response.     

Amino Acid Availability of Four Practical Feed Ingredients Fed to Striped Bass Morone saxatilis

Four dietary protein sources were bio-assayed for amino acid availability, as estimated by true digestibility, when fed to striped bass Morone saxatilis . Diets were formulated to contain either herring fish meal, soybean meal, corn gluten meal or peanut meal as the sole source of dietary protein. A fifth diet, containing no protein, was fed to estimate the level of endogenous amino acids for calculation of true digestibility. The five dietary treatments were randomly assigned to ten tanks of striped bass having an average weight of 150 g per fish. All fish received the assigned diet fed at a rate 1.5% of the biomass per day for a period of 10 d. Fecal samples were collected from anesthetized fish by gentle, manual stripping of the lower digestive tract. Diets and feces were analyzed for dry matter, chromium, nitrogen and amino acid concentrations. There were no statistical differences (P > 0.05) among the protein sources for apparent dry matter digestibility or availability of arginine, threonine, valine and nonessential amino acids with the exception of cysteine. Corn gluten meal had a significantly lower availability coefficient for lysine, and peanut meal had significantly lower availability coefficients for histidine, isoleucine, leucine, and lysine when compared to herring fish meal and soybean meal. Statistically there were no differences between soybean meal and herring fish meal for any nutrient tested. These data suggest that in terms of amino acid availability and overall protein quality, soybean meal could be used to spare herring fish meal in striped bass diets, with corn gluten meal being equally as useful when supplemented with lysine or complemented with other proteins.     

The effect of plant‐based diet and suboptimal environmental conditions on digestive function and diet‐induced enteropathy in rainbow trout (Oncorhynchus mykiss)

This experiment investigated intestinal enteropathy and digestive function of rainbow trout challenged with soybean meal‐based diet (SBM) at optimal or suboptimal environments created by normal or reduced water flow, respectively. Oxygen level remained above 7 mg L^‐1 for optimal environment and between 4 and 5 mg L^‐1 for suboptimal environment. Triplicate groups of fish (mean body weight 74 g) were fed fishmeal‐based diet (FM) or SBM at optimal environment in period 1 (28 days). In period 2 (42 days), fish were subjected to a change from FM to SBM or remained on the same diet as used in period 1. The fish were also exposed to change from optimal to suboptimal environment or remained under optimal conditions. The fish subjected to change from FM to SBM, regardless of their environment, showed similar degree of enteropathy from day 14. Lipid and starch digestibility was lower in SBM‐fed fish at suboptimal environment compared to fish fed the same diet at optimal environment. Crude protein digestibility, however, was highest in SBM‐fed fish at suboptimal environment throughout period 2. In conclusion, in SBM‐fed rainbow trout, exposure to suboptimal environment did not change the degree of enteropathy; however, lipid and starch digestibility were further reduced.     

Effects of the protein/carbohydrate ratio of extruded diets on protein synthesis, protein growth and body composition in juvenile brown trout (Salmo trutta)

High levels of protein in fish feeds result in higher costs and nitrogen waste. Therefore, studies focused on protein substitution by alternative energy sources are necessary. Here we examine whether the protein:carbohydrate ratio in extruded diets affects protein-turnover parameters and the main tissue components in brown trout. Juvenile fish were adapted to two extruded diets: one higher in protein and lower in carbohydrate, C: 45/28 and the other higher in carbohydrate and lower in protein, HC: 37/40. Gross energy was 19 MJ kg⁻¹ DM in both diets. Protein and lipid digestibility were high and similar in both groups (≈90%), whereas total and carbohydrate digestibility and digestible energy were lower in the HC-fed group than in the C-fed group. Consequently, when fish were adapted to the diets, plasma levels of glucose and insulin differed between diets. HC-group presented higher plasma glucose levels and lower plasma insulin levels than C-group. Protein synthesis rates in white muscle, liver and whole body did not differ significantly between diets. In contrast, protein accretion rate of white muscle and whole body were significantly lower in the HC group, indicating an increase of protein degradation in these tissues and a decrease of synthesis retention efficiency. In spite of the daily protein intake of HC group was lower than C-group, the anabolic stimulation efficiency was increased by 34% in HC group. Protein and lipid contents in white muscle and liver were stable throughout the experiment. No hepatomegalia or increased fat deposition was observed in fish fed HC. Differences in specific growth rates (C: 0.88%; HC: 0.77%) were associated more with the lower protein consumption rate and the lower level of digestible energy in fish fed HC than with the higher dietary carbohydrate content of the diet.     

The influence of temperature on the apparent nutrient and fatty acid digestibility of Arctic charr, Salvelinus alpinus L.

To study the influence of temperature on the nutrient and fatty acid digestibility of salmonid fish, Arctic charr, Salvelinus alpinus L., were fed dry pelleted diets at 10 and 0.6 °C for 81 days. The diets had a carbohydrate/lipid content of 23.7/13% and 6.4/ 27% and a constant protein content of around 50%. At the end of feeding period, gut contents were collected from the mid- and hind-gut regions, and analysed for the apparent digestibility coefficient (ADC) of nutrients using chromic oxide as digestibility marker. Fish maintained at 0.6 °C had a lower ADC of protein, carbohydrate, lipid and dry matter compared to those maintained at 10 °C. This shows that increased gastrointestinal holding time following low temperature adaptation does not fully compensate for lowered digestive/absorptive metabolism. Feeding high carbohydrate diets had no significant influence on nutrient utilization at 10 °C, but appeared to reduce the ADC of most macronutrients at 0.6 °C. The ADC of the individual fatty acids increased with decreasing chain length and increased with unsaturation. Maintaining the fish at 0.6 °C significantly reduced the ADC of saturated fatty acids, while the monounsaturated fatty acids, and in particular, the polyunsaturated fatty acids were hardly influenced by environmental temperature. It is suggested that the reason may be a shift in digestive lipase specificity caused by changes in the substrate state or lowered solubilization of saturated fatty acids in bile micelles, which thus reduces the uptake into the enterocyte.     

Digestibility of Different Protein Sources by Penaeus monodon Raised in Brackish Water and in Sea Water

The digestibility of fish meal, soybean meal, and casein by Penaeus monodon was determined in both brackish water (16 ppt) and in seawater (32 ppt). Casein was the most digestible protein, followed by soybean meal and fish meal; the differences were significant (P <: 0.05). Salinity did not affect the digestibility of casein and fish meal but did affect digestibility of soybean meal: It was significantly lower when P. monodon was raised at 32 ppt.