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1.
刘伟  文华  蒋明  吴凡  田娟  杨长庚  黄凤 《水产学报》2016,40(5):751-762
为探讨饲料蛋白质水平与投喂频率对罗非鱼生长及生理健康的影响,采用2×3双因子实验,研究饲料蛋白质水平(36.27%和26.02%)与投喂频率(1、2和3次/d)对吉富罗非鱼幼鱼生长、体成分、血清指标和肝胰脏结构的影响。养殖周期为42 d,结果表明:随饲料蛋白质水平的增加,实验鱼的末体质量(FW)、增重率(WGR)、特定生长率(SGR)、饲料效率(FE)、肥满度(CF)、去内脏全鱼灰分(EWA)、内脏水分(VM)、高密度脂蛋白胆固醇(HDLC)水平显著升高(P0.05),而摄食率(FI)、脏体比(VSI)、饲料成本(FC)、去内脏全鱼粗脂肪(EWF)、内脏粗脂肪(VF)、肝胰脏粗脂肪(HF)显著降低(P0.05);随投喂频率的增加,实验鱼的FW、WGR、SGR、肝体比(HSI)、CF、FC、EWF、VF、HF,血清中的总胆固醇水平(TCHO)、HDLC、低密度脂蛋白胆固醇(LDLC)、总蛋白(TP)、甘油三酯(TGK)水平显著升高(P0.05),而FE、蛋白质效率(PER)、去内脏全鱼水分(EWM)、EWA、VM、肝胰脏水分(HM)显著降低(P0.05)。饲料蛋白质水平和投喂频率对实验鱼的FW、WGR、SGR、VM和HDLC的交互作用显著(P0.05)。投喂26.02%蛋白质水平饲料的实验鱼,肝胰脏细胞肿大变形,呈现透明的空泡化,出现细胞核偏移;而投喂36.27%蛋白质饲料的实验鱼,大多数肝细胞胞浆清晰,可观察到的肝细胞空泡面积较小。综合考虑,饲料蛋白质含量为36.27%是适合吉富罗非鱼幼鱼的,其适宜的投喂频率为2次/d以上,可根据罗非鱼市场情况进行调节。  相似文献   

2.
Gastrointestinal and metabolic influences on short- and medium-term control of voluntary feed intake of European eel were investigated for groups of fish fed at different feeding schedules: 1 meal 2 days−1, 1 meal day−1, 2 meals day−1 and continuous feeding for 12 h and 24 h daily. For fish fed daily, the feeding schedule had no effect on feed intake, metabolism, growth, size variation and body composition. Only fish fed once every 2 days could not completely compensate by increasing their average meal size and showed a reduced feed intake, metabolism and growth. Stomach capacity did not limit meal size and feed intake as large differences in appetite were found for eels with empty stomachs. Feed intake was related to metabolism as the levels of O2 consumption and NH4 excretion just before the meal were correlated to average meal size, suggesting that rate (and duration) of metabolism is sensed and is providing information about the metabolic consequences of feed intake and feed processing. Meal size is based on the (expected) scope for metabolism and eels seem to strive to an average daily feed intake, associated with their developmental state (growth potential). Plasticity in this feed intake behaviour, expressed by individual variation in feed intake and day-to-day fluctuations in individual and group intake, is regarded as adaptive on different time scales.  相似文献   

3.
In the freshwater area of Vietnam's Mekong Delta, Oreochromis niloticus (L.), Barbodes gonionotus (Bleeker) and Cyprinus carpio (L.) are often reared together in rice fields. In this study, we report the results of eight such polyculture experiments, examining variables affecting the specific growth rate and the average daily food energy consumption of individual O. niloticus. The standing biomass of O. niloticus and the wild fish biomass had a negative impact on the specific growth rate, whereas added pig manure, extra feed and inorganic fertilizer had a positive effect. The standing biomass of O. niloticus and C. carpio, and the wild fish biomass had a negative impact on the consumption of natural feed. We inferred that O. niloticus mainly lacks food in rice fields. This results in intraspecific competition. As in rice fields, C. carpio has basically the same feeding niche as O. niloticus; we found interspecific competition between the two species. O. niloticus consumed relatively more food in the vegetative phase of the rice crop, probably because of a higher abundance of phytoplankton. To get higher growth of O. niloticus, we recommend that farmers increase nutrient inputs and stock O. niloticus according to the size of the trench adjoining the rice field and not according to the size of trench plus field as is generally done.  相似文献   

4.
A model for dynamic simulation of the growth of the Nile tilapia, Oreochromis niloticus (L.), in relation to food amount and composition, temperature, and dissolved oxygen concentration was applied to tilapia ponds. To model food competition between stocked fish and fingerling recruits, a pond food module was added. Data for model calibration were from uniform experiments with all-male O niloticus ponds fertilized with inorganic fertilizers and chicken manure in Honduras, Rwanda and Thailand. Calibration consisted of iterative determination of two model parameters: (1) CONLEV, the consumption rate without food or oxygen limitations; and (2) TPFS, the total daily food supply by the pond. Calibration results showed that, in most ponds, final fish weight could be simulated with acceptable values for CONLEV and TPFS. Both CONLEV and TPFS were related to natural productivity indicators (net primary production and chlorophyll a concentration). For each pond, an estimate of the degree of food and/or oxygen limitation could be given. Validation of the model with independent data from Indonesia and Panama was unsuccessful. The relationships used to estimate values of CONLEV and TPFS from primary productivity measurements were not satisfactory. A more detailed approach to modeling food competition and oxygen limitation under these conditions is necessary. The model provides a conceptual framework for the analysis of fish growth in ponds, tying together effects of food quantity and composition, temperature, and dissolved oxygen concentration.  相似文献   

5.
The individual food intake of each fish in each of four groups of Atlantic halibut, Hippoglossus hippoglossus (L.) (mean weight: 422 g) was monitored by direct observation over a period of 21 days. Gross feed conversion efficiency (= growth·feed intake?1), net feed conversion efficiency and maintenance ration were estimated by regression analysis. Specific growth rates were found to be linearly related to weight-specific consumption at a temperature of 8–9°C: growth = 1.922· feed intake ? 0.242. Maintenance ration was 0.126% of body weight day?1. The gross feed conversion efficiency increased asymptotically with increasing feed intakes and growth rates, and was found to approach 1.9 at high growth rates (0.5 on a dry weight basis). One feeding per day seemed to be sufficient for maximum food intake and growth rate.  相似文献   

6.
To examine the effects of different feeding frequencies, moist and dry feeds on the growth of Chrysichthys nigrodigitatus Lacépède and on water quality of freshwater ponds, two experiments were conducted. In one experiment, fish stocked at the same densities were subjected to three different feeding regimes using equal quantities of feed. Water quality was monitored and fish growth in the different treatments was compared. To determine the effects of moist and dry feeds, fish growth and water quality in one set of ponds fed with 5% body weight of dry feed were compared to those in another set of ponds stocked at the same rate but fed with 5% body weight of moist feed. Feeding once a day produced the greatest weight gain but fish fed once on alternate days had the best feed conversion, which was associated with pond water that had the highest dissolved oxygen. This suggests that feeding once on alternate days could be adopted as a strategy for feeding fish under unfavourable conditions. Water quality of ponds holding fish fed dry feed was better than that of ponds holding fish fed moist feed, as indicated by oxygen, carbon dioxide and ammonia contents. A highly significant difference in growth (P < 0.01) was found between fish fed moist and dry with feeds: fish performed better when fed with dry feeds.  相似文献   

7.
孙晓锋  冯健  陈江虹  罗波  赵海祥  赵华林 《水产学报》2011,35(11):1677-1683
通过胃排空试验与养殖试验研究了不同投喂频率对尼罗系吉富罗非鱼幼鱼的胃排空、生长性能以及体组成的影响.在试验开始时,观测尼罗系吉富罗非鱼幼鱼的胃内饲料排空情况,胃排空试验结果表明,胃排空率的最佳描述为平方根函数,胃内饲料在饱食投喂后15 h左右完全排空,达到投喂前水平,80％胃排空为9h,也就是投喂后大约9h恢复食欲.360尾试验鱼(初始体质量3.72 g)以不同的投喂频率(1d4次、1d3次、1d2次、2d4次、2d3次、2d2次)分组,每组设立3个平行组,随机养殖于18个网箱中,每箱养殖20尾鱼,按饱食量投饲膨化饲料.养殖期为6周.尼罗系吉富罗非鱼幼鱼在投喂频率为1d4次、1d3次和1d2次时特定生长率和饲料效率显著高于投喂频率为2d4次、2d3次和2d2次时(P＜0.05);投喂频率为1d2次、2d4次、2d3次和2d2次时其摄食量显著低于1d4次和1d3次时(P＜0.05).随着投喂频率降低,鱼体水分含量逐步上升,脂肪和蛋白质含量逐步下降,其中1d4次、1d3次组鱼与2d2次组鱼有显著性差异(P＜0.05).各投喂频率组间的肝体指数无显著性差异(P＞0.05).3.7～48.0 g尼罗系吉富罗非鱼幼鱼的适宜投喂频率为1d2次,较2d2次、2d3次和2d4次时明显提高了生长速度和饲料效率,较1d3次、1d4次摄食量显著降低.2种试验结果较为一致.  相似文献   

8.
A 56‐day growth trial was conducted to study the utilization of hydrolysed potato starch by juvenile Atlantic salmon Salmo salar L. using a restricted feeding regime. Two diets supplemented with either 15% or 30% hydrolysed potato starch and a control diet without carbohydrate supplementation were each fed to triplicate groups of salmon. Feeding rate varied from 1.4% to 2.0% of body weight per day, so that fish were fed similar amounts of protein and lipid. In spite of the restricted feeding used, no growth stimulation was measured as a consequence of the additional starch intake. No variation was found in protein utilization, measured as protein efficiency ratio values (PER), while feed utilization showed decreased values as starch intake increased. Plasma glucose concentrations did not vary as a consequence of increased starch intake when measured 24 h after feeding, indicating efficient regulation of plasma glucose. In fish fed the 30% starch, the plasma triacylglycerol concentration was significantly increased, which may point to de novo lipid synthesis from the high starch intake. No variation was found in plasma cholesterol or protein concentrations, or asparagine aminotransferase, alanine aminotransferase and lactate dehydrogenase activities. This shows that the fish health status and liver function were normal (no mortality was registered). Liver and muscle showed increased glycogen levels as a function of increased starch intake. The same diets were also fed to juvenile white sturgeon Acipencer transmontanus and hybrid tilapia Oreochromis niloticus×O. aureus. These results are presented separately.  相似文献   

9.
A 12-week feeding trial was undertaken to assess growth, nutrient utilization, some hematological parameters, and proximate composition of Nile tilapia (Oreochromis niloticus) fed diets supplemented with graded levels (0.5%, 1.0%, and 1.5%) of two blends of organic acids or organic salts. Seven isonitrogenous (300 g CP kg?1) and isocaloric (19.0 MJ gross energy kg?1) diets were formulated. The control diet (D1) contained neither added blend of organic acids nor organic salts. Three diets (D2, D3, and D4) were supplemented with 0.5%, 1.0%, and 1.5% of malic acid + oxalic acid blend (OAB), respectively. The other three diets (D5, D6, and D7) were supplemented with 0.5%, 1.5%, and 1.5% of calcium lactate + sodium acetate blend (OSB), respectively. Fingerlings (7.05 ± 0.02 g) were randomly distributed into 21 glass aquaria (160 liter), with each aquarium holding 15 fish. At the end of the feeding trial, O. niloticus offered the control diet showed lower growth and feed utilization than all those fed the organic acids or organic salts blends supplemented diets. Fish fed the diet D3 showed the highest body weight (BW), body length (BL), weight gain (WG), specific growth rate (SGR), feed intake (FI), and the best feed conversion ratio (FCR) and protein efficiency ratio (PER). Fish fed diet supplemented by 1.5% OAB (D4) showed the highest serum protein content, while control group (D1) showed the lower level of total lipids compared with the other treatments. Fish group fed the diet supplemented with 0.5% of OSB (D5) showed the highest protein and ash contents and the lowest lipid content of the whole fish body, while the control group showed the lowest protein and the highest fat content. The present observations suggest that the growth, feed utilization, and health status of juvenile O. niloticus can be enhanced with a supplementation of 1% of OAB or OSB in the diet.  相似文献   

10.
A 21‐day growth trial was undertaken to investigate the effect of water temperature (25, 28, 31, 34, 37 °C) on growth, feed utilization and energy budget of juvenile Nile tilapia (Oreochromis niloticus) (initial body weight around 12 g) with four replicates at each temperature. Feed intake energy (IE), recovered energy (RE), faecal energy (FE), excretory energy (UE + ZE) and heat energy (HE) were calculated to obtain the energy budget. The results showed that feeding rate and ammonia excretion were not significantly affected by water temperature. Specific growth rate in wet weight (SGRw) and FE was significantly lower in the fish reared at 37 °C while no significant difference was observed between the fish reared at 25–34 °C. Protein retention efficiency was highest at 28 °C and lowest at 37 °C. The proportion of IE channelled into RE and UE + ZE was lower while those lost in HE was higher in the fish reared at 37 °C. The optimal growth temperature was estimated as 30.1 °C based on the regression of SGR and water temperature. Energy budget at maximum growth (34 °C) was: 100 IE = 27.0 RE + 1.1 (ZE + UE) + 10.6 FE + 59.2 HE. HE accounted for 69.3% and RE for 30.7% of metabolizable energy.  相似文献   

11.
A two (dietary energy levels; low energy, LE and high energy, HE) × 4 (feeding frequency; one feeding in 2 days, one feeding daily, two times daily and three times daily) factorial experiment was performed to determine the effects of dietary energy level and/or feeding frequency on the growth and body composition of juvenile flounder Paralichthys olivaceus. The survival rate was not significantly different among treatments. Weight gain of fish fed the LE and HE diets significantly increased as feeding frequency increased. The weight gain of fish fed the LE diet was higher at each level of increasing feeding frequency. The weight gain of fish fed the HE diet was higher than that of fish fed the LE diet once in 2 days and once daily, but weight gain of fish fed the HE diet was lower than the LE diet three times daily. Daily feed intake was significantly influenced by feeding frequency, but not by dietary energy level. Feed efficiency of fish fed the HE diet once daily was significantly higher than that of fish fed the LE diet once in 2 days, but no significant difference in feed efficiency was observed among other groups of fish. The protein efficiency ratio of fish fed the LE diet once in 2 days was the lowest. Feeding frequency and dietary energy level had a significant effect on the body lipid content. A feeding frequency of two times or three times daily would be effective, depending on dietary energy level for maximum growth of juvenile flounder grown from 3.5 to 15 g.  相似文献   

12.
An 84‐day feeding trial was carried out to evaluate the effects of aqueous Psidium guajava leaf extract (PGE) on growth, intestinal morphology, physiology, immune response and susceptibility of Oreochromis niloticus to Aeromonas hydrophila. Diets containing 0% (P0), 0.25% (P1), 0.50% (P2), 0.75% (P3) and 1.00% (P4) PGE were fed to triplicate groups of fish (mean weight; 1.32 ± 0.04 g) for 84 days. After the 84‐day feeding trial, test fish were injected with pathogenic A. hydrophila and then fed for 14 days. More feed were consumed in groups of fish fed PGE‐treated diets and resulted in significantly higher weight gain and feed intake. Incidentally, there was an increase in the calculated area of absorption of fish fed PGE diets, as accounted for by marginally higher villi length and width. Antioxidant and immune response were improved with PGE inclusion in diets as total protein, superoxide dismutase, glutathione peroxidase and glutathione S‐transferase significantly increased (p < 0.05) in fish fed PGE diets. Results of the challenge test with A. hydrophila revealed that the highest mortality (100%) was recorded in P0. This study revealed that inclusion of P. guajava extract in the diet of O. niloticus improved growth, nutrient utilization, immune system and survival of O. niloticus fingerlings.  相似文献   

13.
Increasing stocking densities in catfish, Ictalurus punctatus (Rafinesque), aquaculture are making maintenance of water quality a crucial element of production strategy. A bioeconomic simulation model for catfish has been adapted to assess alternative feeding restriction management strategies for US catfish aquaculture operations. The current model includes five decision variables: feeding rate, diet quality, stocking weight, stocking date, and length of growing season. The growth model follows a bioenergetics approach, where the balance between energy intake and energy expenditure determines fish growth. The purpose of this analysis was to simulate changes in production practices resulting from water quality restrictions. Model simulations indicate that restricting maximum daily feeding allowance to maintain higher water quality will actually increase feed requirements to reach a harvestable fish size. In addition, as producers increasingly attempt to spread harvests throughout the year, both for their own cash flow needs and the consistent supply requirements of processors, restricting daily feed allowance will make summer harvests particularly difficult.  相似文献   

14.
A dynamic model to simulate growth of the African catfish. Clarias gariepinus (Burchell), was parameterized and calibrated for Nile tilapia. Oreochromis niloticus (L.), and rainbow trout, Oncorhynchus mykiss (Walbaum). The model predicts fish weight and fat percentage from the amount and composition of the feed and water temperature. The major factor determining the efficiency of feed conversion is the proportion of energy provided by protein oxidation, which is positively related to the protein feeding level and the protein/energy ratio of the feed. The model predicted fresh weight of the herbivorous Oreochromis niloticus in independent experimental data with a mean deviation of -2.1% (range -23% to +37%) of observed values (fish weights 10-40 g), For the carnivorous Oncorhynchus mykiss, this value was 4.8% (range -21% to +24%, 50-800 g), Options for further improvement of the model are discussed. We conclude that the structure of the model applies to a broad range of fish species and feeding schedules, provided that both feed and fish are characterized by a set of specific parameters.  相似文献   

15.
Recirculating aquaculture systems (RASs) are an efficient method for developing sustainable aquaculture and the development of a feed strategy for RASs could be a key factor for the success of culturing Oreochromis niloticus. The daily protein intake (DPI) mathematical function related to body weight (BW) was designed (DPI = ?3.818 ln (BW) + 30.158) named DPI 1.0 = 100%. Three feeding rates were established, DPI 1.4, 1.2 and 1.0, and were implemented in an RAS production cycle (100 fish/m3) for 34 weeks. The final growth measurements were 908.0 ± 57.9 g (DPI 1.4), 887.0 ± 113.5 g (DPI 1.2) and 702.2 ± 38.1 g (DPI 1.0) (p < .05), with feed conversion rates (FCRs) of 2.3, 1.9 and 1.9, respectively; the survival was ≥ 98.3% (p > .05) for all treatments. DPI levels conditioned the growth of the fish and the proportion of lipid: protein in the bodies of O. niloticus but not in the fillets. The mathematical function DPI 1.2 = 120% (DPI = ?4.582 ln (BW) + 36.19) used in the RAS at the 40% protein level improved fish growth, the protein efficiency ratio and FCRs. The DPI values were estimated for 49 different cases and feeding strategies showed lower values than most of the different DPI mathematical functions used and cited in this work. Therefore, DPI metric is a good tool that provides the specific requirements of protein for O. niloticus growth, which can enable farmers to ration feed and improve energy use (kWh / fish) and facilitate the integration of RAS with horticulture.  相似文献   

16.
A 12‐week feeding trial was conducted using Nile tilapia, Oreochromis niloticus (L.) to evaluate the interactive effects of fishmeal replacement and salinity on growth, feed utilization efficiencies and relative expression of growth related genes. Two iso‐nitrogenous and iso‐energetic diets were prepared (32% protein). The control diet included 15% fishmeal (FM diet) and fishmeal component in non‐fishmeal diet (NFM) was eliminated by a mixture of poultry by‐product meal, high protein distillers dried grains and distillers dried grains with soluble. The NFM diet was supplemented with DL‐methionine and L‐lysine. Duplicated group of fish with initial mean weight of 6 g, reared in four salinity levels (0, 4, 8 and 12 g/L) were fed one of the two diets twice a day to near satiety. At the end of the experiment, growth, feed utilization efficiency and expression of growth related genes were compared. The specific growth rate (SGR), mean feed intake (MFI) and feed conversion ratio (FCR) were not affected by the diets while salinity effects were significant. The fish in the 4 g/L salinity showed the highest SGR and MFI while fish in the 0 g/L treatment showed the lowest FCR. Relative expression of hepatic IGF‐I and IGF‐II was regulated by salinity but not by the diet. Expression of growth hormone receptor gene was not affected by either diet or salinity. The present findings provide evidence for the possibility of total fishmeal replacement in saline waters (0–12 g/L) without compromising growth, feed utilization and body composition of Nile tilapia.  相似文献   

17.
不同投饲率对日本黄姑鱼幼鱼生长及鱼体生化成分的影响   总被引：2，自引：1，他引：2  
采用一种饲料5个投喂水平(鱼体重1.0%、2.0%、3.0%、4.0%、5.0%)在水温26~28℃的条件下对日本黄姑鱼幼鱼(26.85±1.69g)进行了40d生长实验。结果表明:特定生长率和相对增重率随着投饲率的增加呈先上升后平稳的趋势,饲料利用率随着投饲率的升高呈先下降后平稳再下降的趋势;鱼体的水分含量随投饲率的增加而下降,蛋白质和脂肪含量随投饲率的增加而升高,投饲率对灰分无影响。根据最大相对增重率和最大饲料利用率,确定日本黄姑鱼幼鱼适宜投饲率在水温26~28℃时为3.0%。  相似文献   

18.
Feed-restricted fish gain less body mass and storage reserves than well-fed fish, and reduced rates of gain often trigger compensatory responses, characterized by increased appetite (hyperphagia) and growth rate. The results of previous investigations have introduced a hypothesis in which adipose tissue (fat stores) had a regulatory role in governing appetite. An extension of this suggests that hyperphagia may relate to the severity of the feed restriction, and that the compensatory responses will cease once fat reserves are restored relative to body size. This was tested in two trials in which feed-restricted or -deprived postsmolt Atlantic salmon, Salmo salar , became hyperphagic after transfer to excess feeding. At the end of the first trial, previously feed-restricted fish had fully compensated for their lost weight gain compared to continuously fed control fish, but had a leaner body composition (i.e. reduced energy stores) and were still showing signs of compensatory growth. In the second trial, feed deprivation drained body lipids and caused a stronger hyperphagic response than restrictive feeding, although it took longer to develop. Feed intake became coincident when fish had a similar body composition for size, but this occurred at different times. Hence, the fish that had been deprived of feed were smaller than the restricted fish at the end of the trial. The results of the present study demonstrate a link between the magnitude of lipid stores, feed intake and weight gain, and provide some evidence for lipostatic appetite regulation in fish.  相似文献   

19.
A 6‐wk feeding trial was conducted to evaluate the effects of different dietary lipid levels and feeding frequencies on the growth performance, feed utilization, and body composition of juvenile spotted seabass, Lateolabrax maculatus. Two experimental diets were prepared with two different dietary lipid contents, low lipid (7%; LL) and high lipid (14%; HL). Each diet was fed to triplicate groups of fish (5.5 ± 0.01 g) to apparent satiation at three meals per day, two meals per day, one meal per day, and one meal every 2 d, respectively, for 6 wk. Fish growth performance in terms of weight gain (WG) and specific growth rate (SGR) was significantly affected by frequency of feeding, with increasing values as feeding frequency increased up to twice daily, regardless of dietary lipid content. In addition, fish fed the diet with the HL level (14%) showed significantly higher WG and SGR than those fed the LL diet (7%) at all the feeding frequencies tested. Feed efficiency (FE) and protein efficiency ratio (PER) were affected by both dietary lipid level and feeding frequency. FE and PER values were significantly higher in fish fed the HL diet and/or when fish were fed twice or thrice a day. However, daily feed intake and daily energy intake were significantly affected only by feeding frequency and were significantly reduced when the fish were fed only once every 2 d compared with those fed more frequently. Whole‐body moisture content of fish tended to decrease with increasing dietary lipid level and frequency of feeding. In contrast, whole‐body lipid content increased in fish as dietary lipid level and feeding frequency increased. Consequently, we can conclude that feeding spotted seabass twice daily to apparent satiation is acceptable and sufficient to achieve good growth and FE, as fish performance was not significantly enhanced when feeding was increased from two to three times daily.  相似文献   

20.
Two experiments were conducted in earthen ponds to evaluate the effect of dietary protein concentration and feeding rate on weight gain, feed efficiency, and body composition of channel catfish. In Experiment 1, two dietary protein concentrations (28% or 32%) and four feeding rates (≤ 90. ≤ 112, ≤ 135 kg/ha per d, or satiation) were used in a factorial arrangement. Channel catfish Ictalurus punctatus fingerlings (average size: 27 g/fish) were stocked into 0.04-ha ponds at a rate of 24,700 fish/ha. Fish were fed once daily at the predetermined maximum feeding rates for 282 d (two growing seasons). In Experiment 2, three dietary protein concentrations (24, 28, or 32%) and two feeding rates (≤ 135 kg/ha per d or satiation) were used. Channel catfish (average size: 373 g/fish) were stocked into 0.04-ha ponds at a rate of 17,300 fish/ha. Fish were fed once daily for 155 d. In both experiments, five ponds were used for each dietary treatment. Results from Experiment 1 showed no differences in total feed fed, feed consumption per fish, weight gain, feed conversion ratio (FCR), or survival between fish fed diets containing 28% and 32% protein diets. As maximum feeding rate increased, total feed fed, feed consumption per fish, and weight gain increased. There were no differences in total feed fed, feed consumption per fish, or weight gain between fish fed at ≤ 135 kg/ha per d and those fed to satiation. Fish fed the 28% protein diet had a lower percentage carcass dressout and higher percentage visceral fat than fish fed the 32% protein diet. Dietary protein concentrations of 28% or 32% had no effect on fillet protein, fat, moisture, and ash. Feeding rate did not affect FCR, survival, percentage carcass dressout, or fillet composition, except fillet fat. As feeding rate increased, percentage visceral fat increased. Fish fed at ≤ 90 kg/ha per d had a lower percentage fillet fat than fish fed at higher feeding rates. In Experiment 2, dietary protein concentration or maximum feeding rate did not affect total feed fed, feed consumption per fish, weight gain, FCR, or survival of channel catfish. Feeding rate had no effect on percentage carcass dressout and visceral fat, or fillet composition. This was due to the similar feed consumption by the fish fed at the two feeding rates. Fish fed the 24% protein diet had lower carcass dressout, higher visceral fat and fillet fat than those fed the 28% or 32% protein diet. Results from the present study indicate that both 28% and 32% protein diets provide satisfactory fish production, dressed yield, and body composition characteristics for pond-raised channel catfish fed a maximum rate of 90 kg/ha per d or ahove.  相似文献   

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