Effects of raw corn starch levels on growth, feed utilization, plasma chemical indices and enzyme activities in juvenile yellowfin seabream Sparus latus Houttuyn

A 10‐week growth trial was conducted to evaluate the effect of raw corn starch levels on the growth, feed utilization, plasma chemical indices and metabolic enzyme activities of juvenile yellowfin seabream Sparus latus. Four semi‐purified experimental diets with different raw corn starch levels (5%, 10%, 20% and 26%) and a high‐protein control diet were prepared before the experiment and hand‐fed to triplicate groups of juvenile yellowfin seabream Sparus latus. Weight gain and specific growth rate for fish fed the diet containing 26% raw corn starch were significantly lower than those for fish fed 10% or 20% corn starch diets or the high‐protein control diet. Fish fed 10% or 20% corn starch diets had a slightly better growth performance than those fed the 5% corn starch diet. Feed efficiency ratio and protein efficiency ratio (PER) for 20% raw corn starch fed fish were the highest among all groups, although no statistically significant differences were found among the experimental groups. The high‐protein control group had a significantly lower PER value than other groups. Protein productive values for fish fed the 5% raw corn starch diet and the high‐protein control diet were significantly lower than those of fish fed the 20% raw corn starch diet, but not significantly different from the values of any other group. The values of intraperitoneal fat ratio, viscerosomatic index and condition factor, as well as body and muscle compositions, were unaffected by corn starch levels. The hepatosomatic index and liver glycogen level for fish fed 5%, 10%, 20% raw corn starch and the high‐protein control diets were equal but significantly lower compared with that of fish fed the 26% raw corn starch diet. Plasma values of the fish were not affected by various dietary treatments, except that a significantly higher plasma glucose concentration was measured in the high‐protein control group compared with the values in the other groups. There were variations in the activities of hepatic hexokinase and pyruvate kinase of the yellowfin seabream after they had been fed different dietary raw corn starch levels for 10 weeks. The overall results showed that a 20% inclusion level of raw corn starch in the diet was better utilized by juvenile yellowfin seabream than 5%, 10% or 26% levels and had a protein‐sparing effect.     

黄鳍鲷幼鱼对几种不同糖源的利用

本研究用来评价黄鳍鲷幼鱼对饲料中葡萄糖、麦芽糖、糊精、玉米淀粉和预糊化玉米淀粉的利用。本试验饲料为6种等氮(粗蛋白:45%,干重)等脂(粗脂肪:9%,干重)的半纯化饲料,其中对照组糖源为纤维素。每种饲料设3个平行。试验鱼初始体重为(3.57±0.13)g(平均值±均差)。试验鱼饲养在含18个水族箱的循环系统中。水温保持在(27±1)℃。试验周期为8周。本试验用来评价黄鳍鲷幼鱼对饲料中不同糖源利用的指标为生长指标、饲料效率、蛋白质效率和肝脏的6-磷酸葡萄糖脱氢酶、苹果酸脱氢酶、异柠檬酸脱氢酶和葡萄糖-6-磷酸脱氢酶。试验结果表明,黄鳍鲷幼鱼体增重、特定生长率、肝体比、肠系膜脂肪体比、饲料效率、蛋白质效率、肝脂肪合成有关酶活性和全鱼、肌肉、肝脏组成均受到饲料中不同糖源的显著影响。预糊化玉米淀粉和麦芽糖组比其它糖源组显著具有更好的体增重和特定生长率,但与对照组没有显著性差异。黄鳍鲷幼鱼生长和体增重与饲料中糖源的复杂性没有相关性。饲喂预糊化淀粉和对照饲料鱼的饲料效率和蛋白质效率显著比其它组高。饲料中糖的添加增加了黄鳍鲷幼鱼的肝体比,但对照组肝体比与糊精组,玉米淀粉组没有显著性差异。预糊化玉米淀粉组肠系膜脂肪体比比其它饲料组要高。结论:基于体增重和特定生长率为指标,饲料中添加25%预糊化玉米淀粉和麦芽糖可以提高黄鳍鲷幼鱼的生长。另外,玉米淀粉预糊化显著提高了黄鳍鲷对玉米淀粉的利用。     

Carbohydrate utilization by juvenile silver perch, Bidyanus bidyanus (Mitchell). III. The protein-sparing effect of wheat starch-based carbohydrates

The ability of juvenile silver perch (Bidyanus bidyanus) to utilize dietary raw wheat meal, raw wheat starch, gelatinized wheat starch and dextrin as energy sources to spare protein for growth was quantified. Energy utilization and protein sparing were assessed by comparing the weight gain, energy retention efficiency, protein retention and body composition of silver perch that had been fed a series of diets in which the basal diet (low carbohydrate) was systematically replaced with graded levels of each carbohydrate ingredient or an inert diluent, diatomaceous earth. The protein content decreased as the carbohydrate content increased, giving four different protein to energy ratios for each of the four carbohydrate sources (except for the 60% inclusion level, at which only three carbohydrate sources were tested). Silver perch were efficient at utilizing carbohydrate for energy to spare protein. Silver perch fed diets containing up to 30% wheat meal, raw wheat starch, gelatinized wheat starch or dextrin exhibited similar growth, protein retention and energy retention efficiency to the fish fed the basal diet. Weight gain of silver perch fed diets containing wheat meal or carbohydrates at 45% inclusion content had significantly reduced weight gain when compared with fish fed the basal diet. However, protein retention and energy retention efficiency were similar or better. Whole‐body protein levels of silver perch remained constant regardless of carbohydrate sources, and there was no evidence of increasing whole‐body lipid concentrations for fish fed diets with up to 60% dietary carbohydrate. Silver perch were more efficient at utilizing processed starch (either gelatinized starch or dextrin) than wheat meal or raw wheat starch.     

Effect of different dietary raw to pre-gelatinized starch ratios on growth performance,feed utilization and body composition of juvenile yellowfin seabream (<Emphasis Type="Italic">Sparus latus</Emphasis>)

The effects of different ratios of dietary raw to pre-gelatinized starch on the growth performance, feed utilization and body composition of juvenile yellowfin seabream (Sparus latus) were evaluated during a 10-week growth trial. Five isonitrogenous, semi-purified diets containing 200 g kg⁻¹ starch comprising different ratios of raw to pre-gelatinized starch [(in g kg⁻¹)100:100 (diet 1), 150:50 (diet 2), 50:150 (diet 3), 200:0 (diet 4), 0:200 (diet 5), raw:pre-gelatinized] were prepared and fed to triplicate groups of juvenile S. latus. Our results showed that fish fed diet 4 (200 g kg⁻¹ raw starch) had the highest weight gain and specific growth rate, followed by those fed diet 2, diet 1, diet 3 and diet 5. Feed efficiency, protein efficiency ratio and protein productive value in the fish on diets 4 and diet 2, respectively, were significantly higher than those on diets 3 and diet 5, respectively. Body and muscle compositions were unaffected by the different dietary raw to pre-gelatinized starch ratios. Values of hepatosomatic index, intraperitoneal fat ratio, viscerosomatic index and condition factor did not vary among experimental treatments. Plasma indices showed variations, but these were not relative to dietary treatments. In conclusion, the partial or total replacement of raw starch by pre-gelatinized starch in diets for yellowfin seabream did not improve its growth performance and feed utilization.     

不同糖源对拟穴青蟹仔蟹的生长、体成分及消化酶的影响

在水温26~30℃,盐度18~22条件下,初始体质量(0.012±0.000)g的拟穴青蟹仔蟹饲养在底铺1~2 cm细沙、边缘放5 cm^2瓦片的塑料水桶(直径20 cm,水深20 cm)中,投喂以葡萄糖、蔗糖、糊精、木薯淀粉、玉米淀粉、糊化木薯淀粉和糊化玉米淀粉为糖源的7种等氮等能饲料,养殖3周,研究不同糖源对拟穴青蟹仔蟹生长、体组成及消化酶活性的影响。试验结果显示,不同糖源显著影响拟穴青蟹仔蟹的生长性能(P<0.05);质量增加率和特定生长率依次为糊化木薯淀粉>糊化玉米淀粉>木薯淀粉>玉米淀粉>糊精>蔗糖>葡萄糖;葡萄糖试验组的成活率显著低于其他各组(P<0.05)。不同糖源对拟穴青蟹仔蟹体组成中粗蛋白和粗脂肪含量影响显著(P<0.05),对仔蟹的水分和灰分含量影响不显著(P>0.05);不同糖源对3种消化酶活性影响显著(P<0.05)。拟穴青蟹仔蟹对大分子糖源的生物利用度要大于小分子糖源。在本试验的研究条件下,7种常见糖源中糊化木薯淀粉是拟穴青蟹仔蟹的最适糖源。     

Effects of Dietary Carbohydrate Source and Level on Growth,Feed Utilization,and Body Composition of the Humpback Grouper,Cromileptes altivelis (Valenciennes)

Six diets were formulated to contain corn starch, tapioca starch, or dextrin at 10% and 20% inclusion levels and fed to humpback grouper fingerlings to apparent satiation for 10 weeks. Growth and feed utilization efficiency of humpback grouper were not affected by dietary carbohydrate source and level. Only slightly higher growth was observed in fish fed 20% dietary carbohydrate compared to the fish fed 10% carbohydrate irrespective of carbohydrate source. Body indices and whole body proximate composition of fish in the present study were generally independent of diet, except that muscle lipid of fish fed diets with 7.6% lipid and 20% carbohydrate was significantly lower than the other groups. In view of the lower price and local availability of tapioca starch compared to corn starch and dextrin, tapioca starch is the preferred source of starch in practical diets for humpback grouper.     

饲料中不同糖源对方格星虫稚虫日增重和消化酶的影响

以葡萄糖、蔗糖、糊精、木薯淀粉、土豆淀粉、玉米淀粉、糊化玉米淀粉为糖源制成7种等氮等脂饲料,投喂方格星虫（Sipunculus nudus）稚虫8周,研究不同糖源对稚星虫日增重和消化酶的影响。结果表明,不同糖源对稚星虫的日增重有显著的影响（P〈0.05）。糊化玉米淀粉组的日增重显著高于其他各糖源组（P〈0.05）;葡萄糖组的日增重显著低于其他糖源组（P〈0.05）;未经糊化的3种淀粉组的日增重显著高于蔗糖、糊精及葡萄糖组（P〈0.05）。消化酶活性的分析结果表明,不同糖源对稚星虫消化酶活性影响显著（P〈0.05）。其中,蔗糖组稚星虫的蛋白酶活性和淀粉酶活性最高,显著高于其他糖源组（P〈0.05）;脂肪酶活性以葡萄糖组最低,显著低于除蔗糖组外的其他糖源组（P〈0.05）。在该研究条件下,大分子糖类（淀粉）的促生长效果优于双糖（蔗糖）和单糖（葡萄糖）,糊化淀粉促生长效果优于未糊化淀粉。     

Utilization of dietary carbohydrates by sea cucumber Apostichopus japonicus (Selenka) as indicated by carbon stable isotope analysis

Carbon stable isotopes were used as trophic markers to investigate the utilization of dietary terrestrial‐source carbohydrates by sea cucumber Apostichopus japonicus. Sea cucumbers were fed by five different types of diets with the ingredients containing Sargassum muticum either without starch or with one of the four starches including corn starch, sweet potato starch, tapioca starch and potato starch. After the 70‐day feeding trial, the carbon isotopic compositions of A. japonicus appeared to reflect those of corresponding dietary components. The average contribution of corn starch (22.0%) to the growth of A. japonicus was slightly higher than the expected contribution (20%). While the proportional contributions of sweet potato, tapioca and potato starches (6.0%, 7.0% and 4.0%, respectively) were all considerably lower relative to the expected contributions. These results indicated that A. japonicus could utilize corn starch more efficiently than sweet potato, tapioca or potato starch. Moreover, A. japonicus fed diet containing corn starch showed the highest specific growth rates which were significantly higher than those fed diets containing potato or tapioca starch. The results of the present study suggested that the corn starch could be used as dietary carbohydrate source in the artificial feeds for A. japonicus farming.     

Optimal dietary carbohydrate to lipid ratio for juvenile yellowfin seabream (Sparus latus)

A growth experiment was conducted to determine the optimal carbohydrate‐to‐lipid (CHO: L) ratio for juvenile yellowfin seabream cultured in 340‐L indoor recirculating tanks. Seven isonitrogenous (450 g kg⁻¹ dietary protein) and isoenergetic (14.1 MJ kg⁻¹) diets with increasing CHO: L ratios (0.03–5.09 g: g) were fed to triplicate groups of 30 fish with an initial weight of 4.91 g for 56 days. Fish were fed to satiation twice a day and the water temperature ranged between 28 and 31.7 °C during the experimental period. Survival was high in all the groups and was not affected by dietary treatments. Best weight gain (WG) and specific growth rate (SGR) were observed in fish fed diets with CHO: L ratios of 0.29 and 0.72, which were not significantly different from that of 0.03, 1.26 and 1.92, but apparently higher than that of 3.22 and 5.09. Feed efficiency (FE), protein efficiency ratio (PER) and protein production value (PPV) followed the same general pattern as WG and SGR. Highest level of energy production value (EPV) was found in fish fed diets with CHO: L ratio of 0.72. Proximate compositions of fish whole body and tissues were markedly affected by dietary CHO: L ratios. Whole body, muscle and liver lipid increased as CHO: L ratios decreased, whereas moisture contents were reduced. Dietary CHO: L ratios had no significant effect on protein content in whole body and muscle. Plasma total cholesterol levels of fish fed diets with CHO: L ratios less than 0.72 were significantly higher than those of the other groups. Triacylglyceride levels decreased linearly as dietary CHO: L ratios increased. Viscerosomatic index (VSI) significantly increased as dietary CHO: L ratios decreased. Intraperitoneal fat ratio (IPF) of fish fed diets with CHO: L ratios less than 1.92 were significantly higher than those fed CHO: L ratios of 3.22 and 5.09. Hepatosomatic index (HSI) did not vary between the test diets. Based on second‐order polynomial regression analysis of WG against dietary carbohydrate and lipid levels, 84.1 g kg⁻¹ of carbohydrate and 136.3 g kg⁻¹ of lipid, corresponding to a CHO: L ratio of 0.62, in a diet holding 450 g kg⁻¹ of crude protein and 14 KJ g⁻¹ of metabolizable energy, proved to be optimal for juvenile yellowfin seabream.     

不同糖源对方格星虫稚虫生长、成活率及体组成的影响

以初始体重为15.49±0.03 mg的方格星虫稚虫为实验对象,分别投喂以葡萄糖、蔗糖、糊精、木薯淀粉、土豆淀粉、玉米淀粉、糊化玉米淀粉作为饲料糖源的7种等氮（45％蛋白）等脂（9％脂肪）饲料56d,研究饲料中的糖源对稚星虫生长、成活率及体组成的影响.结果表明,糊化玉米淀粉组增重率和特定生长率最高,显著高于其他各糖源处理组（P＜0.05）,而饲料中糖源对稚星虫存活率没有显著影响（P＞0.05）.体组成分析的结果显示,不同糖源对稚星虫的体水分和体粗蛋白含量均有显著的影响（P＜0.05）,其中,葡萄糖处理组方格星虫稚虫的体水分含量最高,且显著高于土豆淀粉组（P＜0.05）,其他各实验组差异不显著;葡萄糖处理组方格星虫稚虫的体粗蛋白含量最低,显著低于糊化及非糊化淀粉组（P＜0.05）.不同糖源对稚星虫的体粗脂肪含量及灰分含量没有显著影响（P＞0.05）.在本实验条件下,稚星虫对大分子糖类（淀粉）的利用能力显著优于双糖（蔗糖）和单糖（葡萄糖）.另外,玉米淀粉预糊化显著提高了方格星虫稚虫对玉米淀粉的利用.     

Dietary organic acid salts mitigate plant protein induced inflammatory response and improve humoral immunity,antioxidative status and digestive enzyme activities in yellowfin seabream,Acanthopagrus latus

An eight‐week research was conducted to investigate the effects of single or combined administration of sodium propionate (Na‐P) and sodium acetate (Na‐A) on the performance of yellowfin seabream (Acanthopagrus latus) juveniles (6.5 ± 0.3 g). A plant protein (PP)‐rich diet was supplemented with sole or blends of organic acid salts (OAS) namely Na‐P and Na‐A to design six experimental feeds including control (without OAS), Na‐P5 (5 g/kg Na‐P), Na‐P10 (10 g/kg Na‐P), Na‐A5 (5 g/kg Na‐A), Na‐A10 (10 g/kg Na‐A) and Na‐P + A (5 g/kg Na‐P + 5 g/kg Na‐A). Except for Na‐A5 group, the other OAS‐supplemented treatments had higher growth and feed efficiency ratio than the control (p < .05). The inclusion of OAS in the experimental feeds pronouncedly enhanced plasma lysozyme and alternative complement pathway activities compared to the control. Furthermore, fish fed on the OAS‐supplemented diets had greater catalase and glutathione peroxidase activities in the liver than the control (p < .05). Total antioxidant capacity in the liver of fish fed on the OAS‐supplemented diet also was higher than the control. Fish fed on the OAS‐supplemented diets had higher pepsin, trypsin and lipase activities than the control. The insulin‐like growth factor 1 (IGF‐1) gene expression was remarkably down‐regulated in the liver of fish fed on the OAS‐supplemented diets compared to the control especially in groups fed on the Na‐P10 and Na‐A10 diets. The greatest IGF‐1 gene down‐regulation level in the gut was in fish fed on the Na‐P5 and Na‐P10 diets. The interleukine‐1β in the gut was remarkably up‐regulated in the control compared to the other groups (p < .05). The lactic acid bacterial colonies count in the gut of the control was lower than the OAS‐supplemented groups. Based on the findings of the present study, supplementing PP‐rich diets with 10 g/kg Na‐P or blends of Na‐P (5 g/kg) and Na‐A (5 g/kg) beneficially alleviated inflammatory responses and improved immune parameters and digestive capacity in yellowfin seabream juveniles.     

Investigation of the nutritional requirements of Australian snapper Pagrus auratus (Bloch & Schneider 1801): digestibility of gelatinized wheat starch and clearance of an intra-peritoneal injection of d-glucose

Two experiments were performed to investigate the digestibility and utilization of carbohydrate sources by Australian snapper Pagrus auratus. In the first experiment, snapper of two different size classes (110 and 375 g) were fed a reference diet containing no starch (REF) or diets containing 150 (PN15), 250 (PN25), 350 (PN35) or 450 g kg^?1 (PN45) of 100% gelatinized wheat starch to investigate the interactive effects of fish size and starch inclusion level on apparent organic matter (OM) or gross energy (GE) digestibility (ADC), post‐prandial plasma glucose concentration, hepatosomatic index (HSI) and liver or tissue glycogen content. A second experiment used a 72 h time course study to investigate the ability of larger snapper (300–481 g) to clear an intra‐peritoneal injection of 1 g d ‐glucose kg^?1 body weight (BW). Organic matter and GE ADCs declined significantly in both fish sizes as the level of starch increased (PN45energy small fishenergy large fish). There was no interaction between fish size and inclusion level with respect to GE or OM ADCs. Gross energy ADC for both sized fish was described by the linear function GE ADC=104.97 (±3.39)–0.109 (±0.010) × inclusion level (R²=0.86). Hepatosomatic index, liver and muscle glycogen concentrations were significantly elevated in both small and large snapper‐fed diets containing gelatinized starch compared with snapper fed the REF diet. Three‐hour post‐prandial plasma glucose concentrations were not significantly affected by fish size, inclusion level or the interaction of these factors (REF=PN15=PN25=PN35=PN45), and ranged between 1.60 and 2.5 mM. The mean±SD resting level of plasma glucose (0 h) was 2.4±1.1 mM. Circulating levels of plasma glucose in snapper peaked at 18.9 mM approximately 3 h after intra‐peritoneal injection and fish exhibited hyperglycaemia for at least 12–18 h. There were no significant differences between the plasma glucose concentrations of snapper sampled 0, 18, 24, 48 or 72 h after injection (0=18=24=48=72<12< 1<3=6 h), indicating snapper required almost 18 h to regulate their circulating levels of glucose to near‐basal concentrations. Australian snapper are capable of digesting moderate levels of gelatinized wheat starch; however, increasing the dietary content of starch resulted in a reduction in OM and GE digestibility. Smaller snapper appear to be less capable of digesting gelatinized starch than larger fish, and levels above 250 and 350 g kg^?1 of diet are not recommended for small and large fish respectively. Snapper subjected to an intra‐peritoneal injection of d ‐glucose have prolonged hyperglycaemia; however, the post‐prandial response to the uptake of glucose from normally digested gelatinized starch appears to be more regulated.     

Effect of different sources and forms of dietary carbohydrates on growth performance,body indices and lipogenesis activity of striped catfish Pangasianodon hypophthalmus fingerlings

A 12‐week feeding trial was conducted to determine a suitable carbohydrate source and form for Pangasianodon hypophthalmus. Ten isoenergetic, isonitrogenous and isolipidic diets, including five carbohydrate sources (dextrin, potato starch, wheat starch, corn starch and sago starch) and two carbohydrate forms (raw and cooked), were formulated. Results showed that specific growth rate, weight gain percentage, whole‐body lipid and 6‐phosphogluconate dehydrogenase enzyme activity of fish fed with cooked carbohydrates were significantly lower (p < .05) than those fed with raw carbohydrates (p < .05). Similarly, the fatty acid synthase enzyme activity of fish fed with the cooked form of carbohydrates was significantly lower (p < .05) than that fed with the raw form of carbohydrates except fish fed with cooked potato starch. The blood glucose level and malic enzyme activity of fish fed with cooked carbohydrate were significantly (p < .05) higher than those fed with raw carbohydrate. In summary, this study showed that cooked starch is an unsuitable dietary carbohydrate form for Pangasianodon hypophthalmus fingerlings. The raw forms of dextrin starch and potato are suitable dietary carbohydrate sources for further scientific studies on the carbohydrate utilization of P. hypophthalmus.     

Carbohydrate utilization by juvenile silver perch,Bidyanus bidyanus (Mitchell). IV. Can dietary enzymes increase digestible energy from wheat starch,wheat and dehulled lupin?

The effects of exogenous digestive enzyme supplements on the digestibility of wheat starch or diets containing either wheat or dehulled lupin (Lupinus angustifolius var. gungurra) by silver perch (Bidyanus bidyanus) were investigated. In the first experiment, Natustarch^® (α‐amylase supplement specific to starch) was added at three nominal concentrations (0, 50, 100 or 150 mg kg^?1 diet) to diets containing either raw or 100% gelatinized wheat starch (30% dietary inclusion content) and fed to silver perch. The apparent digestibility coefficients (ADCs) for dry matter, starch and energy were calculated. The action of Natustarch^® on the diet and in the digestive tract was also investigated. The addition of Natustarch^® to diets containing raw and gelatinized wheat starch led to an average increase in reducing sugar content of diets of 67% and 340% respectively, indicating that the α‐amylase was more efficient at hydrolysing wheat starch in the gelatinized form. Gelatinized wheat starch was digested more efficiently than raw wheat starch. However, although the addition of Natustarch^® at ≥ 50 mg kg^?1 led to a significant increase in digestibility of raw wheat starch; the digestibility of gelatinized wheat starch, which was already high, was not further improved. Leaching due to immersion in water caused a minor loss of α‐amylase activity from diet pellets treated with Natustarch^® (～ 13% after 5 min). The α‐amylase activity in the anterior section of the intestinal tract of silver perch fed diets containing Natustarch^® was not affected, indicating that the α‐amylase had been denatured by the acidic conditions in the stomach of silver perch. In the second experiment, diets containing wheat or lupin (at the 30% inclusion content) were treated with Natugrain‐blend^®[an enzyme supplement containing β‐glucanase and β‐xylanase, specific to non‐starch polysaccharides (NSPs)] at three nominal concentrations (0, 75, 150 or 300 μL kg^?1) and fed to silver perch. ADCs for energy and protein were calculated. The addition of Natugrain‐blend^® had no effect on dry matter, energy or protein digestibility of the diets or ingredients.     

Effects on digestibility and growth of juvenile cobia (Rachycentron canadum) fed fish or crab silage protein

The study was conducted in Cam Ranh, Vietnam, in 1000‐L tanks supplied with recirculated and biofiltered saltwater (33‰ and 28.4 °C) to evaluate the potential use of lizard fish (Saurida undosquamis) or blue crab (Portunus pelagicus) acid silage protein for juvenile cobia (23–25 g). Six isoenergetic test moist diets (4915–5125 kcal kg^?1), using either raw fish diet, fish silage diet (FSD), raw crab diet, crab silage diet (CSD), mixed raw fish/raw crab diet or mixed fish/crab silage diet (MSD), as part of the protein sources in the steam‐cooked diets, were fed to satiety to triplicate groups of 20 fish each for a 6‐week growth trial. Y₂O₃ was added as an inert indicator to determine the apparent digestibility coefficients (ADC) for macro nutrients and gross energy. Weight gain (185–286%) and specific daily growth rate (2.5–3.2% per day) were significantly higher in cobia fed the raw‐based diets and FSD than in fish fed CSD and MSD (34–90 and 0.7–1.5% per day). Feed conversion ratios (FCR) were significantly higher in the groups fed CSD and MSD diets (2.1–6.5) than the groups fed the other diets (1.0–1.2), resulting in significantly lower protein productive values (0.1–0.2) in the groups fed CSD and MSD than in the other groups (0.3–0.4). The FCR results were confirmed by significantly lower ADC values in fish fed CSD and MSD than those in fish fed the other diets. We thus conclude that the present raw‐based diets were better utilized by juvenile cobia than silage‐based diets, particularly the diet made from crab silage.     

不同糖源对卵形鲳鲹(Trachinotus ovatus)日增重、饲料利用和消化酶活性的影响

以葡萄糖、蔗糖、糊精、玉米淀粉和糊化玉米淀粉为糖源制成5种等氮等脂饲料,投喂卵形鲳碜(Trachinotus ovatus)8周,研究不同糖源对其日增重、饲料利用和肝脏消化酶活性的影响.结果显示,不同糖源对卵形鲳鲹日增重、饲料效率和蛋白效率均有显著影响(P＜0.05).糊化玉米淀粉组的日增重、饲料效率和蛋白效率均最高,显著高于非淀粉糖源组(P＜0.05),而与玉米淀粉组无显著差异(P＞0.05);葡萄糖组的日增重、饲料效率和蛋白效率均最低,显著低于其他糖源组(P＜0.05).消化酶活性结果显示,饲料中的不同糖源对卵形鲳鲹的肝脏消化酶活性有显著影响(P＜0.05).两个淀粉组的蛋白酶活性显著低于分子量较低其他三组(P＜0.05);蔗糖组的淀粉酶活性最高,显著高于除糊精组外的其他糖源组(P＜0.05);脂肪酶活性随着糖分子量的增大而增大.本研究中淀粉类大分子糖类对卵形鲳鲹的促生长效果优于葡萄糖、蔗糖和糊精,糊化玉米淀粉组的促生长效果最好.     

Effects of Amylopectin/Amylose Starch Ratio on Growth, Body Composition and Glycemic Response of Sunshine Bass Morone chrysops × M. saxatilis

Manipulation of the ratio of amylopectin (α‐[1,4] and α‐[1,6] linked glucose) to amylose (α‐[1,41 linked glucose) starches in the carbohydrate fraction of the diet has been used to improve carbohydrate and lipid metabolism in mammalian models. A 10‐wk feeding trial was conducted to determine the effect of dietary amylopectin/amylose ratio on growth and composition of growth of advanced sunshine bass (Morone chrysops × M. saxatilis) fingerlings (60 g, initial weight). Fish were fed cold‐pelleted, semipurified, isonitrogenous (35% crude protein), isocaloric (3.6 kcaVg protein), isolipidic (5%) diets containing 25% carbohydrate. The carbohydrate fraction of the diets was composed of either glucose, dextrin, 100% amylopectin/0% amylose, 70% amylopectin/30% amylose, or 30% amylopectin/70% amylose. Diets differing in ratios of amylopectin/amylose were achieved by adjusting the proportion of high‐amylopectin (100% amylopectin) to high‐amylose (70% amylose) corn starch. Diets were fed to fish in quadruplicate 76‐L tanks (seven fish/tank) connected to a brackish water (5‐7%v) recirculating culture system with biofiltration. Weight gain ranged from 195 to 236% of initial weight (60 g) and was significantly greater (P < 0.1) for fish fed diets containing 25% carbohydrate as dextrin or as 70% amylose and significantly lower in fish fed diets in which carbohydrate was composed of 30% amylose, 100% amylopectin, or glucose. Feed efficiency ranged from 0.52 to 0.61 and was higher in fish fed the diet containing the highest concentration of amylose and lower in fish fed the diet containing glucose. Hepatosomatic index was highest (2.71) in fish fed the diet containing glucose and lowest (1.401.45) in fish fed diets containing high‐amylose cornstarch. Intraperitoneal fat ratio was distinctly lower in fish fed diets containing some amylose as compared to those fed diets without amylose. Liver lipid was significantly lower (4.8%) in fish fed the diet containing glucose and almost twice as high (7.3‐8.9%) in fish fed the diets containing any starch. Glycogen content of the liver decreased from approximately 12% in fish fed the diet containing glucose to 5% in fish fed the diets containing amylose. Muscle proximate composition and ratio were unaffected by the dietary treatments. Fasting levels (15 h) of blood glucose in fish reared for 10 wk on the diet containing glucose were significantly elevated (5.5 mmol/L) when compared to fasting levels of those that had been reared on diets containing starch (3.4‐1.1 mmol/L). Fish fed the diet containing glucose exhibited maximum blood concentrations (14.6 mmoVL) 4 h postprandial then rapidly declined to nearly fasting levels within 8 h postprandial. In contrast, maximum plasma glucose concentrations in fish fed diets containing starch were roughly half (6.8‐8.1 mmol/L) those of fish fed the diet containing glucose. Blood glucose in fish fed diets containing dextrin or predominantly amylopectin starch remained elevated longer than that of fish fed diets containing glucose or predominantly amylose starch. Glycemic response appeared to decrease with increasing dietary amylose content. These data suggest that feeding diets in which a greater portion of the starch is amylose may be a useful strategy for improving carbohydrate use in sunshine bass.     

Metabolic fitness and growth performance in tropical freshwater fish Labeo rohita are modulated in response to dietary starch type (gelatinized versus non‐gelatinized) and water temperature

This study investigated the modulating effect of temperature variation on the metabolic status and growth performance of tropical freshwater fish, Labeo rohita, when reared with starch‐based gelatinized (G) or non‐gelatinized (NG) diet. Fish were either maintained at ambient water temperature (26 °C) or exposed to 32 °C for 1 week, and then subjected to 26 °C for 4 weeks. Both groups were fed with isoproteinous (300 g kg^?1) diets containing G or NG starch. A significant interaction was evident between increased metabolic activity due to the short‐term exposure to higher temperature and starch type on growth performance, feed efficiency and protein retention. Dietary starch type and water temperature interactions were more effective in modulating the hepatic glucokinase and pyruvate kinase responses than that of hexokinase. Hepatic aspartate amino transferase and alanine amino transferase activities were augmented at low temperature in NG starch fed group. Overall, our findings indicate that enzyme activities are enhanced due to the short‐term exposure to higher temperature (32 °C). This elevated temperature lasted for 3 weeks after exposure during which NG starch tended to support the growth.     

Studies on the effect of increasing proportions of sucrose or gelatinized maize starch in diets for rainbow trout (Salmo gairdneri, R.) on the utilization of dietary energy and protein

Trial 1: eight diets containing between 25 and 54% sucrose and correspondingly between 47 and 23% crude protein were fed to replicate groups of trout for 44 or 45 days. Feed conversion increased only when the sucrose content was above 36% and crude protein correspondingly below 40%. Decreasing the protein content by increasing the proportion of sucrose improved the protein efficiency ratio (PER) between 47 and 40% protein; PER values lower than for the diet containing 47% crude protein were obtained only when the protein concentration was less than 36%.

Trial 2: protein of a fish meal/casein diet was replaced by 10–40% sucrose or gelatinized maize starch. All diets were fed to replicate groups of trout for 60 days. Although gelatinized maize starch did not affect the conversion ratio, with increasing proportions of sucrose in-creasing amounts of feed were required per unit of weight gain. PER values increased with increasing proportions of either carbohydrate. No clear differences could be found in body composition. Efficiency of utilization of gross energy was between 40 and 43% for the basal diet and diets containing gelatinized maize starch, whereas it was reduced to about 31% by increasing the proportion of sucrose to 40%. The percentage of dietary N retained rose from 23 to 29% by increasing sucrose, and to 44% by increasing gelatinized maize starch in the diet.     

Growth and salt-water tolerance of juvenile Atlantic salmon, Salmo salar, reared under different combinations of dietary carbohydrate and photoperiod regime

The present study evaluated how different photoperiods, carbohydrate sources and inclusion levels influenced growth, plasma, organ and body compositions in Atlantic salmon (Salmo salar). Four different diets were used, containing 10 or 20% starch on a dry matter basis, using gelatinized corn (C10 and C20) or wheat (W10 and W20). Two different photoperiods were used, Continuous (Con) light throughout the study, Winter (Wi) two initial weeks of continuous light, thereafter 6 weeks of short day, ending with 6 weeks of continuous light. The winter regime resulted in reduced growth rate compared with continuous light. All Wi groups were smaller than Con groups when the experiment was terminated, except for fish given diet C10. Diet W10 resulted in better growth compared with all other groups when exposed to Con. regime. Atlantic salmon fed with diets containing 20% starch had lower growth rates than fish fed diets containing 10% starch, when the same starch source and light regime were compared. All fish belonging to the Con group exhibited similar and higher condition factors compared with fish from groups Wi. Condition factor was not influenced by dietary starch source. Higher whole body lipid concentrations were found when fish were given the corn compared with the wheat diets, without any responses to starch level or light regime. Whole body protein showed increased values in fish exposed to regime Wi compared with Con, without any influence from dietary manipulation. Liver glycogen values and hepatosomatic index reflected dietary starch levels and were significantly influenced by light regime, whilst muscle glycogen levels varied only as a response to light regime with lower values in fish from the Wi compared with the Con groups. Light regime influenced plasma glucose levels, except in groups fed with diet W10. All measured plasma nutrient concentrations were within normal ranges. At the end of the feeding period, all fish were evaluated for glucose and salt water tolerance to ascertain whether diet and/or light regime influenced glucose regulation capacity and/or smolt quality. Fish fed with 20% starch had reduced osmoregulatory ability measured as plasma chloride after a seawater challenge test. Fish from the Wi regime, but not from the Con regime developed characteristics associated with smoltification. Glucose tolerance in Atlantic salmon was substantially influenced by both photoperiod regime and diet. Fish reared under the Wi photoperiod showed reduced glucose regulation capacity compared with fish held under continuous light. Glucose regulation capacity was also reduced in fish adapted to the highest starch levels.