Partial replacement of fish meal by several plant proteins with or without iron and lysine supplement in diets for juvenile Chinese sucker,Myxocyprinus asiaticus

Two feeding experiments were conducted to evaluate the potential of fermented soybean meal (FSBM), corn gluten meal (CGM) and cottonseed meal (CSM) with or without lysine (L) and iron (Fe) to replace fish meal (FM) in practical diets of juvenile Chinese sucker. In experiment I, four experimental diets (430 g kg^?1 crude protein on dry matter basis) were formulated. Diet containing FM as the main protein source was used as a control (Diet 1). Diets 2–4 had 300 g kg^?1 FM protein replaced with FSBM, CGM or CSM protein without iron or lysine supplement. Fish (average weight, 1.82 ± 0.01 g) were hand‐fed twice daily for 8 weeks. In experiment II, juvenile Chinese sucker (average weight, 3.40 ± 0.08 g) were fed one of five experimental diets twice daily for 8 weeks. Diet 1 in experiment I was used as a control and Diet 4 in experiment I, with ferrous sulphate, with lysine or with both ferrous sulphate and lysine were used as the experimental diets (designated as FM, CSM, CSM+Fe, CSM+L and CSM+Fe&L, respectively). Results from the two feeding trials indicated that about 300 g kg^?1 of FM protein can be replaced by FSBM, CGM or CSM with lysine supplement in Chinese sucker diets without adversely affecting growth. CSM with iron could not improve the growth performance. CSM without lysine supplement significantly affected the growth performance, body composition and digestive enzyme activities.     

Evaluation of fermented soybean meal in the practical diets for juvenile Chinese sucker,Myxocyprinus asiaticus

The study was designed to investigate the influence of fermented soybean meal (FSBM) on the growth and feed utilization of juvenile Chinese sucker, Myxocyprinus asiaticus. Seven isonitrogenous and isolipidic diets were formulated with 0%, 15%, 25%, 35%, 45%, 55% or 65% replacement of fish meal with FSBM on a protein basis. Each diet was fed to three replicate groups of fish with an initial weight 4.59 ± 0.2 g for 8 weeks. Weight gain (WG) and specific growth rate (SGR) was significantly lower when FSBM inclusion was 391 g kg^?1 or greater, replacing more than 45% fish meal protein. A significant negative relationship was observed between growth response and the level of fish meal protein replacement with FSBM. Methionine and Lysine content decreased as FSBM inclusion levels increased, consequently compromising growth performance. Feed intake (FI) were unaffected by dietary FSBM levels. The feed conversion ratio (FCR) of fish fed D‐0, D‐15, D‐25 and D‐35 diets was significantly lower than those fed other diets. The protein efficiency ratio (PER) was highest at the lowest FSBM inclusion level. Experimental diets D‐0, D‐15, D‐25 and D‐35 had apparent dry matter digestibility ranging from 71.2% to 72.6% and apparent protein digestibility (ADPs) from 89.1% to 90.1%, while the diets with higher FSBM inclusion (D‐45 to D‐65) had a significantly lower apparent dry matter digestibility range (69.7–70.3%) and ADPs range (88.5–88.9%). It is concluded that FSBM is an acceptable alternative plant protein source that can replace up to 35% of fish meal protein in diets without significant adverse effects on growth, survival, FCR, PER and body composition.     

Effects of replacing fish meal with soybean meal on growth,body composition and digestive enzyme activities of juvenile Chinese sucker,Myxocyprinus asiaticus

Six isonitrogenous diets (420 g kg^?1 crude protein on dry matter basis) with six levels of soybean meal (SBM) inclusion (0, 112, 225, 336, 449 and 560 g kg^?1) in substitution of fish meal (0%, 20%, 40%, 60%, 80% and 100%) were evaluated in Chinese sucker of 1.81 ± 0.01 g initial weight for 8 weeks. There existed a significant difference (P < 0.001) in fish weight gain, feed conversion ratio, feed intake, protein efficiency ratio and specific growth rate when the replacement level for fish meal protein was increased from 40% to 60%, indicating that up to 40% of fish meal protein could be replaced with SBM protein without causing reduction in growth and protein utilization. Lipid contents in the Chinese sucker body decreased significantly (P < 0.001) as dietary SBM increased. Digestive enzyme activities in the intestine and hepatopancreas of the fish were significantly different (P < 0.001) as the SBM protein replacement level was increased. Results of the present study appear to indicate that 40% FM can be replaced by SBM in practical feeds of Chinese sucker.     

Effect of partial replacement of fish meal with soybean meal and feeding frequency on growth,feed utilization and body composition of juvenile Chinese sucker,Myxocyprinus asiaticus (Bleeker)

A factorial (2 × 4) feeding trial was conducted to investigate the effects of feeding frequency and partial replacement of fish meal (FM) with soybean meal (SBM) on the growth performance, feed utilization and body proximate composition of juvenile Chinese sucker. Two feed types including replacement of 30% FM (diet 1) with SBM (diet 2) were used. Triplicate groups of fish (average weight, 11.80 ± 0.19 g) were fed each feed type to visual satiation at four meals per day, three meals per day, two meals per day and one meal per day for 8 weeks. At the end of the feeding trial, the survival of fish was not significantly different among the treatments. Weight gain was affected by the feeding frequency. The highest weight gain was observed in fish fed with diet 1 at three meals per day. There existed a significant difference in daily feed intake (DFI), daily protein intake (DPI), feed conversion ratio (FCR) and protein efficiency ratio (PER) when the feeding frequency was increased from one or two to three or four meals per day (P < 0.001), but not by the feed types. For both two feed types, the highest DFI and DPI were observed at three meals per day. The highest PER was gained at four meals per day, while FCR was the least. The body proximate composition of fish was altered by feeding frequency. The crude lipid content increased with the increase in feeding frequency. Essential amino acids (EAAs) content showed no significant differences among different treatments. The present findings suggest that three feedings per day at visual satiation may be sufficient for the maximal growth performance of Chinese sucker grown from 11 to 45 g. Results also indicate that about 30% of FM protein can be replaced by SBM protein in Chinese sucker diets without adversely affecting growth.     

Partial replacement of fish meal by a mixture of soybean meal and rapeseed meal in practical diets for juvenile Chinese mitten crab Eriocheir sinensis: effects on growth performance and in vivo digestibility

An 8‐week experiment was conducted to examine the effect of partial replacement of fish meal (FM) by a mixture of soybean meal (SBM) and rapeseed meal (RM) in practical diets of juvenile Chinese mitten crab Eriocheir sinensis of initial body weight of 1.54±0.12 g (means±SD, n=90). Five isonitrogenous diets were formulated to contain 35% protein and 5% lipid. Soybean meal and RM mix (1:1 ratio) were included at five levels of 0 (control), 15%, 30%, 45% and 60%, replacing 0, 20%, 40%, 60% and 80% FM respectively. When FM was replaced by 15% of SBM and RM, crab showed the highest growth, feed utilization and moulting frequency (MF). Fish meal replaced by SBM and RM did not significantly influence crude protein, lipid and moisture contents of whole body crab, but ash content was the lowest for crab fed the diet with FM replaced by 15% of SBM and RM. Apparent digestibility coefficients (ADCs) of dry matter, crude protein and energy tended to decline with increasing inclusion levels of dietary SBM and RM. In general, ADCs of lipid were high (over 90%) and showed no significant differences among the treatments (P>0.05). Based on these observations above, these results indicated that about 40% of FM can be replaced with a mixture of SBM and RM (1:1 ratio) in the diet of E. sinensis without adverse growth performance, compared with the FM‐based diet. However, 20% of FM replaced by SBM and RM produced the best growth performance and feed utilization.     

Optimal dietary methionine requirement of juvenile Chinese sucker,Myxocyprinus asiaticus

A total of 630 juvenile Chinese sucker, with an average initial weight of 1.72 ± 0.05 g, were fed seven diets for 56 days to study the effect of dietary methionine levels on growth, feed utilization, body composition and haematological parameters on juvenile Chinese sucker. Diet 1 using fish meal as the sole protein source and diets 2–7 using fish meal and fermented soybean meal as intact protein sources supplemented with crystalline amino acids contained six levels of l ‐methionine ranging from 6.4 to 18.9 g kg^?1 of dry diet at a constant dietary cystine level of 3.7 g kg^?1. Each diet was randomly assigned to three aquaria. Results indicated that the highest weight gain, specific growth rate (SGR), feed efficiency ratio, protein efficiency ratio and protein productive value occurred at 13.9 g methionine kg^?1 diet among the methionine supplemented dietary groups, beyond which they showed declining tendency. The whole body and muscle protein contents of juvenile Chinese sucker were positively correlated with dietary methionine level, while muscle lipid content was negatively correlated with it. The total essential amino acids content of muscle was increased significantly with increasing dietary methionine level from 6.4 to 13.9 g kg^?1 (P < 0.05). Apparent digestibility coefficients of dietary protein were significantly affected by dietary treatments. Serum protein, cholesterol and triacylglycerol increased with increasing dietary methionine levels, but showed a relatively lower value for fish fed the 18.9 g methionine kg^?1 diet. Quadratic regression analysis of SGR against dietary methionine level indicated that optimal dietary methionine requirement for juvenile Chinese sucker was 14.1 g kg^?1 of the diet in the presence of 3.7 g kg^?1 cystine (corresponding to 32.0 g kg^?1 of dietary protein on a dry‐weight basis).     

饲料中豆粕替代鱼粉比例对牙鲆生长性能及生化指标的影响

以鱼粉和豆粕分别为主要动物性和植物性蛋白源,研究饲料中不同豆粕替代鱼粉比例对牙鲆幼鱼生长性能和生化指标的影响。设计4∶1、3∶1、2∶1和1∶1四种不同动植物蛋白比的等氮等脂饲料配方,按配方制备试验饲料,分别表示为D1、D2、D3和D4。牙鲆幼鱼随机分配到12个设有循环水系统的玻璃钢桶内(900L),每3桶鱼饲喂一种饲料,每天投喂饲料2次,每次达到表观饱食,饲喂期为56d。以增重率(WGR)、饵料系数(FCR)、特定生长率(SGR)、蛋白质效率(PER)、肝体指数(HSI)、肥满度(CF)、鱼体成分和饲料成本为依据,综合评价饲料中不同比例的豆粕替代鱼粉比例对牙鲆的饲养效果。通过测定尿素氮(BUN)、谷丙转氨酶(GPT)、谷草转氨酶(GOT)、游离脂肪酸(FFA)、总蛋白(TP)、甘油三酯(TG)、胆固醇(CHO)、高密度脂蛋白胆固醇(HDL-C)及低密度脂蛋白胆固醇(LDL-C)等生化指标,研究饲料中不同豆粕替代鱼粉比例对牙鲆蛋白质代谢和脂肪代谢的影响。随豆粕比例的增加,WGR、PER和SGR逐渐降低,FCR逐渐增加,当饲料中豆粕比例在24%以上时差异显著(P<0.05);HSI逐渐增加,且D1组显著低于其他...     

Partial replacement of soybean meal by sesame meal in diets of juvenile Nile tilapia,Oreochromis niloticus L.

An 8‐week feeding trial was conducted to determine the effects of replacing of soybean meal (SBM) with sesame meal (SM) in the diets of Oreochromis niloticus fingerlings. Seven practical diets (33 g kg^?1 crude protein, 19.2 MJ kg^?1 dry diet) containing substitution levels of 0%, 8%, 16%, 24%, 32%, 40% and 48% SM for SBM protein were formulated and fed to triplicate groups of O. niloticus fingerlings (mean initial weight of 8.74 ± 0.12 g). The fish survival rate, hepatosomatic index, viscerosomatic index and condition factor were not significantly affected by the contents of SM in the diets (P>0.05). The final body weight, weight gain (WG), specific growth ratio, feed conversion ratio and protein efficiency ratio of the fish fed the diet containing 16% SM were similar (P>0.05) to that of the fish fed the control diet. Except lipid, digestible contents of dry matter, crude protein, ash, gross energy and individual amino acids decreased while phosphorous increased with increasing SM levels. No significant differences were observed in whole‐body dry matter, ash and lipid contents among all the treatments (P>0.05); crude protein contents between fish fed the control diet and a diet containing 24% SM were also not affected significantly (P>0.05), and the phosphorus content was not significantly different when the SM level was increased to 32% (P>0.05). No significant negative differences were observed in the liver composition between fish fed the control diet and the diet containing 24% SM. The most efficient diet in terms of cost per unit WG of fish was obtained in 8% SM dietary substitution, while no significant differences were found among the 0%, 8% and 16% levels. It was indicated that SM can be utilized in the juvenile Nile tilapia diet to replace about 16% of SBM protein without causing negative effects on growth performance, body composition, liver composition and feed utilization.     

石斑鱼配合饲料中发酵豆粕和豆粕部分替代白鱼粉的研究

在浮式海水网箱(1.5m×1m×1.5m)中养殖石斑鱼幼鱼(9.4±0.1g),在等氮(52% CP)基础上进行以发酵豆粕和普通豆粕替代鱼粉的实验, 为期56天.结果显示在石斑鱼饲料中添加14%发酵豆粕,其增重率、特定生长率(SGR)、饲料效率和蛋白质效率与对照组没有显著性差异(P>0.05),以后随着发酵豆粕添加量的上升,这些指标都显著下降(P<0.05).在同样替代水平下,添加21%发酵豆粕组,增重率,SGR,饲料效率和蛋白质效率都比添加20%豆粕组高(P<0.05),表明对海水肉食性鱼类来说,发酵豆粕是一种比豆粕更优良的蛋白源.用折线模型分析增重率随白鱼粉替代水平的变化关系,结果表明在石斑鱼配合饲料中,发酵豆粕替代白鱼粉的最适量为10%.从实际生产的经济效益出发,建议在饲料中添加14%发酵豆粕,对石斑鱼的生长和鱼体组成不会造成显著影响.     

Dietary l‐lysine requirement of juvenile Chinese sucker,Myxocyprinus asiaticus

An 8‐week feeding trial was conducted to quantify the dietary l ‐lysine requirement of juvenile Chinese sucker with an initial weight of 1.81 ± 0.04 g reared in indoor flow‐through and aerated tanks. Six isonitrogenous and isoenergetic practical diets were formulated to contain graded levels of lysine (1.23%, 1.80%, 2.39%, 2.98%, 3.56% and 4.18% dry matter) at 0.6% increments from dietary ingredients and crystalline l ‐lysine. Each diet was randomly assigned to triplicate groups of 30 fish each and was fed to apparent satiation by hand three times a day (09:00, 13:00 and 17:00 hours) for 8 weeks. There were significant differences in growth performance and feed utilization among the treatments. Weight gain (WG), specific growth rate and protein efficiency ratio (PER) significantly increased with increasing lysine levels up to 2.39% of diet (P < 0.05) and remained nearly the same thereafter (P > 0.05). Feed efficiency was the poorest for fish fed the lowest lysine diet (P < 0.05) and showed no significant differences when dietary lysine level increased from 2.39% to 4.18%. The N retention (% N intake) significantly increased with dietary lysine level but did not attain a plateau (P < 0.05). Survival could not be related to dietary treatments. Whole body protein increased (P < 0.05) and whole body lipid decreased (P < 0.05) with increasing dietary lysine level. The condition factor and hepatosomatic index were significantly affected by dietary lysine levels, however, viscersomatic index, whole body moisture and ash did not differ significantly among dietary treatments. Broken‐line analysis on the basis of WG and PER showed that dietary lysine requirements of juvenile Chinese sucker were 2.43% and 2.40% dry diet (5.52% and 5.45% dietary protein) respectively. Based on the ideal protein approach and the A/E ratios determined from muscle amino acid profile an estimation of the EAA requirements of Chinese sucker juveniles were calculated.     

Effect of replacing fish meal with soybean meal on growth,feed utilization and nitrogen and phosphorus excretion of juvenile Pseudobagrus ussuriensis

An 8‐week feeding trial was conducted to evaluate the effects of replacing fish meal with soybean meal (SBM) on growth, feed utilization, and nitrogen (N) and phosphorus (P) excretion of juvenile Pseudobagrus ussuriensis (initial average weight 0.50 ± 0.00 g). Seven isonitrogenous and isolipidic diets were formulated to contain SBM to replace fish meal protein at 0% (S0), 10% (S10), 20% (S20), 30% (S30), 40% (S40), 50% (S50) and 60% (S60) respectively. To investigate the effects of supplementation with crystalline amino acid to balance diet S60, one diet was formulated to add 0.30% methionine (SM60). The results showed that there was no significant difference in weight gain among fish fed S0, S10, S20, S30 and S40 diets, however, a significant reduction in this variable occurred when 50% and 60% of fish meal protein was replaced by SBM (P < 0.05). Apparent digestibility coefficients of dry matter, crude protein and phosphorus of diets were affected by dietary SBM levels. N and P excretion indicate that fish meal replacement by SBM led to an increase in N excretion, but led to a reduction in P excretion. No differences were detected in growth, feed utilization and N and P excretion between fish feed diets S60 and SM60. The results of this study show that 40% of fish meal protein could be replaced by SBM in diets of juvenile P. ussuriensis without having a significant negative effect on growth or feed efficiency, but that higher dietary SBM levels reduce fish performance.     

Dietary phosphorus requirement of juvenile Chinese sucker,Myxocyprinus asiaticus

A growth trial was conducted to estimate the optimum requirement of dietary available phosphorus (P) for Chinese sucker juveniles. Triplicate groups of juveniles Chinese sucker (initial mean weight: 1.77 ± 0.02 g, mean ± SD) were fed diets containing graded levels (3.1, 5.3, 7.5, 9.6 and 11.8 g kg^?1) of available phosphorus. The basal diet (diet 1), containing 3.1 g kg^?1 available P, was supplemented with graded levels of monocalcium phosphate to formulate four experimental diets. The fish were fed twice daily (08:00 and 17:00 h) to satiation for 8 weeks. During the experimental period, the water temperature fluctuated from 27.5 to 30.5 °C and dissolved oxygen was more than 6 mg L^?1. The specific growth rate, protein efficiency ratio were all significantly increased by dietary available phosphorus up to 7.5 g kg^?1 (P < 0.05) and then levelled off beyond this level. Feed conversion ratio significantly decreased with dietary available phosphorus level up to 7.5 g kg^?1 (P < 0.05). Dietary treatments did not significantly affect feed intake (P > 0.05). Efficiency of phosphorus (P) utilization significantly decreased with dietary available phosphorus level (P < 0.05). Body composition analysis showed that the whole‐body lipid, ash, calcium, phosphorus, magnesium (Mg), zinc (Zn) and copper (Cu) contents were all significantly affected by dietary available P concentration (P < 0.05); however, no significance were found for manganese (Mn) concentration and calcium/phosphorus (Ca/P) ratios in whole‐body among all the treatments (P > 0.05). Dietary phosphorus levels also significantly affected the mineralization of vertebrae and scale (P < 0.05), and Ca/P ratios in scale were not influenced by dietary P supplementation, while vertebrae Ca/P ratio decreased with dietary available P levels (P < 0.05) (quadratic effect, P < 0.001). Signs of phosphorus deficiency were characterized by poor growth, slightly reduced mineralization and an increase in body lipid content. The blood chemistry analysis showed that dietary available P had distinct effects on enzyme activities of alkaline phosphatase, as well as contents of triacyglycerol and total cholesterol (P < 0.05). Broken‐line analysis based on weight gain indicated the minimum available phosphorus requirement for the optimal growth of juvenile Chinese sucker was 7.4 g kg^?1. Based on the phosphorus content in whole body, vertebrae or scale indicated that the requirements were 8.3, 8.8 and 8.6 g kg^?1 respectively.     

Dietary vitamin C requirement of juvenile Chinese sucker (Myxocyprinus asiaticus)

An 8‐week growth experiment was conducted to quantify the appropriate dietary vitamin C requirement of juvenile Chinese sucker (Myxocyprinus asiaticus). Triplicate groups of 30 experimental fish [initial body weight: (7.1 ± 0.3) g] were cultured in 500 L aquaria and fed with semi‐purified diets containing six levels [10.1 (unsupplemented diet), 37.4, 64.9, 125.2, 244.2 and 482.0 mg kg^?1 diet, respectively] of vitamin C (supplied as L‐ascorbyl‐2‐polyphosphate). Results showed that weight gain of Chinese sucker was significantly increased with increasing dietary vitamin C levels, but there was no significant difference of weight gain among fish fed the diets containing more than 125.2 mg kg^?1 vitamin C. As dietary vitamin C increased, the liver vitamin C content of fish showed the increasing trend firstly and then stabled, while the muscle vitamin C content significantly increased without reaching a constant level. Lower liver malondialdehyde content was observed in 125.2, 244.2 and 482.0 mg kg^?1 vitamin C groups, and higher antioxidant capacity and superoxide dismutase activities were observed in supplemented groups when compared to the unsupplemented group. Liver aspartate aminotransferase and alkaline phosphatase activities were also significant affected by dietary vitamin C. Ash content of fish fed the diet with 244.2 or 482.0 mg kg^?1 vitamin C was significantly higher than that of fish fed the other diets. However, dietary vitamin C had no significant effects on whole‐body crude protein, lipid and moisture contents. The vitamin C requirement of juvenile Chinese sucker was estimated to be 84.6 and 126.1 mg kg^?1 based on weight gain and liver vitamin C concentration respectively.     

Partial replacement of fishmeal by soybean meal in diets for juvenile cobia (Rachycentron canadum)

An 8‐week feeding experiment was conducted in floating cages (1.5 × 1.0 × 2.0 m) to determine the potential use of defatted soybean meal (roasted and solvent‐extracted) as a partial replacement of fishmeal in the isonitrogenous (approximately 450 g kg^?1 CP [crude protein]) diet for juvenile cobia with an initial average weight of about 8.3 g. Diets were formulated to include 0, 100, 200, 300, 400, 500 and 600 g kg^?1 (diets D0, D10, D20, D30, D40, D50 and D60, respectively) of fishmeal protein being substituted by defatted soybean meal without methionine supplementation. The results showed that weight gain rate decreased significantly when the replacement level of fishmeal protein was increased from 400 g kg^?1 to 500 g kg^?1, and the D60 diet was the lowest in all groups. These results indicate that up to 400 g kg^?1 of fishmeal protein can be replaced by defatted soybean meal without causing significant reduction in growth. Feed conversion ratio (FCR) and protein efficiency ratio (PER) were significantly affected by the replacement level of fishmeal protein being substituted by defatted soybean meal, when the replacement level of fishmeal protein was 200 g kg^?1 (diet, D20), FCR was the lowest and PER was the highest. There were no significant differences in the moisture, lipid, crude protein and ash content in whole body and muscle, while lipid content in liver increased as the dietary soybean meal replacement levels increased. There were significant differences in haemoglobin, haematocrit, red blood cell, plasma glucose and triglyceride concentration in fish fed diets with different soybean meal replacement levels. Results of this trial indicated that the optimum level of fishmeal protein replacement with defatted soybean meal, determined by quadratic regression analysis was 189.2 g kg^?1, on the basis of maximum weight gain.     

Effects of feeding levels on growth performance,feed utilization,body composition and apparent digestibility coefficients of nutrients for juvenile Chinese sucker,Myxocyprinus asiaticus

An experiment was conducted to determine effects of feeding levels on growth performance, feed utilization, nutrient deposition, body composition and apparent digestibility coefficients (ADCs) of nutrients for juvenile Chinese sucker (initial weight, 11.77±0.22 g). Chinese sucker were fed a practical diet from 0% (starvation) to 4.0% (at 0.5% increments) body weight (bw) day^?1 for 8 weeks. The results showed that growth performance, feed utilization, nutrient deposition, body composition and ADCs of dry matter, protein and energy were significantly (P<0.05) affected by feeding levels. Survival was the lowest for the starvation group. Final mean body weight, growth rate, thermal‐unit growth coefficient (TGC) increased with feeding rate from 0% to 3.0% bw day^?1 (P<0.05) and showed no significant differences above the level (P>0.05). Feed conversion rate was significantly lower at a feeding level of 2.5% bw day^?1 than above and below the level (P<0.05). Protein efficiency ratio was markedly highest at the 2.5% bw day^?1 ration level (P<0.05). Fish fed at the feeding level (1.0% bw day^?1), which represented a maintenance ration (energy gain was less than 2.27 kJ fish^?1 day^?1), showed positive protein deposition but negative lipid deposition. This indicates that fish fed a maintenance ration mobilize body lipid reserve to support protein deposition. Lipid contents of whole body, muscle and liver increased with increasing feeding rates from 0.5% to 3.0% bw day^?1 and showed no significant differences above the level (P>0.05). Protein contents of whole‐body composition increased with feeding rate from 0.5 to 3.0% bw day^?1 (P<0.05) and showed no significant differences above the level (P>0.05), whereas muscle and liver remained relatively stable with the different ration amount with the exception of fish fed a ration of 0.5% bw day^?1, at which Chinese sucker possessed significantly lower body protein concentration (P<0.05). The ADCs of dry matter, protein and energy decreased with increasing feeding levels from 0.5% to 3.0% bw day^?1 and then remained relatively constant over the level. Based on the broken‐line regression analysis using WG data, the optimum and maintenance feeding levels for Chinese sucker were 3.10% bw day^?1 and 0.45% bw day^?1 respectively.     

Effects of dietary protein to energy ratios on growth and body composition of juvenile Chinese sucker,Myxocyprinus asiaticus

A growth experiment was conducted to investigate effect of dietary protein to energy ratios on growth and body composition of juvenile Myxocyprinus asiaticus (initial mean weight: 10.04 ± 0.53 g, mean ± SD). Nine practical diets were formulated to contain three protein levels (340, 390 and 440 g kg^?1), each with three lipid levels (60, 100 and 140 g kg^?1), in order to produce a range of P/E ratios (from 22.4 to 32.8 mg protein kJ^?1). Each diet was randomly assigned to triplicate groups of 20 fish in 400‐L indoors flow‐through circular fibre glass tanks provided with sand‐filtered aerated freshwater. The results showed that the growth was significantly affected by dietary P/E ratio (P < 0.05). Fish fed the diets with 440 g kg^?1 protein (100 and 140 g kg^?1 lipid, P/E ratio of 31.43 and 29.22 mg protein kJ^?1) had the highest specific growth rates (SGR) (2.16 and 2.27% day^?1, respectively). However, fish fed the diet with 390 g kg^?1 protein and 140 g kg^?1 lipid showed comparable growth (2.01% day^?1), and had higher protein efficiency ratio (PER), protein productive value (PPV) and energy retention (ER) than other groups (P < 0.05). No significant differences in survival were found among dietary treatments. Carcass lipid content was positively correlated with dietary lipid level, but irrespective of protein level and inversely correlated with carcass moisture content. Carcass protein contents increased with increasing dietary lipid at each protein level. The white muscle and liver composition showed that lipid increased with increasing dietary lipid level (P < 0.05). Dietary protein concentrations had significant effect on condition factor (CF), hepatosomatic index (HSI) and viscerosomatic index (VSI) (P < 0.05). However, dietary lipid concentrations had no significant effect on CF, HSI (P > 0.05). Based on these observations, 440 g kg^?1 protein with lipid from 100 to 140 g kg^?1 (P/E ratio of 29.22 to 31.43 mg protein kJ^?1) seemed to meet minimum requirement for optimal growth and feed utilization, and lipid could cause protein‐sparing effect in diets for juvenile Chinese sucker.     

Partial replacement of fishmeal by fermented soybean meal in diets for juvenile white shrimp (Litopenaeus vannamei)

As an important feed ingredient, fermented soybean meal (FSM) has been widely used in aquatic animals due to its stable sources and reasonable price. Here, we evaluated the potential for replacement of fishmeal (FM) with FSM in diet of Litopenaeus vannamei. Five isonitrogenous (410 g/kg) and isolipidic (80 g/kg) diets were formulated: a control diet containing 320 g/kg FM and four experimental diets in which FM in control diet was replaced by FSM at 10 (FSM10%), 20 (FSM20%), 30 (FSM30%) and 40% (FSM40%). An 8‐week feeding trial was conducted in fifteen fibreglass tanks with 50 shrimps per tank. After 8 weeks trial, FSM20% had significantly enhanced growth performance (p < 0.05). No significant difference was found in body composition and digestive enzyme activities of all groups (p > 0.05). Through real‐time quantitative PCR analysis, tor and s6k expression levels of FSM20% were significantly up‐regulated (p < 0.05). Results of western blot showed that the phosphorylation of S6K was not significantly affected by different dietary treatments (p > 0.05), which suggested mTOR signalling pathway was not affected by FSM diets. Based on the above data, 20% replacement of FM with FSM was reasonable and advantageous for L. vannamei diet.     

Evaluation of Cassia fistula meal as a replacement for soybean meal in practical diets of Oreochromis niloticus fingerlings

This study was undertaken to determine the replacement value of Cassia fistula seed meal (CFM) for soybean meal (SBM) in practical diets of Oreochromis niloticus fingerlings. Five practical diets (350 g kg^?1 crude protein) containing 0 g kg^?1 (control), 170 g kg^?1 (diet II), 340 g kg^?1 (diet III), 509 g kg^?1 (diet IV) and 670 g kg^?1 (diet V) substitution levels of CFM for SBM were formulated and fed to triplicate groups of O. niloticus fingerlings (mean initial weight of 10.22 ± 0.03 g) for 70 days. Fish mortality increased linearly with increase in inclusion levels of CFM in the diet. Growth and diet utilization efficiency were depressed in fish fed diets containing CFM at varying inclusion levels. Feed conversion ratio, specific growth rate and protein efficiency ratio of O. niloticus fed on diet containing 170 g kg^?1 substitution level of CFM were similar (P > 0.05) to the control diet. Digestibility of the different diets decreased with increase in inclusion levels of CFM. Fish fed diet containing 670 g kg^?1 CFM had significantly lower carcass protein. However, no significant differences were observed in carcass protein and lipid contents between fish fed the control diets and diet containing 170 g kg^?1 CFM. The most efficient diet in terms of cost per unit weight gain of fish was obtained in 170 g kg^?1 CFM dietary substitution.     

饲料脂肪水平对胭脂鱼幼鱼生长、体组成和抗氧化能力的影响

试验选用体重(6.73±0.21)g的胭脂鱼(Myxocyprinus asiaticus)幼鱼540尾,随机分成6个组,每组3个重复,每个重复30尾试验鱼。以大豆油为脂肪源,配制成脂肪水平为2.04%、4.43%、6.88%、9.02%、11.98%、13.39%的半精制饲料,进行为期56 d的生长试验,研究脂肪水平对胭脂鱼幼鱼生长、体组成及机体抗氧化能力的影响。结果显示:饲料脂肪水平对胭脂鱼的生长性能有显著影响(P<0.05)。脂肪水平为6.88%时,胭脂鱼增重率、特定生长率、蛋白质沉积效率最高,饲料系数最低。脂肪沉积效率随脂肪水平的增加呈下降趋势。随脂肪水平增加,胭脂鱼全鱼、肌肉和肝胰脏脂肪含量逐渐上升,至6.88%组后稳定,而全鱼水分、粗蛋白含量没有显著变化(P>0.05)。胭脂鱼机体抗氧化能力随着脂肪水平的增加呈现先升后降趋势,脂肪水平为6.88%时,总抗氧化能力(T-AOC)、超氧物歧化酶(SOD)值最大,丙二醛(MDA)值最小,即抗氧化能力最强。以增重率、特定生长率和饲料系数进行回归分析并考虑脂肪水平对胭脂鱼营养组成和抗氧化能力的影响,确定胭脂鱼幼鱼适宜脂肪水平为6.62%~7.02%。