豆油替代鱼油对圆斑星鲽幼鱼生长和肌肉脂肪酸的影响

本实验旨在研究饲料中豆油替代鱼油对圆斑星鲽(Verasper variegatus)幼鱼生长和肌肉脂肪酸组成的影响。用豆油分别替代0、25%、50%和75%的鱼油,配制4组等氮、等脂肪的饲料。选择初始体重为(65.47±1.57)g的圆斑星鲽幼鱼360尾,随机分为4组,每组3个重复,每个重复30尾鱼,养殖56 d。结果显示,(1)随着豆油替代水平的升高,增重率(WGR)呈现降低的趋势(P0.05),饲料系数(FCR)呈现升高的趋势(P0.05),25%替代组的WGR高于鱼油组(P0.05)。(2)豆油替代鱼油对圆斑星鲽肌肉的粗蛋白、粗脂肪、灰分和水分含量无显著性影响(P0.05),对肝体比(HSI)、脏体比(VSI)和肥满度(CF)无显著性影响(P0.05),豆油替代组肝脏的脂肪含量显著高于鱼油组(P0.05)。(3)随着饲料中豆油水平的增加,圆斑星鲽幼鱼肌肉亚油酸(C18:2n-6)和亚麻酸(C18:3n-3)显著升高(P0.05),而二十碳五烯酸(EPA)和二十二碳六烯酸(DHA)则显著降低(P0.05)。研究结果表明,在该实验条件下,饲料中高比例的豆油替代鱼油会降低鱼体的生长性能和肌肉脂肪酸营养品质。     

Effect of Dietary Protein and Lipid Levels on Growth and Body Composition of Spotted Halibut,Verasper variegatus

A 83‐d feeding experiment was undertaken to evaluate the effects of dietary protein and lipid levels on growth and body composition of spotted halibut, Verasper variegatus (initial average weight of 93.0 ± 1.0 g). Nine diets were formulated to contain three protein levels (40, 45, and 50%), each with three lipid levels (8, 12% and 16%). Each diet was randomly fed to triplicate groups of 20 fish per tank in the indoor culture system. Results showed that the survival rate of fish was not significantly affected by protein and lipid levels (P > 0.05). Weight gain, specific growth rate (SGR), and feed intake (FI) significantly decreased with the increasing dietary lipid levels (P < 0.05). Feed efficiency significantly increased while the feed conversion ration significantly decreased with increasing dietary protein levels (P < 0.05). Weight gain, SGR, FI, and feed efficiency of fish fed 50% protein and 8% lipid were significantly higher than that of the other groups. For each level of dietary lipid, the increase in dietary protein resulted in significant increases in whole‐body crude protein (CP) contents (P < 0.05); the increase in dietary lipid caused significant increases in whole‐body crude lipid content and gross energy at each protein level (P < 0.05). The muscle CP, lipid, and gross energy had the same tendency. The results of this study indicated that increasing dietary lipid levels did not result in a protein‐sparing effect. It could be recommended that the proper dietary protein and lipid levels of spotted halibut were 50 and 8%, respectively.     

脱脂磷虾粉对圆斑星鲽(Verasper variegatus)幼鱼生长、非特异性免疫力和血清生理代谢指标的影响

为研究脱脂磷虾粉替代鱼粉对圆斑星鲽(Verasper variegatus)幼鱼生长性能、非特异性免疫力和血清生理代谢指标的影响,实验以鱼粉和脱脂磷虾粉为蛋白源,鱼油为脂肪源,分别以脱脂磷虾粉蛋白替代基础饲料中0、10％、20％、30％、40％、50％和100％的鱼粉蛋白制成7种等氮、等脂的饲料(分别记为R0、R10、R20、R30、R40、R50、R100),投喂初始体重为(60.11±0.13)g、体长为(14.12±0.25) cm的圆斑星鲽幼鱼8周,每组设3个重复,每个重复20尾鱼.结果显示,R10-R50组的特定生长率(SGR)、存活率(SR)和饲料效率(FER)与R0组(对照组)没有显著性差异(P＞0.05),但从R30组开始有下降的趋势.R10-R50组的蛋白质效率(PER)和R0组无显著性差异(P＞0.05),但R100组的PER显著低于R0组(P＜0.05).R10-R20组血清中的酸性磷酸酶(ACP)显著高于R0组(P＜0.05),R30组血清中酸性磷酸酶(ACP)和R0组没有显著性差异(P＞0.05).R30-R100组血清中的碱性磷酸酶(AKP)显著高于R0组(P＜0.05).R10组血清中超氧化物歧化酶(SOD)和R0组差异不显著(P＞0.05).R10组肝脏中ACP显著高于R0组(P＜0.05),R40-R50组和R0组没有显著性差异(P＞0.05).R30-R40组肝脏中AKP和R0组差异不显著(P＞0.05).R10-R40组肝脏中SOD和R0组没有显著性差异(P＞0.05).R10-R50组血清的总蛋白(TP)显著高于R0组(P＜0.05).各处理组和R0组血清中的谷草转氨酶(GOT)和谷丙转氨酶(GPT)没有显著性差异(P＞0.05).综合来看,10％-30％的脱脂磷虾粉替代组和对照组R0组对圆斑星鲽幼鱼的生长、饲料利用、免疫力及蛋白利用有相同的效果.     

Effects of dietary carbohydrate to lipid ratios on growth and body composition of juvenile and grower rockfish, Sebastes schlegeli

Two feeding trials were conducted to determine the optimal dietary carbohydrate to lipid (CHO:L) ratio for juvenile and grower rockfish. Triplicate groups of juvenile (initial mean weight 3.6 g) and duplicate groups of grower (initial mean weight 166 g) were fed the five isonitrogenous (51% CP) and isoenergetic (4.0 kcal g^?1) diets with the different CHO:L ratios (0.4–5.6 g:g) for 8 weeks respectively. The survival of juvenile and grower was above 93% and was not affected by the dietary CHO:L ratios. Weight gain of juvenile fed the diets with CHO:L ratios of 0.8 and 1.6 was significantly higher than that of the fish fed diets with CHO:L ratios of 2.8 and 5.6 (P<0.05). The feed efficiency and protein efficiency ratio of juvenile fed the diet with CHO:L ratio of 5.6 were the lowest among all groups (P<0.05). The daily feed intake of juvenile fed the diet with a CHO:L ratio of 5.6 was significantly higher than that of the other groups (P<0.05). The condition factors of juvenile fed the diets with CHO:L ratios of 0.8 and 1.6 were significantly higher than that of 5.6 (P<0.05). The crude lipid content of whole body, liver and viscera of juvenile decreased as the dietary CHO:L ratio increased, and the opposite was found for the moisture content. Weight gain, feed efficiency, daily feed intake, protein efficiency ratio and condition factor of grower were not affected by the dietary CHO:L ratio. Hepatosomatic and viscerasomatic indexes of grower were significantly influenced by dietary CHO:L ratio (P<0.05). Significant differences were observed in the lipid content of whole body and viscera of grower. Dietary CHO:L ratios significantly affected the major fatty acid composition of whole body in both juvenile and grower. The contents of 18:2n‐6 and 18:3n‐3 linearly decreased as the dietary CHO:L ratio increased, whereas the 20:4n‐6, 20:5n‐3 and 22:6n‐3 contents increased. Based on growth, feed efficiency and body composition, the optimal dietary CHO:L ratio was 1.6 for juvenile rockfish fed isonitrogenous (51% CP) and isoenergetic (4.0 kcal g^?1) diets, and starch could partially replace lipids in the diets with CHO:L ratios ranging from 0.4 to 5.6 for grower.     

饲料中添加生物素对草鱼幼鱼生长、体成分和血清生化指标的影响

在纯化饲料中分别添加生物素0、0.05、0.10、0.20、0.40、0.80、1.60 mg/kg投喂初始质量为(5.92±0.25)g的草鱼(Ctenopharyngodon idellus)幼鱼8周,研究了不同生物素添加量对草鱼幼鱼生长性能、饲料系数、机体营养成分、血清生化指标的影响。试验结果显示:与对照组相比,添加生物素提高了草鱼幼鱼的增重率、特定生长率,降低了饲料系数。添加量为0.40 mg/kg时草鱼幼鱼的特定生长率和增重率最大,饲料系数最低,并与对照组存在显著差异(P<0.05);添加不同水平生物素对草鱼幼鱼全鱼水分、粗蛋白、粗脂肪含量无显著影响,但添加量为0.40 mg/kg时粗蛋白含量最大。0.10 mg/kg组和0.20 mg/kg组的全鱼灰分含量显著高于对照组(P<0.05);添加生物素对血清总蛋白(TP)、血糖(GLU)和总胆固醇(TC)无显著影响,但显著提高了血清甘油三酯(TG)含量,各添加组TG含量均显著高于对照组(P<0.05),1.60 mg/kg添加组的高密度脂蛋白胆固醇(HDL-C)和低密度脂蛋白胆固醇(LDL-C)含量显著高于对照组(P<0.05)。综合本试验结果,草鱼幼鱼饲料中生物素适宜添加量为0.40 mg/kg。     

Response of juvenile tench (Tinca tinca L.) fed practical diets with different protein contents and substitution levels of fish meal by soybean meal

A basal practical diet for juvenile tench (Tinca tinca) was formulated and elaborated to test several protein contents and substitution possibilities of fish meal (FM) by soybean meal (SBM) in a 90‐day trial with 5‐month‐old juveniles (30.54 mm TL, 0.30 g W). A factorial design included nine feeding treatments: three protein contents (50%, 40% or 30%) and three levels of replacement (0%, 25% or 45%) of FM protein by SBM protein. In addition, a commercial carp feed was used as reference. Final survival ranged from 98.2% to 99.4%. The 50% dietary protein with 0% or 25% replacement and 40% dietary protein with 25% replacement diets enabled higher growth (P < 0.05) and lower FCR (P < 0.05) than the rest of practical diets. Fish fed 50% dietary protein had similar growth than those fed carp feed (63.8% protein). Deformed fish averaged 1% for the practical diets and 87.6% for the carp feed. The basal practical diet has showed to be feasible and levels of 40–50% dietary protein with 25% replacement of FM protein by SBM protein can be recommended for juvenile tench aged 5–8 months.     

Role of taurine deficiency in inducing green liver symptom and effect of dietary taurine supplementation in improving growth in juvenile red sea bream <Emphasis Type="Italic">Pagrus major</Emphasis> fed non-fishmeal diets based on soy protein concentrate

This study was conducted to investigate the mechanism of green liver symptom induction and the effect of dietary taurine supplementation on growth performance in juvenile red sea bream fed non-fishmeal diets based on soy protein concentrate (SPC). Juvenile fish (initial BW 72 g) were fed for 20 weeks on SPC diets supplemented with taurine at levels of 0, 1.0, and 2.0%. In the taurine-unsupplemented SPC diet group, specific growth rate (SGR) and feed conversion ratio (FCR) were significantly inferior (P < 0.001), and incidence of green liver was observed in 70% of fish. In this group, hepatopancreatic and plasma taurine concentrations were lowest (P < 0.05), hepatopancreatic content of bile pigments was highest (P < 0.05), and osmotic tolerance of erythrocytes was inferior (P < 0.05) among the dietary treatment groups. Serum osmolality of all treatment groups was at similar levels. These physiological abnormalities as well as SGR and FCR were improved by dietary taurine supplementation. These results indicate that the mechanism for induction of green liver symptom is bile pigment overproduction due to increased hemolysis because erythrocytes become osmotically fragile due to dietary taurine deficiency. Taurine supplementation of SPC diets is essential for maintaining normal physiological condition and growth performance in juvenile red sea bream.     

Replacement of Fishmeal by a Mixture of Soybean Meal and Chlorella Meal in Practical Diets for Juvenile Crucian Carp,Carassius auratus

A growth trial was conducted to evaluate the effect of a mixture of soybean meal and Chlorella meal (SCM) as a dietary fishmeal (FM) substitute on growth performance, apparent digestibility coefficients (ADCs), digestive enzymatic activities, and histology of juvenile crucian carp, Carassius auratus. Five isonitrogenous and isoenergetic diets were formulated to replace 0 (SCM0), 25 (SCM25), 50 (SCM50), 75 (SCM75), and 100% (SCM100) of protein from FM with SCM, respectively. The diets were fed to triplicate groups of juvenile crucian carp for 6 wk. Weight gain, specific growth rate, feed intake, protein efficiency ratio, and intestinal digestive enzymatic activities (amylase, trypsin, and lipase) tended to decline with increasing FM replacement levels (P > 0.05). Dietary SCM substitution significantly influenced dry matter content in muscle, and crude protein and lipid contents in liver (P < 0.05). ADCs for dry matter, protein, lipid, energy, and most amino acids showed no significant differences between the control and SCM25 group, but tended to decline with replacement levels over 25%. Higher SCM substitution (50–100%) caused karyopyknosis and necrosis in liver, but intestinal histology did not show noticeable pathological changes. The present study indicated that FM could be replaced by 25% of SCM, without significant adverse growth performance, feed utilization, and histology of crucian carp.     

Assessing the Effects of Dietary Inclusion of Hydrolyzed Soy Protein on the Growth,Nutrient Retention,Body Composition,and Serum Hormone of Juvenile Starry Flounder,Platichthys stellatus

Enzymatic hydrolysis of soy protein has the potential to be an excellent protein source in marine fish feeds. Here we assessed the effects of different inclusion levels of hydrolyzed soy protein (HSP) on growth performance, nutrient retention, body composition, and serum hormone levels in juvenile starry flounder to define HSP utilization. Five isoenergetic and isoprotein diets were formulated with 0 (control), 10, 20, 30, and 40% HSP (SP10–40) to replace 0, 25, 50, 75, and 100% soy protein concentrate (SPC), respectively. At the end of the feeding trial, fish fed diets SP20 and SP30 had significantly increased weight gain, percent weight gain, and feed efficiency (FE) compared with fish fed the control diet (P < 0.05). Diets SP20 and SP30 supported significantly higher levels of protein retention, and diet SP20 significantly increased energy retention (P < 0.05) in the fish offered these diets. In terms of nutritional composition of whole fish, feeding diets SP20 and SP30 increased crude protein content (P < 0.05) and diets SP10, SP20, and SP30 increased ash content (P < 0.05). Fish fed diets SP20 and SP30 had higher serum insulin‐like growth factor 1 (IGF‐1) level than that of the control treatment (P < 0.05). When SPC was included at 40% of the diet, 20–30% HSP (43% soluble nitrogen) is recommended to replace 50–75% SPC for maximal growth performance and FE of starry flounder.     

Dietary Protein Requirement of Juvenile Fuxian Minnow,Anabarilius grahami

A 10‐wk experiment was conducted to determine the optimum dietary protein requirement of juvenile Fuxian minnow, Anabarilius grahami (initial average weight 4.14 g). Five isocaloric diets were formulated to contain graded levels of protein (29, 34, 39, 44, and 49%). Each diet was fed to triplicate groups of fish in a recirculating rearing system maintained at 17–21 C. Feed intake of fish fed the 39 and 44% protein diets was significantly higher than that of fish fed the 29, 34, and 49% protein diets (P < 0.05). Weight gain and protein gain significantly increased with increasing dietary protein level up to 39% (P < 0.05), but no significant differences were observed among fish fed the 39, 44, and 49% protein diets (P > 0.05). In contrast, feed conversion ratio decreased with increasing dietary protein level up to 39%. Protein retention efficiency or protein efficiency ratio generally increased with increasing dietary protein level up to 39%, and then the value gradually decreased thereafter. Broken‐line regression analysis showed that the optimum dietary protein requirement for maximum weight gain of juvenile A. grahami under the experimental conditions was 38.6% (equivalent to ca. 33.0% estimated digestible protein).     

Dietary substitution of fishmeal by alternative protein with guanosine monophosphate supplementation influences growth,digestibility, blood chemistry profile,immunity, and stress resistance of red sea bream, <Emphasis Type="Italic">Pagrus major</Emphasis>

We determined the effects of complete fishmeal (FM) replacement by alternative protein (soy protein concentrate, SPC) with guanosine monophosphate (GMP) supplementation on growth, digestibility, immunity, blood chemistry profile, and stress resistance of juvenile red sea bream, Pagrus major. FM protein of a FM-based control diet (FM0) was replaced with 33.3 (FM33.3), 66.6 (FM66.7), and 100% (FM100) by SPC protein, and each replacement group was supplemented with 0.4% GMP to formulate four experimental diets. Each diet was randomly allocated to triplicate groups of fish (4.8 g) for 56 days. Results demonstrated that fish fed diet group FM33.3 had the significantly highest final weight, weight gain-specific growth rate, and feed intake. Meanwhile, in comparison to control, growth performance and feed utilization did not significantly differ with 66.7% FM replacement by SPC with GMP supplementation. Apparent digestibility coefficient of protein and lipid also followed a similar trend. All growth, feed utilization, and digestibility parameters were significantly lower in FM100 diet group. Blood urea nitrogen (BUN) and triglycerides (TG) increased (P < 0.05) with increasing FM replacement level by SPC. Interestingly, total cholesterol level reduces with the increasing level of FM replacement by SPC with GMP supplementation. Fish fed FM0 diet group showed the best condition of both oxidative and freshwater stress resistance. Meanwhile, FM33.3 and FM66.7 diet groups showed acceptable conditions. Innate immune responses enhanced with the increasing FM replacement level by SPC with GMP supplementation. In conclusion, FM could be replaced ≤66.7% by SPC with GMP supplementation in diets for red sea bream without any adverse effects on fish performances.     

Effects of exogenous enzyme supplementation in diets on growth and feed utilization in tilapia, Oreochromis niloticus x O. aureus

A 12‐week feeding trial was conducted to investigate the effects of supplemental exogenous enzyme on growth performance in juvenile hybrid tilapia Oreochromis niloticus×O. aureus (18 g, average initial weight). A commercial enzyme complex (neutral protease, β‐glucanase and xylanase) was included at the level of 0.0 (control group), 1.0 and 1.5 g kg⁻¹ diet in three test diets. Each diet was fed to triplicate tanks of the juvenile three times a day at 4–6% of wet body weight, and each tank was stocked with 50 fish. The results showed that specific growth rate and feed efficiency ratio significantly increased (P<0.05) with increasing dietary enzyme levels. The highest feed intake was recorded in the group fed the control diet (P<0.05). The highest apparent protein retention was observed in fish fed the diet containing the 1.5 g kg⁻¹diet (P<0.05). No significant differences were observed in the apparent digestibilities (ADC) of protein, lipid and gross energy among dietary treatments (P>0.05). However, the ADC of dry matter in fish fed high supplementation (1.5 g kg⁻¹) was significantly higher than the control and low supplementation (P<0.05). There were no significant differences in condition factor, whole body moisture, protein, lipid and ash among dietary treatments. Viscera ratio, hepatosomatic index and the liver lipid decreased significantly with increasing enzyme (P<0.05). Both protease and amylase activities in the intestine and the hepatopancreas of juvenile hybrid tilapia significantly increased (P<0.05) with increasing dietary enzyme levels. The results suggested that enzyme supplementation can significantly improve growth performance and feed utilization in juvenile hybrid tilapia.     

Effects of Algae and Shell Pigment Extract‐supplemented Diets on Shell Pigmentation and Growth Performance of Pacific Abalone,Haliotis discus hannai

To improve shell pigmentation and growth performance of Pacific abalone, five extruded diets were prepared by supplementing a formulated control diet with 3% each of three species of algae (Pacific dulse, Porphyra yezoensis, Spirulina) and a pigment extract from the abalone shells (0.02%). Each of the five diets and a commercial feed were randomly assigned to three containers each stocked with 1000 juvenile Pacific abalone (2 g per individual) in a flow‐through seawater system for a 5‐mo feeding trial. Test results showed: (1) all the supplements significantly (P < 0.05) increased percentages of dark‐brown shelled abalone in the test treatments, relative to the control treatment; (2) the abalone fed the experimental diets achieved significantly (P < 0.05) greater final weight, shell‐length growth rates, and higher meat protein contents than those fed the commercial feed (P < 0.05); and (3) the abalone fed the Spirulina‐supplemented diet achieved the best overall growth, pigmentation performances, and feed conversion ratio; and the Pacific dulse supplement generated the highest protein content in abalone meat product (P < 0.05) among the tested diets. These results demonstrate the potential of locally made feed, which can generate desirable characteristics in abalone under aquaculture conditions.     

Effects of Dietary Geniposide on Growth,Flesh Quality,and Lipid Metabolism of Grass Carp,Ctenopharyngodon idella

The aim of this study was to investigate effects of dietary geniposide (GP) on growth performance, flesh quality, and lipid metabolism of grass carp, Ctenopharyngodon idella (95.2 ± 0.6 g), fed seven different diets, including a control diet; Eucommia ulmoides (EU)–supplemented diet (20 g/kg); and GP‐supplemented diets containing 100, 200, 400, 600, and 800 mg/kg GP, respectively. Weight gain rate was significantly improved (P < 0.05) and feed conversation ratio was significantly decreased (P < 0.05) by supplementation of EU. Grass carp fed 100–800 mg/kg GP‐supplemented diets showed significantly higher total collagen and alkaline‐insoluble collagen content in muscle than control (P < 0.05). Contents of total collagen and the alkaline‐insoluble collagen content in the skin of grass carp were significantly increased by dietary 600–800 mg/kg GP and EU (P < 0.05). Fish fed diets containing 600–800 mg/kg GP showed significantly lower muscle crude lipid content than the EU, control, and 100–400 mg/kg GP groups (P < 0.05). Fish fed 400–800 mg/kg GP diets had significantly higher muscle fiber density and lower muscle fiber diameter and serum triglyceride level than the control (P < 0.05). In conclusion, supplementation of GP could improve flesh quality, but not growth of grass carp. The supplemental level of GP for improving flesh quality was estimated to be a 400–600 mg/kg diet.     

Effects of supplementation of crystalline or coated methionine on growth performance and feed utilization of the pacific white shrimp,Litopenaeus vannamei

This study was conducted to evaluate the effects of supplementation of crystalline methionine or coated methionine supplemented in diets of Pacific white shrimp (Litopenaeus vannamei) on growth performance and feed utilization. Five iso‐nitrogen and iso‐caloric diets were prepared in which diets were supplemented with cellulose‐acetate‐phthalate (CAP), tripalmitin‐polyvinyl alcohol (TPA), acrylic resin (RES) coated l ‐methionine, hydroxyl‐methionine calcium (MHA) and crystalline l ‐methionine diet (MET, control), respectively. After 7 weeks, shrimp (0.81 ± 0.01 g in initial body weight) weight gain fed with MET and RES diets were significantly higher than that of the others (P < 0.05), while feed conversion ratio of shrimp fed with RES was significantly lower than the others (P < 0.05). Crude protein (as wet weight basis) in whole body of shrimp fed the RES diet was markedly higher than the others (P < 0.05). Methionine contents in muscle of CAP and MHA groups were significantly higher than those of MET group (P < 0.05). Apparently digestibility for essential amino acid of MET group was the highest except methionine. In the present study, RES coating methionine appeared to effectively improve feed protein utilization and enhance growth performance of Pacific white shrimp fed with low fishmeal practical diet.     

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.     

Effects of the Dietary Fermented Tuna By‐product Meal on Growth,Blood Parameters,Nonspecific Immune Response,and Disease Resistance in Juvenile Olive Flounder,Paralichthys olivaceus

This study evaluated the effects of dietary fermented tuna by‐product meal (FTBM) in juvenile olive flounder, Paralichthys olivaceus. Five diets were formulated to replace fishmeal (FM) with FTBM at 0% (FTBM₀), 12.5% (FTBM_12.5), 25.0% (FTBM₂₅), 37.5% (FTBM_37.5), or 50% (FTBM₅₀). After 8 wk, weight gain, specific growth rate, and feed efficiency of fish fed FTBM₀ and FTBM_12.5 diets were significantly higher than fish fed the other diets (P < 0.05). Also, mean cumulative survival rates (%) of fish fed the FTBM₀ and FTBM_12.5 diets were significantly higher than those fed FTBM₅₀ diet at Day 9 postchallenge with Edwardsiella tarda (P < 0.05). Protein efficiency ratio of fish fed FTBM₀ and FTBM_12.5 diets was significantly higher (P < 0.05) than fish fed diets FTBM_37.5 and FTBM₅₀. Broken‐line regression analysis of weight gain showed an optimal FM replacement level of 10.65% with FTBM. Therefore, the optimal dietary inclusion of FTBM in juvenile olive flounder diets could be greater than 10.65% but less than 12.5% without any adverse physiological effects on fish health.     

Dietary supplemental effects of red seaweed Eucheuma denticulatum on growth performance,carcass composition and blood chemistry of juvenile Japanese flounder,Paralichthys olivaceus

A 56‐day feeding trial was conducted to determine the effects of supplementing diets of juvenile Japanese flounder, Paralichthys olivaceus, with Eucheuma denticulatum (EDP). Isonitrogenous and isolipidic test diets were prepared using a fishmeal‐based positive control diet (PC) and a fishmeal‐soy protein concentrate negative control diet (NC) supplemented with 3 (D3%), 6 (D6%) and 9% (D9%) EDP. The test diets were assigned to tanks (12 fish tank^?1, initial mean body weight of 0.42 ± 0.01 g) in triplicates. Results of the feeding trial indicated that growth rates and feed efficiency significantly improved (P < 0.05) when 3% EDP was supplemented in the diets. However, there was a significant reduction (P < 0.05) of growth and feed efficiency in fish fed diets with higher supplementation levels. Protein, lipid, dry matter and ash contents of carcass and their corresponding nutrient retention values were not markedly altered in all dietary treatments. Fish fed diets supplemented with EDP exhibited higher (P < 0.05) omega‐3 polyunsaturated fatty acid accumulation in dorsal muscle when compared with those of fish fed NC. Blood chemical parameters showed significant differences (P < 0.05) in total cholesterol and triglyceride levels. These results suggest that EDP can be efficiently utilized by Japanese flounder and can promote best growth and feed utilization at a level of 3%.     

Effects of Dietary Gamma Aminobutyric Acid on Growth Performance,Antioxidant Status,and Feeding‐related Gene Expression of Juvenile Grass Carp,Ctenopharyngodon idellus

Gamma aminobutyric acid (GABA) is one of the inhibitory neurotransmitters that may have the ability to regulate the appetite. This study aimed to evaluate the effects of dietary GABA, as a feed additive, on growth performance and antioxidant status of juvenile grass carp. Five isonitrogenous and isoenergetic experimental diets with graded levels of GABA (0, 20, 50, 100 and 200 mg/kg) were fed to grass carp juveniles (mean weight: 2.0 g) for 8 wk. The results showed that the specific growth rate (SGR) increased significantly with dietary GABA level up to the 100 mg/kg diet, and then decreased in the 200 mg/kg group (P < 0.05). The difference in SGR value between the 50 and 100 mg/kg groups was not statistically significant (P > 0.05). The survival rate was not significantly affected by dietary GABA level (P > 0.05). No significant difference was observed in the whole body composition among treatments (P > 0.05). The hepatopancreatic glutathione peroxidase (GPx) activity increased significantly (P < 0.05) with the GABA level, peaked in the group with GABA 100 mg/kg, and then decreased. The hepatopancreatic superoxide dismutase and total antioxidant capacity activities showed the same trend as GPx. Inversely, the hepatopancreatic malondialdehyde content decreased first and then increased with the dietary GABA level (P < 0.05). No significant differences were observed in the gene expression of neuropeptide Y (NPY), cholecystokinin, leptin, and ghrelin in the hepatopancreas among groups. However, the NPY and ghrelin mRNA expression levels in the brain increased significantly with the GABA level, peaked in the groups of 50 mg/kg, and then showed a decreasing trend. On the basis of quadratic regression analysis of SGR, the optimum content of dietary GABA in juvenile grass carp is suggested to be a 87.5 mg/kg diet.     

Evaluation of cottonseed and soybean meal as partial replacement for fishmeal in diets for juvenile Japanese flounder <Emphasis Type="Italic">Paralichthys olivaceus</Emphasis>

This study was conducted to investigate the effect of dietary supplementation of cottonseed and soybean meal (CS) on growth performance, feed utilization, and gossypol accumulation in juvenile (mean body weight 11 g) Japanese flounder Paralichthys olivaceus. Five isonitrogenous and isocaloric experimental diets (designated CS0, CS10, CS20, CS30, and CS40) containing 0, 10, 20, 30, and 40% CS mixture (1∶1 w/w) were formulated. After 9 weeks of feeding trial, fish fed all diets did not show significant differences in growth performances, feed utilization, and whole body compositions. Hemoglobin content gradually decreased (P<0.05) with increments of CS inclusion levels. There was a positive linear relationship between dietary gossypol and total liver gossypol contents. Free radical scavenging activity in the experimental diets gradually increased with increment of dietary CS inclusion. This finding indicates that the mixture of cottonseed and soybean meal with methionine and lysine supplementation could replace up to 40% of fishmeal protein in diets. However, 20% fishmeal protein replacement by dietary inclusion of cottonseed (9.4%) and soybean (8.7%) meal might be the optimum and safe level for the commercial use of CS in juvenile Japanese flounder.