脱酚棉籽蛋白替代豆粕对凡纳滨对虾生长、饲料利用和免疫应答的影响

为研究脱酚棉籽蛋白替代凡纳滨对虾(Litopenaeus vannamei)饲料中豆粕的效果,以初始体质量为(0.81±0.01) g的凡纳滨对虾为研究对象,进行6周的养殖实验。对照组饲料中豆粕含量为25%(编号为S0),分别用4.93%、10.06%、14.80%、19.73%的脱酚棉籽蛋白等蛋白替代25%、50%、75%、100%的豆粕(分别编号为S25, S50, S75, S100)。每个处理3个重复,每个重复70尾对虾。实验表明,与对照组相比,脱酚棉籽蛋白替代100%豆粕对对虾的生长和饲料利用无显著影响,但显著降低了胰蛋白酶和淀粉酶活性,显著降低了干物质和粗蛋白表观消化率。与对照组相比,脱酚棉籽蛋白替代75%豆粕时,对虾肠道中免疫相关基因的表达显著升高。肠道组织形态学观察实验表明,脱酚棉籽蛋白替代100%豆粕会影响对虾的肠道健康,肠道绒毛高度显著降低。结果表明,脱酚棉籽蛋白替代饲料中100%的豆粕不会对凡纳滨对虾的生长和饲料利用产生显著影响,但会影响对虾的消化、免疫应答以及肠道健康。

三种温度下不同饲料方案对大菱鲆幼鱼生长和氧化应激的影响

温度会对鱼类的营养需求产生影响,为研究不同温度条件下不同饲料方案对大菱鲆(Scophthalmus maximus L.)幼鱼生长和氧化应激的影响,确定不同温度下最适合的饲料方案。设计了等脂等能的4种实验饲料,分别为45%蛋白15%糊精的低蛋白组(LP组)、50%蛋白10%糊精的对照组(CON组)、55%蛋白0%糊精的高蛋白组(HP组)和50%蛋白20%糊精的高糖组(HC组)。在3个温度条件下(15、18和21℃)挑选初始质量(7.50±0.10) g的幼鱼进行8周的养殖实验,并对生长、抗氧化应激指标和抗氧化指标应激相关基因表达情况进行研究。研究显示,15℃时,CON组和LP组的特定生长率(SGR)显著高于HP组(P<0.05),且CON组和LP组肝脏丙二醛(MDA)含量显著低于HP组和HC组(P<0.05)。18℃时,CON组的SGR最高,显著高于LP组(P<0.05);且CON组肝脏MDA含量最低(P<0.05)。21℃时,HP组有最高的SGR和最低的饲料系数(FC)(P<0.05),且HP组肝脏MDA含量显著低于LP组和HC组(P<0.05)。在本实验3种温度条件下HC组肝脏MDA含量都最高;同时,CON组和HP组可通过上调Nrf2-ARE信号通路中相关基因来提高鱼体抗氧化能力。研究结果表明,在低温度下适合投喂低中蛋白饲料,在适温度条件下适合投喂中蛋白饲料,在高温度条件下适合投喂高蛋白饲料,高糖饲料会导致严重的氧化应激。

大菱鲆的赖氨酸最适需求量研究

为研究大菱鲆(Scophthalmus maximus L.)的赖氨酸需求量,评估饲料中赖氨酸含量对大菱鲆的血浆生化指标、消化酶活性以及抗氧化和免疫功能的影响,本研究设计了5种等氮(约50%粗蛋白)和等脂(约12.5%粗脂肪)的饲料,饲料中赖氨酸含量分别为1.69%、2.49%、3.32%、4.11%和4.90%,进行了10周的饲养实验。对大菱鲆的生长性能、消化酶活性、肝脏抗氧化和免疫能力等指标进行测量。研究表明,当饲料中赖氨酸添加量增长到3.32%时,大菱鲆的生长性能逐渐提升,此后呈稳定趋势,而缺乏赖氨酸会对大菱鲆的生长和饲料利用造成不利影响。随着饲料中赖氨酸含量从1.69%增加到4.90%,全鱼粗脂肪降低、粗蛋白含量增加。此外,大菱鲆的肝体比(HSI)也随着饲料赖氨酸含量的增加而降低。在肠道消化酶活性方面,脂肪酶和胰蛋白酶表现出随饲料赖氨酸含量的增加先升高后降低的趋势,均在3.32%时活性最高。饲料中赖氨酸添加量的改变不影响血糖含量,但1.69%组和2.49%组的血浆甘油三酯(TG)和总胆固醇(T-CHO)含量显著升高。饲料中适宜的赖氨酸含量能够提高大菱鲆肝脏的抗氧化能力,并通过调节非特异性免疫,缓解炎症反应。本研究结果表明,当饲料中赖氨酸水平为饲料干质量的3.19%(饲料蛋白质的6.39%)左右时,能够最大限度地发挥赖氨酸的有效功能。

低蛋白饲料添加亮氨酸、精氨酸对大菱鲆幼鱼生长、消化、免疫及mTOR信号通路的影响

为探究亮氨酸和精氨酸作为信号分子参与调控mTOR信号通路对大菱鲆(Scophthalmus maximus)生长的作用,本研究以大菱鲆幼鱼(初始体质量(13.50±0.19)g)为实验对象,设置50%蛋白水平饲料作为阳性对照组,45%蛋白水平饲料作为阴性对照组,设置两个实验组,分别为在阴性对照组中添加1%亮氨酸的实验组和添加1%精氨酸的实验组,饲养周期为56 d,测量大菱鲆的生长性能和饲料利用水平。研究表明,添加亮氨酸、精氨酸均能一定程度提高因饲料蛋白水平不足导致的大菱鲆的特定生长率、蛋白质效率和增重率下降。添加1%亮氨酸和1%精氨酸均能在摄食后有效增强大菱鲆肌肉与肝脏mTOR信号通路中的雷帕霉素靶蛋白(mTOR)、核糖体蛋白S6和真核起始因子4E结合蛋白1(4E-BP1)的磷酸化。添加1%精氨酸还能够提高大菱鲆肠道淀粉酶和脂肪酶活性,显著提高血清过氧化氢酶和溶菌酶水平并增加血清总抗氧化能力。研究结果表明,在低蛋白饲料中添加1%亮氨酸、1%精氨酸能够激活大菱鲆mTOR信号通路,有效提高其生长性能和蛋白质效率;此外,添加1%精氨酸还能够提高大菱鲆的消化酶活性、增强非特异性免疫反应。

温度对大菱鲆幼鱼蛋白质需求、生长和代谢的影响

为探究大菱鲆养殖中因水温变化引起的蛋白需求变化问题,本研究以养殖的大菱鲆幼鱼(Scophthalmus maximus L.)为实验对象。在室内可控温循环水养殖系统中开展摄食、生长实验,探讨不同水温(15、18和21℃)下大菱鲆幼鱼((8.00±0.25) g)的蛋白质需求。研究显示,基于特定生长率(SGR)的折线回归分析表明,15、18和21℃水温下大菱鲆幼鱼的最适蛋白需求量分别为饲料干物质的49.16%、50.07%和55.83%。15和18℃水温下大菱鲆幼鱼的生长指标随饲料中蛋白水平的升高而升高,饲料中蛋白水平为50%时生长指标达到峰值,21℃水温下饲料中蛋白水平为55%时生长指标达到峰值。随着饲料中蛋白水平的升高,大菱鲆幼鱼的表观消化率(ADC)、肠道胰蛋白酶活性(Try)和血浆总游离氨基酸含量(TAAs)也发生了显著变化。在15℃水温下大菱鲆幼鱼ADC随饲料中蛋白水平的升高而升高,18℃水温下饲料中蛋白水平为55%时ADC达到峰值,21℃水温下饲料中蛋白水平为50%时ADC达到峰值。在15℃水温下大菱鲆幼鱼肠道Try随饲料中蛋白水平的升高而升高,而在18和21℃水温下分别逐渐升高,至饲料中蛋白水平为50%和55%时肠道Try达到峰值。大菱鲆幼鱼TAAs在15和18℃水温下饲料蛋白水平为50%时达到峰值,21℃水温下饲料中蛋白水平为55%时达到峰值。研究结果表明,在一定范围内,大菱鲆幼鱼的蛋白质需求会随着养殖水温的升高而升高。

Identification,Characterization,and Probiotic Potentials of Lactobacillus pentosus SF-1

In recent years probiotics have been considered as a potential substitution of antibiotics to control pathogens and treat infectious diseases in aquaculture.In the present study a strain of Lactobacillus pentosus,named as L.pentosus SF-1,was isolated from waters in aquaculture.The species identification of this strain was conducted by 16S rRNA sequence,and the physiological and biochemical characteristics of this strain were assessed.Furthermore,the virulence,antibiotic sensitivity,cell surface characteristics and acid/base-resistance of L.pentosus SF-1 were determined to evaluate the probiotic potentials of this strain.Specifically,L.pentosus SF-1 is sensitive to most common antibiotics,and no hemolysin was generated from it,indicating the safety of this strain to hosts.In addition,L.pentosus SF-1 was able to tolerate the artificial gastric juice at pH 3 for 4 h and the artificial intestinal fluid at pH 6.8 or 8.0 for 6 h.Moreover,the analysis of self-aggregation and the adhesion of L.pentosus SF-1 to organic solvents suggested a high potential of L.pentosus SF-1 to inhabit the hosts,which was confirmed by testing the colonization of L.pentosus SF-1 in germ-free zebrafish.Interestingly,L.pentosus SF-1 displayed a high bactericidal activity against several bacterial pathogens.Consistently,the incubation of L.pentosus SF-1 significantly promoted the expression of antimicrobial components in zebrafish,contributing to the protection of the fish from E.tarda infection in vivo.Taken together,the probiotic strain L.pentosus SF-1 could be applied as anti-infection reagent in aquaculture.

饲料中添加亮氨酸和谷氨酰胺对大菱鲆幼鱼生长和肠道健康的影响

为研究在植物蛋白源替代部分鱼粉的饲料中添加晶体或小肽形式的亮氨酸(Leu)或/和谷氨酰胺(Gln)对大菱鲆(Scophthalmus maximus L.)幼鱼的生长性能、血浆代谢及免疫指标、肠道组织形态和Notch-Hes通路基因表达的影响,实验设计了6组等氮等能饲料:全鱼粉组(FM),阴性对照组(Con,以植物蛋白源替代FM组中40%的鱼粉),在Con组的基础上添加0.2%晶体Leu的L组,添加0.2%晶体Gln的G组,添加晶体Leu和晶体Gln(0.095%∶0.105%)的L+G组,以及添加0.2%Leu-Gln二肽的L-G组。选取初始体质量(8.14±0.03)g的大菱鲆幼鱼,进行为期8周的养殖实验。研究表明,与单独添加Leu和Gln相比,共同添加Leu和Gln能更显著地提高大菱鲆幼鱼的终末体质量、特定生长率、蛋白质沉积率和脂肪沉积率,且这些指标均与FM组差异不显著(P>0.05)。L组和L-G组的血清TCHO含量高于Con组,且与FM组无显著差异(P>0.05)。相比Con组,Leu和Gln共同添加可显著提高大菱鲆幼鱼的血清溶菌酶活性(P<0.05)。此外,Leu和Gln共同添加时,大菱鲆幼鱼的肠绒毛高度显著高于Con组(P<0.05),且L-G组的肠道杯状细胞数量显著高于Con组(P<0.05)。Leu和Gln共同添加可提高大菱鲆幼鱼肠道hes1基因的表达水平,且L-G组的肠道hes1基因表达水平显著高于Con组(P<0.05);L+G组的肠道notch1基因表达水平显著高于Con组(P<0.05)。研究结果表明,在植物蛋白源替代鱼粉的饲料中添加Leu和Gln,可以提高鱼体生长性能、饲料利用和免疫力,改善肠道健康状态,并能够通过上调Notch-Hes通路的基因表达来调节肠道细胞分化,且Leu和Gln共同添加(在0.2%的添加量下)效果优于单一添加。

云斑尖塘鳢研究进展与前景展望

云斑尖塘鳢原产于东南亚地区,自20世纪80年代末引进我国,并实现人工繁育和养殖,已发展成为重要的名特优水产鱼类品种。随着养殖规模快速扩大,原有引进品种已经无法满足产业发展的需求,因此迫切需要加快云斑尖塘鳢种质资源研究,培育出能够适应人工配合饲料、生长速率快、抗寒、抗病能力强的适宜本土养殖新品种。本文综述了国内外半个世纪以来云斑尖塘鳢相关的研究进展;首先阐述了云斑尖塘鳢生殖和生长发育等生物学特征及研究进展,探讨了温度、盐度、溶解氧等环境条件对云斑尖塘鳢的影响;然后进一步总结和探讨了云斑尖塘鳢人工养殖领域的进展和面临的饲料、种质资源开发、病害防治等问题;同时也探讨了云斑尖塘鳢未来发展方向。

Effects of Dietary Vitamin D_(3)on Growth Performance,Immune Status,and Calcium and Phosphorus Metabolism in Litopenaeus vannamei Under Different Salinity Conditions

Vitamin D_(3)(VD_(3)) plays a vital role in various physiological processes in addition to its role in regulating the homeostasis of calcium and phosphorus.The present study was conducted to investigate the effects of dietary VD_(3) on growth performance,immune status and the metabolism of calcium and phosphorus in Litopenaeus vannamei under the optimal salinity(25)and high salinity(35)conditions.Shrimp(2.1 g±0.1 g)were fed with experimental diets containing 0,1500,6000 and 12000IUkg^(−1)VD_(3) for 30 days under two salinity conditions respectively.The results showed that the growth performance and intestinal health were reduced,while oxidative stress was induced in the shrimp cultured at salinity 35 compared to those in the shrimp cultured at salinity 25.Interestingly,dietary supplementation of 1500 IU kg^(−1)VD_(3) at salinity 35 promoted the growth performance,improved the intestinal health,and enhanced the antioxidant capacity and non-specific immunity in shrimp.In addition,the content of inorganic phosphorus in shrimp serum was affected by dietary VD_(3) independent of salinity.In contrast,the expressions of calcium transport-related genes,including calmodulin and Ca2+-ATPase,were regulated by salinity,instead of dietary VD_(3).In conclusion,an appropriate supplementation of dietary VD_(3) under high-salt condition can promote the growth,alleviate intestinal inflammation,enhance antioxidant capacity and immunity,and contribute to phosphorus metabolism in L.vannamei.

水产饲料的蛋白源问题——提高饲料蛋白质利用率新思路

提高饲料蛋白质利用率对促进水产养殖业可持续发展具有重要意义。鉴于鱼粉是水产饲料最好的蛋白源,所以文章分析比较鱼粉和其他饲料蛋白源组成的主要差异,发现牛磺酸、羟脯氨酸和维生素D_3等对提高非鱼粉蛋白源饲料的蛋白质利用率作用显著,而一些植物蛋白源的抗营养因子降低饲料蛋白质利用率;同时,深入探讨了影响鱼体蛋白质沉积潜力的内在因素,提出了激活水产动物mTOR信号通路和/或消除其抑制因素,提高饲料蛋白质利用率的新思路,开发新技术,并进行实践应用。

中国水产动物营养研究与饲料工业的发展历程与展望

我国水产动物营养研究与饲料工业的发展历经四个阶段,在过去40年里,取得了举世瞩目的伟大成就,为我国水产养殖业的高速发展,产量雄踞世界第一,提供了物质的保障。鉴于此,本文围绕基本营养需求数据库的建立、饲料生产关键技术的研究开发与产业发展的带动、水产动物营养代谢研究新的突破等方面,阐述了我国水产动物营养研究与水产饲料工业的主要进展。在此基础上,剖析了我国水产饲料技术的创新特色,探讨了蛋白质生产的颠覆性技术,并展望了饲料与水产养殖的绿色发展前景。

饲料营养素对鱼类肠道紧密连接蛋白闭锁小带蛋白-1影响的研究进展

鱼类肠道紧密连接结构是肠道黏膜屏障的重要组成。紧密连接在相邻的上皮细胞之间形成了由跨膜蛋白[如闭合蛋白(Claudin)和闭锁蛋白(Occludin)]和胞质蛋白[如闭锁小带蛋白-1(ZO-1)]所维持的复杂蛋白质结构,其中胞质紧密连接蛋白ZO-1属于膜相关鸟苷酸激酶(MAGUK)家族,是紧密连接的重要组成蛋白质之一。ZO-1在维持细胞极性和紧密连接屏障功能上发挥着重要作用,也与肠道疾病的发生有着密切联系。众所周知,ZO-1的表达在相当程度上受饲料营养素的影响和调节。因此,本文综述了饲料中蛋白质、脂肪、糖类、维生素和矿物质五大营养素对鱼类肠道紧密连接蛋白ZO-1的影响及作用机制的研究进展,这对于保持鱼类肠道屏障的功能稳定和提高饲料的利用效率有重要意义。

植物蛋白质对海水养殖鱼类肠道健康的研究进展

我国是世界最大的海水养殖生产国家,植物蛋白质在海水鱼类饲料中的使用愈发普遍,由此引发的海水鱼类肠道损伤问题也逐渐引起了人们的重视。植物蛋白质在海水鱼类饲料中的大量使用会诱发肠道炎症反应。肠道黏膜屏障的功能完整性和肠道菌群的动态平衡是肠道健康的首要前提和重要保障。本文综述了以豆粕为主的植物蛋白质对海水养殖鱼类的肠道黏膜屏障以及肠道菌群的研究进展,为今后由饲料中植物蛋白质引起的海水鱼类肠道健康问题的深入研究指明了方向。

不同含量水解鱼蛋白添加对大菱鲆幼鱼生长、血浆和肌肉游离氨基酸含量及后肠组织形态的影响

为研究水解鱼蛋白(FPH)对大菱鲆(Scophthalmus maximus L.)幼鱼生长的影响,本实验以60%的鱼粉(FM)组为正对照组,以复合植物蛋白源替代40%的FM作为负对照组(含36%的FM),在负对照组的基础上添加3个梯度水平(3%、6%、9%)的FPH作为实验组,分别喂养大菱鲆幼鱼74 d。研究表明,与负对照组相比,添加6%和9%的FPH可显著提高大菱鲆幼鱼的生长性能,并达到与正对照组相似的效果。添加不同含量的FPH会改善大菱鲆幼鱼的后肠形态,且改善状况随添加量的增加而愈加明显,当FPH添加水平达到9%时,可显著增加大菱鲆幼鱼后肠的肠绒毛直径比、肠上皮细胞高度和微绒毛高度。与负对照组相比,9%FPH组显著提高了血浆和肌肉中必需氨基酸、非必需氨基酸和总氨基酸浓度。此外,饲料中添加6%和9%的FPH显著促进了PepT1的基因表达量。研究结果表明,水解鱼蛋白是一种潜在的替代鱼粉的有效蛋白源,可起到改善大菱鲆幼鱼生长指标、提高机体游离氨基酸含量和促进肠道吸收能力的作用。

Replacement of Dietary Fish Oil with Vegetable Oils Improves the Growth and Flesh Quality of Large Yellow Croaker(Larmichthys crocea)

We investigated the effect of the replacement of dietary fish oil with vegetable oils on the growth and flesh quality of large yellow croaker(Larmichthys crocea). The basal diet(FO) was formulated to contain 66.5% fish meal and 6.4% menhaden fish oil; whereas the other 3 experimental diets were formulated by replacing the fish oil with 50% soybean oil(SO50), 100% soybean oil(SO100) and 100% palm oil(PO100), respectively. The 4 diets were randomly assigned to 4 floating sea cages(3.0 m × 3.0 m × 3.0 m), and each was stocked with 250 fish individuals with an initial average weight of 245.29 g ± 7.45 g. The fish were fed to apparent satiation twice a day at 5:00 and 17:00, respectively, for 12 weeks. Experimental analysis showed that the specific growth rate of fish fed SO50 or PO100 were significantly higher than that of fish fed FO or SO100(P<0.05), and crude lipid contents of ventral muscle and viscera were significantly lower in fish fed FO than in those fed the other 3 diets(P<0.05). No significant differences in condition factor, viscerosomatic index, hepatosomatic index, gutted yield and colorimetric values of fish among the dietary treatments were observed(P>0.05). Compared to FO diet, SO50, SO100 and PO100 diets led to substantial decreases in the liquid loss and water loss from fresh fillets(1 d, 4℃)(P<0.05). Similarly, thiobarbituric acid reactive substance(TBARS) values of fillets under different storage conditions(1 d, 4℃; 7 d, 4℃; 4 weeks,-20℃; 8 weeks,-20℃) decreased significantly after partial or complete replacement of fish oil with vegetable oils. These findings indicated that the growth performance and selected flesh quality properties(liquid holding capacity and TBARS value) of large yellow croaker were substantially improved by replacing dietary fish oil with vegetable oils.

Effects of Dietary β-Glucan and Glycyrrhizin on Non-Specific Immunity and Disease Resistance of the Sea Cucumber (Apostichopus japonicus Selenka) Challenged with Vibrio splendidus

Sea cucumbers, Apostichopus japonicus Selenka, were fed diets containing non-immunostimulant (basal diet), 0.2% β-glucan and 0.02% glycyrrhizin in a recirculatory water system for 45 days, and subsequently challenged with Vibrio splendidus by injection at 1.0×108 cfu/sea cucumber for 15 days.Phagocytic capacity (PC), intracellular superoxide anion production (ISAP), ly-sozyme (LSZ) activity and superoxide dismutase (SOD) activity in the coelomic fluid were analyzed on the 0th, 5th, 10th and 15th days after injection.Results showed that after the 45-day feeding period, PC, ISAP, LSZ activity and SOD activity in sea cucumbers fed with dietary β-glucan or glycyrrhizin were significantly higher than in those fed with the basal diet.On the 5th day after infection, all the immune parameters examined in the sea cucumbers injected with V.splendidus decreased in value significantly.On the 15th day, PC, ISAP and LSZ activity returned to levels similar to those on the 0th day.For the sea cucumbers injected with saline, there were no significant differences in all the immune parameters examined and in the cumulative morbidity during the 15-day challenging trial.After injecting with V.splendidus, the cumulative morbidity of sea cucumbers fed with the basal diet was significantly higher than those fed with dietary β-glucan or glycyrrhizin when challenged with V.splendidus challenged sea cucumber fed with the basal diet was significantly higher than those fed with dietary β-glucan or glycyrrhizin.There was no significant difference in cumulative morbidity between the dietary β-glucan and glycyrrhizin treatments over time.

Effects of Dietary Stachyose on Growth Performance, Digestive Enzyme Activities and Intestinal Morphology of Juvenile Turbot(Scophthalmus maximus L)

A 12-week feeding trial was conducted to evaluate the effects of dietary stachyose on the growth performance, digestive enzymes activities and intestinal structures of juvenile turbot(Scophthalmus maximus L). Five isonitrogenous(49.58% crude protein) and isolipidic(10.50% crude lipid) diets were formulated to contain 0(Control), 0.625%(S-0.625), 1.25%(S-1.25), 2.5%(S-2.5) and 5%(S-5) stachyose, respectively. With the increase of stachyose level, the growth performance and feed utilization of turbot, such as the specific growth rate, final mean body weight, weight gain rate and feed efficiency, increased significantly(P < 0.05) and then stabilized. The feed intake of fish fed S-5 was significantly higher(P < 0.05) than that of fish in other groups. The activities of trypsin, intestinal caseinolytic, stomach and intestinal amylase were significantly influenced by stachyose(P < 0.05). The highest values of trypsin and intestinal caseinolytic activities were observed in group S-1.25, while the highest activity of stomach amylase and the lowest activity of intestine amylase were observed in group S-5. No lesion or damage was found on the distal intestine structures of fish from all treatments, while the height of simple folds in the distal intestine was significantly increased(P< 0.05) when 1.25% or 2.5% stachyose was added in the diets. These results indicated that moderate level of stachyose(1.25%) improves the growth performance, feed utilization, digestive enzyme activities and the distal intestine structures of juvenile turbot.

Effects of Dietary Corn Gluten Meal on Growth Performance and Protein Metabolism in Relation to IGF-I and TOR Gene Expression of Juvenile Cobia (Rachycentron canadum)

A growth experiment was conducted on cobia(Rachycentron canadum,initial weight 108.2 g ± 3.0 g) to investigate the effects of dietary corn gluten meal(CGM) levels on the fish growth,whole body composition and protein metabolism in relation to specific gene expression.Five isonitrogenous(crude protein 45%) and isoenergetic(gross energy 20 kJ g 1) practical diets were formulated by replacing 0%(the control),17.5%,35.0%,52.5%,and 70.0% of fish meal(FM) protein with CGM protein.No significant differences were observed in the survival,feed intake(FI),specific growth rate(SGR),feed efficiency(FE) and protein productive value(PPV) among fish fed diets with 0%,17.5%,35.0%,and 52.5% of CGM protein.However,these indices were significantly lower in fish fed the diet with 70.0% of CGM protein than those in fish fed the control diet(P < 0.05).The whole-body crude protein and lipid contents were significantly lower while the whole-body moisture content was significantly higher in fish fed the diet with 70.0% of CGM protein compared with the control group(P < 0.05).When 70.0% of FM protein was replaced by CGM,plasma total protein and cholesterol contents were significantly lower than those in the control group(P < 0.05).Fish fed the diet with 70.0% of CGM protein had significantly lower hepatic insulin-like growth factor I(IGF-I) expression levels than those in the control group(P < 0.05).However,no significant differences were observed in hepatic target of rapamycin(TOR),dorsal muscle IGF-I and TOR expression levels among dietary treatments.Results of the present study indicated that 52.5% of FM protein could be replaced by CGM in the diets without significant influences on the growth,feed utilization and protein metabolism of juvenile cobia.The present results might be useful for developing cost effective and sustainable cobia dietary formulations.

Comparative study on the organoleptic quality of wild and farmed large yellow croaker Larimichthys crocea

To fill the blank in systematic study on the organoleptic quality of large yellow croaker Larimichthys crocea,we analyzed the organoleptic quality of the fish meat of wild,trash-fish-fed,and compound-feed-fed large yellow croaker.Six fish(weight:500 g)per group were sampled in the same period,and 89 indices of fish organoleptic quality were measured and analyzed.Results reveal significant differences in the body condition factor,skin/muscle color,flesh texture,odor,and taste aspects between wild and farmed fish.Compared with the wild fish,farmed fish showed fatter body shape,whiter skin or muscle color,tender muscle,higher level of fishy odor or volatile intensity,but lower delicious taste.In addition,compared with trash-fish feeding,compound-feed feeding could improve the body shape,skin color,flesh texture,and fish taste of large yellow croaker,but it also increased the fishy odor.In principle component analysis and cluster analysis,the present study preliminarily established the systematic evaluation with multiple indices to the quality of large yellow croaker.It shall be helpful for the evaluation or improvement of the quality of farmed large yellow croaker.

Effects of Dietary Soy Isoflavones on Feed Intake,Growth Performance and Digestibility in Juvenile Japanese Flounder(Paralichthys olivaceus)

An 8-week feeding trial was conducted to investigate the effects of dietary soy isoflavones on feeding intake,growth performance,and digestion of juvenile Japanese flounder(Paralichthys olivaceus).Four isonitrogenous(49% crude protein) and isoenergetic(20.1 MJ kg-1) diets were formulated to contain four graded levels of soy isoflavones,namely,0,1,4 and 8 g soy isoflavones in 1 kg of diet.Each diet was randomly fed to triplicate tanks of fish(Initial average weight:2.58 g ± 0.01 g),and each tank was stocked with 35 fish.No significant difference was observed among diets with levels of 0,1 and 4 g kg-1 soy isoflavones in feed intake,weight gain,feed efficiency ratio(FER),proximate composition of fish whole body and apparent digestibility coefficients(ADC) of nutrients and energy(P>0.05).However,high dietary soy isoflavones level(8 g kg-1) significantly depressed weight gain,FER,whole-body crude lipid content of fish and ADC of nutrients(P<0.05).These results indicate that high level of dietary soy isoflavones(above 4 g kg-1) significantly depresses growth responses and FER of Japanese flounder.However,as the content of soy isoflavones in soybean meal is around 1 to 3 g kg-1,the adverse effects might be neglected when soybean products are used as a fish feed ingredient.