饲料中不同维生素E添加量对黄颡鱼幼鱼生长性能及免疫功能的影响

本研究探讨了饲料中不同维生素E添加量对黄颡鱼(Pelteobagrus fulvidraco)幼鱼生长和免疫的影响。在以鱼粉、豆粕为蛋白源的基础饲料中分别添加0mg/kg(对照组)、25mg/kg、75mg/kg、125mg/kg和175mg/kg的维生素E配成5种实验饲料。在水温(24.0±3.0)℃下,用上述实验饲料分别饲喂平均体质量约为5.1g的黄颡鱼幼鱼50d。实验结果表明,饲料中维生素E的添加量对黄颡鱼的特定生长率和饲料效率的影响不显著(P0.05);而添加量为175mg/kg时,黄颡鱼摄食率显著降低(P0.05);随着饲料中维生素E添加量的增高,黄颡鱼血浆超氧化物歧化酶(SOD)的活性未产生显著变化(P0.05);添加量为125mg/kg和175mg/kg时,血浆中丙二醛(MDA)的含量显著降低(P0.05);白细胞吞噬指数随添加量升高显著上升(P0.05),而吞噬百分率没有显著变化(P0.05)。综合以上结果,饲料中添加适量的维生素E可适当改善黄颡鱼的摄食,增强黄颡鱼的非特异性免疫力和抗氧化能力,从而提高动物的健康状况。推荐在黄颡鱼幼鱼饲料中添加125mg/kg的维生素E。     

组胺对黄颡鱼生长及体色变异的影响

试验在基础饲料中分别添加0、10、100、1 000 mg/kg的组胺,制成4种等氮饲料(分别记为C、H10、H100和H1000),以黄颡鱼(Pelteobagrus fulvidraco)(102.13±0.52)g为试验对象,进行56 d的养殖试验,研究不同添加水平组胺对黄颡鱼生长、皮肤显微结构、皮肤黑色素含量、酪氨酸酶活力和脑中黑素皮质素受体-1(MC1R)mRNA表达量的影响。试验采用微流水室内养殖系统,结果表明:饲料中添加不同量组胺对黄颡鱼生长(增重率和特定生长率)无显著影响(P0.05),而高组胺添加量组(H1000组,组胺含量1 390 mg/kg)黄颡鱼皮肤中黑色素含量及脑组织中MC1R mRNA表达量显著低于对照组(P0.05),低添加量组(H10和H100)黄颡鱼皮肤黑色素含量和脑中MC1R mRNA表达量与对照组无差异(P0.05)。随着饲料中组胺添加量的增加,皮肤酪氨酸酶活力呈下降趋势,但各组间差异不显著(P0.05)。结果表明:组胺对黄颡鱼生长表现无影响,但会引起黄颡鱼体色白化,且白化程度与饲料中组胺含量密切相关。     

养殖密度和抗菌肽含量对网箱养殖的黄颡鱼生长性能的影响

在水温19.1～23.2℃下,将平均湿体质量为(19.9±3.5)g的黄颡鱼Pelteobagrus fulvidraco以2kg/m~3(D1)、3kg/m~3(D2)、4kg/m~3(D3)和5kg/m~3(D4)kg/m~3的密度饲养在水库中长2.0m×宽2.0m×高2.0m的网箱中,投喂基础饲料;再按D2组的密度饲养上述规格黄颡鱼幼鱼,分别投喂基础饲料(CK组,对照组)和添加10mg/kg(G1)、30mg/kg(G2)、60mg/kg(G3)和(G4)100mg/kg饲料抗菌肽(水溶)的饲料,研究养殖密度和饲料中添加抗菌肽对黄颡鱼生长性能和体成分的影响。抗菌肽(水溶)用海藻酸钠(剂量250mL,0.5%)包埋,自然风干。70d的养殖结果表明:黄颡鱼末体质量、末体长、特定生长率(SGR)和肥满度(K)随养殖密度增高而下降,饲料系数则上升;D1组黄颡鱼幼鱼末体长、末体质量、日增重率(DBW)、K、存活率(SR)显著高于D3和D4组(P0.05),但D1和D2组的鱼体K、饲料系数(FC)无显著差异(P0.05)。饲料中添加10～30mg/kg抗菌肽可以显著提高黄颡鱼的DBW以及过氧化氢酶(CAT)的活性,当添加量为30mg/kg时,SGR最高;当添加量为100mg/kg时,肝脏的超氧化物歧化酶(SOD)与血清中溶菌酶(LSZ)活性较对照组显著降低(P0.05)。实验证明,黄颡鱼网箱养殖适宜放养密度为3～4kg/m~3,饲料中抗菌肽添加量不超过60mg/kg能促进鱼的生长。添加抗菌肽10mg/kg组鱼的CAT活性最高,显著高于60mg/kg、90mg/kg以及对照组(P0.05);当添加量为30～60mg/kg时,DBW、SGR、K出现差异显著(P0.05),60mg/kg时DBW、SGR和K达到最高,高于其余各组,饲料系数FC下降。     

四种植物香精对黄颡鱼诱食及生长的影响

利用自制触球及迷宫法评估了百里香酚、香芹酚、丁香酚和肉桂醛4种香精对(4.45±0.58)g黄颡鱼(Pelteobargrus fulridraco)幼鱼的诱食剂量效应反应,试验结果表明:百里香酚、香芹酚和肉桂醛都对黄颡鱼有明显的诱食作用,其最适诱食浓度分别为(0.025~0.05)、0.025、0.007 g/m L;百里香酚诱食效果最佳(P0.05),但浓度过高,也会出现诱食抑制;而丁香酚对黄颡鱼幼鱼均无明显的诱食作用(P0.05)。随后在基础饲料中分别添加75、150、250、500和1000 mg/kg的百里香酚饲喂黄颡鱼幼鱼,8周的养殖结果表明黄颡鱼增重率(Y)与饲料中百里香酚添加量(X)之间可用二次方程式表示Y=-0.000 7 X2+0.796 3 X+107.08(R2=0.777 2),当黄颡鱼获得最大增重时,饲料中百里香酚的添加量为568.8 mg/kg。     

饲料中添加肉毒碱对黄颡鱼生长的影响

以鱼粉和豆粕为蛋白源、大豆油为脂质源配制成1个蛋白质水平（35％）X5个脂肪水平（4％，10％，16％，22％，26％）X2个肉毒碱水平（0mg／Kg,150mg／Kg）的10种配方饲料，投喂平均体重为（10．0±0．6）g的黄颡鱼，进行肉毒碱对黄颡鱼生长影响的研究。经100d饲养表明：饲养中添加150mg/Kg肉毒碱对黄颡鱼生长没有影响。在黄颡鱼低蛋白配合饲料中，体重增长率最大，饵料系数、蛋白质效率较好的是最低的脂肪含量组（4％）。高脂肪含量对黄颡鱼的生长不利。     

维生素E对斑点叉尾鮰生长性能和消化酶活性的影响

试验研究了饲料中不同含量维生素E对斑点叉尾鮰生长性能和消化酶活性的影响，并对其机理进行了初步探讨。选取900尾健康的斑点叉尾鮰，平均体重(5.20±0.15)g，随机分成4个处理（I、Ⅱ、Ⅲ和Ⅳ处理依次分别添加维生素E 0、50、100和1000IU/kg饲料），每个处理3个重复，每个重复75尾。试验期105d。试验结果表明：在一定添加水平内，维生素E能够显著提高斑点叉尾鮰成活率、特定生长率(SGR)、蛋白质效率和摄饵量(P＜0.01)。当维生素E添加量为到100 IU/kg时，以上四个指标均达到最高，分别为97.78±0.96％，2.99±0.50％，163.71±5.62％和7478.00±62.01 g/尾，均极显著高于维生素E添加量为0 IU/kg组(P＜0.01）；维生素E显著影响斑点叉尾鮰胃肠道和肝胰脏蛋白酶和脂肪酶活性（P＜0.01 or P＜0.05）。当饲料中添加维生素为100IU/kg时，胃蛋白酶和脂肪酶活性最高，分别达29.33±1.66 U•min－1 •mg－1，196.52±17.28 U•min－1 •mg－1，极显著高于维生素Ｅ添加量为0 IU/kg组(P＜0.01）和显著高于维生素Ｅ添加量为1000IU/kg组(P＜0.05）。由本试验结果可以看出，维生素E在一定添加水平内能显著提高斑点叉尾鮰消化酶活性，促进此鱼生长，且其适宜添加量为100 mg／kg。     

黄曲霉毒素B1对黄颡鱼幼鱼生长及肝脏功能的影响

为研究黄曲霉毒素B1(Aflatoxin B1, AFB1)对黄颡鱼幼鱼生长、肠道消化酶及肝脏功能的影响,用添加不同梯度黄曲霉毒素B1(AFB1)(0、50、100和200μg/kg)的4种等氮等脂配合饲料饲喂初始体质量为(6.00±0.10) g的黄颡鱼幼鱼8周。结果显示:(1)饲料中添加AFB1对黄颡鱼幼鱼的存活率、饲料系数和特定生长率等均无显著影响,但使胰蛋白酶活性显著提高,而高含量AFB1(100和200μg/kg)显著降低肠道淀粉酶和脂肪酶活性;(2)随着AFB1添加量的上升,血清中谷丙转氨酶、谷草转氨酶活性及葡萄糖、甘油三酯、总胆汁酸和总胆固醇含量显著升高,肝脏中谷丙转氨酶、谷草转氨酶活性显著下降;(3) AFB1添加组的肝脏过氧化氢酶活性和丙二醛含量显著高于对照组,100和200μg/kg AFB1组超氧化物歧化酶活性显著高于对照组,其余各组无显著差异;(4) AFB1添加组肝脏sod基因及炎性因子il-1β基因的相对表达量显著上调,200μg/kg AFB1组cat基因及炎性因子il-8、il-10相对表达量显著上调;(5)通过组织学观察,AFB1会引起部分肝细胞出现轻微萎缩、肝细胞核移位、细胞界限模糊和肝细胞内空泡化的现象。研究表明,在本实验条件下,饲料中AFB1含量低于200μg/kg不影响黄颡鱼幼鱼生长性能,但饲料中AFB1≥50μg/kg时会影响黄颡鱼幼鱼肠道的消化吸收功能,同时引起肝脏氧化应激及炎性反应,造成肝脏功能损伤。     

维生素E对斑点叉尾鱼回生长性能和消化酶活性的影响

试验研究了饲料中不同含量维生素E对斑点叉尾鱼回生长性能和消化酶活性的影响,并对其机理进行了初步探讨.选取900尾健康的斑点叉尾鱼回,平均体重(5.00±0.50) g,随机分成4个处理组(I、Ⅱ、Ⅲ和Ⅳ处理依次分别添加维生素E 0、50、100和1 000 IU/kg饲料),每个处理3个重复,每个重复75尾.试验期105 d.试验结果显示:在一定添加水平内,维生素E能够显著提高斑点叉尾鱼回成活率、特定生长率(SGR)、蛋白质效率和摄饵量(P＜0.01).当维生素E添加量为100 IU/kg时,以上四个指标均达最高,分别为97.78%±0.96%,2.99%±0.50%,163.71%±5.62%和(7 478.00±62.01) g/尾,均极显著高于维生素E添加量为0 IU/kg组(P＜0.01);维生素E显著影响斑点叉尾鱼回胃肠道、--肝胰脏蛋白酶和脂肪酶活性(P＜0.01 or P＜0.05).100 IU/kg添加组胃蛋白酶和脂肪酶活性最高,分别达(29.33±1.66) U/(min*mg),(196.52±17.28) U/(min*mg),极显著高于0 IU/kg添加组(P＜0.01)和显著高于1 000 IU/kg添加组(P＜0.05).结果表明,维生素E在一定添加水平内能显著提高斑点叉尾鱼回生长性能和消化酶活性,促进鱼体生长.     

天然叶黄素对黄颡鱼生长性能和皮肤着色的影响

研究了天然叶黄素(源自万寿菊,含量为4.64％)的添加水平对黄颡鱼生长和皮肤着色效果的影响.在黄颡鱼基础饲料中,分别添加0％、0.15％、0.30％、0.60％、8.00％的受试物,在不影响饲料营养水平的基础上设计最高剂量组为可能摄入剂量组的10倍以上,经挤压熟化工艺加工后,实际检测叶黄素含量为未检出(检出限=0.5 mg/kg)、24.2、54.2、118.0、1 700.0mg/kg,依次命名为C、L24.2、L54.2、L118、L1700.饲养90 d后发现,添加天然叶黄素的4个剂量组的特定生长率和饲料效率、L24.2组的蛋白沉积率、L54.2组和L118组及L1700组的能量沉积率均显著高于对照组(P＜0.05).体侧和腹部皮肤的黄度(b*)和饱和度(C*)随饲料中天然叶黄素含量的增加而逐步升高,L118组可达到饱和,并与L1700组之间没有显著差异(P＞0.05),L118组和最高剂量组皮肤中黄色素过度沉积,并向肌肉中转移.皮肤中叶黄素的蓄积系数呈现先升高后下降的趋势,最高为76.25 mg/kg饲料.结果表明,24.2～1700mg/kg的天然叶黄素显著提高了初始体质量21 9的黄颡鱼的生长性能.天然叶黄素作为黄颡鱼皮肤着色剂的最适剂量为76.25 mg/kg饲料.     

不同剂型维生素C对黄颡鱼生长和几种免疫指标的影响

黄颡鱼(Pelteobagrus fulvidraco)是新兴淡水养殖对象,其养殖技术和适宜饲料蛋白及维生素C磷酸酯的需要量等已有报道,但对包膜维生素C的生长和免疫反应目前尚未见报道,而维生素C是鱼正常生长和抗病的重要微量营养素。为此,在水温(22.0±3.0)℃下,将平均体质量10.0 g的黄颡鱼幼鱼放养在30个60 cm×60 cm×120 cm的微流水网箱中,投喂以鱼粉为蛋白源,粗蛋白含量40.0%和粗脂肪8.0%的半精制饲料,按300 mg.kg-1、600 mg.kg-1、900 mg.kg-1、1 200 mg.kg-1和1 500 mg.kg-1的剂量分别添加维生素C磷酸酯和包膜维生素C。经90 d的饲养表明,饲料中维生素C磷酸酯和包膜维生素C的添加量分别为1 110~1 200 mg.kg-1和659~900 mg.kg-1时,黄颡鱼生长最快,饲料系数最低;添加量为1 200 mg.kg-1和600 mg.kg-1时,血清总蛋白含量最高;961 mg.kg-1和981 mg.kg-1时,溶菌酶活性最高;747 mg.kg-1和507 mg.kg-1时,淀粉酶活性最高;1 014 mg.kg-1和919 mg.kg-1时,蛋白酶活性最高。包膜维生素C的效果优于磷酸酯维生素C,这与其具稳定性且进入机体后缓释及蛋白酶活性和免疫力高有关     

饲料维生素E含量对美国红鱼生长和非特异性免疫的影响

采用单因子实验设计方法，进行了饲料中添加维生素E对美国红鱼生长（存活率、特定生长率和饲料效率）和非特异性免疫相关指标（血清中溶菌酶活性、血清总补体活性和超氧化物岐化酶（SOD）活性）影响的研究，设计了5个不同维生素E水平（0．1、25．3、51．0、102．8和203．2mg／kg）的等氮等能饲料，对美国红鱼进行为期56d的生长实验，每个水平3个重复，每个养殖单元放养初始体重为151g左右的美国红鱼20尾。饲养实验在海水网箱（1．5m×1．0m×1．0m）中进行。结果表明，随着饲料维生素E含量增加，美国红鱼饲料效率、特定生长率和成活率显著提高，美国红鱼最佳生长性能的饲料维生素E添加量为102．8mg／kg；美国红鱼血清溶菌酶和血清总补体活性随着维生素E的添加量的增加而显著升高，并且维生素E的添加量达到最高值102．8和25．3mg／kg，随后变化不明显；美国红鱼血清SOD活性随维生素E添加量的增加而显著升高，并且含量在102．8mg／kg达到最高值，随后显著下降。综上所述，美国红鱼维生素E的适宜添加量为102．8mg／kg。     

维生素E和硒对吉富罗非鱼(Oreochromis niloticus)幼鱼生长及血清抗氧化酶活性的影响

本研究采用2×5双因子试验设计,即在基础饲料中分别添加0和0.15 mg/kg的Se,每一Se水平下分别添加0、30、60、90、120 mg/kg的维生素E(VE),共制成10种试验饲料,饲喂平均初始体质量为(0.37±0.01)g的吉富罗非鱼(Oreochromis niloticus)70 d,每组设3个重复,每个重复组50尾吉富罗非鱼,其中饲喂未添加Se和VE的基础饲料组为对照组。结果表明,(1)VE对吉富罗非鱼幼鱼增重率、特定生长率、摄食量和饲料系数均有显著影响(P0.05),就生长性能而言,单独添加VE的适宜范围是63.86–70.58 mg/kg。Se对吉富罗非鱼的增重率、特定生长率的影响不显著(P0.05),但在VE添加量为0 mg/kg的试验组中,硒的添加使吉富罗非鱼增重率高于对照组。VE和Se对吉富罗非鱼生长的交互作用没有显著影响(P0.05)。(2)VE对谷胱甘肽过氧化物酶(GSH-PX)和过氧化氢酶(CAT)活性有显著影响(P0.05),总超氧化物歧化酶(T-SOD)和CAT活性随VE添加量的增加呈上升趋势。而Se可显著影响T-SOD和GSH-PX的活性(P0.05),在VE添加量范围60–90 mg/kg时,加Se试验组的T-SOD、GSH-PX和CAT活性较不加Se组有所上升。VE和Se对GSH-PX活性的影响具有显著的交互作用(P0.05)。在本研究条件下,VE和Se对吉富罗非鱼的生长及抗氧化有一定促进作用,二者联合使用,没有协同促生长作用,但抗氧化作用得到进一步加强。     

Effects of dietary vitamin C and vitamin E on the growth,antioxidant defence and digestive enzyme activities of juvenile discus fish (Symphysodon haraldi)

A 56‐day experiment was carried out to investigate the effects of dietary vitamin C and vitamin E on the growth, antioxidant status and digestive enzyme activities of discus fish (Symphysodon haraldi; initial body weight: 7.96 ± 0.61 g and body length: 5.45 ± 0.65 cm). Animals were fed with 13 different diets including one control diet and 12 treatment diets containing four levels of vitamin C (magnesium‐L‐ascorbyl‐2‐phosphate; 40, 80, 120 and 160 mg/kg) crossed with three levels of vitamin E (DL‐α‐tocopheryl acetate; 40, 80 and 120 mg/kg). The results showed that the fish fed diets containing additional vitamin C (40 mg/kg) and vitamin E (80 mg/kg) showed higher specific growth rate, length growth rate, total antioxidant capacity and protease activity but had lower feed conversion ratio and total superoxide dismutase activity than those fed the control diet. Collectively, these findings suggest that the inclusion of additional 40 mg/kg of vitamin C and 80 mg/kg of vitamin E in the basal diet could have beneficial effect on the growth, antioxidant defence and digestion of S. haraldi.     

硒和维生素E对牙鲆生长和非特异性免疫力的影响

在基础饲料中分别添加维生素E(VE)(60mg/kg标为e或300mg/kg标为E)和硒(Se)(0mg/kg标为s或2.5mg/kg标为S),制成4种试验饲料(s/e,s/E,S/e,S/E)分别饲喂初始体重为38.5±0.15g的牙鲆70d,观察其对生长性能、肝脏及血清中谷胱甘肽过氧化物酶(GSH-Px)活性、非特异免疫力以及抗病力的影响。结果表明,饲喂添加高剂量VE的两组饲料(s/E,S/E),牙鲆的特定生长率和吞噬率明显地提高(P0.05)。饲喂添加硒的两组饲料(S/e,S/E),牙鲆血液和肝脏的GSH-Px活性显著升高(P0.05)。70d投喂实验结束后,利用鳗弧菌进行攻毒试验,不添加硒和低剂量VE(s/e)使牙鲆的累积死亡率明显高于其他3组。     

Long-term effects and interactions of dietary vitamins C and E on growth and reproduction of yellow perch, Perca flavescens

This study was conducted to examine the effects of dietary vitamin C and/or E and their interaction on growth and reproductive performance in yellow perch. Yellow perch juveniles were divided into four treatments with triplicate groups and fed with one of four semi-purified diets for 32 weeks. The experimental diets were formulated to contain no or high vitamin E levels (160 mg/kg) without or with vitamin C supplementation (250 mg/kg) designated as diets −C−E, −C+E, +C−E, or +C+E, respectively. The growth rates and survival of yellow perch fed with +C−E and +C+E diets were significantly higher than the fish fed with −C−E diet. Total- and dehydro-ascorbate concentrations in liver and testis increased in response to its dietary supplementation. The -tocopherol concentration in sperm was significantly affected by dietary supplementation of vitamin C. Gonadosomatic index of males was lower in the fish fed with −C−E diet compared to that of fish fed with other diets. Hatching rates of embryos obtained from testing sperm viability was significantly improved in fish fed with the diets sufficient in vitamin C (82±7%) compared to the fish fed with the −C−E diet (59±7). This study indicates that supplementation of dietary vitamin C and E increase growth rate, and semen quality can be improved by dietary vitamin C supplementation within one maturation cycle, and vitamin C may spare sperm vitamin E depending on vitamin E stores in tissues.     

黄颡鱼幼鱼对蛋白质和脂肪的需要量

在水温23±5℃下,将平均体质量10．32g的黄颡鱼（Pelteobagrus fulvidraco）放养在27个60cm×60cm×120cm的微流水网箱中,饲喂3个蛋白质水平（32．0％、40．0％、48．0％）,每个蛋白质水平设3个脂肪水平（3．0％、10．0％和17．0％）的饲料,饲养100d。结果表明：在3．0％脂肪水平下,黄颡鱼摄食含40．0％蛋白质的饲料时,平均末体质量、特定生长率和蛋白质效率显著提高,饲料系数降低（P〈0．05）。在10．0％脂肪水平下,黄颡鱼摄食含48．0％蛋白质饲料时,饲料系数显著降低（P〈0．05）,摄食含40．0％的蛋白质饲料次之。黄颡鱼摄食含48．0％蛋白质与3．0％脂肪饲料组和40．0％蛋白质与10．0％脂肪组的干物质消化率最高（P〈0．01）;蛋白质消化率在48．0％蛋白质与3．0％脂肪达到最高（P〈0．01）,脂肪消化率均在40．0％蛋白质与10．0％脂肪达到最高（P〈0．01）。实验表明,黄颡鱼幼鱼较为适宜的蛋白质和脂肪需要量分别为40．0％和10．0％。     

Dietary vitamin E requirement, fish performance and carcass composition of rohu (Labeo rohita) fry

A 90-day feeding experiment was conducted using flow through system to evaluate the requirement of vitamin E for rohu fry in relation to growth performance and to assess the relationship between the dietary vitamin E levels and carcass composition. Five semi-purified diets supplemented with 0, 50, 100, 150, 200 mg vitamin E/kg dry diet as --tocopheryl acetate were fed to rohu fry (av. wt.±S.E.=0.58±0.01 g) in triplicate groups. At the end of the experiment, growth and dietary performance were evaluated and vitamin E deposition in the tissue, erythrocyte fragility, thiobarbituric acid reactive substances (TBARs) were analyzed. The average net weight gains were 6.82±0.09, 7.38±0.03, 8.20±0.03, 8.07±0.09 and 8.12±0.08 (g/90 days), respectively, for fish fed diets 0, 50, 100, 150, 200 mg vitamin E/kg. The fish fed diets containing less than 100 mg supplemental vitamin E/kg had significantly (P<0.05) reduced weight gain, feed efficiency and other nutritional indices compared to those fed diets supplemented with vitamin E at 100–200 mg/kg. With the increasing level of vitamin E, both TBARs and erythrocyte fragility values were reduced. Regression analysis of weight gain data using broken-line model indicated a minimum vitamin E requirement of 131.91 mg/kg dry diet. The erythrocyte fragility and TBARs were maximum in fish fed the vitamin E-deficient diet. From the present experiment, it may be concluded that the vitamin E requirement of Labeo rohita fry for optimum growth and other dietary performances is 131.91 mg/kg of dry diet.     

黄颡鱼营养学的研究进展

黄颡鱼（Pelteobagrus fulvidraco）的营养学研究主要体现在食性分析、肌肉营养成份的测定等基础研究上,而营养需求上的研究主要体现在配合饲料配方上的饲养试验,对于确定某种营养素需要量的研究报道较少。本文综述了黄颡鱼对蛋白质、脂类、碳水化合物、维生素及无机盐的需要量。黄颡鱼配合饲料中蛋白质的适宜含量（稚幼鱼）为39%～45%、（成鱼）为34%～38%,脂肪的适宜含量为7%～9%,碳水化合物的适宜含量为20%～23%、粗纤维的适宜含量为5%～6%,无机盐的适宜含量为1%～2.5%。     

Effects of dietary protein to carbohydrate ratios on growth and body composition of juvenile yellow catfish, Pelteobagrus fulvidraco (Siluriformes, Bagridae, Pelteobagrus)

The present experiment was conducted to investigate the effects of dietary protein to carbohydrate ratios on growth and body composition of juvenile yellow catfish, Pelteobagrus fulvidraco . Nine diets were formulated to contain three protein levels (30%, 36% and 42%), each with three carbohydrate levels (24%, 30% and 36%). Each diet was randomly assigned to triplicate groups of 20 fish (initial mean body weight: 8.24±0.20 g) in indoor flow – through fibreglass tanks. The experiment continued for 8 weeks. Weight gain and specific growth rate were similar for the fish fed the 36% and 42% protein diets but higher than that fed the 30% protein diet. At the 36% protein level, carbohydrate contents varying from 24% to 36% ( P / E ratio of 24.0–28.2 mg protein kJ⁻¹) had no significant effects on growth performance and feed utilization ( P >0.05). Protein efficiency ratio tended to increase with dietary carbohydrate level at the same protein level. Dietary treatments significantly influenced body composition ( P <0.05), but not the condition factor, viscerosomatic index, hepatosomatic index and intraperitoneal fat ratio ( P >0.05). Based on these observations, 36% protein and 24–36% carbohydrate with the P / E ratio of 24.0–28.2 mg protein kJ⁻¹ seemed suitable for optimal growth and feed utilization, and carbohydrate could cause protein-sparing effect in diets for juvenile yellow catfish.     

Requirement of vitamin E of growing sea cucumber Apostichopus japonicus Selenka

This feeding trial was conducted to determine the vitamin E requirement of growing sea cucumber Apostichopus japonicus Selenka. Six isonitrogenous and isoenergetic experimental diets were formulated to contain graded levels of vitamin E (6.7, 81.2, 159.3, 237.8, 314.6, 395.9 mg/kg diet). Each diet was assigned randomly to 30 growing sea cucumber with initial body weight 15.43 g in triplicates for 8 weeks. Survival rate was not affected by dietary vitamin E; meanwhile, both the weight gain (WG) and specific growth rate were presented the trend of increasing first and then kept stable. With the increasing of dietary vitamin E, crude lipid content of body wall was evaluated firstly and dropped afterwards. When dietary vitamin E contents were lower than 159.3 mg/kg, vitamin E contents of body wall were increased by dietary vitamin E levels, but there were no more differences when dietary vitamin E higher than 159.3 mg/kg. There were minor effects on digestive enzymes of intestine by dietary vitamin E. Contents of malondialdehyde were decreased, while the total superoxide dismutase activity was increased first and then decreased with the increasing of dietary vitamin E. Activities of intestinal alkaline phosphatase were increased, and glutamic oxaloacetic transaminase were decreased first and then increased with the increasing of dietary vitamin E. In conclusion, analysis by a linear regression equation of WG or vitamin E contents in body wall indicated that the optimum requirement of vitamin E for growing sea cucumber (initial body weight 15.43 g) was 165.2–187.2 mg/kg diet.