草鱼幼鱼对烟酸需要量

草鱼幼鱼的初始体重为12.43±0.80g,试验分为7组,其饲料中烟酸含量分别为5.1、9.8、16.6、32.2、66.7、130.1、271.5 mg•kg-1,每组设3个重复,每桶30尾鱼,日投喂率2％～3％,饲养试验周期为8周。研究不同含量烟酸对草鱼幼鱼生长性能、饲料系数、机体营养组分、造血功能及血脂的影响,以确定草鱼幼鱼饲料中适宜烟酸需要量。试验结果表明：1.添加烟酸显著提高了特定生长率、增重率和草鱼幼鱼的存活率,对草鱼幼鱼肥满度无显著影响;烟酸含量为32.2 mg•kg-1时草鱼的特定生长率和增重率最大,饲料系数最低,并与其它各组存在显著差异;2.添加烟酸对草鱼全鱼水分、灰分无显著影响,显著提高了全鱼粗脂肪含量,但各添加组间无显著差异;饲料中烟酸含量为66.7mg•kg-1时,粗蛋白显著高于对照组及9.8 mg•kg-1组;3.添加烟酸显著提高了血液红细胞计数和血红蛋白含量,但对血清胆固醇和甘油三酯无显著影响,烟酸含量为16.6 mg•kg-1及以上时显著提高血清高密度脂蛋白胆固醇与低密度脂蛋白胆固醇,与对照组和9.8 mg•kg-1组存在显著差异。基于折线法分析,草鱼幼鱼获得最佳生长时的饲料中烟酸最低需求量为25.5 mg•kg-1。 关键词：草鱼;烟酸;生长;需要量     

草鱼幼鱼对烟酸的需要量

草鱼幼鱼的初始体重为(12.43±0.80) g,试验分为7组,其饲料中烟酸含量分别为5.1、9.8、16.6、32.2、66.7、130.1、271.5 mg·kg-1,每组设3个重复,每桶30尾鱼,日投喂率2%～3%,饲养试验周期为8周.研究不同含量烟酸对草鱼幼鱼生长性能、饲料系数、机体营养组分、造血功能及血脂的影响,以确定草鱼幼鱼饲料中适宜烟酸需要量.试验结果表明:①添加烟酸显著提高了特定生长率、增重率和草鱼幼鱼的存活率,对草鱼幼鱼肥满度无显著影响;烟酸含量为32.2 mg·kg-1时草鱼的特定生长率和增重率最大,饲料系数最低,并与其它各组存在显著差异;②添加烟酸对草鱼全鱼水分、灰分无显著影响,显著提高了全鱼粗脂肪含量,但各添加组间无显著差异,饲料中烟酸含量为66.7 mg·kg-1时,全鱼粗蛋白含量显著高于对照组及9.8 mg·kg-1组;③添加烟酸显著提高了血液红细胞计数和血红蛋白含量,但对血清胆固醇和甘油三酯无显著影响,烟酸含量为16.6 mg·kg-1及以上时显著提高血清高密度脂蛋白胆固醇与低密度脂蛋白胆固醇,与对照组和9.8 mg·kg-1组存在显著差异.基于折线法分析,草鱼幼鱼获得最佳生长时对饲料中烟酸的最低需求量为25.5 mg·kg-1.     

鲈幼鱼对饲料中苏氨酸的需要量

以初始体质量(8.00±0.20)g的鲈为实验对象,在海水网箱(1.5 m×1.5 m×2.0 m)中进行为期8周的摄食生长实验,研究鲈对饲料中苏氨酸的需要量。通过在半精制基础饲料中添加晶体L-苏氨酸使饲料中苏氨酸含量分别达到0.75%、1.03%、1.36%、1.67%、2.04%和2.31%,配制成6水平等氮等能饲料(41.83%粗蛋白质,19.68 kJ/g总能)。每种饲料设3个重复,每个重复随机放养30尾鲈。实验采用表观饱食投喂方式,每天投喂2次(06:00和17:30),实验期间水温为26～32℃,盐度为22～28,溶解氧含量在7 mg/L左右。实验结果表明,各饲料处理组成活率(94.4%～98.9%)无显著差异。随着饲料中苏氨酸含量的增加,鲈的增重率显著升高(150.3%～256.9%)(P<0.05),且在1.67%苏氨酸饲料组达到最大值(256.9%),然而,随着饲料中苏氨酸含量的进一步增加,增重率有下降的趋势。鲈的氮累积率随着饲料中苏氨酸含量的增加而显著升高(13.18%～26.36%)(P<0.05),且在1.67%苏氨酸饲料组达到最大值(26.36%),随着饲料中苏氨酸含量的进一步增加,氮累积率有下降的趋势。饲料苏氨酸含量对鲈鱼体粗蛋白、粗脂肪和灰分含量无显著影响。以增重率和氮累积率为评价指标经二次回归分析得出,鲈对饲料中苏氨酸的需要量分别为1.77%和1.88%,占饲料蛋白质的4.21%和4.47%。     

草鱼对饲料中磷需要量的研究

采用酪蛋白—明胶(7:1,W/W)为基础的精制饲料,以磷酸二氢钙作磷源,用梯度法进行草鱼对饲料中磷需要量的试验,证实草鱼的生长受饲料中磷含量的影响较大。饲料中磷不足,草鱼生长缓慢,饲料系数高,整条鱼体水分、灰分、钙、磷和钙磷比低下,脂肪积累,脊椎骨磷含量低下。饲料中磷含量过高引起草鱼生长缓慢,甚至死亡。根据鱼的增重率、饲料系数等分析判断:草鱼饲料中磷的适宜范围为0.95—1.10％,草鱼对饲料中有效磷的需要量为0.85—1.00％。试验表明:草鱼饲料中的盐类添加应以磷为主体。     

草鱼幼鱼对饲料中泛酸需要量的研究

研究了饲料中泛酸钙添加量对平均体重(4.80±0.32)g的草鱼幼鱼生长和部分生理指标的影响。在相同基础配方中分别添加泛酸钙0、8、15、30、60、120、240 mg/kg饲料,进行为期8周的养殖试验,每个处理3个重复。结果表明:饲料中添加泛酸钙能提高草鱼幼鱼的增重率和特定生长率,降低饲料系数,对成活率无显著影响(P>0.05)。对照组的总胆固醇、高密度脂蛋白胆固醇和低密度脂蛋白胆固醇含量显著低于添加组(P<0.05),各添加组无显著差异(P>0.05)。鱼体灰分含量不受饲料中泛酸钙含量的影响,但能提高鱼体水分、蛋白和脂肪含量(P<0.05)。基于特定生长率折线法分析,草鱼幼鱼获得最佳生长时的饲料泛酸钙最低需求量为25 mg/kg。     

长江草鱼幼鱼的生长研究

依据耳石日轮研究了采自长江的草鱼幼鱼的年龄生长。幼鱼期的生长符合线性或指数模型。体长和体重的平均生长率分别为 2 0 85mm/d和 1 2 47g/d ,特定生长率分别为 2 48%和 7 6 9%。     

草鱼对饲料中磷需要量的研究

在鱼类无机盐需要量的研究中，已查明鱼类对钙、磷的需要量。较多的研究结果指出：鱼类饲料中有效磷的需要量大约在0．5～0．8％之间，饲料中钙的含量对鱼类生长和饲料分数影响不大。但迄今为止，研究较多的是鲑、鳟鱼类、鲤鱼和真鲷等。关于草鱼，黄耀桐等采用正交试验，对草鱼鱼种以酩蛋白为蛋白源的饲料中钙、磷、铁、镁等13种无，机元素的添加量进行了研究。     

草鱼幼鱼对异亮氨酸的需要量

以初始体重（8.25±0.37） g的草鱼幼鱼为试验对象,分别采用异亮氨酸（isoleucine,Ile)水平为0.77 %、1.07 %、1.37 %、1.67 %、1.97 %和2.27 % 6组等氮(粗蛋白35.25 %)半纯化日粮对草鱼进行了72 d生长试验,研究其日粮异亮氨酸需要量。结果表明：（1）日粮Ile水平为1.67 %时,草鱼增重率、特定生长率和蛋白质效率最高,饲料系数最低;鱼体空壳率和肥满度达到最大值,内脏指数最小;草鱼体水分、体脂最低,体蛋白、灰分最高;肌肉水分最低,粗蛋白最高。而各水平之间肌肉粗脂肪无显著差异(P> 0.05);日粮Ile水平为1.67 %时,草鱼肌肉Ile含量和肌肉氨基酸总量最高。（2）随日粮Ile水平增加,肌肉RNA/DNA呈先升后降趋势,Ile 1.67 %水平组最高;而肝脏谷氨酸脱氢酶却呈先降后升趋势,Ile 1.67 %水平组最低。血氨在Ile 0.77 % ~ 1.67 %水平组之间处于稳定状态,高于1.67 %水平后呈上升趋势。血清白蛋白受日粮Ile水平的影响不显著（P> 0.05）。（3）随日粮Ile水平增加,血清甘油三酯和胆固醇均呈先降后升趋势,且在Ile 1.67%水平组,两项指标均为最低值,显著低于其他水平组（P< 0.05）。根据增重率、特定生长率、饲料系数和蛋白质效率与日粮Ile水平的二次曲线关系,确定草鱼幼鱼日粮(粗蛋白35.25 %) Ile适宜需要量范围为1.41 %～1.49 %(日粮基础)或4.0 %～4.23 %(日粮蛋白基础)。     

长江草鱼幼鱼的生长研究

依据耳石日轮研究了采自长江的草鱼幼鱼的年龄生长.幼鱼期的生长符合线性或指数模型.体长和体重的平均生长率分别为2.085mm /d和1.247g/d,特定生长率分别为2.48%和7.69%.     

草鱼幼鱼肌醇营养需要量的研究

以酪蛋白、明胶和鱼粉为蛋白源,配制含肌醇水平分别为0、50 mg/kg、100 mg/kg、200 mg/kg、400 mg/kg8、00 mg/kg、1 600 mg/kg的7组实验饲料。每组设3个重复,连续投喂体质量(4.78±0.18)g的草鱼(Ctenopharyngodon idella)幼鱼9周,通过测定生长指标、部分血清生化指标和全鱼营养成分来评价饲料肌醇添加水平对草鱼幼鱼的影响。结果表明,饲料中肌醇添加水平≥200 mg/kg使草鱼幼鱼增重率(WGR)、特定生长率、血清中总胆固醇(TC)和低密度脂蛋白胆固醇(LDL-C)含量与对照组相比有显著提高(P<0.05),而血清甘油三酯(TG)含量比对照组有显著降低(P<0.05);200 mg/kg和400 mg/kg肌醇添加组草鱼幼鱼饲料系数(FCR)比对照组有显著降低(P<0.05);饲料中添加肌醇对草鱼幼鱼存活率、血清中高密度脂蛋白胆固醇和全鱼营养成分无显著影响(P>0.05)。对WGR、FCR、TC、TG和LDL-C进行折线回归分析得出饲料中肌醇添加水平为166～214 mg/kg对草鱼幼鱼的生长比较适宜。     

Dietary available phosphorus requirement of juvenile grass carp (Ctenopharyngodon idella)

A growth trial was conducted to estimate the optimum concentration of dietary available phosphorus (P) for grass carp (Ctenopharyngodon idella). Triplicate groups of grass carp (5.59 ± 0.02 g) were fed diets containing graded levels (2.36, 4.27, 6.31, 8.36, 10.4 and 14.8 g kg^?1) of available P for 8 weeks. Grass carp fed with the P‐supplemented diets had significantly higher specific growth rate, weight gain, protein efficiency ratio and feed efficiency than fish fed with the basal diet. In whole‐body composition, protein content increased, while lipid content decreased with the increase in P level in diet (P < 0.05). Fish fed with the P‐supplemented diets had significantly higher whole body, vertebrae and scales mineralization (P < 0.05), but Ca/P ratios were not influenced. The blood chemistry analysis showed that dietary available P had distinct effects on P, Ca and Mg contents, as well as on the contents of triacylglycerol and total cholesterol. Broken‐line analysis indicated that 8.49 g kg^?1 dietary available P was required for maximal tissue storage and mineralization as well as optimal growth.     

Total aromatic amino acid requirement of juvenile grass carp (Ctenopharyngodon idella)

This experiment was conducted to investigate total aromatic amino acid requirement of juvenile grass carp Ctenopharyngodon idella. Six isonitrogenous and isoenergetic semipurified diets containing casein and gelatin with graded level of phenylalanine (7.8, 11.1, 14.4, 17.6, 21.7, 24.9 g kg^?1 DM) were formulated. Each diet was randomly assigned to triplicate group of 30 fish (3.58 ± 0.002 g, mean ± SEM) each tank for 8 weeks. The highest weight gain (WG, %), final body weight (g) and specific growth rate were recorded when phenylalanine level was 17.6 g kg^?1 of the diet. Fish muscle protein content, protein efficiency ratio (PER), feed conversion ratio and alanine aminotransferase were significantly affected by dietary phenylalanine level. The polynomial regression calculated using WG and PER indicated that the optimal dietary total aromatic amino acid (phenylalanine + tyrosine) requirement for juvenile grass carp was 24.4 g kg^?1 of the diet, corresponding to 65.9 g kg^?1 of dietary protein.     

Dietary magnesium requirements of juvenile grass carp,Ctenopharyngodon idella

To determine dietary magnesium (Mg) requirements of juvenile grass carp, Ctenopharyngodon idella, magnesium sulphate was added to the basal diet at 0, 150, 300, 600, 1200, 2400 mg Mg kg⁻¹ diet. Each diet was fed to three replicate groups of juvenile grass carp (initial weight: 7.69 ± 0.13 g) in a closed, recirculating rearing system for 76 days. No mortality or nutritional deficiency signs were observed except the growth depression in fish fed the Mg‐deficient diet. Growth performance and activities of serum superoxide dismutase (SOD), glutathione peroxidase (GPx) and lysozyme (LSZ) were highest (P <0.05) in fish fed the diet supplemented with 600 mg Mg kg⁻¹. The serum malondialdehyde (MDA) content was higher (P <0.05) in fish fed the diets supplemented with 0 and 150 mg Mg kg⁻¹ than that in fish fed the diets with ≥300 mg Mg kg⁻¹. Mg concentrations both in whole‐body and vertebrae increased with the increase in dietary Mg level up to 300 mg kg⁻¹, whereupon the response reached a plateau. Analysis by second‐order polynomial regression of weight gain, by broken‐line regression of vertebrae Mg concentration and by linear regression of whole‐body Mg retention of fish indicated that the adequate dietary Mg concentration for juvenile grass carp was 713.5, 627.7 and 469.8 mg kg⁻¹ diet, respectively.     

Dietary zinc requirement of juvenile grass carp (Ctenopharyngodon idella) based on growth and mineralization

A growth trial was conducted to estimate the optimum requirement of dietary zinc (Zn) for grass carp (Ctenopharyngodon idella). Triplicate groups of grass carp (3.97 ± 0.05 g) were fed diets containing graded levels (13, 25, 34, 53, 89 and 135 mg kg^?1) of Zn for 8 weeks. Grass carp fed with dietary Zn levels higher than 34 mg kg^?1 significantly increased final body weight, weight gain and specific growth rate (P < 0.05). For body composition, fish fed with dietary Zn levels higher than 53 mg kg^?1 significantly decreased the moisture contents but increased the lipid contents of whole body and liver. Whole body, scales, vertebrae and liver mineralization were all affected significantly (P < 0.05) by dietary Zn levels. Zn contents in whole body, scales, vertebrae and plasma were linearly increased up to the 53 mg kg^?1 dietary Zn and then remained stable beyond this level. Grass carp fed with dietary Zn levels higher than 53 mg kg^?1 significantly increased triacyglyceride and total cholesterol contents and plasma alkaline phosphatase activity in plasma (P < 0.05). Broken‐line analysis indicated that 55.1 mg kg^?1 dietary Zn was required for maximal tissue storage and mineralization as well as optimal growth of grass carp.     

Dietary arginine requirement of juvenile grass carp Ctenopharyngodon idella (Valenciennes in Cuvier & Valenciennes, 1844)

This experiment was conducted to estimate the optimum requirement of arginine for juvenile grass carp Ctenopharyngodon idella. Six isonitrogenous (38%) and isoenergetics (16 MJ kg^?1) semi‐purified diets containing casein and gelatine with graded level of arginine (0.93, 1.20, 1.51, 1.84, 2.10 and 2.41 g 100 g^?1 DM) were formulated. Each diet was randomly assigned to triplicate groups of 25 fish each tank (initial weight: 3.84 ± 0.01) for 10 weeks. The highest weight gain (WG, %) was recorded when arginine level was 2.10% of the diet. Dietary arginine level higher than 1.84% significantly increased the protein contents of whole body. Whole body amino acid composition of juvenile grass carp was not significantly affected by the dietary arginine level. Plasma‐free arginine level was increased linearly with increasing of arginine level in the diets, and the plasma‐free ornithine level was significantly higher when the dietary arginine level was 2.41% compared with other groups. Quadratic model analysis of SGR data indicated that the minimum recommended dietary arginine requirement for grass carp was 2.17% of the diet, corresponding to 5.71% of dietary protein.     

饲料中添加谷胱甘肽对草鱼组织中谷胱甘肽沉积和抗氧化能力的影响

在基础饲料中分别添加还原型谷胱甘肽(GSH)至0 mg/kg、100 mg/kg、200 mg/kg、300 mg/kg、400 mg/kg和500 mg/kg,分别投喂草鱼(Ctenopharyngodon idella)幼鱼8周,草鱼幼鱼体质量(4.09±0.01)g,观察GSH在草鱼组织中沉积以及对草鱼抗氧化功能的影响.结果表明,饲料中添加外源GSH对草鱼生长影响不显著(P＞0.05),实验组肌肉中GSH含量显著高于对照组(P＜0.05),肝脏中GSH含量在GSH添加水平为200 mg/kg时显著高于对照组(P＜0.05),肝脏和肌肉中丙二醛(MDA)在GSH添加水平为300 mg/kg组达到最低,显著低于对照组(P＜0.05).添加GSH对血清中GSH和MDA影响不显著(P＞0.05).草鱼肝脏中谷胱甘肽还原酶(GR)活力在400 mg/kg组显著高于对照组(P＜0.05),肌肉中GR活力有增高趋势但差异不显著(P＞0.05);肝脏和肌肉中γ-谷氨酰转移酶(γ-GT)均高于对照组,分别在300 mg/kg组和200 mg/kg组达到显著水平(P＜0.05);肝脏中谷胱甘肽过氧化物酶(GSH-PX)活力、总抗氧化能力(T-AOC)和超氧化物歧化酶(SOD)能力不同程度升高,均在200 mg/kg组达到最高,显著高于对照组(P＜0.05);血清GSH-PX活力和T-AOC有增高趋势但与对照组差异不显著(P＞0.05);血清和肝脏中活性氧(ROS)含量分别在400 mg/kg和300 mg/kg组达到最低,显著低于对照组(P＜0.05).结果提示,饲料中添加GSH能够促进草鱼肝脏和肌肉中GSH的沉积,提高肝脏及肌肉中GR和γ-GT活力,以及肝脏中GSH-PX和SOD活力与总抗氧化能力,减少肝脏中MDA含量,降低肝脏及血清中ROS含量,因此GSH在水产饲料中具有广泛的应用前景.     

Dietary potassium requirement of juvenile grass carp (Ctenopharyngodon idella Val.) based on growth and tissue potassium content

A growth trial was conducted to estimate the optimum concentration of dietary potassium (K) for grass carp (Ctenopharyngodon idella). Triplicate groups of grass carp (3.96 ± 0.06 g) were fed diets containing graded levels (0.87, 2.90, 5.37, 7.54, 9.87 and 12.4 g kg^?1) of K for 8 weeks. Final body weight, weight gain and feed efficiency and gill Na⁺‐K⁺ ATPase activity were highest in fish fed with 9.87 g kg^?1 dietary K and lowest in fish fed the basal diet (P < 0.05). The K contents in whole body and muscle were linearly increased up to the 9.87 g kg^?1 dietary K and then levelled off beyond this level, whereas in scales and vertebrae up to the 7.54 g kg^?1 dietary K (P < 0.05). However, dietary K levels had no significant effect on ash, Ca, P and Mg contents in whole body, scales, vertebrae or muscle. Analysis using polynomial regression of weight gain and gill Na⁺‐K⁺ ATPase activity and using the broken‐line regression of whole body K concentrations indicated that the adequate dietary K concentration for grass carp is about 9.45–9.99 g kg^?1 diet.     

Dietary manganese requirement of juvenile grass carp (Ctenopharyngodon idella Val.) based on growth and tissue manganese concentration

A growth trial was conducted to estimate the optimum concentration of dietary Manganese (Mn) for grass carp (Ctenopharyngodon idella). Triplicate groups of grass carp (3.97 ± 0.05 g) were fed diets containing graded levels (4.0, 8.9, 13.8, 18.7, 23.6 and 33.3 mg kg^?1) of Mn for 8 weeks. Weight gain, specific growth rate and feed efficiency were linearly increased up to the 18.7 mg kg^?1 dietary Mn and then levelled off beyond this level. For body composition, lipid contents in whole body, muscle and liver decreased significantly with increasing dietary Mn level. Grass carp fed with dietary Mn levels higher than 19.7 mg kg^?1 significantly decreased condition factor. Whole body, vertebrae and scales mineralization were all affected significantly by dietary Mn levels. Mn contents in whole body, vertebrae and scales were linearly increased up to the 18.7 mg kg^?1 dietary Mn and then levelled off beyond this level. Contrarily, Ca and P contents seem to be inversely related to dietary Mn. However, dietary Mn levels had no significant effect on body Fe contents. Broken‐line analysis indicated that 20.6 mg kg^?1 dietary Mn was required for maximal tissue Mn storage, as well as satisfied for the optimal growth of juvenile grass carp.     

Dietary magnesium requirement and effects on growth and tissue magnesium content of juvenile grass carp (Ctenopharyngodon idella)

A growth trial was conducted to estimate the optimum concentration of dietary magnesium (Mg) for grass carp (Ctenopharyngodon idella). Triplicate groups of grass carp (5.56 ± 0.02 g) were fed diets containing graded levels (187, 331, 473, 637, 779 and 937 mg kg^?1) of Mg for 8 weeks. Weight gain, specific growth rate and feed efficiency were linearly increased up to 637 mg kg^?1 dietary Mg and then levelled off beyond this level. For body composition, dietary Mg levels higher than 473 mg kg^?1 significantly decreased the moisture content but increased the lipid content of whole body, muscle and liver. Dietary Mg levels higher than 473 mg kg^?1 significantly decreased the ash contents of vertebrae, scales and muscle. Mg contents in whole body, vertebrae, scales and plasma were increased up to 637 mg kg^?1 dietary Mg and then levelled off beyond this level. However, Ca and P contents seem to be inversely related to dietary Mg. Dietary Mg levels higher than 473 mg kg^?1 significantly decreased Zn and Fe contents in whole body and vertebrae. Broken‐line analysis indicated that 687 mg kg^?1 dietary Mg was required for maximal tissue Mg storage, as well as satisfied for the optimal growth.