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。     

牛磺酸及相关氨基酸对鲈鱼(Lateolabrax japonicus)幼鱼生长及组织氨基酸含量的影响

以平均体重为(8.13±0.05)g的鲈鱼(Lateolabrax japonicus)幼鱼为研究对象,探讨了在低鱼粉饲料中添加牛磺酸、蛋氨酸和半胱氨酸对鲈鱼幼鱼生长及鱼体氨基酸组成的影响.分别在基础饲料中添加0(对照组T-0)、1.0％牛磺酸(T-1)、2.0％牛磺酸(T-2)、0.5％蛋氨酸(M-0.5)和0.5％半胱氨酸(C-0.5)制成5种等氮等脂的实验饲料,在室内流水养殖系统中进行为期70 d的养殖实验.结果显示,T-1、T-2、M-0.5和C-0.5组鲈鱼幼鱼的终末体重、特定生长率(SGR)、增重率(WGR)和摄食率(FI)均显著高于T-0组(P＜0.05);饲料中添加牛磺酸、蛋氨酸和半胱氨酸均可提高鱼体粗蛋白和粗脂肪含量(P＜0.05),鱼体水分含量则呈现出相反的变化趋势;T-I、T-2组肝脏、肌肉中的牛磺酸含量显著高于T-0组(P＜0.05),但M-0.5、C-0.5组肝脏、肌肉中牛磺酸含量与T-0组无显著差异(P＞0.05);T-1、T-2和C-0.5组肝脏的必需氨基酸及总氨基酸含量均高于T-0组(P＜0.05),但M-0.5组肝脏必需氨基酸及总氨基酸含量与T-0组无显著差异(P＞0.05);T-1、T-2、M-0.5和C-0.5组肌肉的必需氨基酸含量均高于T-0组,但只有M-0.5组显著高于T-0组(P＜0.05);T-1、T-2和M-0.5组肌肉的总氨基酸含量高于T-0组(P＜0.05),C-0.5组与T-0组无显著差异(P＞0.05).研究表明,饲料中添加牛磺酸、蛋氨酸和半胱氨酸均可提高鲈鱼幼鱼的生长,同时可以改善鲈鱼肝脏和肌肉中的氨基酸沉积.     

三丁酸甘油酯在鲤幼鱼配合饲料中的应用

为确定三丁酸甘油酯在鲤幼鱼配合饲料中的添加对鲤(Cyprinus carpio)幼鱼生长性能的影响,进行了为期八周的鲤幼鱼养殖试验,测定试验组和对照组鲤幼鱼的生长指标和鱼体成分,结果表明,0.1%的三丁酸甘油酯添加到配合饲料中可以显著提高鲤幼鱼的增重率、脏体比、肝体比以及全鱼粗蛋白、粗脂肪、粗灰分的含量,推测三丁酸甘油酯可提高鲤幼鱼对营养物质的消化吸收率。     

饲料中添加锌对星斑川鲽幼鱼生长、生理生化指标和机体抗氧化的影响

以酪蛋白和明胶为蛋白源,以七水硫酸锌为锌源,在基础饲料中分别添加锌0、50、100、150、200、400mg/kg,配制成6种等氮等能的精制饲料,饱食投喂初始体重为62.89±0.51g的星斑川鲽幼鱼66d,探讨饲料锌水平对星斑川鲽幼鱼生长、血液生理生化指标和机体抗氧化功能的影响.结果表明,添加150～400mg/kg饲料锌显著提高了星斑川鲽幼鱼的增重率(WGR)(P<0.05),且WGR的最大值及饲料系数(FCR)的最小值均出现在150mg/kg锌饲料组.添加100～200mg/kg饲料锌显著提高了试验鱼血液红细胞数量(P<0.05),0mg/kg锌饲料组的血细胞比容和血红蛋白含量均显著低于其他各组(P<0.05).血清蛋白含量不受饲料锌添加量的影响(P>0.05).血清溶菌酶(LSZ)活力随着锌添加量的增加而显著升高(P<0.05),在锌添加量为150mg/kg时达最高值;当添加量高于150mg/kg时,LSZ活力变化不显著(P>0.05).0与50mg/kg锌饲料组的血清铜锌-超氧化物歧化酶(CuZn-SOD)活力显著低于其他各组(P<0.05).0和50mg/kg锌饲料组肌肉丙二醛(MDA)含量显著高于其他各组(P<0.05),以150mg/kg锌饲料组最低(P<0.05).建议星斑川鲽幼鱼精制饲料中锌的适宜添加量为150mg/kg.     

黄河鲤新品系F3和F4群体的生长和肌肉营养成分差异分析

为探讨黄河鲤新品系群体选育过程中相邻世代F₃和F₄群体的生长和肌肉营养组成差异,分别从2龄黄河鲤新品系F₃和F₄群体中挑选10尾进行肌肉营养组成分析。结果显示：2龄黄河鲤新品系F₄群体的体长和体质量均显著高于F₃群体(P<0.05);黄河鲤新品系F₃和F₄群体的肌肉水分和粗脂肪差异不显著(P>0.05),F₃群体的肌肉粗灰分和粗蛋白含量均显著高于F₄群体(P<0.05);黄河鲤新品系F₃和F₄群体的肌肉总氨基酸含量和必需氨基酸含量差异不显著(P>0.05),F₃群体的肌肉非必需氨基酸含量、鲜味氨基酸含量和鲜味氨基酸/总氨基酸均显著高于F₄群体(P<0.05),但F₄群体的必需氨基酸/总氨基酸却显著高于F₃群体(...     

牛磺酸及相关氨基酸对鲈鱼(Lateolabrax japonicus)幼鱼生长及组织氨基酸含量的影响

以平均体重为(8.13±0.05)g的鲈鱼(Lateolabrax japonicus)幼鱼为研究对象,探讨了在低鱼粉饲料中添加牛磺酸、蛋氨酸和半胱氨酸对鲈鱼幼鱼生长及鱼体氨基酸组成的影响。分别在基础饲料中添加0(对照组T-0)、1.0%牛磺酸(T-1)、2.0%牛磺酸(T-2)、0.5%蛋氨酸(M-0.5)和0.5%半胱氨酸(C-0.5)制成5种等氮等脂的实验饲料,在室内流水养殖系统中进行为期70 d的养殖实验。结果显示,T-1、T-2、M-0.5和C-0.5组鲈鱼幼鱼的终末体重、特定生长率(SGR)、增重率(WGR)和摄食率(FI)均显著高于T-0组(P0.05);饲料中添加牛磺酸、蛋氨酸和半胱氨酸均可提高鱼体粗蛋白和粗脂肪含量(P0.05),鱼体水分含量则呈现出相反的变化趋势;T-I、T-2组肝脏、肌肉中的牛磺酸含量显著高于T-0组(P0.05),但M-0.5、C-0.5组肝脏、肌肉中牛磺酸含量与T-0组无显著差异(P0.05);T-1、T-2和C-0.5组肝脏的必需氨基酸及总氨基酸含量均高于T-0组(P0.05),但M-0.5组肝脏必需氨基酸及总氨基酸含量与T-0组无显著差异(P0.05);T-1、T-2、M-0.5和C-0.5组肌肉的必需氨基酸含量均高于T-0组,但只有M-0.5组显著高于T-0组(P0.05);T-1、T-2和M-0.5组肌肉的总氨基酸含量高于T-0组(P0.05),C-0.5组与T-0组无显著差异(P0.05)。研究表明,饲料中添加牛磺酸、蛋氨酸和半胱氨酸均可提高鲈鱼幼鱼的生长,同时可以改善鲈鱼肝脏和肌肉中的氨基酸沉积。     

饲料中添加氯化胆碱、甜菜碱和溶血卵磷脂对异育银鲫生长、脂肪代谢和血液指标的影响

选取450尾健康的异育银鲫鱼种[体重为(7.46±0.2)g],随机分成5组,其中1组为对照组,2、3、4和5为试验组,投喂的饲料是在基础饲料中分别添加0.05%溶血卵磷脂、0.1%的溶血卵磷脂、0.1%甜菜碱和0.15%氯化胆碱(共含氯化胆碱0.21%),在室内可控温循环水养殖系统中饲养67d,研究3种添加剂对异育银鲫生长、脂肪代谢和血液指标等的影响。结果表明,各试验组异育银鲫的增重率比对照组均有提高,其中0.1%甜菜碱组和高剂量氯化胆碱(0.21%)组增重率分别比对照组提高了10.28%和9.23%,且差异显著(P<0.05)。试验组的饲料系数均比对照组有所下降,其中高剂量氯化胆碱(0.21%)组、0.1%的溶血卵磷脂组和0.1%甜菜碱组与对照组相比显著降低(P<0.05)。试验组的营养物质表观消化率、肌肉中蛋白质的含量与对照组相比均有提高,而肝体比、肝脏中脂肪含量、肌肉中脂肪含量均比对照组有所降低,其中试验组肝体比、肝脏中脂肪含量显著低于对照组(P<0.05)。血浆生化指标显示:高剂量氯化胆碱(0.21%)组和添加0.1%甜菜碱组血浆中的甘油三酯比对照组有所下降(P>0.05),而0.05%溶血卵磷脂、...     

草鱼幼鱼的饲料苏氨酸需要量

选用初始体质量为(8.35±0.06)g的草鱼(ctenopharyngodon idella)540尾,随机分成6组,每组3个重复,每个重复30尾鱼,分别饲喂苏氨酸水平为0.72%、1.02%、1.32%、1.62%、1.92%和2.22%(占饲料的质量分数)的6组等氮半精制饲料(蛋白质质量分数35%),经60 d生长实验确定草鱼幼鱼的苏氨酸需要量.实验结果表明,随着饲料苏氨酸水平增加,草鱼的增重率、特定生长率、蛋白质效率、蛋白质沉积率、肌肉RNA/DNA比值和血氨水平显著升高(P<0.05),均在1.62%组达到最大值;饲料系数和肝脏谷氨酸脱氢酶活力显著降低(P<0.05),均在1.62%组达到最小值;随着饲料苏氨酸水平进一步提高,上述指标不再发生显著变化(P>0.05).随饲料中苏氨酸水平的增加,草鱼血清总蛋白浓度显著升高,1.32%、1.62%和1.92%3组显著高于0.72%和1.02% (P<0.05),2.22%组达最大值,并显著高于其他各组(P<0.05);血清甘油三酯和胆固醇浓度在饲料苏氨酸水平为1.32%～2.22%的4组间没有显著差异(P>0.05),但显著高于0.72%组和1.02%组(P<0.05).饲料中苏氨酸水平为1.62%时,草鱼肌肉苏氨酸含量和肌肉氨基酸总量均为最大值,显著高于其他各组(P<0.05).饲料苏氨酸适宜水平能使草鱼全鱼水分显著降低,增加蛋白质、脂肪和灰分含量(P<0.05),同时降低草鱼肌肉水分,增加蛋白质含量(P<0.05),但不影响脂肪含量(P>0.05).饲料中苏氨酸水平对草鱼肝脏谷丙转氨酶、谷草转氨酶活力无显著影响(P>0.05).以特定生长率、饲料系数、蛋向质沉积率、肌肉RNA/DNA和谷氨酸脱氢酶活力分别对饲料苏氨酸水平进行折线同归分析,并以这些指标达95%最佳值时为判断依据,得出草鱼幼鱼饲料中苏氨酸适宜需要量以占饲料的质量分数计为1.42%～1.61%(饲料蛋白质质量分数35%)或以占饲料蛋白质的质量分数为4.07%～4.60%.     

不同配合饲料对南方鲇幼鱼体组成的影响

主要探索不同饲料组成对鱼体组成的影响.将360尾南方鲇(Silurus meridionalis Chen)幼鱼随机分成24组,饲养于24个水泥池中;共设计了21种饲料;实验持续了40 d.结果表明:(1)不同营养素水平,对鱼体中的蛋白质沉积无明显影响;肌肉中脂肪水平随着饲料中脂肪和碳水化合物(CBH)水平的增加而增加;CBH含量为33%时,肌肉中的CBH的沉积量显著高于其他几个组(P<0.05);(2)脏体比和肠脂比随着饲料中脂肪水平升高而升高,脂肪水平9%～15%,肝脏中沉积的脂肪含量随着饲料中脂肪含量的增加而增加,添加CBH含量为33%的饲料时,肝脏中糖原的沉积含量显著的高丁其他几个CBH含量的组(P<0.05).     

史氏鲟幼鲟对饲料中磷的需要量

通过生长饲养试验研究史氏鲟幼鲟对饲料中磷的需要量.以Ca(H2PO4)2·H2O为磷源,配制含磷水平分别为0.18%(对照组),0.40%,0.71%,0.98%,1.38%和1.66%的6组等能等氮纯化饲料,每组饲料饲喂3个重复,每个重复饲养20尾初体质量约为4.7 g的幼鲟.经过8周的饲养后,对生长、饲料效率、成活率、幼鲟肌肉常规组成及脊椎骨灰分和钙磷含量进行分析.结果表明,随饲料中磷含量的升高,鱼体增重率、饲料效率和特定生长率显著增加(P<0.05),直至0.98%组达最大,然后随着饲料磷含量的增加,这些指标显著降低(P<0.05);试验各添加组的成活率显著高于对照组(P<0.05),但各添加组间没有显著差异(P>0.05);饲料添加磷对鱼体肌肉水分、粗蛋白质和粗脂肪含量无显著影响(P>0.05);当饲料磷含量在0.71%～1.66%之间时,脊椎骨中灰分、钙和磷含量差异不显著(P>0.05),但显著高于对照组和0.40%试验组(P<0.05).经过折线回归分析得出,为维持史氏鲟幼鲟最佳生长和骨骼磷水平,饲料中磷的需要量为0.88%～1.00%(占干饲料).     

Evaluation of Cow Pea Seed Meal,Vigna sinensis,as a Dietary Protein Replacer for Nile tilapia,Oreochromis niloticus (L.), Fingerlings

The main objectives of this study were to evaluate the effect of partial and total replacement of fish meal (FM) protein by cow pea seed meal (CPSM) protein in practical diets on growth performance, feed utilization, and body composition of Nile tilapia, Oreochromis niloticus (L.). Fish of an average initial weight of 4.6 ± 0.2 g were stocked in 15 glass aquariums (80 L each) at a rate of 15 fish per aquarium. FM protein (30% of the diet) was used as the sole source of animal protein in the control diet. Percent replacement of FM by CPSM on the basis of crude protein were as follows: 0% (control diet A), 25% (diet B), 50% (diet C), 75% (diet D), and 100% (diet E). Diets were fed to fish at a rate of 4% of the total fish biomass daily, for a period of 16 wk. The results of this study revealed that the fish fed control diet A (100% FM) had the best average final body weight, specific growth rate (SGR %/d), weight gain (g/fish), weight gain %, while the poorest results for all parameters were obtained with fish fed diet E (100% CPSM). The same parameters of fish fed diets B (25% CPSM) and C (50% CPSM) were not significantly different (P > 0.05) from those of fish fed the control diet A. Feed utilization parameters of fish fed diets A, B, C, and D were better than for diet E. Proximate composition of whole‐body moisture and ash contents were not significantly different (P > 0.05) among all experimental diets and control diet. Whole‐body protein contents for fish fed diets B and C were superior to the control diet A. Incorporation of CPSM in the diets significantly increased whole‐body fat content. Incorporation of CPSM in the diets significantly decreased apparent digestibility coefficient of crude protein crude fat and energy. Diets B and C were not significantly different from control diet A. Therefore, these findings suggest that up to 50% of FM protein can be replaced by CPSM protein in Nile tilapia diets without any adverse effects on growth performance, feed utilization, body composition, and digestibility.     

Phosphorus requirement of European sea bass (Dicentrarchus labrax L.) juveniles

A growth trial was conducted to estimate the phosphorus requirement of European sea bass juveniles. Six experimental isonitrogenous and isoenergetic semi‐purified diets (casein based) were formulated to contain 0.48%, 0.65%, 0.77%, 0.86%, 1.05% and 1.25% phosphorus (diets D1, D2, D3, D4, D5 and D6 respectively). Dicalcium phosphate was used as dietary phosphorus source. Twelve groups of 25 fish of 10 g initial body weight were allocated to 55‐L tanks in a thermoregulated water recirculating system. Each experimental diet was assigned to duplicate groups of these fish. The trial lasted for 10 weeks and fish were fed two times a day, 6 days a week, to apparent visual satiation. At the end of the trial, final weight of fish fed diet D1 was significantly lower than that of the other groups, except of fish fed diet D4. Mortality of fish fed diet D1 was significantly higher than that of fish fed the other diets, except for diet D6. Feed efficiency and protein efficiency ratios were significantly lower with diet D1 than with the other diets. Nitrogen retention (% nitrogen intake) of fish fed diet D1 was significantly lower than in the other groups, except that of fish fed diet D4. Energy retention (% energy intake) was not significantly different among groups. At the end of the trial there were no differences in whole body composition among groups. Whole body phosphorus content averaged 0.72% (on a fresh weight basis) and was not significantly affected by dietary phosphorus content. Phosphorus retention averaged 6.1 g kg^?1 weight gain and was not significantly different among groups. Phosphorus retention (% phosphorus intake) was significantly higher in fish fed diets D2 and D3 than in fish fed higher dietary phosphorus levels. Expressed per unit body weight per day, phosphorus retention was not significantly different among groups fed diets D2 to D6, while phosphorus losses linearly increased with dietary phosphorus intake. Results of this trial indicate that the phosphorus requirement of sea bass juveniles was satisfied with a diet containing 0.65% of phosphorus.     

Fish meal replacement by Cirina butyrospermi caterpillar's meal in practical diets for Clarias gariepinus fingerlings

Fifty‐six days feeding trial was conducted to evaluate the effect of Cirina butyrospermi caterpillar meal (CBM) as protein source in replacement of fish meal (FM) for Clarias gariepinus fingerlings. Six hundred African catfish (initial mean weight = 2.42 ± 0.01 g) were fed with four approximate isonitrogenous (48.97% crude protein), isolipidic (15.85% crude lipid) and isocaloric (21.10 kJg^?1) formulated diets, in which CBM progressively replaced FM at 0 (D1), 50 (D2), 75 (D3), 100% (D4) levels. At the end of the trial period, the best growth performance and nutritional utilization were observed in the group of fish fed with D2 and was not significantly different from those fed with D1 (the control diet). The survival rates, which ranged from 85.33% to 90.33%, were not significantly different among fish from the four diet treatments. The proximate whole‐body composition of C. gariepinus fingerlings fed the different diets showed similar moisture and protein contents. However, in contrary to ash which decreased, whole‐body lipid increased significantly when fish fed with diet containing CBM inclusion superior or equal to 75% (D3 and D4). The higher gross profit was obtained with D2 (16.73$), while the lowest was observed with D4 (10.16$). This study demonstrates that 50% of fish meal can successfully be replaced with CBM in C. gariepinus fingerlings diet without a negative impact on growth or feed utilization. This will yield a cheaper feeding for profitable production of African catfish fingerlings.     

Investigations on the digestibility and metabolizability of the major nutrients and energy of maize leaves and barnyard grass in grass carp (Ctenopharyngodon idella)

In the uplands of northern Vietnam, culture of grass carp contributes significantly to income and household food security of Black Thai farmers. Maize is one of the most important upland crops and barnyard grass is the most important weed in the paddy rice fields. Thus, these are frequently used by small‐scale fish farmers as fish feed. An 8‐week feeding trial was conducted simultaneously in a recirculation and in a respirometric system to determine the digestibility and metabolizability of the nutrients of maize leaves and barnyard grass, to assess their crude protein, lipid and energy conversion and to estimate the energy allocation in grass carp. The following diets were used: diet ‘A’ (reference diet) containing 39% crude protein with 19.8 MJ kg^?1 gross energy; diets ‘B’, ‘C’ and ‘D’, which contained the same amount of the reference diet as the control diet, supplemented with a known amount of dried barnyard grass, dried maize leaves or fresh maize leaves, respectively. Five fish were assigned to each treatment in each experimental unit. Reference and test diets were fed to fish and faecal samples were collected and the oxygen consumption was measured in order to set up an energy budget of the fish over the whole experimental period. The weekly development of the body weight was recorded. The body weight gain of the fish fed diet D was significantly higher than that of the group fed diet A, which also in turn was significantly higher than that of fish fed diet B or C. The apparent digestibility coefficients (ADC) of nutrients and gross energy for the different experimental diets in fish kept in the aquaria were, for diets A, B, C and D respectively, 94.1%, 60.9%, 70.5% and 84.7% for protein, 91.3%, 60.7%, 76.8% and 71.8% for lipid; 95.9%, 44.5%, 60.6% and 69.1% for gross energy. The partial ADC of plant leaf ingredients were determined and barnyard grass and dried maize leaves were found to be not only poorly digestible but having negative impact on the digestibility of the reference diet, while fresh maize leaves were well digested. The results of the present study indicated that fresh maize leaves have a good potential to be used as supplement in diets for grass carp.     

Assessing the feasibility of using pomegranate (Punica granatum) seed oil,rich in conjugated linolenic acid,as a lipid source in the diet of common carp,Cyprinus carpio,juveniles

In this study, the feasibility of using pomegranate seed oil, rich in conjugated linolenic acid and its partial replacement for fish oil in fish diet were investigated. Common carp, Cyprinus carpio, juveniles (1.8 ± 0.1 g) were fed four isonitrogenous and isolipidic diets with similar basal composition but different oil mixture containing 100% fish oil (A), 50% fish oil +50% sunflower oil (B), 50% fish oil +25% sunflower oil +25% pomegranate seed oil (C) and 50% fish oil +50% pomegranate seed oil (D) for 8 weeks. The highest weight gain was observed in fish fed diet D (p < 0.05). Test diets had no significant effect (p > 0.05) on saturated and monounsaturated fatty acid contents of fish muscle. Docosahexaenoic acid (22:6n‐3; DHA) was significantly lower in the muscle of fish fed diet B (p < 0.05) compared to those fed diet A. However, there was no significant difference in the muscle DHA content of fish fed diets A, C, or D. No specific hepatocyte damage associated to dietary pomegranate seed oil was found in this study. This study showed a 50‐50 combination of fish oil and pomegranate seed oil could be used as dietary lipid source for common carp without any adverse effect on growth performance or muscle n‐3 content while accumulated punicic acid in the muscle could be considered as added value for the final human consumer.     

Development of a reference diet for use in indispensable amino acid requirement studies of gilthead seabream Sparus aurata L.

The development of a test diet supporting good fish growth to be used in gilthead seabream indispensable amino acid (IAA) requirement studies based on dose–response relationship was the objective of the present study. Four isonitrogenous diets, one serving as control (diet C) based on fish meal LT, and three others in which the fish meal component was reduced to 45% and the rest of the nitrogen was provided by mixtures of crystalline AA were formulated. Diet S resembled the whole body IAA profile of wild seabream. Diet D was made deficient in all IAA and a 10% excess of IAA compared with diet S was used in diet E. Triplicate groups of fish were fed the diets to satiation for 6 weeks. Growth parameters and nutrient utilization efficiencies among diets C and S were similar, while excessive supplementation of IAA negatively affected most of them, compared with the control. Whole body composition was differentiated in relation to the diet fed. No significant differences were observed among groups fed the control and diet S. As shown by the results, the presence of crystalline AA in diet S does not significantly affect growth, and could therefore serve as control diet in IAA requirement studies of gilthead seabream.     

Evaluation of solid‐state fermented protein concentrates as a fish meal replacer in the diets of juvenile rainbow trout,Oncorhynchus mykiss

We evaluated four fermented protein concentrates (FPCs) as a fish meal replacer in juvenile rainbow trout, Oncorhynchus mykiss. Ten diets were formulated to contain low‐temperature fish meal (LT‐FM), Vietnam fish meal (VT‐FM) and four types of FPCs as fish meal replacers (FPC‐A, B, C & D) at 30% and 50% FM replacement levels. FPC‐A was a mixture of solid‐state fermented soybean meal (SBM) and corn gluten meal (CGM) with Bacillus subtilis; FPC‐B was pretreated acid‐hydrolysed FPC‐A; FPC‐C and FPC‐D were FPC‐A + 2% shrimp soluble extract (SSE) and FPC‐B + 2% SSE, respectively. Triplicate groups of fish (average 15.4 g) were fed one of the experimental diets for 8 weeks. At the end of the feeding trial, fish fed the LT‐FM, FPC‐B, FPC‐C and FPC‐D diets showed significantly higher growth performance at 30% FM replacement than those of fish fed the FPC diets at 50% FM replacement. Fish fed 30FPC‐B, 30FPC‐C and 30FPC‐D diets showed higher weight gain (WG) than fish fed 30FPC‐A diet. Haematological parameters showed no clear trends among the experimental groups. Superoxide dismutase, lysozyme and myeloperoxidase activities were found to be higher in fish fed the LT‐FM, FPC‐A, FPC‐B, FPC‐C and FPC‐D diets at 30% FM replacement than in fish fed the FPC diets at 50% FM replacement. Antinutritional factors such as α‐ and β‐conglycinin, glycinin, trypsin inhibitors or zein were absent in FPC compared with SBM and CGM. Intestinal villi length and muscular thickness were significantly reduced in fish fed the VT‐FM and FPC diets at 50% FM replacement compared to fish fed the LT‐FM and FPC diets at 30% FM replacement. The results show that FPC‐B, FPC‐C, FPC‐D could replace up to 30% of LT‐FM in juvenile rainbow trout.     

Dry whey meal as a protein source in practical diets for Nile tilapia,Oreochromis niloticus fingerlings

ABSTRACT

This study was conducted as a trial of using dry whey meal (DWM) as a substitute for fish meal (FM) in practical diets for Nile tilapia, Oreochromis niloticus. Triplicate fish groups were fed on five isonitrogenous (30.2%) and isolipidic (6.9%) diets. The control diet (D1) used FM as the sole protein source. In the other four diets (D2–D5), FM protein was substituted by 25, 50, 75, or 100% DWM. Fish (3.5 ± 0.1 g) were stocked at a rate of 20 fish per 100-L aquarium and fed one of the tested diets up to satiation twice daily for 12 weeks. Fish growth, feed utilization, protein efficiency ratio, apparent protein utilization, and energy utilization for fish fed DWM diets up to 75% FM (D2–D4) tended to be higher but were not statistically different than the control diet. No significant effect of diet was found in whole-body moisture, crude protein, and total ash contents. Whole-body lipid content in fish fed the 100% DWM (D5) diet was significantly higher than that for fish fed the control diet. The optimal replacement level of FM by DWM was estimated by second-order polynomial regression to be 62.5%.     

Effect of using okara meal,a by‐product from soymilk production as a dietary protein source for Nile tilapia (Oreochromis niloticus L.) mono‐sex males

The main objectives of this study was to evaluate the effect of partial and total replacement of fishmeal protein by okara meal (OM) protein in practical diets on growth performance, feed utilization and body composition of Nile tilapia (Oreochromis niloticus L.) mono‐sex males. Fish of an average initial weight of 2.67 ± 0.01 g were stocked in 15 glass aquariums (80 L each) at a rate of 15 fish per aquarium. Fishmeal protein (18% of the diet) was used as the sole source of animal protein in the control diet. Percent replacement of fish meal (FM) by OM on the basis of crude protein was as follows: 0% (control diet A), 25% (diet B), 50% (diet C), 75% (diet D) and 100% (diet E). Diets were fed to fish at a rate of 5%, and then gradually reduced to 4% of the total fish biomass daily, for a period of 12 weeks. The results revealed that the fish fed diets A (100% FM control), B (25% OM), C (50% OM) and D (75% OM) had significantly the best average body weight, weight gain g, specific growth rate (SGR % day^?1), weight gain % and feed intake g fish^?1 compared with diet E (100% OM) which had the lowest values. There were no significant differences (P > 0.05) among all experimental diets and control in terms of feed conversion ratio (FCR), protein efficiency ratio (PER) and survival rate %. Whole body protein contents for fish fed diets B, C and D were superior to the control diet. Incorporation of OM in the diets increased significantly whole body fat content. Incorporation of OM in the diets significantly increased apparent digestibility coefficient of crude protein crude fat and energy. Therefore, these findings suggest that up to 75% of FM protein can be replaced by OM protein in Nile tilapia, mono‐sex male diets.     

China rose (Hibiscus rosasinensis) petals: a potent natural carotenoid source for goldfish (Carassius auratus L.)

Goldfish (Carassius auratus) are in demand in world markets due to their attractive golden colour. Carotenoids are the primary source of colour in the skin of fish. To optimize the colour in captivity, fish must obtain an adequate level of carotenoids in their feed. With this objective, four natural colour enhancers were tested. A common batch of feed was divided into five equal portions and colour ingredients, spirulina (D‐S), china rose petals (D‐C), marigold petals (D‐M) and Lactobacil, a commercial probiotic (D‐L), were added at 5 mg kg⁻¹ to four portions of feed; one portion (D‐O) was kept as a control without any additive. A feeding trial was conducted for 8 weeks. Each 70 L aquarium was stocked with 10 fish (average weight 1.6 g) and feed was given at 5% of the body weight. Growth rate, survival, biochemical composition and pigmentation in the skin of fish were measured. Histological studies of gonads were also conducted. Growth of fish in different treatments was significantly different. There was no difference in the proximate composition of the fish at the start of the experiment but after 8 weeks of feeding, fish fed the diet supplemented with china rose petals had a lower moisture content (70.48%) and higher protein (17.7%) and lipid (5.25%) levels than the group fed the control diet. Pigmentation was the highest (4.01 μg g⁻¹) in D‐C, followed by D‐M (3.16 μg g⁻¹), D‐S (2.92 μg g⁻¹) and D‐L (2.84 μg g⁻¹) and the lowest (0.24 μg g⁻¹) in D‐O. Gonad development of fish fed with the D‐C diet was better compared with the gonads of control (D‐O) fish, followed by D‐M‐, D‐L‐ and D‐S‐fed fish. Gonads of fish, fed D‐C, showed well‐marked changes in the testis where a large number of seminiferous tubules bound together by means of a thin layer of connective tissue were observed. These tubules were highly convoluted and were separated from each other by thin connective tissue stroma. The intra space contained connective tissue, blood capillaries and interstitial cells. The spermatogonia could be seen as a large spherical cell containing a large central nucleus with a distinct nucleolus. The study shows that the china rose (Hibiscus rosasinensis) petal is a potent natural carotenoid source for goldfish to enhance its colour and also accelerate gonadal development.