豹纹鳃棘鲈(Plectropomus leopardus)早期形态与色素变化及添加剂对其体色的影响

为研究豹纹鳃棘鲈色素变化过程以及添加剂对其产生的影响,本研究在室内工厂化养殖条件下,对豹纹鳃棘鲈的早期色素积累、转变过程进行描述,并采用螺旋藻粉和虾青素两种添加剂对其仔、稚、幼鱼的生长及体色变化的影响进行观察。结果显示,从2 d仔鱼开始,眼点色素增多,并由透明转为黑色,摄食明显;3 d仔鱼其背部鳍褶上的树枝状黑色素扩大,脊椎下方出现1列黑色素细胞丛;22 d的鱼体脊椎上方出现1排黑色素斑点,下方黑色素斑点数量减少,此时口、各鳍基部及沿脊椎两侧黄色素增加;28 d的稚鱼体表黄色素与红色素进一步增多,各鳍沿鳍条均有红色素斑点分布,鱼体呈橘红色,颜色鲜艳;30–33 d的幼鱼体表两侧布满黑色与橘红色斑点,脊椎下方斑点消失,仅在尾椎下方存有1块黑色素斑点。增色剂实验结果显示,实验15 d时,螺旋藻粉组与虾青素组全长、体重差异不显著,但均显著高于对照组(P0.05),各实验组内梯度之间差异不显著(P0.05)。30 d时,3%和6%螺旋藻粉组较对照组的体重值高,但差异不显著(P0.05),9%螺旋藻粉组显著低于对照组(P0.05);虾青素组均高于对照组,除与0.6%组差异不显著(P0.05)外,其他组均差异显著(P0.05)。0.1%实验组体重高于对照组和螺旋藻粉组,并高于组内其他梯度组。经过15 d添加虾青素的幼鱼体色红色素有明显增加,与对照组差异显著;30 d时,螺旋藻组没有达到增色效果。结果表明,螺旋藻粉对幼鱼生长初期有促进作用,随着添加浓度与养殖时间的增加其效果不明显,出现负效应;添加浓度为0.1%的虾青素可使全长、体重增长率最高并具有明显增色效果。     

虾青素和角黄素对虹鳟肌肉着色和肝脏总抗氧化能力的影响

分别在基础饲料(对照组)中添加100 mg/kg的虾青素、角黄素，混合色素(50 mg/kg虾青素+50 mg/kg角黄素)饲喂初始体重为(56.60±0.63) g的虹鳟60 d，考察虾青素和角黄素对虹鳟肌肉着色和肝脏总抗氧化能力的影响。结果显示，饲料中添加了虾青素、角黄素和混合色素后对虹鳟增重率、饲料系数及肌肉常规成分、肌肉失水率、含肉率均无显著影响(P> 0.05)。虾青素组、角黄素组和混合色素组虹鳟肌肉的比色卡得分、红度、虾青素含量和血清总类胡萝卜素含量均比对照组有显著提高(P< 0.05)；虾青素组虹鳟肌肉比色卡得分(26.25)和红度值(18.40)显著高于角黄素组(22.38, 14.13)和混合色素组(24.00, 15.70)(P< 0.05)；虾青素组虹鳟肌肉虾青素含量为4.75 mg/kg (30 d)和6.45 mg/kg (60 d)，均显著高于混合色素组的3.87 mg/kg (30 d)和5.48 mg/kg (60 d)(P< 0.05)；在虹鳟血清总类胡萝卜素含量方面，虾青素组 > 混合色素组 > 角黄素组；虾青素组、角黄素组、混合色素组虹鳟肝脏的总抗氧化能力之间无显著差异(P> 0.05)，分别为2.39 U/mg，2.25 U/mg，2.39 U/mg，均较对照组(2.03 U/mg)显著提高(P< 0.05)。上述结果表明：饲料中添加100 mg/kg虾青素、角黄素及虾青素+角黄素混合(1∶1)均能有效改善虹鳟肌肉颜色，提高肝脏总抗氧化能力，虾青素、虾青素+角黄素混合(1∶1)对虹鳟肌肉的着色效果优于角黄素。     

色素添加对咖啡金黄水母体色影响的初步研究

在人工繁殖水母的饵料中添加食用性人工合成色素、人工合成荧光色素、天然虾青素、铁元素和饲喂含有色素的海蜇等,测定水母采食饵料后感官指标、酪氨酸酶活力和总类胡萝卜素含量的变化,分析添加物质对水母生理机能的影响。试验结果显示,4种人工食用色素均能大大提升水母的观赏性,但颜色保持时间短,3 h后,所有水母均恢复原来的体色,水母状态未发现改变。水母注射水溶性荧光色素,10 h后才能通过水循环扩散到全身,荧光色维持时间可达30 d。水母饲喂天然虾青素、铁元素和含有色素的海蜇1个月后,肉眼观察,海蜇组的水母比对照组的水母颜色深,而虾青素组、FeSO_4组与对照组差异不明显。各组酪氨酸酶活力和总胡萝卜素含量均较低。组内个体间酪氨酸酶活力差异较大,但各组间差异均不显著(P0.05)。总胡萝卜素在450 nm处吸收值最高。海蜇组水母的酪氨酸酶活力和总胡萝卜素含量均最高,分别为0.133 U/mL和251.01 mg/kg。虾青素组酪氨酸酶活力最低,为0.109 U/mL。食用色素组总胡萝卜素含量最低,仅为158.83 mg/kg,酪氨酸酶活力仅高于虾青素组,可能与色素并未在表皮和中胶层形成色素沉淀有关。试验结果表明,人工添加色素能获得颜色各异的水母,水溶性荧光色素能长期保存在动物体内,可作为体色调控色素。水母的色素合成与酪氨酸酶活力和总胡萝卜素含量有关。     

虾青素对日本沼虾血细胞密度及吞噬活力的影响

从雨生红球藻粉中提取虾青素，以60mg/kg的浓度添加到日本沼虾（Macrobrachium nipponemis）的配合饵料中，在实验室条件下饲养三周，研究虾青素对日本沼虾血淋巴密度及吞噬活力（吞噬百分比和吞噬指教）的影响。结果显示添加虾青素组的日本沼虾不论是血细胞密度还是吞噬活力都显著高于对照组，表明虾膏素可显著提高日本沼虾的免疫力。     

饲料中添加红辣椒粉对红草金鱼体色及生长的影响

对红草金鱼分别投喂红辣椒粉添加量为0、7%、10%、13%、16%和19%的人工配合饲料,每隔15d测定一次皮肤和鳍条的色素吸光度,并同时进行体长及体重的测量.实验时间45d e,结果表明,红辣椒粉具有增强红草金鱼色素沉积和促进生长的作用;添加量为13%时,鱼的鳍条和皮肤的吸光度最大,与对照组差异显著(P<0.05);红辣椒粉添加量为7%时,鱼的体长增加值最大,添加量为10%时,其体重的增加最大;3次测定同一添加水平组之间增色差异不显著.     

饲料中茶树油与虾青素对克氏原螯虾生长性能、抗氧化能力及免疫相关基因表达的影响

为探究饲料中茶树油与虾青素对克氏原螯虾(Procambarus clarkii)生长性能、抗氧化能力及免疫相关基因表达的影响, 设计了 6 组等氮等能饲料, 分别为基础饲料组(CT)、50 mg/kg 虾青素组(AS50)、50 mg/kg 虾青素与 50 mg/kg 茶树油组(AS50+AST50)、50 mg/kg 虾青素与 100 mg/kg 茶树油组(AS50+AST100)、50 mg/kg 虾青素与 200 mg/kg 茶树油组(AS50+AST200)、50 mg/kg 虾青素与 400 mg/kg 茶树油组(AS50+AST400), 进行了 8 周的养殖实验。添加了虾青素后, AS50 组与 CT 组相比, 饵料系数显著降低(P＜0.05), 末均重、增重率、特定生长率虽有提高但差异不显著(P＞0.05), 血淋巴及肠道中总抗氧化能力(T-AOC)显著提高(P＜0.05), 肠道丙二醛(MDA)含量显著降低(P＜0.05), Crustin、Astacidin、CuZnSOD 以及 HSP70 基因表达显著升高(P＜0.05)。添加了虾青素与茶树油后, AS50+AST100 组末均重, 增重率, 特定生长率, 总抗氧化能力(T-AOC)均显著高于 AS50 和 CT 组(P＜0.05), 肠道丙二醛含量显著低于 AS50 组和 CT 组(P＜0.05)。肠道组织 Crustin 与 Astacidin 基因随茶树油含量提高, 其表达量呈升高趋势, AS50+ AST50 组显著低于其余各组(P＜0.05), CuZnSOD 表达量随茶树油浓度提高呈先升高后降低趋势, AS50+AST50 以及 AS50+AST100 显著高于其余各组(P＜0.05)。HSP70 表达量随茶树油含量的提高与对照 CT 组差异显著(P＜0.05)。 研究结果显示, 饲料中存在 50 mg/kg 虾青素条件下, 添加 100 mg/kg 茶树油可以提高克氏原螯虾抗氧化能力与免疫能力, 促进生长。     

不同LED光谱对红鳍东方鲀幼鱼生长、摄食及消化酶活性的影响

为探究不同 LED 光谱对红鳍东方鲀(Takifugu rubripes)幼鱼摄食、生长发育和生理活性的影响, 选取 525 尾红鳍东方鲀幼鱼养殖在海水循环水养殖系统中, 分别用 5 种不同 LED 光谱(红、黄、蓝、绿、白)照射处理 30 d, 光周期为 12 L : 12 D, 实验期间测定饵料转化效率, 实验结束时测定其存活、生长指标及消化酶活性。结果表明, 不同 LED 光谱对红鳍东方鲀幼鱼的存活、生长和摄食的影响具有显著性差异(P＜0.05)。其中绿光组红鳍东方鲀的存活率最高, 为(65.71±0.00)%; 绿光组红鳍东方鲀幼鱼体重最大, 为(29.36±3.78) g。在饵料转化效率方面, 绿光组幼鱼的饵料转换效率显著高于其他各组(P＜0.05)。在消化酶活性方面, 不同 LED 光谱处理组中红鳍东方鲀幼鱼的消化酶活性均存在显著性差异(P＜0.05), 其中绿光组的酸性磷酸酶、碱性磷酸酶、己糖激酶、丙酮酸激酶活性均显著高于其他各处理组(P＜0.05); 绿光组肝脂肪酶活性较高, 显著高于蓝光与黄光组(P＜0.05); 绿光组肠脂肪酶活性显著高于红光、白光组(P＜0.05)。综上所述, 绿光对红鳍东方鲀幼鱼的生长发育具有较好的促进作用。     

虾青素对红小丑鱼消化酶活性的影响

本实验以初始体质量为(4.88±0.90)g、体长为(4.85±0.32)cm的红小丑鱼(Amphiprion frenatus)为养殖对象,研究饲料中添加0(对照组)、2‰、4‰、6‰、8‰的虾青素对红小丑鱼消化酶活性的影响。本试验每组3个重复,每个重复6尾鱼,饱食投喂2次/d(投喂时间为08∶30和14∶30),试验周期为20 d。结果表明:添加虾青素组的红小丑鱼胃肠消化酶活性均高于未添加虾青素组,当虾青素添加量为4‰时,红小丑鱼前肠蛋白酶、脂肪酶、淀粉酶以及后肠淀粉酶活性达到最高(P0.05);当添加量为6‰时,其胃脂肪酶和淀粉酶活性最高(P0.05);当添加量为8‰时,其胃和后肠的蛋白酶以及后肠脂肪酶的活性达到最高(P0.05)。因此,在饲料中添加4‰~8‰的虾青素能够较有效地提高红小丑鱼消化器官的消化酶活性。     

富含虾青素的法夫酵母对金鱼体色的影响

在饵料中添加60mg/g富含虾青素的法夫酵母(Phaffiarhodozyma)喂养中国金鱼(Carassiusauratus)(体重约5 5g),60d的实验结果表明,实验组的鱼头、鱼鳞、鱼肉、鱼尾各部位单位质量色素含量比对照组分别提高了22.6%、45.5%、31.0%和21.2%,差异均极显著(P<0.01)。通过HPLC初步分析了金鱼色素组成,结果表明虾青素在中国金鱼体内以酯化形式沉积。     

投喂虾青素对哲罗鲑虾青素含量和抗氧化力的影响

水温12～18℃,将体质量(435.63±21.32) g的哲罗鲑饲养在6.0 m×2.5 m×1.2 m的流水水泥池中,投喂含100 mg/kg人工合成虾青素(对照组)和10、20、40、60 mg/kg天然虾青素(雨生红球藻)饲料,每两周检测试验鱼肌肉中的虾青素含量和鳃、肝脏、前肠、后肠、幽门垂、肌肉、血清、血细胞的总抗氧化能力和碱性磷酸酶活性,研究人工合成虾青素和天然虾青素对肌肉中虾青素含量及其组织抗氧化力的影响。70 d的饲养结果显示:(1)与对照组相比,20 mg/kg和40 mg/kg组的试验鱼虾青素含量显著升高(P0.05),且40 mg/kg含量组试验鱼虾青素含量显著优于20 mg/kg组(P0.05);(2)各组试验鱼鳃、肝脏、前肠、后肠、幽门垂、血清、血细胞的总抗氧化能力显著高于对照组(P0.05);(3)各组试验鱼鳃、后肠、幽门垂、肌肉、血清、血细胞的碱性磷酸酶活性显著高于对照组(P0.05)。试验结果表明,与添加100 mg/kg人工合成虾青素相比,饲料中添加20～40 mg/kg天然虾青素,能显著提高哲罗鲑肌肉虾青素含量、总抗氧化能力以及碱性磷酸酶活性,建议哲罗鲑饲料中天然虾青素添加量为40 mg/kg。     

水温对东星斑幼鱼存活、摄食及生长的影响

在实验室条件下,初步研究了水温对东星斑幼鱼摄食、生长及存活的影响。温度设5个水平(15、20、25、30、35℃),东星斑幼鱼在玻璃蓄养槽内养殖40d。结果显示20℃组、25℃组和30℃组的鱼没有死亡,35℃组的存活率为88.9%,15℃组的存活率仅为50%;总摄食量在30℃组最高,15℃组最低;特定生长率在30℃组最高,15℃组、35℃组为负值;在可以生长的组别里,30℃组饵料系数最小。本研究表明,水温对东星斑幼鱼生长发育的影响明显,东星斑的适宜摄食温度为20～30℃,最佳摄食温度为25～30℃;水温<20℃东星斑幼鱼不能正常摄食、生长,甚至会死亡,水温15℃时,几乎不摄食;水温>30℃,东星斑幼鱼可以正常摄食,但是不能正常生长,甚至会死亡。     

豹纹鳃棘鲈消化道粘液细胞的类型与分布

应用AB-PAS染色法对工厂化养殖条件下豹纹鳃棘鲈(Plectropomus leopardus)消化道粘液细胞的类型与分布进行了观察研究。结果显示:豹纹鳃棘鲈粘液细胞在消化道各部位均有分布,不同部位的粘液细胞密度和类型均有差异,豹纹鳃棘鲈消化道粘液细胞可分为Ⅰ型、Ⅱ型、Ⅲ型、Ⅳ型。其中,食道粘液细胞以Ⅲ型为主,胃以Ⅰ型为主,幽门盲囊和肠以Ⅲ型为主,直肠以Ⅲ型和Ⅳ型为主;胃部粘液细胞分布密度最大,达(111.37±21.74)cell·mm~(-2),极显著高于消化道其它部分,直肠、幽门盲囊、肠的粘液细胞分布密度分别为(35.09±8.74)、(30.23±5.37)、(28.00±4.67)cell·mm~(-2),相互之间差异不显著,食道的粘液细胞分布密度最低,为(10.83±1.94)cell·mm~(-2),与消化道其它部分相比差异极显著。另外,消化道各段单位面积内粘液细胞的分泌能力顺序为食道直肠肠幽门盲囊胃。通过对消化道各部位粘液细胞的分类对比可以发现,粘液细胞的类型和分布与其所在部位的功能有密切关系。     

环境光色对工业化养殖豹纹鳃棘鲈幼鱼生长、肤色及生理指标的影响

为探究环境光色对工业化养殖豹纹鳃棘鲈(Plectropomus leopardus)幼鱼生长、肤色和生理指标的影响,本试验设计了红色光、蓝色光、黑暗和昼夜4种养殖光照环境处理,进行豹纹鳃棘鲈幼鱼(64.2g±1.1g)94 d动物实验及其相关指标检测。结果表明:1)试验鱼增重率,昼夜组较黑暗组和红光组分别显著和极显著提高28.6%和39.2%(P0.05,P0.01),与蓝光组差异不显著;而蓝光组比红光组显著提高31.2%(P0.05)。2)试验鱼皮肤胡萝卜素含量,昼夜组分别显著高于蓝光组和黑暗组45.7%和68.5%(P0.05),与红光组的差异不显著。同时新发现,各处理组试验鱼皮肤胡萝卜素和黑色素含量出现增减同时进行,但增减量前者较大后者较小的"同步异幅"现象。3)昼夜组试验鱼胃蛋白酶活性较其他组显著提高48.0%~88.5%(P0.05),血清SOD和LZM活力极显著提高20.4%~39.7%和140.4%~161.2%(P0.01);蓝光组试验鱼胰蛋白酶活力显著高于红光组和昼夜组(P0.05);红光组试验鱼Na~+,K~+-ATP酶活力极显著高于蓝光组和黑暗组(P0.01)。总之,豹纹鳃棘鲈幼鱼在昼夜组光照下,生长、肤色及生理等指标都表现出显著优势;蓝色光提高蛋白质消化能力、促进生长;红色光提高皮肤胡萝卜素含量和吸收能力;"同步异幅"新发现,对调控和优化鱼类肤色具有重要价值。     

豹纹鳃棘鲈室外大型水泥池的人工育苗技术

为了探索利用室外大型水泥池进行豹纹鳃棘鲈(Plectropomus leopardus)人工育苗的技术模式,通过在室外大型水泥池顶部加盖遮光太阳板半封闭顶棚,对育苗水体进行控光、控温和防雨,进行该鱼人工育苗过程中水处理技术、饵料培育技术和育苗方法的研究。2010年3～7月,累计放卵5批次,共培育出全长2.5～3.0 cm的鱼苗21.9×104ind,受精卵平均孵化率达81.4%,育苗平均成活率达5.59%;初孵仔鱼平均全长1.6mm,在早期发育阶段每经历一次饵料转变,都会带来仔稚幼鱼的快速增长;该鱼摄食时间主要集中在白天,随着个体生长发育,饵料出现顺序依次为原生动物、轮虫、桡足类、蒙古裸腹蚤。研究表明,豹纹鳃棘鲈室外大型水泥池人工育苗模式克服了池塘育苗受自然环境影响大和室内水泥池育苗水体小、开口饵料匮乏的缺点,育苗成功率和出苗率比较稳定。     

Effects of thyroxine and thiourea on the metamorphosis of coral trout grouper Plectropomus leopardus

The contribution of the thyroid hormone to the metamorphosis of the coral trout Plectropomus leopardus was examined. Juveniles, aged 35 days, were exposed to thyroxine (T4, 0.1 p.p.m) and thiourea (TU; inhibitor of thyroid hormone synthesis, 30 p.p.m) for 13 days. All the fish in the T4-treated group had completed metamorphosis (second metamorphosis, pigmentation and resorption of fin spines) within three days after the beginning of the experiment (day 3), whereas it took 13 days for this to occur in the control fish. Moreover, the fish in the TU group had not completed metamorphosis even by day 13. Settling behavior was significantly stimulated by T4 treatment, as was the resorption of the dorsal and pelvic fin spines, the reduction of serration on the spines, and the transition of body color into an opaque reddish hue. Fish in the TU group had longer dorsal and pelvic spines, retarded pigmentation and an abnormal black coloration. These results suggest that thyroid hormone accelerates most changes during the second metamorphosis in the coral trout.     

Effect of Astaxanthin on the Pigmentation of Goldfish Carassius auratus

The optimal dosage of astaxanthin for goldfish Carassius auratus was determined by feeding a series of diets containing 0, 25, 50, 75, and 100 mg of astaxanthin/kg of diet for 4 wk. The pigmentation on fish skin was measured by visual assessment against a color chart and by counting chromatophores produced in the dermis layer of fish skin. Both criteria showed that 36–37 mg/kg astaxanthin was the optimal dosage to stimulate fish color. A 4-wk observation after this experiment demonstrated that fish color stimulated by dietary astaxanthin was stable in its intensity. Therefore feeding astaxanthin could be a suitable way for goldfish producers to stimulate color among fish grown in an algae-free environment. The survival rate of fish fed diets with astaxanthin was significantly higher than fish fed diets without astaxanthin. However, there was no significant effect of astaxanthin on fish weight gain.     

Effect of dietary bile extracts on serum response of astaxanthin in rainbow trout (Oncorhynchus mykiss): a preliminary study

Effects of porcine bile extracts added at three different dietary concentrations 0, 10 and 20 g kg^?1 were studied on astaxanthin serum concentration in rainbow trout (mean weight 200 ± 7 g). Astaxanthin from micro‐algae Haematococcus pluvialis and synthetic astaxanthin (CAROPHYLL® pink) were incorporated in diets of rainbow trout at a rate of 100 mg astaxanthin kg^?1 of feed. Fish were hand fed twice a day. After 5 days of feeding there was a significant effect of the pigment source on the ratio (total blood astaxanthin per unit body weight to cumulative astaxanthin intake per unit body weight). Trout receiving synthetic astaxanthin showed a significantly (P < 0.05) higher ratio than trout fed algal astaxanthin. Increasing dietary bile extract did not lead to produce any effect on this ratio. The power of the statistical analysis is discussed. Therefore, the interaction (pigment source × dietary bile concentration) showed no more effect.     

Dorsal aorta cannulation: a method to monitor changes in blood levels of astaxanthin in voluntarily feeding Atlantic salmon, Salmo salar L.

This study was undertaken to assess dorsal aorta cannulation as a method to evaluate alterations in diet composition and feeding protocol on pigment retention in salmonid fish. Temporal changes in blood astaxanthin concentrations of dorsal aortacannulated Atlantic salmon, Salmo salar L., were followed in relation to variations in dietary pigment concentration and fish-feeding husbandry protocol. The fish were held individually in 200-L fibreglass tanks supplied with running sea water. Each fish was forced to swim at 0.5 body lengths s^?1 and was fed daily by hand to satiation. The fish had an average growth rate of 1% day^?1. Blood astaxanthin concentrations were noted to be highly correlated (r= 0.995) with dietary levels of astaxanthin, but not as well correlated (r= 0.71) with total gut content of this pigment. Marked variations in blood astaxanthin concentration were noted between individual fish at each dietary pigment concentration, but the ranking of the fish was generally unaffected between each dietary pigment level. After cessation of feeding a diet supplemented with 75 mg of astaxanthin kg^?1, salmon fed a diet with no pigment showed more-rapid blood pigment clearance than those that were starved. Likely, feed remaining in the alimentary tract of the starved fish functioned as a reservoir of pigment for the blood until the intestinal tract was empty. Blood pigment levels were not depressed in salmon fed a diet supplemented with 75 mg of astaxanthin kg^?1 once daily instead of twice daily.     

Effect of Astaxanthin from Xanthophyllomyces dendrorhous on the Pigmentation of Goldfish, Carassius auratus

Two experiments were conducted to evaluate the addition of astaxanthin from red yeast, Xanthophyllomyces dendrorhous, in the diets of goldfish, Carassius auratus. The first was designed to investigate the distribution of pigments in different tissues of goldfish and the effect of astaxanthin in the diet. The carotenoid concentration of tissues was not homogenous. The content of pigments in fish caudal fin was the highest followed by those of scales and head. Flesh had the least carotenoid deposition. Fish fed the diet containing 60 mg/kg astaxanthin had increased concentration of pigment in its head (22.6%), scales (45.5%), flesh (31.0%), and fin (21.2%), compared to fish fed basal diet (P < 0.05). Sixty parts per million astaxanthin had no effect on the weight gain and survival rate. High‐performance liquid chromatography analysis showed astaxanthin in its esterified form in goldfish. The second experiment was aimed at determining the dietary level of astaxanthin that improved color of goldfish. Goldfish were fed the same diet supplemented with 0, 10, 20, 40, 60, and 80 mg yeast astaxanthin/kg for 60 d. The deposition of carotenoids in goldfish fed diets supplemented with astaxanthin increased significantly (P < 0.05) after 15 d of feeding compared to that of the fish fed the diet without astaxanthin, but the effect of dosage of astaxanthin in the diets on the color of goldfish was not completely evident until Day 60 (P < 0.05). During the period of 15–45 d, the deposition of pigments in fish did not increase significantly (P > 0.05) in any treatment with the exception of the diet with 40 mg yeast astaxanthin/kg.     

Effect of alternate distribution of astaxanthin on rainbow trout (Oncorhynchus mykiss) muscle pigmentation

The aim of the present study was to determine the effects of the use of astaxanthin alternate feeding on rainbow trout pigmentation in term of astaxanthin serum concentration, muscle colour and astaxanthin muscle retention. Four hundred and fifty rainbow trout were fed the same basal diet supplemented with two different astaxanthin levels, 100, and 200 mg astaxanthin kg^? 1 of diet, hereafter designated as AX100 and AX200, respectively. An additional astaxanthin-free (AX0) diet was used. The experimental treatments were as follows: (1) REF = AX100 diet at each meal each day, served as reference; (2) SD1 = AX100 diet at each meal the first day followed by AX0 diet at each meal every second day; (3) SD2 = AX100 diet and AX0 diet in alternate meals each day; (4) R2 = AX200 diet and AX0 diet in alternate meals each day; (5) R4 = AX200 diet at the first meal the first day followed by AX0 diet at the second meal the first day and at each meal every second day. Fish were fed the experimental feeding schedule for 42 days.At the end of the experiment there were no significant differences among fish fed the different feeding schedules in term of final mean weight, specific growth rate and feed efficiency ratio. SD2 fish group displayed the highest (P < 0.05) astaxanthin serum concentration and the R4 fish group the lowest one. REF and R2 fish groups showed similar astaxanthin serum concentrations. Muscle chroma showed the most pronounced effect. It increased significantly for all fish groups during the experiment. At the end of the experiment REF and R2 fish groups displayed higher values than SD1 and R4 fish groups. Muscle astaxanthin concentrations increased significantly during the experiment whatever the astaxanthin feeding schedule. At the end of the experiment, the highest muscle astaxanthin concentration was recorded for R2 fish group while the lowest was noted for R4 fish group. Except for SD1 and R4 fish groups, muscle astaxanthin retention decreased significantly during the experiment. At the end of the experiment, muscle astaxanthin retention coefficients for SD2 fish group were significantly higher than those for REF fish group. The results reported here provide further evidence of the potential applicability of alternate astaxanthin feeding on rainbow trout pigmentation. Extending the optimisation of the SD2 treatment will therefore be subject for future studies. Its application could result in cost saving in the fish farming industry.