循环流水槽养殖草鱼与池塘精养草鱼营养品质比较

为了解循环流水槽养殖草鱼与池塘精养草鱼营养品质的差异,选取相同饲料源的循环流水槽养殖草鱼[平均体重:(723.89±71.54)g,平均体长:(340.86±8.88)mm]和池塘精养草鱼[平均体重:(680.35±155.13)g,平均体长:(334.00±21.40)mm]各12尾,测定形态指标与肌肉剪切力、质构特性、色泽以及常规营养成分、氨基酸、脂肪酸和矿物元素含量。结果显示:1)循环流水槽养殖草鱼的硬度、黏性、咀嚼性、回复性和剪切力均显著高于池塘精养草鱼(P<0.05)。2)循环流水槽养殖草鱼的肌肉水分含量显著低于池塘精养草鱼(P<0.05),肌肉粗脂肪含量低于池塘精养草鱼,但差异不显著(P>0.05),肌肉粗蛋白质和粗灰分含量均高于池塘精养草鱼,但差异不显著(P>0.05)。3)循环流水槽养殖草鱼的肌肉氨基酸总量(TAA)、必需氨基酸总量(TEAA)和呈味氨基酸总量(TDAA)高于池塘精养草鱼,但差异不显著(P>0.05)。循环流水槽养殖草鱼和池塘精养草鱼肌肉中TAA分别为77.11%和76.61%,TEAA和TDAA分别占TAA的40.87%和40.43%、46.10%和46.06%。4)循环流水槽养殖草鱼肌肉中不饱和脂肪酸(UFA)占脂肪酸总量的百分比(69.68%)高于池塘精养草鱼(68.44%),但差异不显著(P>0.05)。循环流水槽养殖草鱼和池塘精养草鱼肌肉中饱和脂肪酸(SFA)占脂肪酸总量的百分比分别为21.78%和18.58%,两者差异显著(P<0.05)。循环流水槽养殖草鱼肌肉中未检测到二十碳五烯酸(EPA),二十二碳六烯酸(DHA)含量为0.44%;池塘精养草鱼肌肉中EPA含量为0.10%,DHA含量为0.55%。5)循环流水槽养殖草鱼肌肉中钾、镁、铁、铜含量显著高于池塘精养草鱼(P<0.05),钠、锌显著低于池塘精养草鱼(P<0.05)。由此得出,循环流水槽养殖草鱼的营养品质总体上优于池塘精养草鱼。     

七彩山鸡的蛋品质与营养组成分析

为了对比七彩山鸡与罗曼鸡的蛋品质与营养成分差异,本试验收集了产蛋高峰期的七彩山鸡蛋与罗曼鸡蛋各30枚,进行蛋品质指标测定与氨基酸、脂肪酸等营养组成分析。结果显示:七彩山鸡蛋的蛋壳厚度、强度、蛋重、色泽、哈氏单位和蛋黄重等指标显著低于罗曼鸡蛋(P<0.05),而蛋黄比率显著高于罗曼鸡蛋(P<0.05),两者蛋形指数无显著差异(P>0.05);七彩山鸡蛋的脂肪含量显著低于罗曼鸡蛋(P<0.05),蛋白质含量两者无显著差异(P≥0.05);七彩山鸡蛋的总氨基酸(TAA)和必需氨基酸(EAA)含量均显著低于罗曼鸡蛋(P<0.05),芳香类氨基酸酪氨酸含量高于罗曼鸡蛋(P<0.05),天冬氨酸和谷氨酸等鲜味氨基酸含量均低于罗曼鸡蛋(P<0.05);在脂肪酸组成方面,七彩山鸡蛋的硬油酸、油酸和亚油酸含量显著低于罗曼鸡蛋(P<0.05),且棕榈酸和棕榈油酸含量更高(P>0.05)。综上所述,七彩山鸡蛋的蛋黄含量高,脂肪含量低,营养成分有自身特点,适合作为特色禽蛋开发。     

杜仲皮水提物对虹鳟生长和肌肉品质、质构特性的影响

本试验旨在研究杜仲皮水提物对虹鳟(Oncorhynchus mykiss)生长和肌肉品质、质构特性的影响。选取体质健康、平均体重(145.56±4.12) g的虹鳟450尾,随机分为5个组,每组3个重复,每个重复30尾。各组分别在基础饲料中添加浓度为0(对照组)、0.5%、1.0%、2.0%和4.0%的杜仲皮水提物。试验期为10周。结果表明:1)各组之间终末体重、增重率、成活率、特定生长率均无显著差异(P>0.05)。2)各组间肌肉pH45 min、pH24 h均无显著差异(P>0.05)。对照组肌肉pH下降率最高,且显著高于2.0%和4.0%组(P<0.05),0.5%和1.0%组显著高于4.0%组(P<0.05)。3)各组间肌肉离心失水率、冷冻渗出率均无显著差异(P>0.05),1.0%组肌肉滴水损失显著高于其他各组(P<0.05)。4) 4.0%组肌肉弹力和弹性显著高于对照组(P<0.05),4.0%组肌肉胶着性和咀嚼性显著高于1.0%组(P<0.05),4.0%组肌肉内聚性显著高于1.0%、2.0%和对照组(P<0.05)。5) 1.0%和4.0%组肌肉肌纤维直径显著低于对照组(P<0.05)。肌肉肌纤维密度随着杜仲皮水提物浓度的增加而增大,0.5%、1.0%、2.0%和4.0%组之间肌纤维密度无显著差异(P>0.05),但均显著高于对照组(P<0.05)。综合以上各项指标,建议饲料中添加浓度为4.0%杜仲皮水提物以改善虹鳟肌肉品质。     

儿茶素对草鱼生长性能、血清抗氧化指标和肌肉品质的影响

本试验旨在研究儿茶素对草鱼生长性能、血清抗氧化指标和肌肉品质的影响。试验选取平均体质量为(18.5±0.2)g的草鱼360尾,随机分为6组,分别饲喂在基础饲料中添加0(对照组)、0.1、0.3、0.5、0.7和0.9 g/kg儿茶素的6种饲料,每组3个重复,每个重复20尾。试验期60 d。结果表明:1)随着儿茶素的添加,各组间鱼体增重率和饲料系数无显著差异(P>0.05),添加0.5、0.7和0.9 g/kg儿茶素显著提高了鱼体肥满度(P<0.05),显著降低了血清丙二醛含量(P<0.05)。除0.1 g/kg组外,其余各儿茶素添加组血清超氧化物歧化酶活性均显著高于对照组(P<0.05),各组间在血清碱性磷酸酶和过氧化氢脱氢酶活性上无显著差异(P>0.05)。2)在肌肉游离氨基酸和脂肪酸组成方面,0.5、0.7 g/kg组的总氨基酸、呈味氨基酸含量和C20∶5、n⁃3不饱和脂肪酸含量显著高于对照组(P<0.05)。3)各组间在肌肉水分、粗蛋白质、粗脂肪、粗灰分含量及肌肉质构特性、肌肉失水率以及肌纤维密度和直径上差异均不显著(P>0.05),但0.7和0.9 g/kg组的肌肉胶原蛋白含量显著高于对照组(P<0.05)。上述结果显示,儿茶素对草鱼生长性能没有显著影响,可提高血清抗氧化能力,在一定程度上改善肌肉品质。草鱼饲料中儿茶素的推荐添加量为0.5~0.7 g/kg。     

饥饿胁迫对淡水石首鱼形体指标、肌肉脂肪酸组成及肝脏脂肪代谢基因表达的影响

本试验旨在研究饥饿胁迫对淡水石首鱼形体指标、肌肉脂肪酸组成及肝脏脂肪代谢基因表达的影响。选用淡水石首鱼(Aplodinotus grunniens)180尾,平均体重为(20.88±0.91)g,设置3个重复,每个重复60尾,分别在饥饿0、1、4、8、12、24、36、48 h及3、4、6、10、14、21、28、42 d时采集样本,每个重复随机采集3尾,每个饥饿时间点共采集9尾,分析形体指标、肌肉脂肪酸组成及肝脏脂肪代谢基因表达。结果显示:1)部分饥饿时间显著降低肥满度(CF)、脏体比(VSI)、肝体比(HSI)、腹脂比(IPF)(P<0.05)。2)肌肉饱和脂肪酸(SFA)含量在饥饿前后无显著差异(P>0.05),饥饿14 d后单不饱和脂肪酸(MUFA)含量显著下降(P<0.05),多不饱和脂肪酸(PUFA)含量显著上升(P<0.05)。3)饥饿14、42 d,肝脏中过氧化物酶体增殖物激活受体α(PPARα)、肉碱棕榈酰转移酶1A(CPT1A)基因相对表达量显著高于饥饿0和24 h(P<0.05),脂肪酸合成酶(FAS)基因相对表达量显著低于饥饿0和24 h(P<0.05);饥饿24 h及14、42 d,酰基辅酶A氧化酶(ACO)相对表达量无显著变化(P>0.05),但显著高于饥饿0 h(P<0.05)。研究表明,饥饿胁迫降低了淡水石首鱼的CF、HSI、IPF、VSI,影响了肌肉不同类型脂肪酸的组成,促进了脂肪分解代谢而抑制了脂肪合成代谢。     

5种光色环境对欧洲舌齿鲈营养品质的影响

为了解不同光色(全光谱光、蓝光、绿光、黄光、红光)环境对欧洲舌齿鲈(Dicentrarchus labrax)营养品质的影响,对欧洲舌齿鲈幼鱼[体质量为(29. 91±0. 39) g、体长为(13. 78±0.35) cm)]在不同光色环境下进行为期50 d的养殖试验。试验设全光谱光组、蓝色组、绿色组、黄色组、红色组,每组设置4个重复,每个重复30尾欧洲舌齿鲈幼鱼。采用国家标准方法对各组欧洲舌齿鲈全鱼和肌肉常规营养成分含量以及肌肉氨基酸与脂肪酸组成进行测定,并对肌肉营养品质进行分析。结果表明:1)绿光组全鱼及肌肉的粗脂肪含量均显著高于其他4组(P<0.05),但各组全鱼及肌肉水分、粗蛋白质、粗灰分含量均差异不显著(P>0.05)。2) 5种光色环境下欧洲舌齿鲈肌肉中均检测到18种氨基酸,其中绿光组7种氨基酸(天冬氨酸、谷氨酸、甘氨酸、丙氨酸、苯丙氨酸、酪氨酸、精氨酸)以及总氨基酸、必需氨基酸及非必需氨基酸的含量均显著高于全光谱光组、黄光组和红光组(P<0.05),而略高于蓝光组(P>0.05)。3)根据氨基酸评分(AAS)和化学评分(CS),欧洲舌齿鲈肌肉中含有丰富的赖氨酸,欧洲舌齿鲈必需氨基酸指数(EAAI)由高至低依次为绿光组、蓝光组、全光谱光组、黄光组、红光组。4) 5种光色环境下欧洲舌齿鲈肌肉脂肪酸组成类似,均检测出16种脂肪酸,其中绿光组欧洲舌齿鲈肌肉中饱和脂肪酸(SFA)、多不饱和脂肪酸(PUFA)的含量均显著高于黄光组和红光组(P<0.05),而单不饱和脂肪酸(MUFA)的含量在各组间均差异不显著(P> 0. 05);肌肉中C22∶6n-3(DHA)、C20∶5n-3(EPA)以及EPA+DHA含量均以绿光组最高,黄光组最低。由此可见,不同光色环境对欧洲舌齿鲈营养组成及比例产生了一定的影响,相对而言,绿光环境更适合欧洲舌齿鲈的养殖。     

池塘内循环流水养殖模式对黄颡鱼生长性能、形体指标、血清生化指标及肌肉营养成分的影响

为了综合评价池塘内循环流水养殖(IPA)模式在黄颡鱼养殖中的应用效果,选取IPA模式、常规池塘养殖(UPA)模式和野生环境(WE)下的黄颡鱼各50尾为研究对象,在养殖322 d后对其生长性能、形体指标、血清生化指标及肌肉营养成分差异进行比较。结果显示:1) IPA组黄颡鱼的成活率显著高于UPA组(P<0.05),但增重率和特定生长率略低于UPA组(P>0.05)。2) IPA组和WE组黄颡鱼的肥满度、肝体指数和脏体指数显著低于UPA组(P <0.05); IPA组的肥满度显著高于WE组(P<0.05),而肝体指数和脏体指数2组间差异不显著(P>0.05)。3) IPA组和UPA组血清中总蛋白含量显著低于WE组(P<0.05); IPA组血清中总胆红素、碱性磷酸酶、总胆汁酸和总胆固醇含量显著低于UPA组(P<0.05); IPA组血清中γ-谷氨酰基转移酶和谷草转氨酶活性显著高于WE组(P<0.05); IPA组血清中肌酐、葡萄糖含量显著低于UPA组(P<0.05)。4) IPA组和WE组肌肉中粗脂肪含量显著低于UPA组(P<0.05),但粗蛋白质含量显著高于UPA组(P<0.05); IPA组肌肉中氨基酸总量显著高于UPA组(P<0.05),而显著低于WE组(P<0.05); IPA组必需氨基酸和鲜味氨基酸总量显著高于UPA组(P <0.05); 3组黄颡鱼肌肉中第一限制性氨基酸均为苯丙氨酸+酪氨酸,且IPA组和WE组的必需氨基酸指数显著高于UPA组(P<0.05); IPA组和WE组黄颡鱼肌肉中n-3多不饱和脂肪酸(PUFA)和二十碳五烯酸(EPA)+二十二碳六烯酸(DHA)含量显著高于UPA组(P<0.05),且饱和脂肪酸总量显著低于UPA组(P<0.05)。由此得出,IPA组黄颡鱼具有较高的成活率,较好的体形,其肌肉营养品质优于UPA组黄颡鱼,且健康状况也优于UPA组黄颡鱼,但仍差于WE组黄颡鱼。因此,应进一步优化IPA的环境条件(如流速因子、养殖密度等)以及人工配合饲料配方以迎合消费者对于黄颡鱼营养和味道的需求。     

饲料中维生素K3含量对大口黑鲈消化能力、血清代谢指标、肌肉氨基酸和脂肪酸组成的影响

为研究饲料中维生素K₃含量对大口黑鲈消化能力、血清代谢指标、肌肉氨基酸和脂肪酸组成的影响,在基础饲料中分别添加不同水平的维生素K₃,配制成维生素K₃含量分别为0.78(K0组)、5.80(K5组)、10.82(K10组)、15.84(K15组)和20.85 mg/kg(K20组)的5种试验饲料,对初均重为(12.96±0.07)g健康大口黑鲈幼鱼进行为期8周的饲养试验。结果表明:添加维生素K₃的各组胃和肠道的蛋白酶、淀粉酶和脂肪酶活性均显著低于K0组(P<0.05)。K10组、K15组和K20组的表观消化率和蛋白质表观消化率显著低于K0组(P<0.05)。K20组的血清尿素氮含量显著高于其他4组(P<0.05),血清总蛋白、白蛋白、总胆固醇和甘油三酯含量在各组之间无显著差异(P>0.05)。肌肉必需氨基酸、非必需氨基酸和总氨基酸含量以及必需氨基酸指数在各组之间无显著差异(P>0.05),但是随着饲料中维生素K₃含量的增加,必需氨基酸和总氨基酸含量呈增加的趋势。K15组的肌肉单不饱和脂肪酸含量显著高于其他4组(P<0.05),其中C16∶1n7和C18∶1n5含量均较其他组显著升高(P<0.05)。肌肉饱和脂肪酸和多不饱和脂肪酸含量在各组之间无显著差异(P>0.05)。综上可知,饲料中添加维生素K₃可以改善大口黑鲈肌肉氨基酸组成,但当饲料中维生素K₃含量≥5.80 mg/kg时会使大口黑鲈的消化能力下降,并且高剂量的维生素K₃会改变大口黑鲈的蛋白质和脂质代谢。     

池塘投喂膨化饲料主养模式对鳙形体指标、肌肉营养成分和品质特性的影响

为了综合评价投喂膨化饲料主养鳙(Aristichthys nobilis)模式在池塘养殖中的应用效果,本试验选取太湖区捕捞野生鳙(野生组)、膨化饲料池塘主养鳙(池塘组)、网箱生态养殖混养鳙(网箱组)各12尾,对它们的形态学指标及肌肉的常规营养成分、质构特性、重金属含量以及氨基酸和脂肪酸含量进行比较分析。结果显示:池塘组鳙的肥满度、肝体指数和脏体指数均显著高于野生组(P0.05);野生组和网箱组鳙肌肉中粗脂肪含量均显著低于池塘组(P0.05),而各组间鳙肌肉中粗蛋白质含量无显著差异(P0.05);野生组和网箱组鳙肌肉的硬度和回复性显著高于池塘组(P0.05),而各组间肌肉弹性、凝聚性和胶黏性差异不显著(P0.05);野生组和网箱组的鳙肌肉中重金属镉含量显著高于池塘组(P0.05),而鳙肌肉中铜含量显著低于池塘组(P0.05);网箱组和野生组鳙肌肉中氨基酸总量和鲜味氨基酸总量显著高于池塘组(P 0.05),且肌肉中各种氨基酸的氨基酸评分(AAS)和化学评分(CS)以及必需氨基酸指数(EAAI)均显著高于池塘组(P0.05);网箱组和野生组鳙肌肉脂肪酸中的油酸、花生五烯酸(EPA)和二十二碳六烯酸(DHA)含量显著低于池塘组(P0.05),其余脂肪酸含量均无显著差异(P0.05)。综述所述,池塘膨化饲料主养鳙的肌肉具有高脂肪及EPA和DHA含量更丰富的特点,但肌肉硬度、回复性和鲜味氨基酸含量均较低。     

饲养方式对北京油鸡生长和屠宰性能、肉品质以及肌肉脂肪酸含量的影响

本试验旨在研究不同饲养方式对北京油鸡生长和屠宰性能、肉品质以及肌肉脂肪酸含量的影响。试验选取8周龄北京油鸡公鸡1 200只,体重(561.75±7.39) g,随机分成2个组,对照组为集约化笼养(笼养组),试验组为林下放养(放养组),每组6个重复,每个重复100只鸡。试验分为9～14周龄和15～20周龄2个阶段,试验期间饲喂相同饲粮。结果表明:1) 14周龄,笼养组北京油鸡活体重与放养组相比无显著差异(P>0.05),而20周龄,放养组油鸡活体重较笼养组显著下降(P<0.05); 2个饲养阶段放养组油鸡腿肌率较笼养组显著上升(P<0.05),腹脂率显著降低(P<0.05),而胸肌率组间无显著差异(P>0.05)。2) 20周龄,放养组胸肌和腿肌亮度(L*)和红度(a*)值显著高于笼养组(P<0.05); 2个饲养阶段放养组胸肌黄度(b*)值显著下降(P<0.05),而腿肌b*值组间无显著差异(P>0.05)。3) 20周龄,放养组北京油鸡胸肌粗蛋白质含量较笼养组显著升高(P<0.05),而粗脂肪含量显著下降(P<0.05); 2个饲养阶段放养组北京油鸡胸肌肌苷酸含量较笼养组显著上升(P<0.05),腿肌粗蛋白质和肌苷酸含量显著升高(P<0.05),而粗脂肪含量显著下降(P<0.05);饲养方式对肌肉水分含量无显著影响(P> 0.05)。4)北京油鸡胸肌和腿肌中脂肪酸种类基本一致,棕榈酸、油酸和亚油酸含量最高,放养组肌肉不饱和脂肪酸和必需脂肪酸含量显著高于笼养组(P<0.05),而饱和脂肪酸和总脂肪酸含量显著下降(P<0.05)。综上所述,饲养方式对北京油鸡生长和屠宰性能、肌内脂肪酸的组成和含量存在影响,林下放养方式可改善北京油鸡肌肉品质和肉质风味。     

Comparative susceptibility of Atlantic salmon and rainbow trout to Yersinia ruckeri: Relationship to O antigen serotype and resistance to serum killing

A study was undertaken to compare the virulence and serum killing resistance properties of Atlantic salmon and rainbow trout Yersinia ruckeri isolates. Five isolates, covering heat-stable O-antigen O1, O2 and O5 serotypes, were tested for virulence towards fry and juveniles of both species by experimental bath challenge. The sensitivity of 15 diverse isolates to non-immune salmon and rainbow trout serum was also examined. All five isolates caused significant mortality in salmon fry. Serotype O1 isolate 06059 caused the highest mortality in salmon (74% and 70% in fry and juveniles, respectively). Isolate 06041, a typical ERM-causing serotype O1 UK rainbow trout strain, caused mortalities in both rainbow trout and salmon. None of the salmon isolates caused any mortalities in 150–250 g rainbow trout, and only serotype O2 isolate 06060 caused any significant mortality (10%) in rainbow trout fry. Disease progression and severity was affected by water temperature. Mortality in salmon caused by the isolates 06059 and 05094 was much higher at 16 °C (74% and 33%, respectively) than at 12 °C (30 and 4% respectively). Virulent rainbow trout isolates were generally resistant to sera from both species, whereas salmon isolates varied in their serum sensitivity. Convalescent serum from salmon and rainbow trout that had been infected by serotype O1 isolates mediated effective classical pathway complement killing of serotype O1 and O5 isolates that were resistant to normal sera. Overall, strains recovered from infected salmon possess a wider range of phenotypic properties (relative virulence, O serotype and possession of serum-resistance factors), compared to ERM-causing rainbow trout isolates.     

青贮杂交构树对杜湖杂交肉羊生长性能、血清生化指标和肉品质的影响

本研究旨在探讨青贮杂交构树对肉羊生长性能、血清生化指标、免疫指标、肉品质及肌肉氨基酸和脂肪酸组成的影响。选用健康、体重（24.2±0.65） kg相近的杜泊×湖羊F₁代公羔36只,随机分为4组,每组3个重复,每个重复3只。对照组（CG）饲喂基础饲粮,试验组（LG、MG、HG）在基础饲粮中分别添加6%、12%和18%的青贮杂交构树。试验期为90 d,其中预试期10 d,正试期80 d。结果表明：1）饲粮中添加不同比例的青贮杂交构树后,试验羊末重、平均日增重差异均不显著（P>0.05）。2）MG和HG组血清中免疫球蛋白G、免疫球蛋白A和免疫球蛋白M含量显著高于CG组（P<0.05）;LG、MG和HG组血清中尿素氮含量显著低于CG组（P<0.05）。3）MG和HG组背最长肌粗蛋白质和熟肉率显著高于CG组（P<0.05）,粗脂肪、胆固醇、剪切力、失水率显著低于CG组（P<0.05）;各组间pH、滴水损失、肉色、大理石纹、脂肪色差异不显著（P>0.05）。4）MG组背最长肌中必需氨基酸、鲜味氨基酸、总氨基酸含量和必需氨基酸/总氨基酸显著高于CG、LG和HG组（P<0.05）,鲜味氨基酸/总氨基酸显著高于CG组（P<0.05）;MG组背最长肌必需氨基酸中缬氨酸、亮氨酸、苯丙氨酸、赖氨酸和精氨酸含量显著高于CG、LG和HG组（P<0.05）。5）LG、MG和HG组肌肉中饱和脂肪酸含量均显著低于CG组（P<0.05）,而多不饱和脂肪酸含量均显著高于CG组（P<0.05）;MG组亚油酸、α-亚麻酸、花生四烯酸、二十二碳六烯酸和二十碳五烯酸的含量显著高于CG组（P<0.05）。综上,饲粮中添加青贮杂交构树对肉羊生长性能无显著影响,但能提高肉羊免疫力,同时改善肌肉营养成分、肉品质、氨基酸和脂肪酸的组成,且以添加12%效果最佳。     

The partial substitution of digestible protein with gelatinized starch as an energy source reduces susceptibility to lipid oxidation in rainbow trout (Oncorhynchus mykiss) and sea bass (Dicentrarchus labrax) muscle

We evaluated the influence of dietary gelatinized starch and protein on the fatty acid composition of muscle in rainbow trout and European sea bass and on the susceptibility of flesh to lipid peroxidation. The possibility that flesh peroxidation could be accounted for by lipogenesis and the deposition of fat was also explored. The inclusion of gelatinized starch in the diet of rainbow trout improved growth with respect to that observed in fish fed crude starch (P<.001). This was especially noticeable at the lowest concentration of dietary protein tested (P = .037); suggesting that gelatinized starch may partially replace protein in the production of energy without inducing a negative effect on growth. However, in European sea bass, the gelatinization of starch and dietary protein concentration showed no significant effect on final body weight. The intramuscular neutral lipid concentration of the sea bass was reduced by the gelatinization of dietary starch (P = .034). The highest dietary protein concentration increased the proportion of saturated fatty acids in the neutral (P = .0742) and polar (P = .0033) lipid fractions. The dietary inclusion of high levels of protein in rainbow trout led to a lower concentration of total (n-3) (P = .0457) and (n-6) (P = .0522) fatty acids and a higher concentration of total monounsaturated fatty acids (P = .0006). The inclusion of gelatinized starch led to a lower concentration of (n-3) fatty acids (P = .0034) and a higher concentration of saturated fatty acids (P = .0007). The polar fraction was hardly affected by the same treatment. A significantly lower susceptibility of the dorsal muscle to oxidation was observed in groups of European sea bass fed gelatinized starch (P<.01). A similar trend was observed in rainbow trout, although differences were not significant. The findings suggest that the digestible protein concentration of nutrient-dense diets for rainbow trout and European sea bass can be reduced with a beneficial effect on tissue lipid oxidation and no negative effects on growth and muscle composition.     

不同养殖模式翘嘴鲌肌肉营养品质比较

为评价池塘与大湖不同养殖模式翘嘴鲌(Culter alburnus)肌肉营养品质差异,试验分析了商品翘嘴鲌肌肉常规营养成分、氨基酸、脂肪酸、矿物元素含量等营养指标。结果表明:大湖翘嘴鲌肌肉水分含量显著低于池塘翘嘴鲌(P<0.05),粗蛋白质含量高于池塘翘嘴鲌,差异不显著(P>0.05)。池塘与大湖翘嘴鲌肌肉,除了赖氨酸和组氨酸以外(P<0.05),绝大部分氨基酸含量均无显著性差异(P>0.05)。大湖翘嘴鲌肌肉的总氨基酸、必需氨基酸和鲜味氨基酸含量分别较池塘翘嘴鲌高出2.72%、2.87%和2.50%。根据氨基酸评分(AAS)和化学评分(CS)结果,池塘与大湖翘嘴鲌肌肉中第一限制性氨基酸均为蛋氨酸+胱氨酸,赖氨酸相对含量最高,必需氨基酸指数(EAAI)分别为68.81和69.62。池塘翘嘴鲌的棕榈油酸(C16:1)含量显著高于大湖翘嘴鲌(P<0.05),而大湖翘嘴鲌肌肉的单不饱和脂肪酸(MUFAs)、高不饱和脂肪酸(HUFAs)、必需脂肪酸(EFA)、EPA+DHA含量则高于池塘翘嘴鲌(P>0.05)。试验检测了池塘与大湖翘嘴鲌肌肉11种矿物元素,其中镁有显著差异(P<0.05),重金属元素(铬、镉、铅)含量均在限量范围以内。综上所述,大湖养殖翘嘴鲌营养品质优于池塘养殖。     

Differing Resistance of Atlantic Salmon Strains and Rainbow Trout to Gyrodactylus salaris Infection

Abstract

Laboratory studies were conducted on the susceptibility of different strains of Atlantic salmon Salmo salar and rainbow trout Oncorhynchus mykiss to infection with the monogenean Gyrodactylus salaris. This parasite, probably originating from the Baltic Sea region, is known to minimally affect Neva River (Baltic Sea) Atlantic salmon. However, following its introduction into Norway, G. salaris has caused severe mortality and morbidity among Norwegian Atlantic salmon, which are considered a highly susceptible strain. The cohabitation experiment included one stock of rainbow trout and four different strains of Atlantic salmon from the Baltic Sea region (Mörrum River, Sweden), Europe (Skjern River, Denmark; Conon River, Scotland), and North America (Bristol Cove River, Canada). Fish were exposed to a Norwegian strain of G. salaris, and parasite population development and distribution were monitored for 7 weeks. Rainbow trout exhibited low susceptibility to G. salaris infection, whereas Conon River and Skjern River Atlantic salmon were highly susceptible and exhibited high mortality rates. Mörrum River Atlantic salmon exhibited intermediate susceptibility and low mortality. Bristol Cove River Atlantic salmon harbored relatively low parasite numbers, but fish mortality was high. Our experiment showed that the Danish Skjern River strain of Atlantic salmon is highly susceptible to G. salaris infection, further supporting the hypothesis that Atlantic Ocean strains are more susceptible to G. salaris infection than are Baltic strains.     

Lipid concentrations of fillets, liver, plasma and lipoproteins of African catfish, Clarias gariepinus (Burchell 1822), fed diets with varying protein concentrations

This study investigated the effect of the dietary protein concentration on lipid concentrations in fillet and liver and concentrations of lipids in plasma and lipoproteins in African catfish. Two experiments were carried out, in which African catfish were fed diets with various protein concentrations. In experiment 1, semisynthetic diets with various concentrations of casein (350, 450 or 550 g protein/kg) were used. In experiment 2, diets were based on a commercial trout diet supplemented with various amounts of casein or carbohydrates, resulting in protein concentrations between 282 and 545 g/kg diet. In both experiments, the dietary protein concentration had a significant effect on growth, feed conversion ratio and carcass composition. Maximum of body weight gains and feed efficiency ratios were reached in both experiments at the highest dietary protein concentrations. Increasing the dietary protein concentration continuously increased masses of fillets and reduced masses of the liver and adipose tissue in the abdominal cavity. Fish fed the diets with the highest protein concentrations had the lowest concentration of total lipids, triglycerides and cholesterol in the fillets, the highest percentage of polyunsaturated fatty acids (PUFA) in total lipids of fillets and the lowest concentrations of saturated fatty acids (SFA). Fish fed the diets with the highest protein concentration also had the lowest concentrations of triglycerides in the liver, the highest percentages of PUFA in liver total lipids and the lowest percentages of SFA. Moreover, fish fed diets with high protein concentrations (501 and 545 g/kg) had significantly lower concentrations of triglycerides, cholesterol and phospholipids in plasma than fish fed diets with lower protein concentrations. In conclusion, this study shows that the dietary protein concentration does not only influence growth, feed efficiency and carcass composition in African catfish, but also influences their lipid metabolism and lipid concentrations of liver and fillet.     

Early Life Stage Survival and Susceptibility of Brook Trout,Coho Salmon,Rainbow Trout,and Their Reciprocal Hybrids to Infectious Hematopoietic Necrosis Virus

Abstract

Triploid (heat-shocked) and diploid groups of rainbow trout Oncorhynchus mykiss, brook trout Salvelinus fontinalis, coho salmon Oncorhynchus kisutch, and reciprocal hybrids were produced, monitored for early life stage survival, and evaluated for susceptibility to infectious hematopoietic necrosis virus (IHNV). The female rainbow trout × male brook trout triploid hybrids had significantly greater (P < 0.01) survival than the diploid hybrids of this cross. The heat-shocked hybrid group of the female rainbow trout × male coho salmon also exhibited significantly greater survival to the eyed egg stage of development than the untreated group of this hybrid. Studies of the susceptibility of treatment groups to a 1990 IHNV isolate from the Hagerman Valley were conducted by using a standardized immersion exposure procedure at one or two different mean body weights. The diploid brook trout and coho salmon and two triploid hybrids (female rainbow trout × male brook trout or male coho salmon) were significantly less (P < 0.05) susceptible to IHNV than the pure-species diploid and triploid rainbow trout groups.     

Comparing efficiency of metabolizable energy utilization by rainbow trout (Oncorhynchus mykiss) and Atlantic salmon (Salmo salar) using factorial and multivariate approaches

A study was conducted to compare utilization of ME for growth vs. maintenance in rainbow trout and Atlantic salmon. Fish were hand-fed to satiation one of four isoenergetic diets (DE = 20 MJ/kg, as-fed basis) with different digestible protein (DP) to DE ratios (24, 22, 20, and 18 g/MJ). Intake of ME (kJ/d), energy deposited as protein (PD, kJ/d), and energy deposited as lipid (LD, kJ/d) were determined by a comparative slaughter technique. Data were analyzed by a factorial approach or by multivariate analysis of PD and LD on ME. Maintenance energy requirements (ME(m)) and efficiency of ME utilization for PD (k(p)) and LD (k(f)) were estimated with both approaches. For the multivariate analysis, an additional parameter, the fraction of ME intake above maintenance used for PD (X) was defined as linear function of BW, with slope (d) and intercept (c) estimated simultaneously with the above parameters. Estimates were highly dependent on the approach and assumptions used. The ME(m) and k(p) values were higher and less accurate with the factorial approach than with multivariate analysis. The factorial approach estimated unrealistic k(f) values (k(f) > 1). With the multivariate analysis, ME(m) did not differ between species (20 kJ x d(-1) x kg(-0.8)). On the other hand, k(p) was significantly higher (e.g., 0.52 +/- 0.06 vs. 0.43 +/- 0.06; P < 0.05) for salmon than for trout and independent of diet, but k(f) was 0.81 (+/-0.13) regardless of species or diet. The ME intake above ME(m) used for PD (c) was higher in salmon than trout (57 vs. 55%; P < 0.05). The change in partitioning of ME for PD due to the change in BW was negative for trout (d = -0.18), but positive for salmon (d = 0.16). The d values agreed well with the increase of LD:PD ratio with BW for trout and the decrease of LD:PD with BW for salmon, which may have been related to the maturation status of this fish and the associated loss of body lipid observed by maturing salmon. In conclusion, ME(m) and cost of LD were similar for rainbow trout and Atlantic salmon, but the cost of PD was lower for salmon than for trout.     

Use of solid fat in dry mixed feed for rainbow trout (Salmo gairdneri). 2. Fatty acid composition of feed and tissue lipids

The effect of supplemental dietary fat on the fatty acid composition of some tissue lipids of rainbow trout fingerlings was studied. Data showed that dietary fatty acids were deposited nearly unchanged in the adipose tissue. The level of eicosapentaenoic acid, however, dropped significantly. Muscle showed remarkable capacity for deposition of dietary fat, while only minor changes were observed in the fatty acid composition of liver lipids. Levels of some polyenoic acid (e.g. 18: 2 omega 6, 20:4 omega 6, 20:5 omega 3, 22:6 omega 3) showed, that the fish converted lower unsaturated fatty acids to highly unsaturated fatty acids. It was observed that dietary acids had little effect on the fatty acid composition of tissue phospholipids. This result shows, that 17% fat in the diet are tolerated by trout, without alterations in the fat composition of the liver tissue. Probably the low rearing temperature (11 degrees C) had a more pronounced effect on the fatty acid composition of phospholipids than the diet.