膨化与非膨化饲料对草鱼生长及部分生理生化指标影响

为了研究不同饲料对草鱼生长、体成分及部分生理生化指标的影响,在水温20~29℃下,将初始体重(394.96±13.21)g的草鱼(Ctenopharynodon idellus)养殖在水库网箱(2 m×2 m×2 m)中,投喂以商业配方为基础配制的膨化和非膨化饲料,养殖时间120 d,每个处理组3个重复,每个重复30尾鱼。结果显示,膨化饲料组草鱼成活率和增重率、肥满度、肝体比、脏体比和肠体比显著高于非膨化料组相,饵料系数和增重成本显著降低(P0.05);鱼体血清血糖、甘油三酯含量和过氧化氢酶、肝脏谷丙转氨酶活性显著升高(P0.05);胰蛋白酶、淀粉酶、脂肪酶、肝脏谷草转氨酶活性显著降低(P0.05)。膨化饲料组草鱼水分和灰分无显著差异(P0.05),但粗脂肪显著升高、粗蛋白显著降低(P0.05)。研究表明,与非膨化饲料相比,饲喂膨化饲料可提高大规格草鱼生长性能和养殖效益,但会导致鱼体肥满度和粗脂肪含量增加。     

不同碳水化合物和蛋白质水平膨化饲料对大规格草鱼生长、肠道消化酶及血清指标的影响

为探究不同碳水化合物和蛋白质水平膨化饲料对大规格草鱼生长、体成分、肠道消化酶和血清指标的影响,以初始体质量(398.6±5.9)g的大规格草鱼为研究对象,设置不同碳水化合物/蛋白质水平分别为C31P30、C34P28、C37P26、C40P24、C43P22、C46P20、C49P18的7组膨化饲料,养殖周期为16周。实验结果显示,各饲料组草鱼成活率(SR)差异不显著,随着蛋白质水平的下降、碳水化合物水平的升高,增重率(WGR)呈下降趋势,蛋白质效率(PER)呈升高趋势;肝体比(HSI)、脏体比(VSI)、肠体比(ISI)、肌肉和肝脏粗脂肪(CF)含量均有随饲料碳水化合物水平升高而升高的趋势。随着饲料中碳水化合物水平升高、蛋白质水平下降,各组间草鱼肌肉粗蛋白质(CP)含量无显著差异;肝糖原、肌糖原含量呈升高趋势,饲料中碳水化合物水平分别高于46%和40%时,肝糖原、肌糖原含量显著升高。肠道胰蛋白酶(PRS)和淀粉酶(AMS)活性随饲料中碳水化合物水平的升高呈先下降后升高趋势,脂肪酶(LPS)活性呈升高趋势;血清总胆固醇(TC)、甘油三酯(TG)、低密度脂蛋白(LDL)、高密度脂蛋白(HDL)含量及谷草转氨酶与丙转氨酶(GOT/GPT)比值都随饲料中碳水化合物水平升高和蛋白质水平下降而呈升高的趋势。本实验结果显示:当饲料碳水化合物水平高于37%、蛋白质水平低于26%时,将显著影响草鱼的生长,饲料中高碳水化合物水平将导致鱼体肝体比、脏体比、肠体比以及肌肉和肝脏脂肪含量升高。     

膨化沉性饲料和粉状饲料对菊黄东方鲀生长和氮磷收支的影响

为进一步探究膨化沉性饲料在菊黄东方鲀(Takifugu flavidus)养殖中的合理应用,在盐度7~10、水温22.6~29.4℃条件下,于室内水泥池开展了为期62 d的膨化沉性饲料与粉状饲料饲喂菊黄东方鲀的对比试验,比较2种饲料对鱼体生长和养殖系统氮(N)、磷(P)收支的影响。结果表明:(1)2个饲料组鱼的终末体质量、增重率、特定生长率、净产量、成活率、比肠长、肥满度等指标均无显著差异(P0.05);膨化沉性饲料组鱼的肝体比、脏体比显著高于粉状饲料组(P0.05),饲料系数显著低于粉状饲料组(P0.05)。(2)饲料是养殖系统中N、P的主要输入源,分别占总输入的67.7%~72.9%和76.4%~82.6%,其次为水体和养殖生物;养殖试验中膨化沉性饲料组投入的N、P量(51.46、9.64 g/m~2)显著低于粉状饲料组(65.97、14.18 g/m~2)(P0.05)。(3)废水(换水+终末水体)为N、P的主要输出源,分别占输入总量的61.7%~62.8%和45.2%~51.7%,其次为鱼体固定和吸污输出;膨化沉性饲料组经废水输出的P(5.71 g/m~2)和经吸污输出的N、P量(4.18、3.48 g/m~2)均低于粉状饲料组(8.88、6.11、4.50 g/m~2)(P0.05);被鱼体固定的N、P量组间差异不显著(P0.05)。(4)膨化沉性饲料组N、P的利用率分别为18.0%和16.5%,较粉状饲料组分别高42.9%和139.1%;水体N、P负荷量分别为70.55、15.35 kg/t,较粉状饲料组分别低32.9%和44.1%。研究表明,采用膨化沉性饲料饲喂菊黄东方鲀能提高饲料中N、P的利用效率,降低养殖系统的N、P排放。     

膨化饲料和颗粒饲料对哲罗鲑生长、体成分、消化酶活性和血液生化指标影响的比较

本试验用膨化饲料和颗粒饲料饲喂初体重6.91±0.33 g哲罗鲑(Hucho taimen),比较两种饲料对其生长、体成分、消化酶活性和血液生化指标的影响.试验在室内玻璃钢水族箱中进行,分2个处理,每处理3个重复,每重复100尾鱼.处理1为膨化饲料组,处理2为颗粒饲料组.试验期间水温9.8～16.2℃,溶氧>8.0 mg/L,试验共进行56d.试验结果表明,同颗粒饲料组相比,膨化饲料组哲罗鲑成活率显著提高(P<0.05),饵料系数显著降低(P<0.05);鱼体粗蛋白和粗脂肪含量显著升高(P<0.05),水分和灰分显著降低(P<0.05);胃蛋白酶、前肠+幽门盲囊胰蛋白酶、后肠胰蛋白酶活性显著降低(P<0.05);消化道淀粉酶活性显著降低(P<0.05);血清总蛋白、白蛋白、球蛋白和白球比差异不显著(P>0.05),而碱性磷酸酶活性显著降低(P<0.05).结论,与颗粒饲料组相比,哲罗鲑饲喂膨化饲料后生长性能提高,但消化道消化酶活性降低.     

饲料不同加工方式对草鱼生产性能的影响

采用同一营养水平的饲料配方,试制了非膨化沉性硬颗粒饲料和膨化浮性颗粒饲料(简称非膨化饲料和膨化饲料)。设非膨化饲料、膨化饲料和膨化与非膨化饲料混合投喂三个处理组(A非膨化饲料组; B膨化饲料组; C非膨化饲料∶膨化饲料=1∶1组)。每个处理三个平行,网箱养殖。结果:三个处理组,增重率、特定生长率、肥满度等均有差异;全鱼营养成分、水分、蛋白质和灰分含量差异不显著;脂肪含量差异显著。结果表明:膨化饲料喂养草鱼生长速度更快,肥满度较大;而非膨化饲料喂养的草鱼脂肪含量更低,肥满度相对较小;混合投喂介于两者之间。因此,草鱼养殖户可根据市场需求选择不同加工方式的饲料投喂。     

不同糖源膨化饲料对大规格草鱼生长、越冬及血清部分生化指标的影响

以商业配方为基础，研究不同糖源(小麦、大麦、玉米、白高粱、木薯)膨化饲料对大规格草鱼[初始体质量(400.77±7.45) g]生长、体成分、越冬及部分生理生化指标的影响。共设置5个处理，每处理3个重复，每个重复30尾鱼，养殖实验于水库网箱(2.0 m×2.0 m×2.0 m)中进行，饲养时间为16周，养殖实验结束后，每网箱保留15尾进行越冬实验，时间为16周。结果显示，玉米组草鱼增重率(WGR)和蛋白质效率(PER)显著低于其他各组，饲料系数(FCR)显著高于其他各组，其他4组差异不显著；肥满度(CF)小麦组最高，脏体比(VSI)玉米组最高，肝体比(HSI)和肠体比(ISI)木薯组最高；小麦组血糖(GLU)含量显著高于其他各组，大麦和白高粱组总胆固醇(T-CHO)含量显著高于其他3组，木薯组甘油三酯(TG)含量显著低于其他各组。小麦、大麦和玉米组的肌肉粗脂肪含量显著高于白高粱和木薯组，木薯组的粗蛋白含量显著低于其他4组。白高粱和木薯组的肝糖原显著高于其他组，大麦和白高粱组的肌糖原显著高于其他组。越冬后，大麦组草鱼体质量下降幅度显著高于其他各组，HSI下降幅度显著小于其他各组，肝糖原含量显著升高，GLU下降幅度显著低于其他各组，肌肉粗蛋白含量下降幅度最高，其他各组越冬后体质量下降幅度差异不显著，小麦组CF下降比例最高，玉米和木薯组HSI下降幅度显著大于其他各组，玉米组的VSI下降比例最大。研究表明，在膨化工艺条件下，以生长、增重成本和越冬为评价指标，小麦、木薯和白高粱是大规格草鱼适合的糖源，木薯增重成本最低。     

壳聚糖复合物对草鱼种生长性能的影响

将均重132g草鱼种540尾随机分成3个处理（每处理3个重复）。分别饲喂含壳聚糖复合物（以壳聚糖为主要活性成分）0、300g／T、500g／T的三种饲料，进行70天网箱养殖试验。结果表明：草鱼鱼种饲料中添加壳聚糖复合物500g／T后，增重率显著提高（P〈0．05），饵料系数显著降低（P〈0．05），对肥满度和成活率没有显著影响（P〈0．05），对草鱼过氧化氢酶和谷草转氨酶都没有显著影响（P〉0．05）：300g／T壳聚糖复合物添加后，丙二醛的量显著提高，谷丙转氨酶活性显著下降（P〈0．05），但500g／T添加组丙二醛的量和谷丙转氨酶的活性与对照组无显著差异（P〉0．05）。建议壳聚糖复合物在草鱼中的适宜添加量为500g／T。     

不同饲料对哲罗鲑生长性能和营养成分的影响

在人工养殖条件下,分别投喂野生鲫鱼和人工饲料对哲罗鲑生长性能和营养成分进行比较。每组养殖实验鱼50尾,每个实验组设3个重复,试验水温10.8～16.5℃,pH值7.2～7.5,溶氧〉6.0mg/L,试验共进行56d。试验结果：野生鲫组增重率、特定生长率、肥满度、水分均显著高于人工饲料组（P〈0.05）。野生鲫组粗脂肪显著低于配合饲料组（P〈0.05）。两试验组鱼体粗蛋白、粗灰分、肌肉氨基酸含量及组成差异均不显著（P〉0.05）。野生鲫组与人工饲料组相比,野生鲫组哲罗鲑生长性能较好,鱼体成分发生改变,而肌肉氨基酸营养价值未发生变化。     

饲料中添加蛋氨酸寡肽对大黄鱼(Larimichthys crocea)生长、饲料利用和蛋白质代谢反应的影响

为研究饲料中添加蛋氨酸寡肽(OMet)对大黄鱼(Larimichthys crocea)幼鱼生长、饲料利用和蛋白质代谢反应的影响,并与在饲料中添加等量的晶体蛋氨酸(CMet)的效果相比,实验以初始体重为(26.0±1.6)g的大黄鱼幼鱼为研究对象,以鱼粉和豆粕为主要蛋白源,设计1个低鱼粉(31.8％)对照饲料(LF).在LF的基础上分别添加0.35％、0.65％和0.95％的晶体蛋氨酸或蛋氨酸寡肽,配制其他6组饲料,并分别命名为CMet 0.35、CMet 0.65、CMet 0.95、OMet 0.35、OMet 0.65和OMet 0.95,养殖周期为8周.结果显示,与LF组相比,OMet组和CMet组大黄鱼的增重率均显著升高,并随着蛋氨酸水平的增加而显著提高(P＜0.05),其中,OMet 0.95组的增重率最高.与CMet组相比,OMet组大黄鱼的增重率和蛋白质效率均显著提高(P＜0.05).不同饲料处理对大黄鱼存活率、饲料系数、体组成(粗蛋白、粗脂肪、灰分和水分)、脏体比和肥满度没有显著影响(P＞0.05).OMet组大黄鱼的肝体比较CMet组显著降低(P＜0.05).饲料中添加晶体或蛋氨酸寡肽显著影响了大黄鱼幼鱼的肝脏谷丙转氨酶和谷草转氨酶活力,OMet组大黄鱼肝脏中这两种酶的活力均显著高于CMet组的(P＜0.05),蛋氨酸添加水平对大黄鱼肝脏谷草转氨酶活力也有显著影响(P＜0.05).但各饲料处理组之间血清中的血氨浓度和尿素氮含量没有显著差异(P＞0.05).综上所述,等量添加蛋氨酸寡肽比晶体蛋氨酸更能促进大黄鱼幼鱼的生长及其对饲料的利用.     

不同投喂率和投喂频率对大杂交鲟幼鱼生长、体成分和生化指标的影响

为探讨大杂交鲟(Huso dauricus♀×Acipenser schrenckii♂)适宜投喂率和投喂频率,本实验分别设计了5个投喂率(0.4%、0.8%、1.2%、1.6%和2.0%)和5个投喂频率(1次/d、2次/d、3次/d、4次/d和5次/d),研究不同投喂率和投喂频率对大杂交鲟生长、体成分和生化指标的影响。投喂率实验中鱼初重(335.87±0.82)g,投喂频率实验中鱼初重(334.77±1.06)g,养殖周期为10周。结果表明,随着投喂率升高,实验鱼增重率、特定生长率、肝体比、脏体比、肥满度,肌肉粗蛋白、粗脂肪和肝粗脂肪含量显著升高(P0.05),血清谷丙转氨酶、谷草转氨酶和胃蛋白酶活性均显著升高(P0.05);饲料效率、全鱼和肌肉水分含量均显著降低(P0.05);全鱼粗脂肪含量,血清总蛋白、白蛋白和高密度脂蛋白胆固醇含量,肠脂肪酶活性呈先升高后降低趋势(P0.05)。随着投喂频率增加,实验鱼增重率、特定生长率和饲料效率无显著差异(P0.05);1次/d投喂频率组脏体比、肥满度和全鱼粗脂肪含量显著低于其他各组(P0.05),2次/d投喂频率组全鱼粗蛋白含量显著高于其他各组(P0.05)。不同投喂频率对实验鱼除血清葡萄糖含量以外的其他血清生化指标和胃肠消化酶活性或含量均无显著影响(P0.05)。综合以上结果认为,在300～600g大杂交鲟的养殖过程中日投喂率在1.2%～1.6%,投喂频率为2次/d比较适宜。     

Effects of feed processing and forms of dietary methionine on growth and IGF‐1 expression in Jian carp

In this study, a practical basal diet (control, C) was supplemented with crystal methionine (Met) (CM) or encapsulated Met (EM), and then was pelleted (P) or extruded (E) to form six diets, PC, PCM, PEM, EC, ECM and EEM. The six diets were fed to Jian carp with initial body of 8.6 ± 0.4 g for 8 weeks to evaluate the effects of Met supplementation and feed processing on growth of the fish. In pelleted diets, weight gain (WG) increased and feed conversion ratio (FCR) decreased (P < 0.05) in response to the supplementation of EM, but both WG and FCR were not affected by the supplementation of CM in the pelleted diet, when compared with PC group. In extruded diets, WG of fish fed ECM or EEM diets was higher and FCR was lower (P < 0.05) than those of fish fed EC diet. In the pelleted diets, the highest level of serum free Met was observed at the 1st, 2nd and 3rd h after feeding for PCM, PEM and PC group, respectively, but the three extruded diet groups showed the same peaking time at the 3rd h after feeding. In both pelleted and extruded diets, the supplementation of EM increased the expression of IGF‐1 gene in muscle (P < 0.05) when compared to PC and EC respectively. Results above indicated that the growth of Jian carp can be improved by the supplementation of EM in pelleted diet, or by the supplementation of EM, CM in extruded diet deficient in Met, but not by the supplementation of CM in pelleted diet.     

不同投喂频率下草鱼对5种非粮蛋白源利用效率的比较

采用双因素正交试验(3ｘ5)评估了草鱼在3种投喂频率下对豆粕(美国)、乙醇梭菌蛋白、黄粉虫、小球藻、棉籽蛋白粉的利用效率。以5种原料为单一蛋白源配制5种等氮等能饲料,在池塘网箱(1mｘ1.5mｘ1.5m)中,分别以投喂频率(2次/d、3次/d和4次/d)投喂初始体质量~80g的草鱼8周,考察草鱼的生长性能,全鱼和肌肉营养成分以及血清生化指标。研究结果表明：黄粉虫试验组(2次/d)草鱼表现出最低的生长性能;豆粕(4次/d)和乙醇梭菌蛋白(3次/d和4次/d)试验组草鱼表现出最高的生长性能;投喂频率与蛋白源对草鱼的末重,饲料系数,蛋白质效率和增重率有交互作用(P＜0.05)。除小球藻试验组,各试验组草鱼的终末体质量和蛋白质效率随着投喂频率的增加而增加。不考虑蛋白源,投喂频率为4次/d的草鱼生长性能显著高于2次/d。 不考虑投喂频率,黄粉虫和棉籽浓缩蛋白组的增重率和蛋白质效率显著低于豆粕、乙醇梭菌蛋白和小球藻三组(P＜0.05),饲料系数则表现出相反的趋势(P＜0.05)。不同的投喂频率下,五种蛋白源对草鱼的形体指标(肝体比、脏体比、肥满度)和全鱼和肌肉的基础营养成分均无显著影响(P＞0.05)。投喂频率对草鱼血清的碱性磷酸酶和葡萄糖有显著影响(P＜0.05),投喂2次/d的碱性磷酸酶的活性显著高于投喂3次/d和投喂4次/d(P＜0.05),投喂4次/d试验鱼的葡萄糖含量显著高于投喂2次/d和3次/d(P＜0.05)。黄粉虫试验组草鱼血清中的谷丙转氨酶和谷草转氨酶活性显著高于豆粕组和小球藻组(P＜0.05)。本试验条件下,以生长性能为评价指标,草鱼适宜的投喂频率为3~4次/d,草鱼对五种蛋白源饲料的利用能力为：乙醇梭菌蛋白=豆粕=小球藻>棉籽浓缩蛋白>黄粉虫。     

投喂蚕豆对草鱼生长及肌肉营养特性分析

分别用配合饲料、浸泡蚕豆和发芽蚕豆喂养平均体重(1000±20)g草鱼70d,分析投喂蚕豆对草鱼生长及肌肉营养的影响。结果表明,配合饲料组、浸泡蚕豆组和发芽蚕豆组的草鱼增重率分别为79.5%、40.32%和50.10%,饵料系数分别为2.11、4.78和4.31,投喂蚕豆降低了草鱼增重率(P<0.05),显著增加了饵料系数(P<0.05)。与配合饲料组相比,浸泡蚕豆组和发芽蚕豆组肌肉中粗脂肪和粗蛋白含量显著降低(P<0.05)。浸泡蚕豆组和发芽蚕豆组的必需氨基酸含量、鲜味氨基酸含量、氨基酸总量比配合饲料组显著提高(P<0.05)。投喂蚕豆降低了草鱼的生长性能,但是显著提高了草鱼肌肉品质。投喂发芽蚕豆的效果要优于投喂浸泡蚕豆。     

Effect of dietary carbohydrate‐to‐lipid ratios on growth performance,body composition,nutrient utilization and hepatic enzymes activities of herbivorous grass carp (Ctenopharyngodon idella)

Six isonitrogenous (390 g kg^?1) and isoenergetic (16.2 kJ g^?1) diets with varying carbohydrate : lipid (CHO : L) ratios (202.5–1.74), were fed to triplicate groups of 25 fish in indoor recirculation system. Over 8‐week‐growth trial, best weight gain (WG), specific growth rate, feed conversion ratio, protein efficiency ratio and protein production value (P < 0.05) were observed in fish‐fed diets with CHO : L ratio of 7.5. Fish fed either the lowest (1.7) or highest (202.5) CHO : L ratio tended to produce lower (P < 0.05) growth and feed conversion efficiencies. The values of viscerosomatic index, hepatosomatic index and intraperitoneal fat ratio increased as dietary CHO : L ratios decreased. There were no significant differences in whole body and liver crude protein among dietary treatments. Whole body and liver lipid increased as CHO : L ratios decreased. Plasma cholesterol and triacylglyceride levels increased linearly as dietary CHO : L ratios decreased. Activities of glucokinase and pyruvate kinase were stimulated by elevated levels of dietary carbohydrate; however, activities of lipase (LPS) and alkaline phosphatase were stimulated by elevated levels of dietary lipid. Based on a second‐order polynomial regression analysis of WG against dietary carbohydrate and lipid levels, 275 g kg^?1 of carbohydrate and 59 g kg^?1 of lipid, corresponding to a CHO : L ratio of 4.7, in a diet holding 390 g kg^?1 of crude protein and 16.3 kJ g^?1 of gross energy, proved to be optimal for grass carp. These results indicated that utilization of dietary lipid and carbohydrate was moderate in grass carp, but the fish were a little more capable of utilizing lipid compared with carbohydrate.     

饲料中添加生物素对草鱼幼鱼生长、体成分和血清生化指标的影响

在纯化饲料中分别添加生物素0、0.05、0.10、0.20、0.40、0.80、1.60 mg/kg投喂初始质量为(5.92±0.25)g的草鱼(Ctenopharyngodon idellus)幼鱼8周,研究了不同生物素添加量对草鱼幼鱼生长性能、饲料系数、机体营养成分、血清生化指标的影响。试验结果显示:与对照组相比,添加生物素提高了草鱼幼鱼的增重率、特定生长率,降低了饲料系数。添加量为0.40 mg/kg时草鱼幼鱼的特定生长率和增重率最大,饲料系数最低,并与对照组存在显著差异(P<0.05);添加不同水平生物素对草鱼幼鱼全鱼水分、粗蛋白、粗脂肪含量无显著影响,但添加量为0.40 mg/kg时粗蛋白含量最大。0.10 mg/kg组和0.20 mg/kg组的全鱼灰分含量显著高于对照组(P<0.05);添加生物素对血清总蛋白(TP)、血糖(GLU)和总胆固醇(TC)无显著影响,但显著提高了血清甘油三酯(TG)含量,各添加组TG含量均显著高于对照组(P<0.05),1.60 mg/kg添加组的高密度脂蛋白胆固醇(HDL-C)和低密度脂蛋白胆固醇(LDL-C)含量显著高于对照组(P<0.05)。综合本试验结果,草鱼幼鱼饲料中生物素适宜添加量为0.40 mg/kg。     

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.     

Effect of replacing soybean meal with cottonseed meal on growth, hematology, antioxidant enzymes activity and expression for juvenile grass carp, Ctenopharyngodon idellus

An 8-week feeding trial was conducted to evaluate the effect of replacing soybean meal (SBM) with cottonseed meal (CSM) on growth and health of grass carp. Four isonitrogenous diets containing 0, 16.64, 32.73 and 48.94% of CSM, respectively, as replacements of 0, 35, 68 and 100% of SBM were fed to fish (initial body weight 7.14 ± 0.75 g/fish) in triplicate aquaria twice daily. The results indicated that fish fed diet containing 16.64% CSM as a replacement of 35% of SBM was not affected in weight gain (WG), feed efficiency ratio (FER) and feed conversion ratio (FCR) (P>0.05), while fish fed diets containing higher level of dietary CSM (32.73 and 48.94%) significantly decreased WGand PER and significantly increased FCR (P<0.05). Fish fed diets containing 16.64% of CSM had significantly increased hematocrit (Ht) and hemoglobin (Hb) values compared with fish fed with other diets (P<0.05). The activity of catalase (CAT), glutathione peroxidase (GSH-Px) and superoxide dismutase (SOD), gene expression levels of GSH-Px and CAT, and content of malondialdehyde (MDA) were significantly lower for fish fed diets containing 16.64% CSM compared with fish fed other diets (P<0.05). These results showed 16.64% CSM could be used to replace 35% SBM in the diets of juvenile grass carp and without health impact.     

Protein‐sparing capability of dietary lipid in herbivorous and omnivorous freshwater finfish: a comparative case study on grass carp (Ctenopharyngodon idella) and tilapia (Oreochromis niloticus × O. aureus)

Two, 8‐week feeding trials were conducted to compare protein‐sparing capability of dietary lipid in herbivorous grass carp (Ctenopharyngodon idella) and omnivorous tilapia (Oreochomis niloticus × O. aureus). Utilizing a 2 × 3 factorial design, experimental diets containing two levels of crude protein (380 and 250 g kg⁻¹) and three levels of lipid (0, 40 and 100 g kg⁻¹) were formulated for use in both feeding trials. Growth performances showed better response of both fish fed 380 g kg⁻¹ protein diet than those fed 250 g kg⁻¹ protein diet. Despite the dietary protein level, weight gain (WG), specific growth ratio (SGR), feed conversion ratio (FCR) and protein efficiency ratio were much higher (P < 0.05) for grass carp fed 40 g kg⁻¹ lipid diet than those fed 100 g kg⁻¹ lipid diet; however, there were no significant differences in tilapia fed the two diets. The feed intake of grass carp fed lipid‐free diet was the lowest, but it tended to decrease with increase in dietary lipids in tilapia. Lipid retention (LR) was negatively correlated with dietary lipid concentration of both fish. Viscerosomatic index (VSI), hepatosomatic index (HSI), intraperitoneal fat ratio (IPF) and whole‐body and liver lipid content positively correlated with dietary lipid concentration of both fish. Plasma parameters and liver enzymes activities were also positively correlated with dietary lipid concentration of both fish. Liver lipid contents were higher and enzymes activities were lower in grass carp when compared with tilapia. These data suggested that there was no evidence of a protein‐sparing effect of dietary lipids in grass carp. Tilapia has relatively higher capacity to endure high dietary lipid level compared to grass carp.     

微生态制剂对草鱼生产性能和肠道菌群的影响

在水温25~30℃下,将体质量为(110.23±0.43)g的草鱼饲养在3.0 m×2.0 m×1.2 m的加盖网箱中,分别投喂添加0%(对照组)、0.5%和2%的由芽孢杆菌、乳酸菌以及酵母菌复配且以麸皮为载体制成的微生态制剂(8.0×10~9 cfu/g)的膨化饲料饲养60 d,探究微生态制剂对草鱼生产性能和肠结构、菌群及酶活性的影响。试验结果显示,饲料中添加2%微生态制剂显著提高草鱼质量增加率、特定生长率(P<0.05),显著降低饲料系数、脏体比(P<0.05);饲料中添加2%微生态制显著提高肠伸展率、中肠肌层厚度和绒毛高度(P<0.05),提高中肠淀粉酶和脂肪酶活性(P<0.05)。饲料中添加微生态制剂增加草鱼肠道菌群α多样性、丰富度;改变草鱼肠道微生物组成,门水平上,对照组的草鱼肠道微生物中梭杆菌门和厚壁菌门含量最高(63.56%、32.52%)。0.5%添加组的草鱼肠道微生物中梭杆菌门和厚壁菌门含量最高(61.82%、20.27%)。2%添加组的草鱼肠道微生物中厚壁菌门含量最高(64.20%)。属水平上,2%添加组草鱼肠道优势菌属直接发生改变,Paeniclostridium和Erysipelatoclostridium丰度大幅上升。随着微生态制剂添加量的增加,肠道微生物的代谢功能增强,组成中与无机离子转运和代谢、碳水化合物转运与代谢、氨基酸转运与代谢等功能相关的菌群丰度升高。综上可知,饲料中添加芽孢杆菌、乳酸菌以及酵母菌等组成的微生物制剂可作为生产草鱼绿色饲料的重要措施。