不同循环饥饿投喂模式对许氏平鲉生长和体成分的影响

为探究不同循环饥饿投喂模式下许氏平鲉的补偿生长和体成分的变化，分别采用每日投喂(对照组)、饥饿2 d投喂1 d、饥饿2 d投喂2 d、饥饿2 d投喂3 d、饥饿2 d投喂4 d和饥饿2 d投喂5 d的循环饥饿投喂模式，对初始体长(10.25±0.74) cm、体质量(16.77±2.72) g的许氏平鲉幼鱼进行为期67 d的养殖试验。试验结果显示：饥饿2 d投喂5 d试验组的终末体质量、质量增加率、特定生长率均最高，表现为超补偿生长；饥饿2 d投喂4 d组的终末体质量、质量增加率和特定生长率与对照组差异不显著(P>0.05),表现为完全补偿生长；饥饿2 d投喂1 d、饥饿2 d投喂2 d和饥饿2 d投喂3 d试验组的终末体质量、质量增加率和特定生长率均显著低于对照组(P<0.05),表现为不能补偿生长。各组间的饲料效率、肝体指数和肥满度差异不显著(P>0.05),但对照组的脏体指数显著高于循环饥饿投喂组(P<0.05)。与对照组相比，循环饥饿投喂组(除饥饿2 d投喂5 d试验组外)的鱼体粗脂肪含量显著降低(P<0.05),粗蛋白质和灰分含量各组间差异不显著...     

锦鲤幼鱼循环饥饿后的补偿生长和体成分变化

为研究体长(10.63±0.20)cm、体重(17.63±0.72)g锦鲤(Cryprinus carpiod)幼鱼循环饥饿后的补偿生长和体成分变化,试验设5个组,分别为正常投喂和4个循环饥饿投喂组,其中循环饥饿投喂组投喂方式分别为:饥饿1 d后投喂3 d、饥饿1 d后投喂5 d、饥饿2 d后投喂3 d、饥饿2 d后投喂5 d,试验水温为(27.0±1.0)℃,试验周期为40 d。试验结果表明:循环饥饿1 d后投喂的特定生长率、摄食率均显著高于正常投喂的(P0.05),但末均长、末均重、总摄食量、相对增重率和饲料利用率的差异均不显著(P0.05),表现为完全补偿生长,推测其补偿生长应是通过提高摄食率来实现的;循环饥饿2d后投喂的末均长、末均重、总摄食量、特定生长率、相对增重率均显著低于正常投喂的(P0.05),而摄食率、饲料利用率的差异均不显著(P0.05),表现为不能补偿生长,但是否对其生理机能造成伤害有待于进一步研究确定;4个循环饥饿投喂组的鱼体粗蛋白和粗脂肪含量较正常投喂组有所降低,而水分和灰分含量有所升高。因此,循环饥饿1 d后投喂3 d的实际投喂时间较短,且为完全补偿生长,是最佳的循环饥饿投喂模式。     

循环饥饿后异育银鲫幼鱼的补偿生长及部分生理生化指标的变化

在(28±1)℃水温条件下,以4种循环饥饿的投喂方式饲养初始体重为1.58 g的异育银鲫(Carassius auratus gibelio)幼鱼,研究其补偿生长和部分生理生化指标的变化。实验分为四组,第一组每天投喂,为对照组,第二组投喂4 d后饥饿1 d,第三组投喂2 d后饥饿1 d,第四组投喂1 d后饥饿1 d,4种方式分别以C、R1/4、R1/2和R1/1表示,试验持续60 d。结果显示,3个试验组的实际摄食率均显著高于对照组(P<0.05),但饲料转化效率均显著低于对照组,导致3个试验组的特定生长率显著下降,体重未赶上对照组,而且饥饿时间越长,体重增长率越低。鱼体的蛋白质、灰分含量未受到投喂方式的显著影响,干物质、脂肪和能量含量随饥饿时间增加显著下降;肥满度、肝体比、ATP酶、SOD酶活性以及谷丙转氨酶和谷草转氨酶活性也随饥饿时间的增加显著下降。     

千年笛鲷幼鱼的饥饿和补偿生长

研究了在22.5～31.9 ℃条件下，千年笛鲷幼鱼在不同饥饿时间（0、2、4、6、9、11 d）处理后再投喂的补偿生长。千年笛鲷幼鱼的体重在短时间（2～6 d）的饥饿后下降不大，9 d以上的饥饿可导致幼鱼的体重明显下降。经过饥饿11 d后，鱼体蛋白质含量明显下降，脂肪含量略有下降，灰分含量有所上升，水分含量明显上升，表明千年笛鲷幼鱼在饥饿过程中主要依靠消耗蛋白质作为能量来源。恢复投喂后，各组的鱼体生化组成均恢复到对照组水平。饥饿11 d组鱼在恢复投喂后全部死亡，半致死时间为10～11 d。结果表明：饥饿2 d组的千年笛鲷幼鱼在恢复生长过程中具有超补偿生长能力，该补偿现象通过提高食物转化率达到；饥饿4 d组幼鱼具有完全补偿生长能力；饥饿6 d组幼鱼仅有部分补偿生长能力；饥饿9 d组幼鱼不具有补偿生长能力；饥饿11 d组幼鱼为饥饿致死。图5表1参13     

饥饿与再投喂及投喂频率对条石鲷幼鱼生长和消化酶活力的影响

研究了饥饿与再投喂及不同投喂频率对条石鲷(Oplegnathus fasciatus)幼鱼生长和消化酶活力的影响.饥饿与再投喂的实验结果表明:条石鲷幼鱼体质量、蛋白酶(胃蛋白酶、胰蛋白酶)与脂肪酶活力随着饥饿时间的延长均呈现明显的下降趋势,体质量与蛋白酶活力在饥饿6d后与对照组表现出显著性差异(P＜0.05),脂肪酶活力在饥饿9d后才与对照组表现出显著性差异(P＜0.05),而淀粉酶活力在饥饿过程中呈波动性变化；恢复投喂后,除饥饿3d的幼鱼体质量、特定生长率与对照组无明显差异外,其他各处理组均明显低于对照组；蛋白酶与脂肪酶活力在恢复投喂后均有明显回升,且蛋白酶活力与对照组相比已无显著性差异,但较长时间的饥饿处理(9～12 d)并未使脂肪酶活力恢复至对照组水平.投喂频率实验的研究结果表明:随着投喂频率的增加,条石鲷幼鱼的特定生长率呈上升趋势,在投喂频率达到投喂2次/d后,条石鲷幼鱼的特定生长率、消化酶活力及肝体指数差异均不显著.结论认为,在本实验条件下,饥饿3d后再经投喂,条石鲷幼鱼具有完全补偿生长效应,但随着饥饿时间的延长补偿生长的效应逐渐降低.对条石鲷幼鱼而言,选择日投喂两次最合适.     

不同循环饥饿投喂模式对尼罗罗非鱼补偿生长的影响

为了探讨尼罗罗非鱼对不同循环饥饿投喂模式的补偿生长效应,本实验分别采用每天投喂(S0)及饥饿1 d+投喂3 d(S1F3)、饥饿1 d+投喂5 d(S1F5)、饥饿1 d+投喂7 d(S1F7)、饥饿2 d+投喂3 d(S2F3)、饥饿2 d+投喂5 d(S2F5)和饥饿2 d+投喂7 d(S2F7)6种不同的循环投喂模式,用含33%蛋白质和8%脂肪的饲料饲养尼罗罗非鱼(均重13.50 g),饲喂期为43 d。结果显示,S0组的增重率(806.74%)最高,与S1F3、S1F5和S1F7组差异不显著,但分别比S2F3、S2F5和S2F7组显著提高40.3%、33.6%和10.4%;S0组的特定生长率最低(5.36%),显著低于其他各组;与对照组相比,采用循环投喂模式没有改善饲料转化率和蛋白质效率,但却能明显提高日摄食率;各实验处理组肝体比、脏体比、肥满度、鱼体灰分含量、肌肉RNA/DNA比值及血清总胆固醇、高密度脂蛋白胆固醇、低密度脂蛋白胆固醇和尿素氮含量与对照组差异不显著;S1F3、S1F5和S1F7组鱼体蛋白质和脂肪含量、血清甘油三酯含量及血清谷丙转氨酶和谷草转氨酶活性与S0组差异不显著,但S2F3、S2F5和S2F7组鱼体蛋白质和脂肪含量及血清甘油三酯含量显著低于S0组,血清谷丙转氨酶和谷草转氨酶活性显著高于S0组。研究表明,尼罗罗非鱼在S1F3、S1F5和S1F7模式下获得了完全补偿生长,而在S2F3、S2F5和S2F7模式下仅获得了部分补偿生长,且均是通过提高恢复投喂期间的摄食量来实现补偿生长。在获得完全补偿生长的3组中,S1F3组的实际投喂天数最短,仅为33 d,比每天投喂模式缩短了23.3%,因此在本实验条件下,饥饿1 d+投喂3 d是最佳的循环饥饿投喂模式。     

循环投喂对虹鳟的生长、身体组成及生长激素的影响

不足1龄的虹鳟(Oncorhynclus mykiss)用编码标签标识后分为两组:一组采用饥饿三周饱食三周的循环投饵制度;另一组对照每天饱食投喂。试验期24周,每周记录其生长、身体组成及血浆生长激素水平。两组实验末的虹鳟标准体长和体重没有显著差异。对于循环投喂鱼来说,特定生长率及肥满度在投喂的最后一周达到最大值。与对照组相比,循环投喂鱼体的含水量和蛋白含量显著提高,而脂肪水平较低。在饥饿阶段绝对体重和脂肪的损失随着循环周期逐渐降低,说明这是成鱼对不利影响的适应。血浆生长激素浓度不受循环投喂的影响,表明血浆生长激素浓度不是虹鳟补偿生长的原因。     

不同循环投喂模式对半滑舌鳎的生长、体成分组成、代谢和能量收支的影响

研究了不同循环投喂模式对半滑舌鳎的生长、体成分组成、代谢和能量收支的影响。其中包括5个处理:C(对照组,实验过程中持续投喂);S2F4组(饥饿2 d,投喂4 d);S4F8组(饥饿4 d,投喂8 d);S8F16组(饥饿8 d,投喂16 d);S12F24组(饥饿12 d,投喂24 d),实验时间72 d。结果表明,对照组的特定生长率(SGR_w和SGR_e)显著高于循环投喂各组(P<0.05)。对照组和S2F4组半滑舌鳎幼鱼的末体重没有显著差异(P>0.05),并且均显著高于其它各组(P<0.05)。对照组半滑舌鳎幼鱼的消化率显著低于其它各组(P<0.05),而能量消化率与S12F24组没有显著差异(P>0.05),但显著低于其它3个处理组(P<0.05)。S4F8组半滑舌鳎幼鱼饲料转化率显著低于S12F24组(P<0.05),对照组饲料转化率低于S2F4组和S12F24组但没有显著差异(P>0.05)。对照组半滑舌鳎幼鱼的摄食率显著低于其它各组(P<0.05)。体成分组成中,蛋白含量随饥饿、投喂周期的延长而下降,S2F4组和对照组半滑舌鳎的蛋白含量没有显著差异(P>0.05)。S2F4组的耗氧率和排氨率均较低。对照组的摄食能显著高于其它各组(P<0.05),S2F4组的呼吸能占摄食能的比例显著高于对照组(P<0.05)。研究表明,半滑舌鳎幼鱼在循环投喂模式下,具有较强的补偿生长能力,S2F4组具有完全补偿生长能力;在较长的周期性饥饿条件下,半滑舌鳎幼鱼体内的蛋白质含量会受到显著影响。     

哲罗鱼继饥饿后的补偿生长及其机制

对平均初始体重为80 g的哲罗鱼(Hucho taimen)进行了8周养殖实验,以检验其继饥饿后的补偿生长。实验共设5个处理组,4组鱼分别被饥饿1周、2周、3周、4周后再恢复正常投喂,1组正常投喂作为对照,分别用S1、S2、S3、S4、C表示。实验结果显示:饥饿过程中各饥饿组鱼体重随饥饿时间的延长而逐渐下降,饥饿结束时S2、S3、S4组鱼体重均显著低于对照组(P<0.05),恢复投喂结束时S1、S2、S3组鱼体重与对照组无显著差异(P>0.05),S4组鱼体重与对照差异显著(P<0.05)。恢复投喂期间除S1组外其他饥饿组鱼的摄食率和特定生长率均显著高于对照组(P<0.05)。在饥饿过程中,其耗氧率随着饥饿时间的延长逐渐下降,恢复投喂后逐渐上升,其中S1、S2、S3组在各自恢复投喂后5 d、9 d、12 d恢复到对照组水平,而S4组则在其恢复投喂后24 d恢复到对照组水平。饥饿导致鱼躯干脂肪含量下降,躯干水分和灰分含量升高,蛋白质含量变化不大。恢复投喂结束时各饥饿组鱼躯干水分、脂肪、蛋白质含量与对照无显著性差异(P>0.05);躯干灰分含量除S4组显著高于对照组(P<0.05)外,其余与对照差异不显著(P>0.05)。实验结果表明,人工养殖哲罗鱼饥饿1~3周表现出完全补偿生长,饥饿4周表现出部分补偿生长。恢复投喂期间各饥饿组鱼对食物的利用效率得到明显提高,表明哲罗鱼恢复生长中出现的补偿生长效应主要是通过提高摄食水平和食物转化率共同作用实现的。     

饥饿和再投喂对白斑狗鱼生长性能和生化组成的影响

选用体重196.77±7.60g的白斑狗鱼（Esox Lucius Linnaeus）为研究对象，试验设置饥饿14d、21d、28d、35d、42d组和正常投喂对照组，各组饥饿结束后恢复饱食投喂，试验周期为56d，水温为22～26℃，研究了饥饿和再投喂对白斑狗鱼生长性能、体生化组成和肌肉、肝脏RNA/DNA比值的影响。结果表明：饥饿再投喂后各处理组均出现补偿生长现象，在恢复生长结束后，饥饿14d组体重显著高于对照组（P＜0.05），其他各饥饿处理组体重与对照组无显著性差异（P＞0.05）；随着饥饿时间的延长，饥饿各处理组肌肉的脂肪含量显著下降（P＜0.05），水分含量显著升高（P＜0.05），恢复投喂结束时各饥饿处理组蛋白质和水分含量恢复到对照组水平；在恢复投喂初期各处理组的特定生长率、摄食率和食物转化效率显著高于对照组水平（P＜0.05），随着恢复生长时间的延长，逐渐恢复到对照组水平（P＞0.05）；肌肉和肝脏的RNA/DNA比值均随饥饿时间的延长呈逐渐下降的趋势，在恢复投喂结束时，RNA/DNA比值均在饥饿28d组达到最大值。由此表明饥饿14d组的白斑狗鱼在恢复生长过程中出现了超补偿生长效应，21d组、28d组、35d组和42d组出现了完全补偿生长效应，该补偿效应是由摄食率和食物转化效率升高共同作用的结果。     

饥饿后再投喂对异育银鲫生长和体成分的影响

在(25±2)℃条件下,对体重(15.6±0.84)g的异育银鲫(Carassius auratus gibelio)进行了不同时间的饥饿处理和再投喂的恢复生长实验。实验把异育银鲫分为4组,为Ⅰ组(持续投喂48 d)、Ⅱ组(饥饿8 d后再投喂40 d)、Ⅲ组(饥饿16 d后再投喂32 d)和Ⅳ组(饥饿24 d后再投喂24 d),每组20尾鱼,研究再投喂后体重和体成分(粗蛋白、粗脂肪、水分和灰分)的变化。结果显示:与持续投喂组相比,饥饿8 d后异育银鲫体重下降了13.28%,饥饿16 d和24 d后体重分别下降了22.36%和33.03%。短期饥饿(Ⅱ)组,再恢复投喂8 d后能实现完全补偿生长,而中长期饥饿组(Ⅲ和Ⅳ)分别在投喂16 d和24 d后表现为部分补偿生长。在饥饿和恢复投喂过程中其体成分呈现规律性变化:各试验组饥饿后,粗蛋白和粗脂肪显著下降,而水分和灰分含量上升,而再投喂后,各营养成分逐渐恢复。Ⅱ组再投喂8 d后,粗脂肪和粗灰份恢复到对照组水平,蛋白质显著低于对照组水平,水分显著高于对照组;再投喂40 d后,粗蛋白和水分亦恢复到对照水平,Ⅲ组恢复投喂16 d后,粗蛋白、粗脂肪和灰分不能恢复到对照水平,恢复投喂32 d后,除灰分外,其余成分皆不能恢复到对照水平。Ⅳ组再投喂24 d后,除水分外,其余各营养成分皆不能恢复到对照水平。结果表明,实现异育银鲫完全补偿生长,其饥饿时间以短时间饥饿8 d为宜。     

饥饿不同时间后投喂对许氏平鮋生长及体成分的影响

在室内水温21.8~25℃条件下,将初始体质量为(8.87±0.16)g的许氏平鮋Sebastes schlegeli放养在50cm×50cm×100cm网箱中,饥饿0(S0)、3(S3)、6(S6)、9(S9)和12d(S12)后分别投喂30d、27d、24d、21d和18d,每组3个重复,测定其体质量、肥满度、脏体指数、肝体指数、摄食率、食物转化率及全鱼和肝脏主要生化组成的变化。结果表明:随着饥饿时间的延长,幼鱼体质量逐渐降低,各饥饿组鱼体质量显著低于同期对照组(P0.05)。恢复投喂后,S3组体质量、增重率(WGR)和特定生长率(SGR)显著高于对照组S0(P0.05),S6与S0组无显著差异(P0.05),而S9与S12组未能达到S0水平(P0.05)。S3组食物转化率(FCE)显著高于其余各组(P0.05),S9、S12组则显著低于对照组(P0.05)。饥饿状态下,各饥饿组鱼肝体指数与脏体指数显著小于S0组(P0.05));恢复投喂后各组肝体指数、脏体指数与对照组无显著差异。随着饥饿时间的延长,鱼体粗灰分含量显著升高(P0.05),水分与粗蛋白含量呈上升趋势(P0.05)。饥饿6d后,鱼体粗脂肪含量显著低于对照组,饥饿12d时粗脂肪含量比饥饿前降低了19.33%(P0.05)。恢复投喂后,各试验组间鱼体水分、粗蛋白、粗脂肪和粗灰分含量差异不显著(P0.05)。S9和S12组中肝脏粗脂肪含量显著低于S0组(P0.05)。     

Compensatory Growth of Olive Flounder,Paralichthys olivaceus,Fed the Extruded Pellet with Different Feeding Regimes

This study was performed to determine compensatory growth of juvenile olive flounder fed the extruded pellet (EP) with different feeding regimes. Seven treatments with triplicates of different feeding regimes were prepared; α fish was daily fed for 6 d a week throughout 8 wk (8WF); α fish was starved for 1 wk and then fed for 3 wk twice [(1WS + 3WF) × 2]; β fish was starved for 2 wk and then fed for 6 wk (2WS + 6WF); χ fish was starved for 5 d and then fed for 9 d four times [(5DS + 9DF) × 4]; δ fish was starved for 10 d and then fed for 18 d twice [(10DS + 18DF) × 2]; δ fish was starved for 2 d, fed for 5 d, starved for 3 d, and then fed for 4 d four times [(2DS + 5DF + 3DS + 4DF) × 4]; and φ fish was starved for 4 d, fed for 10 d, starved for 6 d, and then fed for 8 d twice [(4DS + 10DF + 6DS + 8DF) × 2], respectively. Total feeding day was all same, 36 d except for control group (48 d). Weight gain of flounder in the 8WF treatment was higher than that of fish in other treatments. And weight gain of flounder in the 2WS + 6WF treatment was higher than that of fish in the (5DS + 9DF) × 4 and (4DS + 10DF + 6DS + 8DF) × 2 treatments. Feed consumption of flounder in the 8WF treatment was higher than that of fish experienced feed deprivation. Feed efficiency ratio (FER), protein efficiency ratio (PER), and protein retention (PR) were not significantly different among treatments. Chemical composition of the whole body of fish with and without liver, except for moisture content of liver, was not different among treatments. T₃ level of fish in the 8WF and 2WS + 6WF treatments was higher than that of fish in the (5DS + 9DF) × 4 treatment. It can be concluded that juvenile olive flounder achieved better compensatory growth at 6‐wk refeeding after 2‐wk feed deprivation compared with that of fish with different feeding regimes. And T₃ level of fish seemed to partially play an important role in achieving compensatory growth.     

饥饿和补偿生长对点带石斑鱼幼鱼摄食和生长的影响

在水温29.2±0.2℃条件下,对点带石斑鱼幼鱼(1.832±0.03 g)进行了不同时间的饥饿后再供食的恢复生长试验。对照组(S0)持续投喂30 d,饥饿组S2、S4、S6、S8和S10分别饥饿2 d、4 d、6 d、8 d和10 d后再分别恢复投喂28 d、26 d、24 d、22 d和20 d。结果表明:饥饿组在恢复投喂后,体重迅速增重,且S2的体重超过了S0,但两者体重差异不显著(P>0.05),而其他各饥饿组的体重均显著低于S0和S2组(P<0.05)。点带石斑鱼经饥饿再恢复投喂,其特殊生长率和摄食率均显著高于S0(P<0.05);食物转化率呈波动变化,各饥饿组的食物转化率大部分均低于S0。比较分析认为,S2为完全补偿生长,其他各试验组为部分补偿生长,且这种补偿生长效应主要是通过恢复生长阶段提高摄食水平来实现。     

Effect of Dietary Lipid Level and Feeding Frequency on the Growth,Feed Utilization,and Body Composition of Juvenile Spotted Seabass,Lateolabrax maculatus

A 6‐wk feeding trial was conducted to evaluate the effects of different dietary lipid levels and feeding frequencies on the growth performance, feed utilization, and body composition of juvenile spotted seabass, Lateolabrax maculatus. Two experimental diets were prepared with two different dietary lipid contents, low lipid (7%; LL) and high lipid (14%; HL). Each diet was fed to triplicate groups of fish (5.5 ± 0.01 g) to apparent satiation at three meals per day, two meals per day, one meal per day, and one meal every 2 d, respectively, for 6 wk. Fish growth performance in terms of weight gain (WG) and specific growth rate (SGR) was significantly affected by frequency of feeding, with increasing values as feeding frequency increased up to twice daily, regardless of dietary lipid content. In addition, fish fed the diet with the HL level (14%) showed significantly higher WG and SGR than those fed the LL diet (7%) at all the feeding frequencies tested. Feed efficiency (FE) and protein efficiency ratio (PER) were affected by both dietary lipid level and feeding frequency. FE and PER values were significantly higher in fish fed the HL diet and/or when fish were fed twice or thrice a day. However, daily feed intake and daily energy intake were significantly affected only by feeding frequency and were significantly reduced when the fish were fed only once every 2 d compared with those fed more frequently. Whole‐body moisture content of fish tended to decrease with increasing dietary lipid level and frequency of feeding. In contrast, whole‐body lipid content increased in fish as dietary lipid level and feeding frequency increased. Consequently, we can conclude that feeding spotted seabass twice daily to apparent satiation is acceptable and sufficient to achieve good growth and FE, as fish performance was not significantly enhanced when feeding was increased from two to three times daily.     

Compensatory Growth of Juvenile Flounder Paralichthys olivaceus L. and Changes in Biochemical Composition and Body Condition Indices during Starvation and after Refeeding in Winter Season

Compensatory growth and changes in biochemical composition, hematocrit and body condition indices of juvenile flounder Paralichthys olivaceus were assessed during starvation and after refeeding. Twenty juvenile fish were stocked into each 200‐L flow‐through tank to give five treatments with three replicates per treatment: control group fish (C) were hand fed to apparent satiation twice daily for 8 wk, whereas the Sl, S2, S3, and S4 fish were hand fed to apparent satiation twice daily for 7, 6, 5, and 4 wk after 1, 2, 3, and 4 wk of starvation, respectively. During starvation, weight decreased linearly with periods of feed deprivation up to 3 wk. Survival was not significantly different among treatments. At the end of the feeding trial, weight gain (g/fish) and specific growth rate (SGR) of flounder in S2 was significantly (P < 0.05) higher than those of fish in S3 or S4, but not significantly different from those of fish in C or Sl. Feed consumption of flounder (g/fish) was proportional to duration of feeding except for that of fish in S2. Feed efficiency ratio (FER) and protein efficiency ratio (PER) values for flounder in S2 were significantly (P < 0.05) higher than those for fish in C, but not significantly different from those for fish in Sl, S3, or S4. During starvation, hepatosomatic index (HSI) and lipid content of flounder without liver decreased with periods of feed deprivation. However, HSI and condition factor (CF) for flounder in S2 were significantly (P < 0.05) higher than those for fish in Sl, S3, S4 and C except for CF in Sl at the end of the feeding trial. Proximate composition of flounder without the liver was not significantly different among treatments at the end of the feeding trial. In considering above results, juvenile flounder achieved compensatory growth with up to 2‐wk feed deprivation. Compensatory growth of flounder fed for 6 wk after 2‐wk feed deprivation was well supported by improvement in SGR, FER, and PER. HSI could be a good index to monitor changes in body condition during starvation and after refeeding.     

Compensatory Growth of Juvenile Olive Flounder, Paralichthys olivaceus L., and Changes in Proximate Composition and Body Condition Indexes during Fasting and after Refeeding in Summer Season

Compensatory growth of juvenile olive flounder, Paralichthys olivaceus L., and changes in proximate composition and body condition indexes of fish during fasting and after refeeding were investigated during the summer season. Groups of 25 fish each (initial body weight of 16 g) were randomly distributed into fifteen 180‐L flow‐through tanks. Fish were fed the experimental diet containing crude protein 46.9% and crude lipid 8.0% with estimated energy level of 14.6 kJ/g diet for 6 d/wk. Five treatments in triplicate were prepared for this study: C, S1, S2, S3, and S4. Fish in the control group (C) were hand‐fed to apparent satiation twice daily. Fish in treatments S1, S2, S3, and S4 experienced 1, 2, 3, and 4 wk of starvation and were then hand‐fed to apparent satiation twice daily during the remaining 7, 6, 5, and 4 wk of the experiment, respectively. A group of starved fish in the similar size was stocked and fasted throughout the 8‐wk feeding trial for chemical and blood analysis. The feeding trial lasted for 8 wk. Weight of fish linearly decreased with week of starvation (P < 0.0001). Linear relationship between condition factor (CF) and hepatosomatic index (HSI) against week of starvation was observed in the starved group of fish. Survival was not significantly (P > 0.05) affected by feeding strategy. However, weight gain and specific growth rate (SGR) of olive flounder in C, S1, and S2 were significantly (P < 0.05) higher than those of fish in S3 and S4. The poorest weight gain and specific growth rate (SGR) were obtained in fish of S4. Feed consumption of olive flounder in C, S1, and S2 was significantly (P < 0.05) higher than that of fish in S3 and S4. Feed efficiency, protein efficiency ratio, and protein retention of olive flounder in C and S1 were not significantly (P > 0.05) different from those of fish in S2 but significantly (P < 0.05) higher than those of fish in S3 and S4. Hematocrit, CF, and HSI of olive flounder were not significantly (P > 0.05) affected by feeding strategy. Chemical composition of fish was not significantly (P > 0.05) affected by feeding strategy. In considering these results, it can be concluded that juvenile olive flounder have the ability to fully compensate for 2‐wk feed deprivation during the summer season. Besides, feed efficiency in fish fed for 7 and 6 wk after 1‐ and 2‐wk feed deprivation was comparable to that in fish fed for 8 wk.     

Evaluation of mixed feeding schedules with respect to compensatory growth and body composition in African catfish Clarias gariepinus

An 8‐week feeding trial was conducted in a recycling water system at 28 ± 1 °C to investigate compensatory growth and body composition in African catfish Clarias gariepinus (13.05 ± 0.05 g). A fishmeal‐based diet containing 350 g kg^?1 protein and 17.5 kJ g^?1 gross energy was fed to triplicate groups of 20 fish (per 30‐L tank). Fish were fed the diet either to satiation or feed restricted in six feeding schedules as satiation 56 days; restricted 28 days + satiation 28 days; restricted 14 days + satiation 14 days; restricted 7 days +satiation 7 days; restricted 3 days + satiation 4 days; and restricted 2 days + satiation 2 days. The restricted regime was achieved by offering fish 1% (maintenance ration) of their body weight per day adjusted after fortnightly weighing. African catfish showed partial compensatory growth under alternating periods of feed restriction and satiation feeding with significantly different values (P < 0.05) from fish fed in satiation throughout. However, significantly indifferent (P > 0.05) values of feed, protein, lipid and energy utilization were found under alternating periods of feed restriction and satiation feeding. Significantly higher (P < 0.05) feed intake was observed in treatment with satiation throughout than those in other treatments. All the feeding schedules showed no significant differences (P > 0.05) on body composition, organ indices, eviscerated carcass composition, viscera lipid and liver lipid. These studies reveals that C. gariepinus showed partial compensatory growth responses at alternating periods of restricted and satiation feeding.     

Effect of feeding ratio on growth and body composition of juvenile olive flounder Paralichthys olivaceus fed extruded pellets during the summer season

The effect of feeding ratio on growth and body composition of juvenile olive flounder fed extruded pellets was determined during the summer season. Thirty juvenile olive flounder (initial body weight of 17 g) per tank were distributed into 21, 180-l flow-through tanks. Seven treatments that included triplicate groups of feeding ratio in 5% decrement were prepared for this study: 100% (satiation), 95%, 90%, 85%, 80%, 75% and 70% of satiation. Fish in the control group were hand-fed to apparent satiation twice a day. Then feed allowance in the rest of the six groups was determined based on average feed consumption in the control group. The feeding trial lasted for 7 weeks. Survival was over 97% and was not significantly (P > 0.05) affected by the feeding ratios. Weight gain and SGR of fish fed to 100% of satiation were not significantly different from those fed to 95% of satiation but significantly (P < 0.05) higher than those of fish fed to 90%, 85%, 80%, 75% and 70% of satiation. Weight gain, SGR and feed consumption of flounder linearly (P < 0.001) decreased with a decrease in feeding ratio. However, feed efficiency ratio, protein efficiency ratio and protein retention in fish body were not significantly (P > 0.05) affected by the feeding ratio. The crude protein levels of the whole body without liver or liver were significantly affected by the feeding ratio. Hepatosomatic index and condition factor of fish were not significantly (P > 0.05) affected by the feeding ratio. It can be concluded that optimum feeding ratio for growth of juvenile olive flounder could be lowered to 95% of satiation without growth suppression.