养殖密度对克氏原螯虾大规格苗种生长和存活的影响

以体重(2.03±O.19)g克氏原螫虾(Procambarus clarkii)大规格苗种为研究对象,研究了26℃下,27、36、45、55、64、73尾/m~2 6种养殖密度下,克氏原螯虾大规格苗种生长及存活情况。实验周期为32 d。结果显示:克氏原螯虾幼虾的体长增长、平均日增重、增重率和存活率都随养殖密度的增大而降低,其中日增重由0.110 6 g下降到0.067 8 g,存活率由100%下降到63%。结果表明,养殖密度的增大不利干克氏原螯虾苗种的生长和存活,养殖密度为45尾/m~2是克氏原螯虾大规格苗种生长的最佳密度。     

克氏原螯虾掘洞行为研究

克氏原螯虾(Procam barus clarkii)掘洞时间多在夜间,可持续掘洞6~8 h,一夜挖掘深度成虾可达40 cm,幼虾可达25 cm。成虾的洞穴深度大部分在50~80 cm之间,少部分可以达到80~150 cm;幼虾洞穴的深度在10~25 cm之间;体长1.2 cm的稚虾已经具备掘洞的能力,洞穴深度在10~20 cm之间。洞穴分为简单洞穴和复杂洞穴两种:85%的洞穴是简单的,即只有一条穴道,位于水面上、下10 cm之间;15%较复杂,即有2条以上的穴道,位于水面以上20 cm处。洞穴的密度为2.8~5.6个/m2。每个洞穴中一般有1~2只虾,但冬季也常发现一个洞中有3~5只虾。克氏原螯虾在繁殖季节掘洞强度增大,在寒冷的冬季,掘洞强度微弱。     

盐度对克氏原螯虾幼虾生长的影响

研究了不同盐度对克氏原螯虾幼虾生长的影响.试验于水族箱内进行,试验幼虾的初始体质量(1.82±0.21)g,体长(3.13±0.30)cm.在25 ℃条件下,试验设置0、2、4、6、8、10、12、14计8个盐度梯度,试验结果表明,盐度为0～14时,克氏原螯虾的幼体均能存活与生长.盐度为0～6,成活率较高,生长较快,饵料系数较低,各项指标与对照组差异不显著(P>0.05).当盐度超过此范围时,随着盐度增加,幼虾的成活率下降,生长变慢,饵料系数增大,与对照组差异显著(P<0.05).     

谷胱甘肽对克氏原螯虾生长和抗高温应激的影响

为探明谷胱甘肽(GSH)对克氏原螯虾(Procambarus clarkii)生长和抗高温应激能力的影响,将实验虾随机分成6组,每组设置3个平行,每个平行30尾虾,空白对照组投喂市售商品饲料,另外5组分别投喂谷胱甘肽添加量为0.06、0.12、0.18、0.24、0.3 g/kg的饲料.饲养6周后,测定各实验组的增重率...     

不同克氏原螯虾养殖模式下幼虾生长、体成分和血淋巴生化指标的比较

为几种克氏原螯虾(Procambarus clarkii)养殖模式的优劣提供数据参考,对池塘单养克氏原螯虾、虾鱼混养、虾蟹混养、稻虾养殖四种模式进行比较,研究了其水体理化指标、幼虾生长、体成分、血淋巴生化等指标,试验周期60 d.结果 表明:体长和体重均呈现虾单养组＞虾鱼组＞虾蟹组＞稻虾组;克氏原螯虾的体长增长率随时间...     

克氏原螯虾繁殖生物学研究

对克氏原螯虾(Procambarus clarkii)繁殖生物学进行了研究。结果显示:克氏原螯虾的性成熟年龄为1年左右;雌虾最小体长为6.4 cm,最小体重为10 g;雄虾最小体长为7.1 cm,最小体重为20 g。5~9月为交配期,其中以6~8月为交配高峰期。克氏原螯虾交配后大约为30 d左右产卵。繁殖期为7~10月,高峰期为8~9月。10月底以后抱卵的虾由于水温逐步降低,一直延续到第2年春季才孵化。克氏原螯虾的繁殖行为与掘洞行为密切相关,繁殖期的掘洞数量较非繁殖期明显增多。7~10月,亲虾均栖息在洞内繁殖,洞穴深度为50~80 cm。卵巢为一次产卵类型。雌雄比例为1∶1。克氏原螯虾的个体绝对繁殖力的变动范围为172~1158粒,平均为517粒。个体相对繁殖力(F/W)的变动范围为2~41粒/g,平均为21粒。个体相对繁殖力(F/L)的变动范围为47~80粒/cm,平均为63粒。     

13种稻田常用农药对克氏原螯虾幼虾的急性毒性

本研究采用室内静水法(试验用水pH 7.48,温度(25±1)℃,水体耗氧量≤1.2 mg/L)测定了13种水稻田常用药剂对质量约8～15 g的克氏原螯虾(Procambarus clarkii)幼虾的急性毒性。结果显示：60 g/L二甲四氯·400 g/L灭草松、200 g/L氯虫苯甲酰胺、10%井冈霉素、50%戊唑醇·25%肟菌酯和30%吡唑醚菌酯等5种药剂在10 000 mg/L攻毒条件下试验虾72 h的存活率均为100%,稻虾田可放心使用;50%丁草胺、10%氰氟草酯、25 g/L五氟磺草胺、20%氯氟吡氧乙酸、20%烯啶虫胺·80%吡蚜酮、5%阿维菌素乳油、5%阿维菌素水分散粒剂、3%阿维菌素微乳剂等8种药剂对克氏原螯虾幼虾的24 h LC₅₀分别为1 945.36、112.85、2 884.03、141.25、5.13、39.58、275.42、358.92 mg/L;48 h LC₅₀分别为931.11、74.56、2 275.10、117.49、4.07、37.15、173.78、272.27 mg/L;72 h LC     

冬季温度刺激对克氏原螯虾繁育的影响

通过加温刺激克氏原螯虾(Procambarus clarkii)雌虾在冬季抱卵,并对卵及幼体在不同水温下的发育过程进行观察。结果显示:经过38 d的加温刺激,在26℃下陆续观察到有虾抱卵,18℃以下未观察到抱卵虾,但该水温能促进雌虾性腺发育。雌虾经加温刺激后所抱卵在18℃,21℃和26℃下均能正常孵化出幼虾。18℃,21℃和26℃下孵化时间分别为(39.67±3.06)d,(28.33±2.52)d和(15.00±2.00)d,孵化所需时间随着温度的提升而减少(P<0.05)。孵化的幼虾经45 d养殖后,在18℃,21℃和26℃下体长分别为(1.90±0.25)cm,(2.73±0.38)cm和(3.78±0.70)cm,体重分别为(0.223±0.100)g,(0.688±0.331)g和(2.145±1.272)g。18℃,21℃水温下的幼虾在此生长阶段为非异速生长(b=3),26℃水温下的幼虾为异速生长(b>3)。在3种温度下,幼体生长速度随温度的升高明显加快(P<0.05)。     

不同脂肪源对克氏原螯虾生长性能与肠道菌群的影响

为研究饲料中不同脂肪源对克氏原螯虾(Procambarus clarkii)生长、营养代谢及其肠道菌群组成的影响,本实验通过在人工配合饲料中分别添加5%的豆油(SO)、鱼油(FO)、猪油(LO)和混合油(豆油∶鱼油=1∶1,MO)作为主要脂肪源,对克氏原螯虾进行60 d饲喂实验后检测其生理生化指标与肠道菌群组成。结果显示：不同脂肪源对克氏原螯虾存活率与特定生长率影响显著,MO组存活率与特定生长率均为最高,LO组均显著低于其他组;营养代谢指标检测结果显示,LO组肝胰脏的脂肪酶、谷丙转氨酶、谷草转氨酶和血清的总胆固醇均显著高于其他实验组;运用16S rDNA高通量测序技术对肠道微生物组成进行测定,结果显示四个组共有优势菌属只有拟杆菌属(Bacteroides),可见脂肪源是克氏原螯虾肠道菌群的较大影响因素;未知的RsaHf231菌属和Anaerorhabdus＿furcosa＿group属是除了SO组外其他三组的共有优势菌群;柠檬酸杆菌属(Citrobacter)是SO组和FO组的优势菌群;Candidatus＿Bacilloplasma是MO组特有优势菌群。综上所述,混合油更能满足克氏原...     

复方中草药对克氏原螯虾生长和脱壳的影响

研究了饲料中添加复方中草药(质量分数为1%,2%和4%)对克氏原螯虾(Procambarus clarkii)生长和脱壳的影响。结果显示,添加复方中草药后,虾的脱壳周期缩短,脱壳死亡率和非脱壳死亡率均明显降低(P<0.05),但各中草药添加组间差异不显著(P>0.05)。三个剂量的复方中草药添加组均能不同程度地提高虾的脱壳数、成功脱壳数、硬壳虾重和软壳虾重,与未添加组相比差异显著(P<0.05),其中2%组增加最为显著,分别比对照组高出71.1%、103.2%、20.3%、10.0%。回归分析表明,克氏原螯虾的特定生长率达到最大值时的中草药添加质量分数为2.74%。试验表明克氏螯虾饲料中复方中草药水平以2%左右为宜。     

Effects of density on growth and survival of juvenile Red Swamp Crayfish, Procambarus clarkii (Girard), reared under laboratory conditions

The aim of this study was to quantify the importance of population density on the growth and survival of juvenile red swamp crayfish, Procambarus clarkii (Girard), and to understand the effects of density on both the period between moults and the increment per moult at high densities without food limitation. A laboratory experiment was performed to determine growth and survival of juvenile crayfish at five densities (20, 40, 60, 80 and 100 crayfish m^?2). Density clearly affected crayfish growth. The impact of density on final weight was higher than on total length increase, growth rate and final length (FL) (by decreasing order of effect). When comparing minimum and maximum densities, we observed that FL suffered a 34% reduction. Number of moults, mean intermoult period (IP) and survival were not significantly affected by density. Our results indicated that the IP and the percentage of increment per moult are affected by the size of crayfish before moult and we provide equations for these relations. Our findings are relevant both for crayfish aquaculture management and for the management of wild or harvested rice‐field crayfish populations.     

Effects of feeding frequency and feed type on the growth,feed utilization and body composition of juvenile olive flounder,Paralichthys olivaceus

A factorial (3 × 4) feeding trial was conducted to investigate the effects of feeding frequency and feed type on the growth performance, feed utilization and body proximate composition of juvenile olive flounder. Three feed types including a sinking moist pellet (MP), a sinking dry pellet (DP) and a floating extruded pellet (EP) were used. Fish (average weight, 11.1 ± 0.4 g) were randomly distributed in thirty‐six 300 L tanks in a flowthrough system. Triplicate groups (30 fish per tank) of fish were fed each feed type to visual satiation at three meals per day, two meals per day, one meal per day and one meal every 2 days for 7 weeks. At the end of the feeding trial, the survival of fish was not significantly different among the treatments. Weight gain was affected by the feeding frequency. The highest weight gain was observed in fish fed the EP at three meals per day. The daily feed intake of fish fed the MP and DP tended to be higher than that of fish fed the EP at each feeding frequency. The feed efficiency and the protein efficiency ratio of fish fed the EP were higher than those of fish fed the MP and DP. The body proximate composition of fish was altered by the feeding frequency. The crude lipid content increased with the increase in the feeding frequency. The present findings suggest that three feedings per day at visual satiation of the floating EP may be sufficient for the maximal growth performance of olive flounder grown from 11 to 60 g.     

Shadow area and partitioning influencing mortality,healthiness and growth of juvenile Red Swamp Crayfish Procambarus clarkii (Decapoda)

Crayfish show both shelter‐seeking behaviour and agonistic behaviour. Agonistic interactions among crayfish combatants can be triggered and released by the access of shelter, which is a necessary resource for crayfish. The use of shadow as a shelter has not been thoroughly tested in experiments. In this study, we provided the Red Swamp Crayfish Procambarus clarkii (Girard) with different shadow area and shadow partition to test if shadow can act as a solid shelter. Eleven different treatments designed with different shadow area and partition, and 2640 juvenile crayfish were used. The survival rate increased with the increase of shadow area ratio. The shadow area contributed less to the body weight gain and the number of the survivals without injury. The growth variance of the juveniles under shadow conditions was significantly lower than those maintained without providing shadow. Under the recent experimental settings, generally, more partitioned shadow resulted in lower mortality. With 60% shadow area, more partitioned shadow led to higher body weight gain. The more the partition was provided, the fewer were the injury events, and the lower body weight variance observed. Our experiments indicated that both area and partition of the shadow influenced the growth of juvenile Red Swamp Crayfish.     

盐度对克氏原螯虾幼虾耗氧率和排氨率的影响

研究了不同盐度对克氏原螯虾幼虾耗氧率和排氨率的影响.试验用虾体长(3.13±0.30) cm,体质量(1.82±0.21) g.25 ℃条件下,试验设置盐度0、2、4、6、8、10、12七个梯度.结果表明,试验范围内,盐度为2时,克氏原螯虾幼虾的耗氧率与排氨率最低,表明幼虾对盐度调节的等渗点约为2.随着盐度升高,幼虾的耗氧率和排氨率上升,Tukey HSD test发现,对照组、2、4、6盐度组的耗氧率、排氨率差异不明显.盐度超过0～6时,幼虾的耗氧率、排氨率影响与对照组相比差异显著.     

Replacing fish meal with vegetable protein sources in feed for juvenile red swamp crayfish,Procambarus clarkii: Effects of amino acids supplementation on growth and feed utilization

An 8‐week growth trial was conducted to investigate the effects of dietary fish meal replacement with a vegetable mixture of soybean meal and rapeseed meal (1:1) on growth of juvenile red swamp crayfish. Nine isonitrogenous diets were designed: V0, V34, V50, V65, V73 and V81 with six levels of vegetable proteins, and VA48, VA63 and VA78 by further adding crystalline lysine and methionine into V50, V65 and V81. Compared with V0, V34 significantly improved the specific growth rate (SGR), while V65, V73, V81 and VA78 depressed the SGR (p < .05). Feeding rate showed a decreasing trend as dietary vegetable protein level increased (p < .05), except that in VA48 group. Significantly lower FCR and higher PER were observed in V34 group, whereas all vegetable protein diets depressed the feed utilization of crayfish (p < .05). Crayfish fed with diets containing vegetable proteins showed significantly lower hepatosomatic indices and higher condition factors than the control (p < .05). Muscle lipid content was significantly (p < .05) lowered in V81 group, but not in VA78 group. The results suggested that 338 g/kg vegetable protein improved growth performance of crayfish. Excessive vegetable protein depressed the growth of crayfish, which could be prevented by lysine and methionine supplementation except for the all vegetable protein diets.     

饲料脂肪水平对克氏原螯虾幼虾生长性能及肌肉品质的影响

本研究旨在探讨饲料脂肪水平对克氏原螯虾(Procambarus clarkii)幼虾生长性能和肌肉品质的影响。实验选取600尾初始体重为(4.00±1.00) g的克氏原螯虾幼虾,随机分为5组(L1、L2、L3、L4和L5组),分别投喂脂肪水平为2.86%、5.11%、7.67%、10.19%和13.02%的等氮实验饲料,养殖周期为60 d。结果显示,随着脂肪水平的升高,特定生长率(SGR)呈先升高后降低的趋势(P<0.05),饲料系数(FCR)呈先降低后升高的趋势(P<0.05),L3组的FCR显著低于其余组(P<0.05);对SGR进行折线回归分析,得出最适脂肪含量为6.82%。饲料脂肪水平对克氏原螯虾肌肉的水分、粗蛋白和粗灰分含量无显著影响(P>0.05);随着饲料脂肪水平的增加,肌肉的蒸煮损失率、粗脂肪含量、总多不饱和脂肪酸(∑PUFA)和总氨基酸(∑TAA)含量呈上升趋势,L5组的二十碳五烯酸(EPA)显著高于其余组,L5组的二十二碳六烯酸(DHA)含量显著高于L1和L2组(P<0.05);随着饲料脂肪水平的增加,肌肉硬度、弹性、凝聚性和黏性呈下降趋势,且L1~L3组间均无显著差异(P>0.05),L5组的总鲜味氨基酸(∑FAA)、丙氨酸(Ala)及天门冬氨酸(Asp)的含量显著低于L1组(P<0.05)。综上所述,适宜的饲料脂肪含量可以提高克氏原螯虾幼虾的生长性能和肌肉的营养品质,在本实验条件下,克氏原螯虾幼虾饲料中脂肪的建议添加量为6.82%~10.19%。     

投喂频率对龙虎斑幼鱼生长和饵料利用的影响

在室内车间采用4种不同的投喂频率养殖龙虎斑幼鱼（47．6±5．2 g）,分析和比较不同投喂频率对其生长和饵料利用的影响。试验设S1、S2、S3、S4共4组,分别按照1、2、3、4次/d进行投喂,共进行60 d。结果显示：（1）投喂频率显著影响龙虎斑幼鱼的生长（P＜0．05）。 S1的平均体质量显著低于S2、S3、S4（P＜0．05）,为149．7 g;S2、S3、S4组间差异不显著（P＞0．05）,S4最大（168．7 g）,其次为S3（168．0 g）和S2（162．2 g）;S1日增体质量、增重率、特定生长率显著小于S2、S3、S4（P＜0．05）,分别为1．68 g,204．83％,1．86％/d,S2、S3、S4组间差异不显著（P＞0．05）,S2特定生长率最大,为2．12％/d;S2的体质量回归方程斜率最大,为1．915,S1最小,为1．532。（2）投喂频率对龙虎斑幼鱼的饵料利用影响显著（P＜0．05）。 S2的摄食率和饵料系数显著小于S1、S3、S4（P＜0．05）,分别为1．31％/d、0．70;S4摄食率最大,为1．64％/d;S1、S3、S4组间饵料系数差异不显著（P＞0．05）,分别为0．88、0．84、0．88。因此,综合养殖效果和劳动强度考虑,S2的投喂频率最适合龙虎斑的养殖,建议在龙虎斑的养殖生产中,最适宜的投喂频率为2次/d。     

养殖密度对克氏原螯虾生长及消化酶、免疫酶活性的影响

水温(25±1)℃时,将体质量(3.11±0.10)g的克氏原螯虾幼虾饲养在120 cm×60 cm×20 cm的水族箱中,密度分别为14尾/m2(低密度组)、28尾/m2(中密度组)和42尾/m2(高密度组),研究室内养殖不同密度对生长、摄食、消化酶活性及非特异性免疫的影响.8周的养殖结果显示,克氏原螯虾的存活率随养...     

Effect of combined photoperiod, water calcium concentration and pH on survival, growth, and moulting of juvenile crayfish (Procambarus clarkii ) cultured under laboratory conditions

The red swamp crayfish, Procambarus clarkii (Girard), is one of the most commonly farmed freshwater species in inland China due to its high market value and consumer demand. The aim of this study was to determine the optimum combinations of photoperiod, water calcium concentration and pH for juvenile survival, growth and moulting. In our orthogonal experiment, the three environmental factors were varied at three levels (photoperiod: 16L:8D, 12L:12D and 8L:16D; calcium concentration: 45.5, 65.5 and 85.5 mg L⁻¹; and pH: 6.8, 7.8 and 8.8). Range analysis showed that the maximum survival of juvenile crayfish occurred at photoperiods of 16L:8D or 8L:16D, water calcium concentration of 45.5 mg L⁻¹ and pH of 7.8; maximum weight gain at photoperiod 16L:8D, water calcium concentration 65.5 mg L⁻¹ and pH 7.8; maximum length increase at photoperiod 16L:8D, water calcium concentration 65.5 mg L⁻¹ and pH 7.8; and the highest moult frequency at photoperiod 12L:12D, water calcium concentration 65.5 mg L⁻¹ and pH 7.8. Analysis of variance indicated that photoperiod, water calcium concentration and pH significantly influenced only the weight gain of juvenile crayfish ( P <0.05). Taking growth into consideration, we suggest that a photoperiod of 16L:8D, calcium concentration of 65.5 mg L⁻¹ and pH 7.8 might be optimal conditions for rearing juvenile P. clarkii .