不同脂肪(能量)蛋白比饲料对梭鲈幼鱼生长的影响

比较了5种不同脂肪(能量)蛋白比的配合饲料对初始平均体重(7.75±1.17)g梭鲈幼鱼生长性能的影响。结果表明,投喂不同脂肪蛋白水平的饲料,以能量蛋白比为45.94kJ/g试验组的生长速度最快[SGR为(2.86±0.17)%/d]、饲料系数最低(FCR为1.57±0.12)、蛋白质沉积率和能量保留率最大,分别为98.44%±2.38%和30.88%±3.83%;以饲料中蛋白质含量、脂肪含量为变量因子,以梭鲈幼鱼的特定生长率、蛋白质沉积率和能量保留率为指标,通过二元二次回归方程得出梭鲈最大生长速度时饲料中蛋白质含量为39.80%,脂肪含量为8.79%,总能为18.53MJ/kg,脂肪蛋白比为0.22,能量蛋白比为46.56kJ/g;梭鲈获得最大的蛋白质沉积率时,饲料蛋白质含量为38.76%,脂肪含量为9.18%,总能为18.65MJ/kg,脂肪蛋白比为0.24,能量蛋白比为48.12kJ/g;梭鲈获得最大的能量保留率时饲料蛋白质含量为38.55%,脂肪含量为9.45%,总能为18.72MJ/kg,脂肪蛋白比为0.25,能量蛋白比为48.56kJ/g;饲料中脂肪水平的增加可以降低鱼类耗能时对蛋白质的需求量,表...     

养殖密度对克氏原螯虾幼虾生长、摄食和饵料利用影响

以体重(0.015±0.004)g克氏原螯虾(Procambarus clarkii)幼虾为研究对象,研究了50、100、300、600、900尾/m25种养殖密度对克氏原螯虾幼虾生长、摄食和饲料利用的影响,实验周期为30 d。结果显示:克氏原螯虾幼虾的体长、特定生长率、平均日增重、存活率和蜕壳率都随养殖密度的增大而减小,其中日增重由(0.007±0.002)g下降为(0.002±0.001)g,蜕壳率由(100±0.000)%下降为(37.222±3.928)%,降幅明显;体长、体重变动系数随养殖密度的增大而增大。每组个体的平均摄食量和摄食率均与养殖密度成反比。此结果表明养殖密度的增大总体来说不利于克氏原螯虾幼虾的生长和摄食。在饲料利用方面,饵料转化率在各养殖密度组之间无明显差异;蛋白质特定生长率、脂肪特定生长率和脂肪储积率随养殖密度增大呈减小趋势,蛋白质储积率呈增大趋势。     

底泥悬浮物对海水养殖凡纳滨对虾仔虾生物毒性影响

为评价疏浚、吹填过程中产生的底泥悬浮物对南海区凡纳滨对虾仔虾的毒性影响,根据《水质-物质对淡水鱼(斑马鱼)急性致死毒性的测定》方法,对南海区凡纳滨对虾仔虾的生物毒性影响进行了分析。结果表明:疏浚区海水中底泥悬浮物浓度超过10mg/L,持续12h,对凡纳滨对虾仔虾产生一定的致死效应。底泥悬浮物浓度超高80mg/L,且持续48h以上,将对仔虾产生严重的影响,甚至导致全部仔虾的死亡。根据仔虾的死亡概率和底泥悬浮物浓度对数,分别计算出12h、24h、36h、48h的半致死量(LC50)为54.56、40.29、25.89、19.18mg/L。     

饲料脂肪水平对江黄颡鱼幼鱼生长性能的影响

研究了饲料中脂肪水平对江黄颡鱼幼鱼(平均体重0.44g)生长性能的影响。实验共设5个水平组,饲料脂肪水平分别为3.77%,4.82%,7.29%,8.37%,9.87%。每组20尾,3个平行,饲养66d。结果显示:随着饲料脂肪水平的升高,江黄颡鱼幼鱼的饲料系数呈上升趋势,蛋白质效率则呈下降趋势,增重率和特定生长率呈抛物线变化,但饲料系数和蛋白质效率差异不显著(P0.05),增重率和特定生长率差异显著(P0.05)。江黄颡鱼幼鱼肝脏中脂肪的蓄积量随饲料中脂肪水平的增加而增加。综合各项指标并分析增重率、特定生长率与脂肪水平的回归性关系,可以推测江黄颡鱼幼鱼期的饲料脂肪水平应该维持在7.59%~7.65%。     

Dietary strategies to improve the growth and feed utilization of barramundi,Lates calcarifer under high water temperature conditions

Several dietary strategies to ameliorate poorer growth observed to occur at temperatures above the upper thermal optima were examined with juvenile barramundi (Lates calcarifer). A reference (REF) and three experimental diets, one with an increased protein to energy ratio (PRO), another with an increased level of the amino acid histidine (HIS) and a third with supplementation of dietary nucleotides (NUC), were each fed to fish at either 30 °C or 37 °C for a 28‐day period. Growth was affected by both temperature and diet. Fish fed the PRO diet at 30 °C grew fastest, but not faster than those fed the NUC diet at the same temperature. The addition of the amino acid histidine to the diet did not improve growth rates at either temperature. At water temperatures of 37 °C, only the fish fed the PRO diet had growth rates equivalent to those of fish at the 30 °C temperatures. Other key factors including feed intake, feed conversion rate, nutrient and energy retention and plasma enzymology were also all affected by temperature and diet. This study shows that the use of a diet with an increased protein to energy ratio provides significant benefits in terms of reducing the impact of growth retardation at higher temperatures.     

盐度对珍珠龙胆石斑鱼幼鱼渗透调节与耗氧率的影响

为研究盐度对珍珠龙胆石斑鱼（）渗透调节与耗氧率的影响,设计实验一,将（162.5±12.1）g珍珠龙胆石斑鱼置于不同盐度（6、12、18、24、30）下养殖10 d,测定血清渗透压及Na⁺、Cl^-、K⁺离子浓度。实验结果表明,随盐度的升高血清渗透压及Na⁺、Cl^-、K⁺离子浓度也随着升高,各组[Na⁺]：[Cl^-]比值无显著差异（>0.05）;经回归分析得到血清等渗点渗透压为365.95 mOsm/kg,所对应盐度为12.75。实验二,将（26.4±2.7）g幼鱼置于不同盐度（6、12、18、24、30）下养殖30 d,测定在开始暴露后0 h、3 h、24 h、72 h鳃Na⁺/K⁺-ATPase活性及表达和第30天耗氧率,结果表明鳃Na⁺/K⁺-ATPase活性随盐度的增大呈“U”形变化;鳃Na⁺/K⁺-ATPase α1基因表达量波动较大,在72 h后随盐度增大先降低后增加,变化趋势与酶活性一致;第30天耗氧率随盐度的增加先降低后增加又降低。综上所述,珍珠龙胆石斑鱼幼鱼10 d内能够完全适应6~30盐度急性变化,耗氧率除了受离子渗透调节的影响,还可能与其生活史阶段有关。     

Vitamin A functions and requirements in fish

Vitamin A (VA) is an essential dietary nutrient for fish and plays an important role in a range of physiological processes including vision, reproduction, embryogenesis, growth and differentiation and maintenance of epithelial cells. Knowledge of effects of VA on aquatic organisms is limited, but new information continues to be published. The aim of the present review is to present an overview of the dietary requirements and functions of VA in fish of commercial importance in aquaculture production. The effects of VA on reproduction and early embryonic development are described, and the estimated dietary requirements for VA of several species of fish are discussed. New research findings on how VA requirements vary with the life stages of fish are explored that will expand understanding of the complex role of VA. Sources of VA in feeds are described, and the potential need to consider how changes in fish feed formulations towards higher use levels of sustainable ingredients may affect dietary VA supplementation recommendations is discussed.     

Diurnal stream habitat use of juvenile Atlantic salmon, brown trout and rainbow trout in winter

Abstract  The diurnal winter habitat of three species of juvenile salmonids was examined in a tributary of Skaneateles Lake, NY to compare habitat differences among species and to determine if species/age classes were selecting specific habitats. A total of 792 observations were made on the depth, velocity, substrate and cover (amount and type) used by sympatric subyearling Atlantic salmon, subyearling brown trout and subyearling and yearling rainbow trout. Subyearling Atlantic salmon occurred in shallower areas with faster velocities and less cover than the other salmonid groups. Subyearling salmon was also the only group associated with substrate of a size larger than the average size substrate in the study reach during both winters. Subyearling brown trout exhibited a preference for vegetative cover. Compared with available habitat, yearling rainbow trout were the most selective in their habitat use. All salmonid groups were associated with more substrate cover in 2002 under high flow conditions. Differences in the winter habitat use of these salmonid groups have important management implications in terms of both habitat protection and habitat enhancement.     

盆地环境条件下幼蟹养殖对水环境影响的初步研究

为探究盆地环境条件下中华绒螯蟹幼蟹养殖对水环境的影响,于2021年5—9月对四川开江地区幼蟹养殖池塘及其水源的温度、溶解氧等11项水质因子进行监测,并采用单样本t检验法进行分析。结果表明,养殖期间,幼蟹养殖池塘水体电导率、水温、亚硝态氮和硝态氮含量与水源水体差异显著（P<0.05）,pH、溶解氧和氨氮含量总体低于水源水体。幼蟹养殖池塘水体可溶性磷酸盐、高锰酸盐指数、总氮和总磷含量均超出Ⅲ类水域标准。盆地环境条件下中华绒螯蟹幼蟹养殖期间除总氮、可溶性磷酸盐、总磷和高锰酸盐指数外,其他水质指标基本符合地表水环境质量的III级标准和渔业水质标准,且养殖后期幼蟹池塘可溶性磷酸盐、总磷和高锰酸盐指数较水源水体差,表明幼蟹养殖对水环境存在一定污染,应当在幼蟹养殖过程中及养殖结束后对水环境进行改善和处理。养殖期间定期使用微生态制剂和养殖结束后对尾水进行净化处理是未来提高盆地环境条件幼蟹养殖生态效益的两大方向。     

添加嗜酸乳杆菌对凡纳滨对虾生长、酶活性及相关酶mRNA表达的影响

本实验旨在研究饲料中添加嗜酸乳杆菌(Lactobacillus acidophilus)对凡纳滨对虾(Litopenaeus vannamei)幼虾生长、非特异性免疫酶活性、抗病力和相关酶m RNA表达的影响。选取840尾初始均重为(0.58±0.01)g的凡纳滨对虾幼虾为研究对象,分为7个处理,每个处理3个重复。投喂添加不同比例(0%,0.1%,0.2%,0.4%,0.6%,0.8%,1.0%)嗜酸乳杆菌的饲料,养殖期8周。结果显示:添加不同比例嗜酸乳杆菌对凡纳滨对虾的成活率无显著影响(P0.05)。增重率与特定生长率随添加量的增加呈先上升后下降的趋势,但均显著高于对照组(P0.05),在0.4%组达到最大值;当添加0.2%时,饲料系数最低,其他各组显著低于对照组(P0.05),而蛋白质效率的变化规律则与饲料系数相反。血清酚氧化物酶(phenoloxidase,PO)、碱性磷酸酶(alkaline phosphatase,AKP)和酸性磷酸酶(acid phosphatase,ACP)活性随添加量的增加先升高后降低,分别为0.4%、0.1%和0.2%时,达到最大值。过氧化氢酶(catalase,CAT)、溶菌酶(lysozyme,LZM)和超氧化物歧化酶(superoxide dismutase,SOD)活性,实验组均显著高于对照组(P0.05)。实验组过氧化氢酶(CAT)m RNA表达量和溶菌酶(LZM)m RNA表达量均显著高于对照组(P0.05)。哈维弧菌(Vibrio harveyi)攻毒96 h,对虾存活率随添加量的增加显著升高(P0.05)。以增重率(weight gain rate,WGR)为判断依据,根据折线模型得出,饲料中添加0.23%嗜酸乳杆菌可显著促进凡纳滨对虾生长,并提高非特异性免疫酶活性。