不同玉米脱水酒精糟及其可溶物含量饲料中添加非淀粉多糖酶对大菱鲆幼鱼生长性能、营养物质消化率及抗氧化能力的影响

本试验旨在研究不同玉米脱水酒精糟及其可溶物(DDGS)含量饲料中添加非淀粉多糖酶对大菱鲆幼鱼生长性能、营养物质消化率及抗氧化能力的影响。选用720尾初重为(13.00±0.01)g的大菱鲆幼鱼,随机分为8个组,每个组设3个重复,每个重复30尾鱼。D3、D6、D9、D12组为不加酶对照组,分别饲喂以玉米DDGS替代基础饲料中3%、6%、9%、12%鱼粉的试验饲料;D3+、D6+、D9+、D12+组为加酶试验组,分别饲喂以玉米DDGS替代基础饲料中3%、6%、9%、12%鱼粉并添加木聚糖酶(活性为120 163U/g,添加量为20g/t)和纤维素酶(活性为13 424U/g,添加量为300g/t)的试验饲料。试验期为9周。结果表明:大菱鲆幼鱼饲喂相同玉米DDGS含量的饲料时,加酶试验组的终末体重、增重率、特定生长率、饲料效率均高于不加酶对照组,但差异未达显著水平(P0.05)。各组大菱鲆幼鱼摄食率以及全鱼水分、粗蛋白质、粗脂肪含量无显著差异(P0.05),肥满度、肝体比和脏体比也无显著差异(P0.05)。大菱鲆幼鱼饲喂相同玉米DDGS含量的饲料时,加酶试验组的干物质和粗蛋白质表观消化率均高于不加酶对照组,其中D9+组的干物质表观消化率较D9组显著升高(P0.05),D3+组的粗蛋白质表观消化率较D3组显著升高(P0.05),D12+组的粗蛋白质表观消化率较D12组显著升高(P0.05)。大菱鲆幼鱼饲喂相同玉米DDGS含量的饲料时,加酶试验组大菱鲆幼鱼血清超氧化物歧化酶和谷胱甘肽过氧化物酶的活性均较不加酶对照组显著提高(P0.05),血清丙二醛的含量较不加酶对照组显著降低(P0.05)。由此得出,在不同玉米DDGS含量饲料中添加非淀粉多糖酶提高了大菱鲆幼鱼对饲料的利用效果。     

Effects of temperature on non-specific immune parameters in two scallop species: Argopecten irradians (Lamarck 1819) and Chlamys farreri (Jones & Preston 1904)

The effect of chronic (2 weeks) temperature (19, 22, 25, 28 and 31°C) on certain non‐specific immune parameters of two species of scallops, Argopecten irradians (Lamarck 1819) and Chlamys farreri (Jones & Preston 1904) were studied. The survival ratio of the two species of scallops at 31°C was the lowest. Haemocyte concentration of C. farreri in the 19 and 22°C treatment groups was significantly lower than that of the 25 and 28°C treatment groups but significantly higher than that of the 31°C treatment group. With elevation of seawater temperature, the alkaline phosphatase (ALP) and acid phosphatase (ACP) activities in sera of two scallop species increased and reached the peak at 25°C and then decreased. However, the specific activity of ALP and ACP of the 31°C treatment group was the highest. The results demonstrated that temperature of seawater significantly affected immunity of scallops. The concept that the stress of high environmental temperature on C. farreri may be partially responsible for the mass mortality of the organism is also introduced.     

Effect of high dietary intakes of vitamin E and n-3 HUFA on immune responses and resistance to Edwardsiella tarda challenge in Japanese flounder (Paralichthys olivaceus, Temminck and Schlegel)

A feeding experiment was conducted to investigate the effects of high dietary intake of vitamin E (supplied as dl ‐α‐tocopheryl acetate) and n‐3 highly unsaturated fatty acid (n‐3 HUFA) on the non‐specific immune response and disease resistance in Japanese flounder Paralichthys olivaceus. Nine practical diets were formulated to contain one of three levels of vitamin E namely, 0, 80 or 200 mg kg^?1 (the total α‐tocopherol contents in the diets were 21, 97 and 213 mg kg^?1 based on analysis), and at each vitamin E level with one of three n‐3 HUFA levels i.e. 0.5%, 1.5% or 2.0%. Each diet was randomly assigned to triplicate groups of Japanese flounder (initial body weight: 40.5±1.0 g, mean±SD) in a re‐circulation rearing system. Fish were fed twice daily to apparent satiation at 07:00 and 18:00 hours for 12 weeks. During the experimental period, water temperature was maintained at 18±1°C, salinity 31–35 g L^?1, and pH 7.8–8.2. Dissolved oxygen was not less than 6 mg L^?1, and there were negligible levels of free ammonia and nitrite. The results showed that the increase in dietary n‐3 HUFA from 0.5% to 1.0% significantly decreased muscle α‐tocopherol contents in fish‐fed diets with 21 and 97 mg α‐tocopherol kg^?1 diet (P<0.05). In 1.0% HUFA groups, alternative complement pathway activity (ACH₅₀) of fish fed the diet containing the 213 mg α‐tocopherol kg^?1 diet was significantly higher than noted for fish fed the diet containing 97 mg α‐tocopherol kg^?1 diet (P<0.05). Fish fed the diet with 213 mg α‐tocopherol kg^?1 and 2.0% n‐3 HUFA had the highest lysozyme activity (131.7 U mL^?1) among all the dietary treatments. Fish fed the diets containing 97 and 213 mg α‐tocopherol kg^?1 with 1.0% n‐3 HUFA had significantly higher respiratory burst activity than those fed the diets containing 21 mg α‐tocopherol kg^?1 with 0.5 and 1.0% n‐3 HUFA (P<0.05). In the disease resistance experiment, high intake of dietary vitamin E with 213 mg α‐tocopherol kg^?1 significantly decreased cumulative mortality and delayed the days to first mortality after a 7‐day Edwardsiella tarda challenge (P<0.05). In addition, under the experimental conditions, dietary vitamin E and n‐3 HUFA had a synergistic effect on the non‐specific immune responses and disease resistance in Japanese flounder (P<0.05).     

大豆浓缩蛋白替代鱼粉对大菱鲆摄食、生长及体组成的影响

研究了大豆浓缩蛋白(SPC)替代鱼粉对大菱鲆生长及生理生化指标的影响。5种饲料分别含有0、12.0%、25.0%、37.0%和49.5%的SPC以替代相应的鱼粉,并分别添加0、0.83%、1.65%、2.48%和3.30%的必需氨基酸混合物(L-lysine∶DL-methionine∶L-leucine∶Lvaline∶L-threonine=18∶6∶3∶2.5∶2)以平衡各组饲料的氨基酸组成。每种饲料投喂3个水族箱(300 L),每个水族箱放养实验鱼16尾,实验鱼初始体质量为(31.1±0.1)g。经过9周生长实验,结果显示随着饲料中SPC替代水平的升高,大菱鲆摄食率、特定生长率均显著下降(P0.001)。然而,当使用0~37.0%的SPC替代鱼粉时,各处理组饲料效率和蛋白质效率未出现显著差异(P0.05)。饲料中SPC替代鱼粉对大菱鲆鱼体水分、粗蛋白、粗脂肪及灰分含量均无显著影响(P0.05)。各处理组干物质和粗蛋白的表观消化率之间也未出现显著差异(P0.05)。研究表明,在本实验条件下SPC不能作为大菱鲆饲料中替代鱼粉的有效蛋白源,造成SPC替代效果较差的主要原因是其对大菱鲆饲料适口性的显著影响。     

饲料中添加姜黄素对大菱鲆幼鱼生长、体组成及抗氧化酶活力的影响

为研究饲料中添加姜黄素对大菱鲆幼鱼生长、体组成及血清抗氧化酶活力的影响,在饲料中分别添加0、0.02%、0.04%和0.06%的姜黄素,配制成4种等氮等脂的实验饲料。选择初始体质量(5.12±0.04)g大菱鲆幼鱼420尾,随机分成4组,每组3个重复,每个重复35尾鱼。每种饲料随机饲喂1组实验鱼,养殖周期为77 d。结果显示,饲料中添加姜黄素对大菱鲆幼鱼的成活率(SR)、特定生长率(SGR)、摄食量(FI)、肝体比(HSI)和脏体比(VSI)没有显著影响。饲料中添加姜黄素对鱼体水分含量无显著影响;饲料中添加姜黄素后,鱼体脂肪含量显著下降,而肝脏和肌肉脂肪含量则呈显著上升趋势;0.02%和0.06%姜黄素添加组鱼体蛋白质含量显著高于0.04%组。0.06%姜黄素添加组的血清超氧化物歧化酶(SOD)活力显著高于其他组;姜黄素添加组的血清过氧化氢酶(CAT)活力高于对照组,但各组间差异不显著;饲料中添加姜黄素后,血清丙二醛(MDA)含量和谷胱甘肽酶(GSH)活力呈显著降低的趋势。研究表明,饲料中添加姜黄素对大菱鲆幼鱼成活和生长无显著影响,但能够显著提高幼鱼的血清抗氧化能力。     

植物油替代鱼油对虹鳟、花鲈和大黄鱼组织结构的影响

以初始体重分别为(11.24±0.07 g)、(18.60±0.36 g)和(8.93±0.21 g)的虹鳟、鲈鱼和大黄鱼幼鱼为研究对象,用植物油(亚麻籽油:豆油=1:1)分别替代0%(FO,对照组)、50%(FV)和100%(VO)的鱼油来配制三种等氮(粗蛋白含量为41%)等脂(粗脂肪含量为12%)的实验饲料。通过投喂实验探讨不同植物油替代鱼油水平对虹鳟(淡水鱼)、鲈鱼(广盐性鱼类)和大黄鱼(海水鱼)肝脏和肠道组织结构的影响差异。70 d投喂实验后发现,随着替代水平增加虹鳟、鲈鱼和大黄鱼的肝细胞中脂肪滴累积程度逐渐增高,相同替代水平下肝细胞中脂肪滴累积程度为大黄鱼>鲈鱼>虹鳟;肠道组织中杯状细胞随植物油替代水平升高而增多,而在大黄鱼全植物油组出现脂肪滴累积和上皮细胞死亡现象。以上结果表明植物油替代鱼油对虹鳟组织结构影响最小对大黄鱼影响最大。