Dietary bovine lactoferrin induces changes in immunity level and disease resistance in Asian catfish Clarias batrachus

The effects of including bovine lactoferrin (Lf) in the diet of the Asian catfish (Clarias batrachus) on specific and non-specific immunity as well as disease resistance were investigated. The catfish were fed four different diets for 2 weeks: a commercial diet as control and the same diet supplemented with 50, 100 and 200mg bovine Lf/kg feed. After 1 and 2 weeks, serum bacterial agglutination titre against Aeromonas hydrophila as a measure of specific immunity; natural serum haemolysin titre, lysozyme activity and oxidative radical production by neutrophils as a measure of non-specific immunity as well as disease resistance against A. hydrophila challenge to vaccinated and non-vaccinated animals were evaluated. The results showed that Lf supplements, particularly at 100mg level, significantly (P<0.05) enhanced serum lysozyme level, oxidative radical production and level of protection against A. hydrophila challenge in non-vaccinated animals irrespective of length of exposure. The specific immunity was not influenced by Lf feeding as evidenced from the bacterial agglutination titre and level of protection in vaccinated animals. As Lf feeding at 100mg/kg for 1 week is able to enhance the non-specific immunity and disease resistance of catfish efficiently, these results support the possible use of Lf as an immunostimulant for farmed catfish.     

Gut microbial status induced by antibiotic growth promoter alters the prebiotic effects of dietary DVAQUA® on Aeromonas hydrophila-infected tilapia: production, intestinal bacterial community and non-specific immunity

The purpose of the present study was to investigate whether dietary antibiotic-induced changes in the fish intestinal microbiota altered host physiological responses to the infection with Aeromonas hydrophila in hybrid tilapia (Oreochromis niloticus ♀ × O. aureus ♂). After an 8-week induction period with an antibiotic-supplemented or antibiotic-non-supplemented diet, 160 hybrid tilapias in 16 tanks were each injected with phosphate buffered saline (PBS) or A. hydrophila at a dose of one-half of the LD(50). Then, all of the diets were changed to a prebiotic-supplemented one for the sequential 8-week response period. Parameters including production, gut microbial diversity and count, and non-specific immunity were determined at the end of the response period. Our results showed that A. hydrophila infection had no effects on the growth and diet conversion of tilapia, but it caused the decrease of the gut bacterial count, the number of visual bands, and the Shannon diversity and equitability indexes of gut bacteria in antibiotic-non-supplemented fish based on PCR-DGGE fingerprints. Infection with A. hydrophila reduced the gut bacterial evenness (lower Shannon equitability index), and slightly improved the gut bacterial richness (more visual bands) in antibiotic-supplemented tilapia. In addition, A. hydrophila infection affected non-specific immunity such as serum lysozyme activity and serum alternative complement pathway (C3 and C4) activities regardless of hybrid tilapia fed antibiotic-supplemented diets. These changes varied based on the intestinal microbial status of the fish before infection with A. hydrophila.     

长时间连续投喂β-葡聚糖对鲤生长性能及非特异性免疫功能的影响

本研究旨在探讨长时间连续投喂β-葡聚糖对鲤生长性能及非特异性免疫功能的影响及嗜水气单胞菌攻毒后的抵抗能力.试验采用初始体重为(61.53±0.34)g的健康鲤(Cyprinus carpio)为研究对象,在饲料中分别添加0、0.15%和0.50%的β-葡聚塘,饲养60 d.结果显示:投喂β-葡聚糖对鲤增重率和饲料系数均没有显著影响(P>0.05);肝胰脏中溶菌酶和酸性磷酸酶活力显著降低于对照组(P<0.05),髓过氧化物酶活力各组之间没有显著差异(P>0.05);攻毒试验结果显示:注射嗜水气单胞菌148 h后试验组鲤存活率明显低于对照组.由此可知,长期投喂β-葡聚糖不影响鲤生长性能,但会降低其非特异性免疫功能及对嗜水气单胞菌攻毒的免疫保护力.     

Effect of Dietary Supplementation with Achyranthes aspera Seed on Larval Rohu Labeo rohita Challenged with Aeromonas hydrophila

Abstract

Larval rohu Labeo rohita were fed four different diets: three of the diets contained Achyranthes aspera (prickly chaff-flower) seeds at 0.10% (D1), 0.25% (D2), or 0.50% (D3); the fourth diet was a control diet (D4; no A. aspera supplementation). After 70 d, the rohu were injected intraperitoneally with live Aeromonas hydrophila. Mortality of fish was recorded for 7 d. In the D4 group, the first mortality was observed within 12 h of exposure, whereas in the D1–D3 treatment groups, mortality was first observed at 24 h postexposure. In the D4 group, 50% of fish died within 72 h of exposure, whereas in the D3 group, 10–15% mortality occurred between 72 and 84 h. The cumulative mortality rate was 50% for D4, 40% for D1, 35% for D2, and 15% for D3. Total tissue protein level in the larvae was higher for the D2 and D3 groups than for the other groups. Glutamic oxaloacetic transaminase, glutamate pyruvate transaminase, and thiobarbituric acid reactive substance levels were significantly lower in D3 larvae than in the other groups, whereas lysozyme and nitric oxide synthase levels were significantly higher in D3 larvae compared with the other groups. Dietary supplementation with A. aspera seeds at the 0.50% level provided protection against oxidative stress, prevented tissue damage, and enhanced disease resistance in rohu larvae.

Received December 26, 2011; accepted May 7, 2012     

军曹鱼幼鱼维生素C需要量的研究

选用初体均重为25.85 g的军曹鱼幼鱼225尾随机分为5组,每组设3个重复,每个重复15尾.分别投喂添加5种不同剂量维生素C(添加量分别为0、37.5、75、150和300 mg/kg)的试验饲料,试验期为56 d,观察维生素c对军曹鱼幼鱼生长、组织维生素C积累量及非特异性免疫的影响.结果表明,随着饲料中维生素C添加量增加,军曹鱼幼鱼增重率和特定生长率呈现出上升后下降趋势,在75 mg/kg时达到最高值,显著高于0和300 mg/kg组(P<0.05).全鱼粗蛋白质含量随着饲料中维生素C添加量的升高亦呈现先上升后下降趋势,在75 mg/kg时达到最高值,全鱼干物质、粗蛋白质、粗脂肪、灰分含量在各组之间均无显著差异(P>0.05).血清维生素C积累量随着饲料中维生素C添加量的增加呈现先上升后下降趋势,在150 mg/kg时达到最高值且显著高于0 mg/kg组(P<0.05);脑和肝脏中维生素C含量在300 mg/kg时达到最高值.300 mg/kg组脑中维生素C含量显著高于0,37.5和75 mg/kg组(P<0.05),肝脏中维生素C含量显著高于0,37.5和150 mg/kg组(P<0.05).随着饲料中维生素C添加量的增加,溶菌酶活性呈现先上升后下降趋势,在75 mg/kg达到最高,显著高于0,37.5和300 mg/kg组(P<0.05);血清总抗氧化能力呈现上升趋势,75、150和300 mg/kg组显著高于0 mg/kg组(P<0.05);肾抗氧离子自由基在150 mg/kg组达到最高,但各组之间无显著差异(P>0.05).以鱼体增重率和血清溶菌酶含量为指标,经折线模型回归分析求得军曹鱼幼鱼饲料中维生素C的适宜添加量分别为70和80.72 mg/kg.     

蛋氨酸对幼建鲤疾病抵抗能力及免疫应答的影响

本试验旨在研究蛋氨酸对幼建鲤疾病抵抗能力及免疫应答的影响.选择体重为(12.34±0.02)g健康建鲤864尾,平均分成6组,每组144尾(每组设3个重复,每个重复48尾),分别饲喂蛋氨酸水平为0.39%、0.70%、1.00%、1.30%、1.60%和1.90%的饲料,饲养60 d后用嗜水气单胞菌攻毒17 d,考察蛋氨酸对幼建鲤免疫功能的影响.结果表明:适宜蛋氨酸水平极显著提高了攻毒前头肾体指数、后肾体指数、脾体指数、血液红、白细胞数量和攻毒后红细胞数量(P<0.01);显著提高了攻毒前白细胞吞噬率和攻毒后成活率、白细胞数量、白细胞吞噬率、血清酸性磷酸酶活力、溶菌酶含量、补体C3含量、凝集素水平和抗嗜水气单胞菌抗体效价(P<0.05).由此得出,蛋氨酸通过增强白细胞吞噬能力和提高特异性抗体效价从而提高幼建鲤的非特异性和特异性免疫力,增强疾病抵抗力.     

Effect of oral administration of high vitamin C and E dosages on the gilthead seabream (Sparus aurata L.) innate immune system

The effect of the oral administration of high dosages of vitamins C and E on the innate immune system of the seabream was investigated. Gilthead seabream (Sparus aurata L.) were fed four different diets for 45 days: a commercial diet as control, a 3g/kg vitamin C-supplemented diet, a 1.2g/kg vitamin E-supplemented diet or a diet containing both vitamin supplements. After 15, 30 and 45 days, serum ascorbic acid and alpha-tocopherol levels, growth, complement titers and head-kidney leucocyte phagocytic and respiratory burst activities were evaluated. The results showed that serum vitamin levels reflected dietary input. Fish fed the vitamin C-supplemented diet showed an enhanced respiratory burst activity, while fish fed the vitamin E-supplemented diet exhibited increased complement and phagocytic activities. All of these positive effects were found in fish fed the joint diet, as well as a synergistically enhanced respiratory burst activity at day 30. The results demonstrate that in vivo vitamins C and E exert a synergistic effect enhancing the respiratory burst activity of seabream phagocytes.     

Effects of dietary lysozyme levels on growth performance,intestinal morphology,non‐specific immunity and mRNA expression in weanling piglets

The aim of the present study was to determine the effect of dietary lysozyme levels on growth performance, gut health and non‐specific immunity of weanling piglets. A total of 150 weanling piglets were allocated to six treatments. The piglets were fed the same basel diet supplemented with 0, 30, 60, 90 and 120 mg/kg lysozyme as well as antibiotics for 28 days. From day 14 to day 28 of dietary treatment, piglets fed 90 mg/kg lysozyme had greater average daily gain than piglets fed control diet. During the whole experimental period, piglets fed 120 mg/kg lysozyme tended to have greater average daily gain than piglets fed control diet. Compared with piglets fed control diet, piglets fed diets containing antibiotics and 90 mg/kg lysozyme had greater villus height to crypt depth ratio in duodenum and jejunum. Additionally, dietary supplementation of 60 and 90 mg/kg lysozyme as well as antibiotics enhanced the phagocytic activity of peritoneal macrophages in piglets. In conclusion, dietary lysozyme can accelerate the growth of weanling piglets by improving gut health and non‐specific immunity and supplementing 90 mg/kg lysozyme is as effective as antibiotics (20 mg/kg colistin sulphate + 50 mg/kg kitasamycin) in improving the growth performance of weanling piglets.     

肽聚糖对鲫鱼嗜水气单胞菌灭活疫苗免疫增强效果的研究

为了探讨肽聚糖在鱼类抗嗜水气单胞菌（Aeromonas hydrophila，AH）感染中的免疫佐剂作用，用添加A3a肽聚糖的饲料投喂接种F-AH疫苗的彭泽鲫（Carassius auratus var．pengze）；通过测定鲫白细胞吞噬活性、血清和体表黏液溶菌酶活性、抗体效价以及活菌攻毒后的免疫保护率，证明肽聚糖与F-AH疫苗联合使用，鲫体表黏液和血清溶菌酶活性、白细胞吞噬活性、抗体效价以及活菌攻毒后的免疫保护率均显著提高，表明A3a肽聚糖是F-AH疫苗的良好佐剂，能增强鱼类F-AH疫苗免疫应答。     

大口黑鲈维生素A需求量

为了评定大口黑鲈饲料中维生素A的需求量,本研究在基础饲料中添加不同量(0、1 000、2 000、3 000和4 000 IU/kg)的维生素A醋酸酯,配制5种不同维生素A含量(实测维生素A含量分别为415、1 406、2 755、3 501和4 646 IU/kg)的等氮等能饲料(粗蛋白质含量48.47%;总能18.15 M J/kg)。用上述饲料饲喂初始体重为(52.75±0.12)g的大口黑鲈49 d,每个处理设3个重复,每重复30尾鱼。结果表明:随着饲料中维生素A水平从415 IU/kg升高到2 755 IU/kg,试验鱼的增重率、特定生长率、饲料效率和蛋白质效率均显著升高(P0.05);而随饲料维生素A水平的进一步增高,上述指标则呈平稳的趋势。随着饲料中维生素A水平从415 IU/kg升高到3 501 IU/kg,鱼的肝脏中维生素A含量、肝脏总超氧化物歧化酶活性、血清溶菌酶活性,头肾白细胞呼吸爆发活性、血清补体活性及血红蛋白含量显著升高(P0.05),而肝脏丙二醛含量显著降低(P0.05);随饲料维生素A水平的进一步增高,上述指标变化幅度较小。饲料中不同维生素A水平对鱼的血清总蛋白含量和红细胞压积的影响不显著(P0.05)。分别以增重率和肝脏维生素A含量为评价指标,采用折线模型求得,大口黑鲈对饲料中维生素A的最适需求量分别为2 600和3 550 IU/kg;而以非特异性免疫为评价指标,通过方差分析得出的最适需求量与以肝脏维生素A含量为评价指标所得出的需求量相近。本研究得出,大口黑鲈对饲料中维生素A水平的最适需求量为2 600~3 550 IU/kg。     

Immunosuppressive effects of aflatoxin B1 in Indian major carp (Labeo rohita).

Aflatoxin B1 (AFB1) is a potent immunomodulator in endotherms. The experiment was carried out to study the immunosuppressive nature of AFB1 in one ectothermic species of Indian major carp. Graded levels (0, 1.25, 5.00 mg/kg of body weight) of purified AFB1 were intraperitoneally (i.p.) injected into rohu (Labeo rohita) fingerlings weighing 30-50 g, and the fish were observed for a period of 90 days. At the end of the trial, blood samples were collected from the control group as well as the AFB1 injected fish and were screened for nitroblue tetrazolium (NBT) assay, serum total protein, albumin, globulin, albumin-globulin ratio (A:G), serum bactericidal activity and bacterial agglutination titre against Edwardsiella tarda. The aflatoxin-treated fish revealed a reduction of total protein, globulin levels, bacterial agglutination titre, NBT and serum bactericidal activities, as well as an enhanced A:G ratio without change in albumin concentration, irrespective of dose levels of toxin treatment, when compared to the control group. Thus, AFB1 proved to be immunosuppressive in rohu even at the lowest dose (1.25 mg/kg body weight) of toxin treatment. This could be of economic significance in intensive culture systems of rohu.     

中华鲟幼鲟维生素C营养需要的研究

本研究旨在确定中华鲟幼鲟对维生素C(VC)的营养需要量。配制含VC分别为0.5、59.8、119.5、239.1、478.1和956.2 mg/kg饲料的6组日粮(分别编号为C0.5、C59.8、C119.5、C239.1、C478.1和C956.2),连续投喂中华鲟幼鲟8周后,以生长速度、组织VC含量和部分相关酶活性来确定中华鲟对VC的需求量。结果表明,C0.5和C59.8组鲟鱼的增重率、饲料效率、蛋白质效率都低于C119.5组,进一步提高饲料VC含量,也没有显著变化(P>0.05);C478.1组的肝脏和肌肉组织VC含量达最高水平;C239.1组血清溶菌酶活性最高;C239.1组SOD活性最低。根据平均增重率和饲料效率做折线法分析表明,维持中华鲟最佳生长的饲料VC含量为108.5 mg/kg;肝脏中VC含量达最大时饲料VC添加量为309.4 mg/kg;肌肉中VC含量达最大时饲料VC添加量为273.3 mg/kg。     

Effect of Low Dietary Magnesium on Immune Response and Osmoregulation of Atlantic Salmon

Abstract

The influences of dietary magnesium on immune response and on osmoregulation in parr of Atlantic salmon Salmo salar were determined. Groups of fish were fed a casein–gelatin diet unsupplemented (containing about 200 mg Mg/kg) or supplemented with either 300 or 500 mg Mg/kg dry diet (as MgSO₄) for 12 weeks before vaccination to produce fish with different Mg levels, and the feeding regime was continued throughout the study. No differences were observed between the treatment groups in serum-specific antibody levels every second week for 8 weeks after vaccination against Vibrio anguillarum serotypes O1 and O2. Both lysozyme levels and spontaneous hemolytic activities in serum were elevated in vaccinated fish compared with unvaccinated fish. Neither lysozyme activity, complement hemolytic activity, total protein in serum nor blood hemoglobin were affected by dietary Mg. The spontaneous hemolytic activity in serum was lower in fish fed the unsupplemented diet and highest in fish fed the diet supplemented with 500 mg Mg/kg. After 28 weeks on the diets supplemented with graded levels of Mg, a salinity tolerance test (32.5 g/L, 24 h) was performed. High mortality and elevated serum chloride concentrations in all groups after 24 h reflected a general salinity intolerance, but the highest serum chloride level was observed in fish fed the unsupplemented diet. This indicates that low dietary Mg affects the osmoregulation of Atlantic salmon.     

Effect of Fermented Chinese Medicine Preparation by Bacillus subtilis on Growth Performance,Biochemical Indices,Antioxidant Parameters and Ability of Anti-infection of Common Carp

The objective of this study was to evaluate of the growth performance, serum biochemical indices, liver antioxidant parameters and ability of anti-infection with Aeromonas hydrophila by adding the fermented Chinese medicine by Bacillus Subtilis to the carp fish feed, and to find out the appropriate supplemental level of fermented Chinese medicine in diets. Carp fingerling with an initial body weight of (35±0.5) g were set up to 6 experimental diets supplemented with 0 (control group), 0.1‰, 0.5‰, 1‰, 2‰ and 3‰ fermented Chinese medicine for 56 days, respectively. Each group had 30 fish and set up 3 repetitions. After the feeding trail,the fish were challenged with Aeromonas hydrophila to calculate the relative percentage survival (RPS).The results showed as follows:Supplementing fermented traditional Chinese medicine by Bacillus subtilis, the weight gain rate (WGR), specific growth rate (SGR), condition factor (CF), the activities of lysozyme (LSZ), complement 3 (C3),total protein (TP),total anti-oxidation capacity (T-AOC),total superoxide dismutase (T-SOD) and catalase (CAT) in serum of common carp were enhanced at different degrees, while the feed coefficient (FCR)and malondialdehyde (MDA) in serum were declined at different degrees.When the fermented Chinese medicine supplemental levels were 2‰ and 3‰,the effects were significant (P<0.05)(except for C3, ALP and Cr).The experimental results of the virulence of common carp infected with pathogen Aeromonas hydrophila showed that,the fermented herbal could obviously improve the ability of anti-infection, the immune protective rate of the group with 2‰, 3‰ doses of the fermented Chinese medicine could reach 77.23% and 74.63%, respectively. From what had been discussed above, the group with 2‰ and 3‰ doses of the fermented Chinese medicine had significant effect on the growth performance, serum biochemical indices, liver antioxidant parameters and Aeromonas hydrophila anti-infection ability. Considering the cost of adding fermented Chinese medicine, the recommendations for the best additive quantity was 2‰.     

枯草芽孢杆菌发酵中药制剂对鲤鱼生长性能、生化指标、抗氧化指标及抗感染能力的影响

本试验旨在研究饲料中添加枯草芽孢杆菌发酵中药制剂对鲤鱼生长性能、血清生化指标、抗氧化指标及对嗜水气单胞菌抗感染能力的影响,并确定其适宜的添加水平。将枯草芽孢杆菌发酵中药制剂投喂初始体重为（35±0.5）g的鲤鱼,试验设6个组,添加水平分别为0（对照组）、0.1‰、0.5‰、1‰、2‰、3‰,每组30尾,设3个重复,试验周期56 d。养殖试验结束后,腹腔注射嗜水气单胞菌进行感染试验,计算免疫保护率（RPS）。结果显示,饲料中添加枯草芽孢杆菌发酵中药制剂,鲤鱼增重率（WGR）、特定生长率（SGR）、肥满度（CF）、溶菌酶（LSZ）、补体3（C3）、总蛋白（TP）、总抗氧化能力（T-AOC）、超氧化物歧化酶（SOD）、过氧化氢酶（CAT）均不同程度提高,饲料系数（FCR）、丙二醛（MDA）含量不同程度降低,且当饲料中发酵中药添加量为2‰、3‰时,与对照组相比各指标（C3、碱性磷酸酶（ALP）和肌酐（Cr）除外）均差异显著（P<0.05）。用嗜水气单胞菌对鲤鱼感染试验结果表明,发酵中药可显著提高鲤鱼的抗感染能力,添加发酵中药2‰、3‰组免疫保护率可达77.23%和74.63%。可见,饲料中添加枯草芽孢杆菌发酵中药2‰、3‰能显著提高鲤鱼的生长性能、血清生化指标、肝脏抗氧化能力及抗嗜水气单胞菌感染能力。基于对添加成本的考虑,建议发酵中药的最佳添加剂量为2‰。     

Effects of a prebiotic, Immunogen®, on feed utilization, body composition, immunity and resistance to Aeromonas hydrophila infection in the common carp Cyprinus carpio (Linnaeus) fingerlings

This study evaluated the effects of a commercial prebiotic, Immunogen, on feed utilization, growth rate, immunity promotion and carcass composition of the common carp Cyprinus carpio fingerlings. The fingerlings were adopted for 2 weeks and then reared in triplicate groups in 250-l tanks (n = 15 per tank with average initial weights of 11.12 ± 0.55 g). The fish fed on five isonitrogenous and isoenergetic experimental diets containing different levels of Immunogen (0, 0.5, 1, 1.5 and 2.5 g prebiotic/kg diet) to apparent satiation thrice a day for 8 weeks. Weight gain showed no differences among the groups fed different Immunogen levels. Both feed efficiency ratio and protein efficiency ratio significantly (p < 0.05) increased with increasing Immunogen levels from 0.5 to 1.5 g/kg diet. The highest protein content (p < 0.05) was found in the fish fed a diet containing 2.5 g/kg prebiotic. Haematological parameters and plasma total protein concentration were also significantly higher (p < 0.05) in the fingerlings fed diets containing 1.5 and 2.5 g/kg prebiotic in relation to the control. The control fish contained the highest mean of total bacterial counts. The lowest mean (p < 0.05) of total bacterial counts was observed in the fish fed the diet containing 2.5 g/kg Immunogen. The present study reveals that a dietary Immunogen supplementation from 1 to 1.5 g/kg is capable to improve the feed efficiency and growth performance of C. carpio fingerlings as well as their resistance to A. hydrophila infection.     

Effect of dietary vitamin E on cortisol and glucose responses to handling stress in juvenile beluga Huso huso

An 8-week feeding experiment was conducted to investigate the effect of dietary vitamin E on the physiological response to handling stress in juvenile beluga Huso huso. Fish were fed six experimental diets supplemented with 0, 25, 50,100, 200, or 400 mg Dl-all-rac-alpha-tocopherol acetate/kg diet. At the end of the experiment, the fish in each tank were subjected to acute handling and air exposure stress. Cortisol and glucose were measured as the primary hormonal and secondary metabolic responses to the stressors, both before and 3 h after application of the stressors. The growth parameters and feed utilization rates were significantly lower in fish fed the diet not supplemented with vitamin E than in fish fed diets supplemented with vitamin E. Cortisol concentration was not affected by dietary treatment but glucose concentration was. Fish fed vitamin E at 0, 25, 100, and 400 mg/kg diet had higher concentrations of glucose than those fed vitamin E at 50 and 200 mg/kg. However, fish fed diets with 50 and 200 mg/kg exhibited higher growth rates. These results indicate that dietary vitamin E has some effect on plasma glucose but no effect on plasma cortisol. In general, when the stressors were applied to belugas, the glucose and cortisol responses were relatively low. This may be due to higher resistance and lower physiological responses to these types of stressors by this species or by chondrosteans in general.     

Effect of Dietary Vitamin E on Cortisol and Glucose Responses to Handling Stress in Juvenile Beluga Huso huso

Abstract

An 8-week feeding experiment was conducted to investigate the effect of dietary vitamin E on the physiological response to handling stress in juvenile beluga Huso huso. Fish were fed six experimental diets supplemented with 0, 25, 50, 100, 200, or 400 mg Dl-all-rac-α-tocopherol acetate/kg diet. At the end of the experiment, the fish in each tank were subjected to acute handling and air exposure stress. Cortisol and glucose were measured as the primary hormonal and secondary metabolic responses to the stressors, both before and 3 h after application of the stressors. The growth parameters and feed utilization rates were significantly lower in fish fed the diet not supplemented with vitamin E than in fish fed diets supplemented with vitamin E. Cortisol concentration was not affected by dietary treatment but glucose concentration was. Fish fed vitamin E at 0, 25, 100, and 400 mg/kg diet had higher concentrations of glucose than those fed vitamin E at 50 and 200 mg/kg. However, fish fed diets with 50 and 200 mg/kg exhibited higher growth rates. These results indicate that dietary vitamin E has some effect on plasma glucose but no effect on plasma cortisol. In general, when the stressors were applied to belugas, the glucose and cortisol responses were relatively low. This may be due to higher resistance and lower physiological responses to these types of stressors by this species or by chondrosteans in general.

Received January 10, 2011; accepted August 4, 2011     

谷氨酰胺对黄颡鱼幼鱼抗氧化能力和非特异性免疫力的影响

本试验旨在研究谷氨酰胺对黄颡鱼幼鱼抗氧化能力及非特异性免疫力的影响。选取平均体重为(2.49±0.04)g的黄颡鱼幼鱼240尾,随机分为4组,每组3个重复,每个重复20尾。4组试验鱼分别饲喂谷氨酰胺添加量为0(对照)、0.1%、0.2%、0.4%的等氮等能试验饲料。试验期为10周。结果表明:饲料中添加0.2%的谷氨酰胺可以显著提高黄颡鱼幼鱼的血清总蛋白、球蛋白、甘油三酯、高密度脂蛋白和低密度脂蛋白含量(P0.05);各组黄颡鱼幼鱼的血清谷丙转氨酶、谷草转氨酶和碱性磷酸酶活性差异不显著(P0.05);饲料中添加0.1%的谷氨酰胺可以显著提高黄颡鱼幼鱼肝脏中过氧化氢酶、谷胱甘肽过氧化物酶及肌肉中超氧化物歧化酶、谷胱甘肽过氧化物酶的活性(P0.05);随着饲料中谷氨酰胺添加量的增加,头肾巨噬细胞的吞噬指数呈升高趋势,且0.2%和0.4%组较对照组显著升高(P0.05),但0.2%和0.4%组间差异不显著(P0.05)。由此可见,饲料中添加0.1%~0.2%的谷氨酰胺能够提高机体的抗氧化能力和非特异性免疫力。     

饲料中维生素A水平对凡纳滨对虾生长、饲料利用、体组成成分及非特异性免疫反应的影响

本文旨在研究5种等氮等能饲料中,维生素A添加水平对凡纳滨对虾(Penaeus vannameiBoone)生长、饲料利用、体组成成分及非特异性免疫反应的影响。试验选用平均初始体重为(0.069±0.005)g的凡纳滨对虾450尾,随机分为5个处理组,每组90尾,每组设3个重复,每个重复30尾。试验采用单因素设计,以维生素A醋酸酯为维生素A源,用添加不同水平维生素A(添加量分别为0、18、365、4和72 mg/kg)的饲料喂养凡纳滨对虾,试验期11周。结果表明:在养殖前4周,饲料中添加维生素A显著促进凡纳滨对虾的生长(P<0.05),提高其对饲料利用效率(P<0.05),而对对虾的成活率不产生显著的影响(P>0.05);第11周的结果表明,饲料中添加维生素A并不能显著影响凡纳滨对虾的生长、饲料利用效率和成活率(P>0.05)。维生素A对对虾体脂肪、蛋白质含量的影响显著(P<0.05),对对虾体水分和灰分含量无显著影响(P>0.05)。维生素A对对虾血清中溶菌酶活力、酚氧化酶活力和血液红细胞数量的影响显著(P<0.05),饲料中未添加维生素A或过量添加(超过36 mg/kg)均导致血清中溶菌酶活力、酚氧化酶活力和血细胞总数显著下降(P<0.0 5),而对血清超氧化物歧化酶活力无显著影响(P>0.0 5)。用折线回归模型分析饲料维生素A添加量与对虾增重率的变化关系,表明在试验前4周,凡纳滨对虾饲料中维生素A的适宜添加量为2 2.5 0 mg/kg;1 1周试验期间,凡纳滨对虾饲料中维生素A适宜添加量为1 8 mg/kg;以溶菌酶、酚氧化酶活力为指标,凡纳滨对虾饲料中维生素A最适添加量为5 9.5 1 mg/kg。