分离大豆蛋白对幼建鲤生长性能及肠道的影响

选择体重为(11.34±0.16) g健康建鲤720尾,平均分成5组,每组3个重复,分别饲喂分离大豆蛋白代替白鱼粉蛋白0、40%、60%、80%和100%的等氮饲料,进行为期9周的生长试验,探讨对其生长性能及肠道的影响.结果表明,与全鱼粉蛋白组相比,当替代60%～100%时,增重、特定生长率、采食量、肠重、肠长和前肠后肠皱襞高度显著降低(P＜0.05),饲料系数显著升高;同时,前、后肠出现上皮顶端细胞脱落、固有层变宽且其中白细胞数量增多等病理症状;当替代80%～100%时,中肠后肠溶菌酶含量显著升高,而中肠、后肠抗体水平分别于替代60%～80%和60%时显著升高(P＜0.05),之后则相对降低.由此可知,与白鱼粉相比,分离大豆蛋白降低幼建鲤生长性能;高比例替代导致肠道生长发育受阻、上皮完整性受损;肠黏膜受损的原因涉及肠道非特异性和特异性免疫反应的变化;以饲料系数为衡量指标所确定的分离大豆蛋白在幼建鲤饲料中代替白鱼粉蛋白的适宜比例为40%.     

棉粕酶解蛋白肽对建鲤生产性能和生化指标的影响

以2%棉粕酶解蛋白肽(以下简称蛋白肽)分别等质量替代基础日粮中2%鱼粉和2%植物蛋白原料(1.0%豆粕+0.5%菜粕+0.5%棉粕),考察蛋白肽对(48.56±1.39)g建鲤(Cyprinus carpio var.Jian)生长性能、血清及肠道相关酶活的影响。结果表明:蛋白肽替代鱼粉或植物蛋白后试验组增重率和特定生长率均显著性高于对照组(P<0.05),同时饵料系数显著降低(P<0.05);蛋白肽可降低脏体比和肝体比,并显著性提高鱼体粗蛋白含量(P<0.05);同时可提高试验组建鲤血清溶菌酶、碱性磷酸酶和肠道中蛋白酶的活性。     

去皮豆粕对幼建鲤生长性能和肠道的影响

幼建鲤(Cyprinus carpiovar.jian)初始体质量(10.29±0.10)g,分别饲喂去皮豆粕蛋白占总蛋白0、25%、50%、75%和100%的等氮饲料代替白鱼粉蛋白,进行为期9周的生长实验。结果表明,随去皮豆粕增加,SGR下降,饲料系数升高。当替代50%时,SGR、肠重和前肠后肠皱襞高度显著降低(P<0.05),饲料系数、中肠后肠溶菌酶含量和抗体水平显著升高(P<0.05);50%~100%大豆蛋白组出现肠道皱襞顶端上皮细胞脱落、固有层白细胞数量增多等症状。由本结果可知,高比例去皮豆粕抑制幼建鲤生长,并使其肠道生长受阻和结构受损从而导致消化吸收能力下降,降低饲料利用率;肠道损伤的原因涉及肠道非特异性和特异性免疫反应;在饲料总蛋白水平为33%时,去皮豆粕在体质量为10~35g幼建鲤饲料中替代白鱼粉蛋白的适宜比例为25%。     

复合植物蛋白源替代鱼粉对半滑舌鳎生长、生理生化指标和肠组织结构的影响

实验以6种植物蛋白源(谷朊粉、大豆浓缩蛋白、豆粕、棉籽蛋白、花生粕和玉米蛋白粉)配比成复合植物蛋白源,以其替代半滑舌鳎(Cynoglossus semilaevis Güntuer)饲料鱼粉蛋白,共设计9种实验饲料,分别为全鱼粉组(FM)以及替代鱼粉蛋白水平分别为20%(PP20)、30%(PP30)、40%(PP40I、PP40II、PP40III和PP40IV)、60%(PP60)和80%(PP80)组,旨在最大限度替代舌鳎饲料中鱼粉蛋白,而不影响鱼体生长、生理生化指标和肠组织结构形态。以初重为(255.21±0.79)g的半滑舌鳎为研究对象,在室内流水系统中进行9周摄食生长实验,每个处理设3个重复,每桶放养15尾鱼。结果表明,各处理组实验鱼的增重率、特定生长率、饲料效率、摄食量、蛋白质效率、蛋白质沉积率和成活率均无显著性差异(P0.05);复合植物蛋白源替代鱼粉后对鱼体粗蛋白和水分含量以及血浆甘油三酯含量无显著影响(P0.05);但当复合植物蛋白源替代高比例鱼粉蛋白时,显著降低鱼体粗脂肪和血浆胆固醇含量(P0.05),且肝体比随植物蛋白源的添加而降低,PP30组显著低于FM组(P0.05);另外,4个PP40组相比,PP40III组的脏体比显著高于其他3个40%替代组。复合植物蛋白源替代鱼粉比例不超过60%时,对半滑舌鳎后肠组织结构无损伤或仅有轻微损伤,而PP80组后肠绒毛出现严重损伤现象。以上结果表明,复合植物蛋白源可以有效替代80%的鱼粉蛋白而不影响半滑舌鳎的生长性能和饲料利用率,但综合考虑鱼体生理生化和肠道组织结构指标,认为在半滑舌鳎饲料中复合植物蛋白源替代鱼粉的比例不宜超过60%。     

不同生长阶段鲤肠,肝胰脏蛋白酶活性研究

研究表明,鲤鱼生长阶段不同,其肠道、肝胰脏蛋白酶活性也不同。同一生长阶段的鲤,肝胰脏具有较强的蛋白酶活性,肠道蛋白酶以后肠最高,前、中肠次之。     

转基因大豆对建鲤抗氧化、生化及免疫指标的影响

为评价抗草甘膦转基因大豆对建鲤的饲用安全性，试验以480尾平均体质量(60±10) g的建鲤幼鲤为对象，随机分为4组，分别添加15%和30%经过高温预处理的抗草甘膦转基因大豆制成的试验饲料，以同等添加比例的高温预处理非转基因大豆饲料作为对照，饲养周期为180 d,采用常规方法测定生长指标，采用可见光法、干粉法等测定相关肝胰脏与血液指标。试验结果表明：饲料中添加15%和30%抗草甘膦转基因大豆对建鲤的生长性能、脏器指数和肌肉常规营养组分均未见显著影响(P>0.05),建鲤肝胰脏谷胱甘肽过氧化物酶活性显著升高(P<0.05);饲料中添加30%的抗草甘膦转基因大豆会显著降低肝胰脏过氧化氢酶活性(P<0.05),显著升高丙二醛水平(P<0.05),显著降低建鲤血清中碱性磷酸酶活性(P<0.05)。综上，饲料中添加高水平的抗草甘膦转基因大豆会对建鲤的碱性磷酸酶活性产生一定程度的负面影响，而影响建鲤肝胰脏抗氧化能力的根本原因是否为转基因这一因素还需进一步探究。     

青海湖裸鲤和花斑裸鲤消化酶活力对比

本实验对比研究青海湖裸鲤(Gymnocypris przewalskii)和花斑裸鲤(Gymnocypris eckloni)消化酶活性差异。两种鱼各挑选9尾体重100g左右的鱼作为实验对象,分别检测肝胰脏、前肠、中肠及后肠中的脂肪酶、淀粉酶、糜蛋白酶和胰蛋白酶活性。结果表明:作为无胃鱼,两种鱼肠道消化酶活性显著高于肝胰脏,其中前肠是主要的消化器官,后肠具有较高的蛋白质消化能力。通过对比研究发现青海湖裸鲤具有较高的脂肪和糖类消化能力,而花斑裸鲤具有较高的蛋白质消化能力。     

有效微生物制剂(EM)对建鲤肠道菌群及其蛋白酶和肝胰脏蛋白酶活性的影响

本实验以有效微生物制剂(Effective Microorganisms, 简称EM)作为饲料添加剂饲养建鲤。45d后对建鲤肠道菌群和蛋白酶活性进行研究,结果发现:EM对饲养后的建鲤肠道菌群有明显的改善,实验组乳酸菌比对照组分别增加了125.10％、345.19％和488.50％。大肠杆菌比对照组分别减少了82.01％、92.45％和90.57％,定植效果良好;实验组的肠道蛋白酶活性比对照组高,分别提高6.18％、9.38％和17.70％。添加2％、4％EM的实验组的肝胰脏蛋白酶活性与对照组相近,而添加6％的实验组其肝胰脏蛋白酶活性比对照组提高5.78％,实验组建鲤生长加快,饵料系数比对照组分别降低了1.35％、7.74％和22.90％。     

鲤鱼肝胰脏和肠道淀粉酶活性的研究

以可溶性淀粉为底物,采用次碘酸法测定鲤鱼肝胰脏和肠道淀粉酶活性。结果表明,淀粉酶比酶活在后肠最强,中肠,前肠和肝胰脏分别为后肠比酶活的79.13%、27.10%和62.60%。肠道与肝胰脏提取液等量混和后,其比酶活与肠道提取液、肝胰脏提取液各自比酶活1/2的和相比较,虽有一定强度增加,但不显著。肝胰脏和肠道淀粉酶在pH5.8—8.0范围内,其最大比酶活均在pH6.4。     

饲料中高水平维生素A对幼建鲤生长、饲料利用及免疫反应的影响

通过对幼建鲤(平均初重11.37±0.55 g)投喂5组不同维生素A水平的饲料(维生素A含量分别是3 969、23 816、39 693、99 233及158 773 IU·k~(-1)),进行70 d的饲养试验以及攻毒(为期15 d)和免疫接种试验(为期24 d),研究饲料中高水平维生素A对幼建鲤生长、饲料利用及免疫反应的影响。结果表明,饲料中过高维生素A显著地降低幼建鲤的体增重、净蛋白沉积率、肝胰脏重量、肠道皱襞高度、脾体指数、血红细胞、白细胞数量、血清溶菌酶活力及用灭活嗜水气单胞菌免疫后17、24 d血清抗体水平(P<0.05);显著提高饲料系数、肝胰脏维生素A含量(P<0.05),而对成活率、摄饵量、头肾体指数、后肾重量、后肾体指数,而用灭活嗜水气单胞菌免疫后0、10 d血清抗体水平影响不显著(P>0.05)。当饲料维生素A含量为158 773 IU·kg~(-1)时,对幼建鲤产生毒性作用。     

Dietary pyridoxine requirement of juvenile Jian carp (Cyprinus carpio var. Jian)

In a 80-day feeding trial, a total of 1050 juvenile Jian carp ( Cyprinus carpio var. Jian) with an average initial weight of 10.71 ± 0.05 g were fed semi-purified diets containing seven graded levels of pyridoxine (0.20, 1.71, 3.23, 4.96, 6.32, 8.58 and 12.39 mg pyridoxine kg⁻¹ diet). Results indicated that with increasing dietary pyridoxine levels up to 4.96 mg kg⁻¹ diet, percent weight gain (PWG) and specific growth rate (SGR) were improved, and no differences were found with further increase of pyridoxine levels. Feed intake also followed the similar pattern to that observed with PWG and SGR when dietary pyridoxine levels were ≤6.32 mg kg⁻¹ diet. But feed efficiency and protein efficiency ratio were not affected by pyridoxine levels. Crude protein of carcass, productive protein value and plasma ammonia concentration were improved with increasing dietary pyridoxine levels up to 4.96 mg kg⁻¹ diet. Amylase activities in the intestine were improved with increasing dietary pyridoxine levels up to 4.96 mg kg⁻¹ diet, but protease and lipase activities in the intestine were not affected by pyridoxine levels. Na⁺, K⁺-ATPase and Gamma-glutamyl transpeptidase activities in proximal intestine, mid intestine (MI) and distal intestine (DI) were lowest when fed the diet containing 1.71 mg pyridoxine kg⁻¹ diet. The alkaline phosphatase activities in MI and DI followed the same pattern. The dietary pyridoxine requirement of juvenile Jian carp based on PWG estimated by broken line model was 6.07 mg pyridoxine kg⁻¹ diet.     

建鲤遗传改良的初步研究

用单养和混养法，对建鲤（Cyprinus carpio var.jian)后代选育群体和未选育群体；建鲤和黄河鲤（C.carpio)，建鲤和荷包红鲤（C.Carpio Var,wuyuanensis)的杂交种，亲本黄河鲤和荷包红鲤自后代6个试验组进行生长对比，结果表明，建鲤选育效果明显，品质提高；建鲤与黄河鲤杂交具有杂种优势，生长快且生长性能进一步提高。     

Dietary lysine requirement of juvenile Jian carp (cyprinus carpio var. Jian)

This study was designed to determine the dietary lysine requirement of juvenile Jian carp (cyprinus carpio var. Jian). A total of 990 juvenile Jian carps (initial weight 7.89 ± 0.04 g) were randomly allocated six groups of each three replicates, feeding isonitrogenous (320 g kg^?1 crude protein) and isolipidic (50 g kg^?1 crude fat) diets containing graded levels of coated l ‐lysine, with dietary lysine content ranging from 22 to 69 g kg^?1 of protein, respectively, for 80 days. Final weight, protein deposition and protein production value were significantly improved in response to the increasing levels of dietary lysine up to 59 g kg^?1 of protein and remained nearly constant thereafter. Whole‐body protein content followed a similar pattern as growth parameters in relation to dietary lysine level. Hepatopancreas and intestine protein content, hepatopancreas index (HSI) and intestine index (ISI) were positively affected by dietary lysine level. The dietary lysine requirement of juvenile Jian carp estimated by broken line analysis based on weight gain was 59 g kg^?1 of protein.     

Effect of methionine on intestinal enzymes activities, microflora and humoral immune of juvenile Jian carp (cyprinus carpio var. Jian)

An 8-week feeding experiment was conducted to determine the effect of dietary methionine supplementation on intestinal microflora and humoral immune of juvenile Jian carp (initial weight of 9.9 ± 0.0 g) reared in indoor flow-through and aerated aquaria. Eight amino acid test diets (350 g kg⁻¹ crude protein, CP), using fish meal, soybean-condensed protein and gelatin as intact protein sources supplemented with crystalline amino acids, were formulated to contain graded levels of methionine (0.6–22.0%) at a constant dietary cystine level of 3 g kg⁻¹. Each diet was randomly assigned to three aquaria. Growth performance and feed utilization were significantly influenced by the dietary methionine levels ( P  < 0.05). Maximum weight gain, feed intake occurred at 12 g kg⁻¹ dietary methionine ( P  < 0.05). Methionine supplementation improved hepatopancreas and intestine weight, hepatosomatic and intestine index, intestinal γ-glutamyltransferase and creatine kinase activity, Lactobacillus count, Bacillus count, lysozyme activities, lectin potency, sim-immunoglobulin M content, addiment C3,C4 contents and serum total iron-binding capacity and declined Escherichia coli and Aeromonas counts. Quadratic regression analysis of weight gain against dietary methionine levels indicated that the optimal dietary methionine requirement for maximum growth of juvenile Jian carp is 12 g kg⁻¹ of the dry diet in the presence of 3 g kg⁻¹ cystine.     

Growth,body composition,intestinal enzyme activities and microflora of juvenile Jian carp (Cyprinus carpio var. Jian) fed graded levels of dietary phosphorus

A 9‐week feeding trial was carried out with juvenile Jian carp (Cyprinus carpio var. Jian) to study the effects of dietary phosphorus on growth, body composition, intestinal enzyme activities and microflora. Quadruple groups of juvenile Jian carp (7.17 ± 0.01 g) were fed practical diets containing available phosphorus 1.7 (unsupplemented control), 3.6, 5.5, 7.3, 9.2 and 11.0 g kg^?1 diet to satiation. Feed intake, specific growth ratio and feed efficiency were the lowest in fish fed the basal diet (P < 0.05). Body moisture, protein, lipid content and ash were all significantly affected by dietary available phosphorus levels (P < 0.05). Activities of trypsin, amylase, Na⁺, K⁺‐ATPase, alkaline phosphatase and gamma‐glutamyl transpeptidase were improved with increasing dietary phosphorus levels. Intestinal Aeromonas and Escherichia coli decreased with increasing dietary phosphorus up to 3.6 and 5.5 g kg^?1 diet respectively (P < 0.05), while Lactobacillus increased with the increasing dietary phosphorus up to 9.2 g kg^?1 diet (P < 0.05). These results suggested that phosphorus could enhance intestinal enzyme activities of juvenile Jian carp and the minimum dietary available phosphorus requirement for SGR of juvenile Jian carp (7.2–63.8 g) was 5.2 g kg^?1 diet.     

Effect of dietary riboflavin on growth,feed utilization,body composition and intestinal enzyme activities of juvenile Jian carp (Cyprinus carpio var. Jian)

A total of 1050 Jian carp, Cyprinus carpio var. Jian (23.39 ± 0.06 g) were randomly divided into seven groups of each three replicates, which were fed respectively with seven semi‐purified diets contained 1.25, 2.71, 4.22, 5.78, 7.23, 8.83 and 11.44 mg riboflavin kg^?1 diet for 6 weeks. The results showed that riboflavin significantly improved percent weight gain, specific growth rate, feed efficiency and protein efficiency ratio at the level of 4.22 mg kg^?1 diet. Gross protein retention efficiency and lipid production value improved with increasing dietary riboflavin levels from 1.25 to 5.78 mg kg^?1. Activities of trypsin, lipase, α‐amylase, Na⁺,K⁺‐ATPase and alkaline phosphatase in the intestinal tract were significantly improved with increasing riboflavin levels. Weight and protein content of hepatopancreas, intestine protein and intestine length index were also significantly improved.     

Effects of dietary biotin supplement on growth,body composition,intestinal enzyme activities and microbiota of juvenile Jian carp (Cyprinus carpio var. Jian)

A total of 1400 juvenile Jian carp (Cyprinus carpio var. Jian) (7.72 ± 0.02 g) were fed seven purified diets containing 0.010 (basal diet), 0.028, 0.054, 0.151, 0.330, 1.540 and 2.680 mg biotin kg^?1 for 63 days to investigate the effects of biotin on growth, body composition, intestinal enzyme activities and microbiota. Specific growth rate (SGR), feed intake, feed efficiency and protein retention value were the highest when dietary biotin level was 0.151 mg kg^?1 diet. Crude protein, lipid and ash content of fish carcass improved with increasing dietary biotin levels up to 0.054, 0.151 and 0.028 mg kg^?1 diet, respectively (P < 0.05). Intestinal folds height, trypsin, chymotrypsin, lipase, amylase, alkaline phosphatase, Na⁺, K⁺‐ATPase, γ‐glutamyl transpeptidase and creatinekinase activities increased with dietary biotin levels up to 0.151–0.330 mg kg^?1 diet (P < 0.05). Intestinal Aeromonas and Escherichia coli significantly decreased with increasing dietary biotin up to 0.151 mg kg^?1 diet, while Lactobacillus and Bacillus significantly increased with dietary biotin levels up to 0.054 and 0.151 mg kg^?1 diet, respectively. In conclusion, biotin could improve digestive and absorptive ability of fish, and the dietary biotin requirement for SGR of juvenile Jian carp (7.72–32.67 g) was 0.15 mg kg^?1 diet.     

Growth,body composition,intestinal enzyme activities and microflora of juvenile Jian carp (Cyprinus carpio var. Jian) fed graded levels of dietary valine

This study investigated the effects of valine on growth, intestinal enzyme activities and microflora in juvenile Jian carp (Cyprinus carpio var. Jian). A total of 1200 fish with an average initial weight of 9.67 ± 0.03 g were fed diets containing 5.3 (unsupplemented control), 8.7, 11.8, 14.9, 18.7 and 20.1 g valine kg^?1 diet for 60 days. Results indicated that the specific growth rate, feed efficiency, body protein and lipid content of fish were significantly improved by the dietary valine (P < 0.05). The hepatopancreas weight and activities of trypsin, amylase, lipase, chymotrypsin, glutamate oxaloacetate transaminase (GOT) and glutamate pyruvate transaminase (GPT) took the similar trends. Similarly, the optimum levels of dietary valine induced increases in the intestinal length, weight, folds height and activities of alkaline phosphatase, gamma‐glutamyl transpeptidase and creatine kinase. In contrast, the trends of muscle GOT activity and plasma ammonia content were opposite. Intestinal Aeromonas, Escherichia coli, Lactobacillus and Bacillus were changed by dietary valine supplementations. The dietary valine requirement for Jian carp (9.67–76.4 g) based on SGR was 13.7 g valine kg^?1 diet (4.0 g valine 100 g^?1 CP). Together, these results indicated that valine improved fish growth, digestive and absorptive ability.     

Influence of dietary zinc on lipid peroxidation,protein oxidation and antioxidant defence of juvenile Jian carp (Cyprinus carpio var. Jian)

This study was conducted to study the effects of dietary zinc on lipid peroxidation, protein oxidation and antioxidant defence of juvenile Jian carp (Cyprinus carpio var. Jian) by feeding fish with increasing levels of zinc (15.3, 26.9, 40.8, 58.2, 68.9 and 92.5 mg Zn kg^?1) for 6 weeks. Results indicated that malondialdehyde (MDA) content and protein carbonyls (PC) in serum were the highest in fish fed diet containing 15.3 mg zinc kg^?1 diet (P < 0.05). Serum antisuperoxide anion (ASA), superoxide dismutase (SOD), glutathione peroxidase (GSH‐Px), glutathione reductase (GR) activities and glutathione (GSH) content were improved with increasing dietary zinc levels up to 40.8 mg zinc kg^?1 diet (P < 0.05) and levelled off (P > 0.05). Serum antihydroxy radical (AHR), catalase (CAT) and glutathione‐S‐transferase (GST) activities followed the similar pattern to that observed in ASA. The MDA and PC levels, ASA, AHR, SOD, CAT, GPx, GR, GST activities and GSH content in intestine, hepatosomatic and muscle tissue followed the similar pattern to that observed in serum. The present results indicated that zinc decreased lipid peroxidation and protein oxidation and improved antioxidant defence in fish.