【作者】 苏传福；

【导师】 罗莉；

【作者基本信息】 西南大学 ， 水产养殖， 2008， 硕士

【摘要】 硒是动物机体必需的微量元素,对动物的生长发育、免疫机能和抗氧化功能发挥着重要作用。本文选用草鱼(grass carp,Ctenopharyngodon ideelus)作为实验对象,研究日粮不同硒水平对草鱼生长性能、营养组成、消化酶、抗氧化功能、部分血液指标、组织硒含量以及组织结构等方面的影响,确定草鱼硒最适需要量,并探讨硒对草鱼的作用机理。本试验采用单因子浓度梯度试验法,以酪蛋白、明胶、糊精、a-淀粉、豆油、微晶纤维素和复合添加剂等原料配制纯化日粮为基础日粮,在基础日粮(实测硒含量为0.04±0.02 mg/kg)中分别添加Se 0.00,0.15,0.30,0.60,1.20,2.40,4.80 mg/kg配制成7组试验日粮,其实测硒含量分别为0.04±0.02,0.18±0.02,0.36±0.03,0.66±0.02,1.29±0.07,2.67±0.13,4.05±0.04mg/kg。以0.00 mg Se/kg添加组为对照组。选择当年同批草鱼幼鱼(体长10.16±0.14cm,体重21.20±0.24g),随机分成7组,每组设置3个重复,用1m×1m×1m的小体积网箱在微流水池塘中进行为期84天(12周)的养殖试验。养殖试验结束后,测定草鱼生长性能指标;采集血清、肌肉、肝胰脏、肠道等样品,对其进行营养组成、消化功能、部分血液指标、抗氧化能力和组织硒含量的分析测定;并观察草鱼肝胰脏、肌肉、心脏等器官组织结构的变化。主要研究结果具体如下:1日粮硒含量对草鱼生长性能和饲料利用的影响养殖试验结果表明,日粮不同硒含量对草鱼存活率无显著影响(P＞0.05),显著影响草鱼的增重率、特定生长率、饲料效率、蛋白质效率和饲料蛋白沉积效率(P＜0.05)。日粮硒含量0.66 mg/kg-2.67 mg/kg能显著提高草鱼的生产性能,日粮硒含量0.66 mg/kg-1.29 mg/kg硒能显著提高草鱼的饲料利用率。通过回归分析,草鱼幼鱼在获得最佳增重率、特定生长率、饲料效率、蛋白质效率时,日粮中硒含量分别为0.631 mg/kg、0.614 mg/kg、0.614 mg/kg、0.614mg/kg。2日粮硒含量对草鱼形体指标、营养组分及部分血液指标的影响试验结果表明,日粮不同硒含量对草鱼的体重/体长、内脏比、肝胰脏比、脾脏指数和肥满度等形体指标无显著影响(P＞0.05);日粮硒含量对营养组分及血红蛋白和红血细胞数目影响显著(P＜0.05),草鱼日粮硒含量为0.66 mg/kg时,草鱼鱼体蛋白含量最高,脂肪含量最低;草鱼血红蛋白含量最高,红血细胞数目最多。3日粮硒含量对草鱼消化酶活性的影响日粮不同硒含量对草鱼肝胰脏和肠道消化酶活性有显著影响(P＜0.05),添加组的酶活性均较对照组明显提高。日粮硒含量对草鱼蛋白酶和脂肪酶活性的影响更为显著;肠道蛋白酶和淀粉酶活性比肝胰脏高,脂肪酶活性比肝胰脏的要低。当日粮硒含量为0.66 mg/kg时,草鱼肝胰脏和肠道蛋白酶、淀粉酶以及脂肪酶活性均达最大值。4日粮硒含量对草鱼抗氧化机能的影响对草鱼肝胰脏和血清中过氧化氢酶(CAT)、超氧化物歧化酶(SOD)、谷胱甘肽过氧化物酶(GPX)等抗氧化酶活性和脂质过氧化物丙二醛(MDA)含量及总抗氧化能力(T-AOC)等指标的测定结果表明:日粮不同硒含量对草鱼肝胰脏和血清抗氧化酶活性及MDA含量和T-AOC有显著影响(P＜0.05)。日粮硒含量为0.66 mg/kg时,显著提高草鱼血清和肝胰脏CAT、GPX活性以及总抗氧化能力,降低血清和肝脏MDA浓度,草鱼肝胰脏和血清中的抗氧化物酶系统总体达到相对平衡,能有效地抵抗氧化损害。5日粮硒含量对草鱼组织硒含量及沉积量的影响日粮不同硒含量显著影响草鱼全鱼、肌肉和肝胰脏含硒量以及草鱼硒沉积量和排泄量(P＜0.05)。全鱼和肌肉硒含量在日粮硒含量为0.04～0.36mg/kg,肝胰脏在日粮硒含量为0.04～1.29 mg/kg时,随着饲料中硒含量的增加而显著递增;全鱼和肌肉硒含量在日粮硒含量0.36～4.05 mg/kg,肝胰脏硒含量在日粮硒含量1.29～4.05 mg/kg时,差异不显著。同一组中,硒含量以肝胰脏最高,肌肉中最低。硒沉积量在日粮硒含量为0.04～0.66 mg/kg时,随着饲料中硒含量的增加而显著递增;当日粮硒含量大于1.29 mg/kg时,硒沉积量略为下降。硒排泄量随着硒添加量的增加表现出先降低后升高的趋势,日粮硒含量为0.438 mg/kg时,草鱼硒排泄量最低;当日粮硒含量为0.695 mg/kg,草鱼硒排泄量为0 mg。6日粮硒含量对草鱼组织结构的影响对草鱼肝胰脏、肌肉和心脏等器官的组织结构观察结果表明,日粮硒含量显著影响草鱼组织结构,低硒和高硒均损害草鱼肝胰脏、背肌和心脏的组织结构。当日粮硒含量为0.66mg/kg时,草鱼肝胰脏、背肌、心脏组织结构完整。综上所述,硒是草鱼生长的必需营养要素。通过对草鱼生长指标和饲料利用情况以及鱼体硒含量和沉积等指标的回归分析,确定草鱼幼鱼硒需要量为0.438 mg/kg-0.631 mg/kg。研究结果还表明,日粮适宜硒含量能显著增强草鱼机体抗氧化功能,提高草鱼消化机能,且能有效保持草鱼器官组织结构的完整性和功能性。更多还原

【Abstract】 Selenium（Se）is one essential trace mineral which plays an important part in growth,immunity and antioxidant activity in animal nutrition.This paper chose juvenile grass carp as experimental object to study the effect of dietary selenium on growth performance,quality,digestive enzyme, antioxidant ability,hematopoiesis function,selenium concentration and histological structure in order to determine dietary selenium requirements for grass carp as well as to discuss the mechanism of selenium on grass carp.The study used Single-factorial concentration grade arrangement.Na₂SeO₃ was added to the basal diet（0.04±0.02 mg Se/kg）constituted with casein,gelatin,dextrin,a-starch,soybean oil,MCC and compound additive at 0,0.15,0.30,0.60,1.20,2.40,4.80 mg Se/kg to put up seven experimental diets which providing 0.04±0.02,0.18±0.02,0.36±0.03,0.66±0.02,1.29±0.07,2.67±0.13,4.05±0.04 mg Se/kg,respectively.The basal diet which is added 0 mg Se/kg was used as control group.540 juvenile grass carp（mean length:10.16±0.14 cm,mean weight:21.20±0.24 g）randomly divided into seven treatments which each had three replicates were put into small-cubage cages（1.0×1.0×1.0 m） to conduct the feeding trial in the ponds with slowly flowing water.At the end of the feeding trial, calculated the growth performance indices;collected samples of serum,muscle,hepatpancreas, intestine to analyze nutritional composition,partial blood index,antioxidant ability and digestive function;observed histological changes of internal organs（hepatopancreas,back muscle and heart） of juvenile grass carp.The main results were summarized as follows:1 Effects of dietary selenium on production performance and feed utilization of juvenile grass carpThe feeding trail results turned out that,the dietary selenium has no significant effect on survival ration（P＞0.05）while remarkably affected specific weight gain（WG）,specific growth rates （SGR）,feed efficiency ratio（FER）,protein efficiency ratio（PER）and protein reservation rates（PRR） of juvenile grass carp（P＜0.05）.Diets containing 0.66 mg Se/kg to 2.67 mg Se/kg can remarkable raise the production performances and diets containing 0.66 mg Se/kg to 2.67 mg Se/kg can remarkable raise the feed utilization ration of juvenile grass carp.By regression analysis,when juvenile grass carp has optimal GR,SGR,FER and PER,dietary selenium concentration is 0.631 mg/kg、0.614 mg/kg、0.614 mg/kg、0.614 mg/kg,respectively.2 Effects of dietary selenium on body indices,nutritional composition and partial blood indices of juvenile grass carpThe results turned that dietary selenium has no significant affect on weight/length,visceral index,hepatosomatic index,spleen index and condition factor（P＞0.05）;but remarkable affected quality,hemoglobin and red blood cells number of juvenile grass carp（P＜0.05）.The crude protein of fish body and muscle as well as hemoglobin and red blood cells number were highest in fish feed diet with 0.66 mg Se/kg;while the fat content is the lowest.3 Effects of dietary selenium on digestive enzyme activities of juvenile grass carpThe results showed that the dietary selenium had a significant effect on digestive enzyme activities of juvenile grass carp（P＜0.05）.All the tested groups had higher activities than the control group.Dietary selenium affects the protease and lipase more remarkably.The activities of protease and amylase were higher in intestine while the activities of lipase were higher in hepatopancreas.The activities of the three digestive enzymes were highest with dietary 0.66 mg Se/Kg.4 Effects of dietary selenium on antioxidant function of juvenile grass carpThe results of activities of three antioxidant enzymes such as superoxide dismutase（SOD）, catalase（CAT）and glutathione peroxidase（GPX）,levels of malondialdehyde（MDA）and total antioxidative competence（T-AOC）in hepatopancreas and serum showed that dietary selenium had significant effects on the antioxidant enzymes activities as well as the MDA and T-AOC（P＜0.05）. When 0.60 mg/kg Se added,the activities of GPX,CAT as well as the T-AOC value increased to the highest,while the MDA level decreased to the lowest.All of those mentioned above indicated that a optimum selenium level（0.66 mg Se/kg）could keep the antioxidant enzymes in a balanced level, which could protect grass carp from oxidant damage. 5 Effects of dietary selenium on selenium concentration and deposition of juvenile grass carpThe results showed that dietary selenium had a significant effect on selenium concentration in whole-body,muscle and hepatopancreas as well as selenium deposition and excretion in whole-body of juvenile grass carp（P＜0.05）.Selenium concentration in whole-boy and muscle with dietary Se from 0.04 mg Se/kg to 0.36 mg Se/kg as well as selenium concentration in hepatopancreas with dietary Se from 0.04 mg Se/kg to 1.29 mg Se/kg remarkably increased as increasing of dietary selenium,beyond which the selenium concentration had no significant difference（P＞0.05）.In the same test group,the highest selenium concentration was found in hepatopancreas while lowest in muscle.The selenium deposition had increased with increasing selenium up to 0.66 mg Se/kg,beyond which it showed a decline tendency.The selenium excretion first increased and then decreased as dietary selenium increased,and the lowest excretion diet of grass carp was loud to be dietary 0.438 mg Se/kg,while the excretion of grass carp feed diets with 0.695 mg/kg was 0 mg.6 Effects of dietary selenium on histological structure of juvenile grass carpThe results of observation to the histological structure of hepatopancreas,back muscle and heart showed that dietary selenium had a significant affect on histological structure of juvenile grass carp.Both low selenium and high selenium were harmful to the histological structure of internal organs of juvenile grass carp.Only optimum dietary selenium（0.66 mg Se/kg）can maintain normal histological structure.All these results demonstrated that selenium was an essential nutrient for grass carp.Dietary selenium requirement for juvenile grass carp was determined as 0.438 mg/kg-0.631 mg/kg by inspecting indices of production performance,feed utilization as well as selenium concentration and deposition of juvenile grass carp.The results also indicated that,dietary selenium can remarkably enhance antioxidant ability,increase digestive faction as well as effectively maintain integrity and functionality of internal organs for juvenile grass carp.更多还原