【作者】 刘平；

【导师】 占秀安；

【作者基本信息】 浙江大学 ， 动物营养与饲料科学， 2007， 硕士

【摘要】 本课题以草鱼为研究对象,通过养殖试验、解剖试验和生化指标分析,研究赖氨酸甲酯对草鱼生长性能、饲料利用、体形和体组成、整鱼和肝脏营养成分、血清和肌肉氨基酸等常规生化指标的影响,并探讨其作用机理。选择健康草鱼幼鱼360尾(始重8.34±0.02g),按照养殖试验的要求分为4组(每组3个重复,每个重复30尾)。对照组饲喂赖氨酸缺乏的基础饲粮(含赖氨酸1.25%),3个实验组在对照组饲粮的基础上分别添加了赖氨酸0.375%(赖氨酸盐酸盐形式,含赖氨酸1.625%)、0.25%和0.375%(赖氨酸甲酯盐酸盐形式,分别含赖氨酸1.50%和1.625%)。在循环滤水和充氧的水族箱(300L)中进行了养殖试验,水温24～30℃,水中溶解氧9.71±0.5mg/L,pH7.2～7.4。按鱼体重量的2%-5%投饵,采用限饲方式,每日2次,每次投饵40min后及时将剩饵吸出,烘干称重,空白对照校正。预试期14天,正式期56天。饲养期间,每日观察鱼的活动、摄食、粪便等情况,记录投料量和死亡鱼重。饲养结束禁食24小时后称重,计算增重率、摄食量、饵料系数等指标。从每重复中选体重相近的试验鱼9尾,按常规方法测量体长、称重、采血制备血清后,进行解剖试验,同时采集肝胰脏和肌肉样品。剩下试验鱼分别在投料后1、3、5、7小时每重复选3尾进行采血制备血清。此外,正试前、后,每重复取全鱼样品3尾。所有样品先浸入液氮,后转移至-70℃低温冰箱保存,待实验室分析用。实验研究结果如下：(1)在饲料中添加赖氨酸甲酯(盐酸盐)显著提高了草鱼的增重率、特定生长率、饲料转化效率和蛋白质效率(P<0.05),而添加普通饲用赖氨酸(盐酸盐)效果不明显(P>0.05)。(2)赖氨酸甲酯显著提高了鱼体的肥满度(形体参数)和去内脏比(P<0.05),降低了内脏比和肝胰脏比(P<0.05),而普通饲用赖氨酸未产生显著影响(P>0.05)。(3)赖氨酸甲酯显著提高了鱼体的蛋白质沉积率、体蛋白及肌肉氨基酸含量(P<0.05),显著降低了肝脂比、肠脂比和体脂含量(P<0.05),而添加普通饲用赖氨酸效果不明显(P>0.05)。(4)肝脏谷草转氨酶和谷丙转氨酶活力组间差异均不显著(P<0.05)。(5)赖氨酸甲酯显著增高了血清总蛋白和白蛋白含量(P<0.05),而降低了尿素氮、Ca、P含量(P<0.05)；普通饲用赖氨酸除了使血清Ca、P含量下降外(P<0.05),其余指标均未有显著改变(P>0.05)。(6)对照组和普通饲用赖氨酸组草鱼摄食后7小时内血清游离EAA(色氨酸除外)一般在1小时左右达到高峰水平,而赖氨酸甲酯组血清游离EAA一般在3小时左右达到高峰水平。上述研究结果提示：(1)在赖氨酸缺乏的日粮中,添加赖氨酸甲酯(盐酸盐)可显著提高草鱼的增重速度和饲料转化效率,总体效果明显优于普通饲用赖氨酸(盐酸盐)。(2)赖氨酸甲酯能显著提高草鱼体蛋白沉积效率而增加体蛋白及肌肉氨基酸含量；降低肝脂比、肠脂比和体脂含量；提高去内脏比,并增高肥满度,具有改善鱼体食用品质的功效。(3)赖氨酸甲酯可能在体内脂肪酶的作用下缓慢释放赖氨酸,与蛋白质结合态氨基酸消化、吸收和利用同步,延缓血清多数游离必需氨基酸达到高峰浓度的时间,而促进机体组织氨基酸的有效利用和蛋白质的合成。更多还原

【Abstract】 This research was conducted to evaluate the effects of lysine methyl ester on growth performance,feed utilization,body figure,serum and muscle amino acids,serum biochemical parameters,nutrition of whole fish and its muscle, and approaching to the mechanism by feeding experiment, dissection experiment and lab analysis of related samples.A total of 360 healthy juvenile grass carp were divided into four groups, each of which included 3 replicates of 30 individuals with initial weight 8.34±0.02g.The control group were fed basal diet which was short of lysine (contain 1.25% lysine).The 3 experimental groups were supplemented with lysine of 0.375% (in the form of lysine·HCl),0.25% and 0.375% (in the form of lysine methyl ester·HCl)respectively. The feeding experiment was done in tanks (300L) under the conditions of circulaton,filtration,temperature 24-30℃, dissolved oxygen 9.71±0.5mg/L,pH 7.2～7.4, NH4+<0.5 mg/L.The fish were restrictly fed twice per day, total feed weight per day was 2-5%(wet weight basis) of fish biomass.Fish was weighed biweekly and the daily ration was adjusted accordingly. Fecal matter and uneaten diets were collected by siphoning from the tank after feeding for 40 minutes. The experiment lasted for 56 days while the preparing experiment was 14 days.During the experimental period,fish activity, feed intake and feces conditions were observed every day, feed intake and weight of the dead fish were recorded. At the end of rearing, the grass carp were fasting for 24 hours.Then,the fish were weighed,and weight gain,feed intake and feed conversation ratio were caculated.Nine grass carp with the same size in each replicates were fetched to determine the length and weight, then,the serum was collected and the fish were dissected. Liver and muscle were collectedThe fish left were fed again as usual,on 1, 3,5,7 hours after fed,three fish per replicate were chosen and the serum was collected.Besides, three fish were collected per replicate before and after the experiment as whole fish samples.All samples were snap-frozen in liquid nitrogen for analysis.The main results were as follows:(1)Supplementation with lysine methyl ester-HCl in the feed improved weight gain rate,specific growth rate,feed conversion ratio and protein convertion ratio of grass carp compared with the control group (P<0.05),while lysine HCI had no significant effect(P>0.05).(2) Lysine methyl ester·HCl increased coefficient of fatness and deinternal organ ratio(P<0.05),decreased internal organ ratio and liver ratio (P<0.05), while lysine·HCl had no significant effect on figure and internal organ ratio of grass carp (P>0.05)(3) Lysine methyl ester-HCI enhanced protein sediment rate,whole body protein content and amino acid level of grass carp muscle(P<0.05), and decreased fat content, mesenterium fat ratio and liver fat ratio(P<0.05),while lysine·HCl had no significant effect(P>0.05).(4) Lysine·HCl and lysine methyl ester·HCl had no significant effect on the activity of GOT and GPT in the liver (P>0.05).(5) Compared with control group,lysine methyl ester·HCl increased total serum protein and albumin as(P<0.05) while decresed the contents of SUN, Ca and P (P<0.05),lysine·HCl improved contents of Ca and P (P<0.05) but had no significant effect on other parameters.(6) The results of serum free amino acid level of grass carp at various time intervals after feeding showed that addition of lysine methyl ester·HCl achieved pinnacle of EAA individuals after feeding on about 3 hours,while control group and supplementation with lysine·HCl achieved pinnacle on about 1 hour.These results implicated that:(1)Adding lysine methyl ester·HCl to the feed which is short of lysine could improve weight gain rate and feed conversion ratio of grass carp,so as had a better effect than ordinary lysine·HCl.(2) Supplementation with methyl ester lysine·HCl could improve protein sediment rate,whole body protein content and most of amino acid contents in muscle of grass carp,and decrease fat content, mesenterium fat ratio and liver fat ratio,so as increase coefficient of fatness and improve edible ratio of the fish.(3) Lysine maybe released slowly with lysine methyl ester·HCl under the effect of lipase,then digested,absorbed and utilized with protein-combined amino acid at the same time, so as induce serum essential amino acids reaching pinnacle later. As a result, tissue amino acids could be utilized and protein synthesis improved effectively.更多还原