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1、摘要本研究根据常态下成年蛋鸡嗉囊、胃和肠道各消化器官的形态结构及消化参数的变化规律，建立成年蛋鸡消化环境参数模型，并依据原理，设计一套蛋鸡体外消化生物反应器，建立成年蛋鸡常规饲料营养价值的体外评定方法。试验一成年蛋鸡体内消化参数变化规律的研究实际测定不同日龄成年蛋鸡消化参数，了解成年蛋鸡消化道内的生理环境，建立蛋鸡消化参数模型，为成年蛋鸡体外消化生物反应器提供依据。试验选择 22 周龄健康海蓝褐蛋鸡 1440 只，随机分为 4 组，每组 8 个重复，每个重复 45 只鸡，采食玉米- 豆粕常规日粮。在常规饲养情况下，分别于 24、25、34 、44、 54 周龄每组随机选取 8 只鸡，分别测定食
2、糜水分含量、pH 值、总胆汁酸含量和各种消化酶活；同时测定十二指肠、空肠和回肠长度。结果表明:在 2454 周龄期之间，嗉囊、胃食糜 pH 值均随周龄增加而逐渐升高，但是变化范围非常小，空场内 pH值相对稳定。随周龄的增加，嗉囊、胃和空肠食糜的水分含量均无明显变化，相对稳定，但是空肠食糜含水量明显高于嗉囊和胃。小肠发育已稳定，随周龄增加无明显变化。总胆汁酸含量随周龄的增加逐渐升高，2444 周龄时总胆汁酸含量较高且相对稳定，44 周龄后降低较快。成年蛋鸡胃蛋白酶随周龄增加而降低，但在 2434 周龄时相对稳定，且酶活水平较高，44 周龄后酶活明显降低。脂肪酶、胰蛋白酶和糜蛋白酶活 2444 周
3、龄相对稳定，44 周龄后糜蛋白酶和淀粉酶下降较快。分别建立成年蛋鸡消化参数模型。试验二成年蛋鸡消化代谢试验本试验选取 35 周龄健康海蓝褐蛋鸡 240 只，随机分为 3 组，每组 40 只，每组 2个重复，每个重复 20 只鸡。日粮为玉米-豆粕常规日粮，日粮中添加 0.2%外源指示剂三氧化二铬，预试期为 1 周，试验期为 3 周。采用全收粪法连续收集 3 天粪样，65 烘干，测定常规日粮中粗蛋白质、能量和各种氨基酸在成年蛋鸡体内的消化利用率（%） 。结果表明：35 周龄成年蛋鸡对常规日粮中粗蛋白质、代谢能和各种氨基酸等营养物质的表观消化利用率水平较高且相对稳定。试验三成年蛋鸡体外消化方法的建立
4、成年蛋鸡体外消化方法的建立包括四部分：消化参数的确立、生物反应器的设计、消化步骤的确立以及体外消化方法的优化。1 消化参数的确立: 根据成年蛋鸡体内消化参数的测定结果及相关文献资料，确立成年蛋鸡嗉囊、胃和小肠内食糜的 pH 值、水分含量、胆汁酸含量、各种消化酶水平和食糜的停留时间等主要消化参数，应用商品胃蛋白酶、胰蛋白酶、糜蛋白酶、脂肪酶、淀粉酶和猪胆汁提取物替代成年蛋鸡消化道内的消化酶和胆汁酸。2 生物反应器的设计: 依仿生学原理设计生物反应器。生物反应器有以下几部分组成：消化装置、恒温振动装置、流速控制装置、消化液接收装置。3 消化步骤的确立：消化步骤分为嗉囊消化期、胃消化期和小肠消化期。
5、4 体外消化方法的优化：主要是饲料粒度和透析液流速的优化。经过优化后确定饲料体外消化方法中饲料样品的粒度为 60 目、透析液流速为 1.5ml/min。试验四体外消化方法的检验应用试验三建立的体外消化方法，通过测定饲料氨基酸的消化率来检验此体外消化方法的可行性。结果表明:总氨基酸的消化差异不显著；单个氨基酸的消化率：除天门冬氨酸、谷氨酸、精氨酸、缬氨酸、亮氨酸苯丙氨酸和酪氨酸体内外消化率差异显著外，其余氨基酸消化率差异均不显著。关键词：成年蛋鸡；常规饲料；营养价值；体外消化；消化参数 Study on the evaluation mothod for nutritional value of
6、 conventional feedstuff ofadult layers in vitroAuthor： Mei XueWenTutor：Chen BaoJiangMajor：Animal Nutrition and Feed ScienceAbstractThe study was on the rule of variation of digestive gut(gizzard,proventriculus and smallintestine)and juice development of adult layers to set up an in vitro digestion m
7、ethod fornutritional value of conventional feedstuff.Experiment 1 Study on the Gastrointestinal Parameters of adult layersIn this experiment，Digestion parameters of adult layers in different age were determinedto set up the gastrointestinal parameters model.1440 22-weeks layers were randmly assigned
8、 to 4 groups with 8 repeats 45 each and fedcorn-soybean meal diet.Layers at 24,25,34,44,54 weeks old were killed to get thechyme in crop,proventriculus and gizzard,duodenum,jejunum and ileum.Moisture,pHand digestive enzyme activities were measured respectively.The length of duodeum,jejunum and ilenu
9、m were measured too.The result showed that chyme pH in gizzard and proventriculus increased gradually withage in 2454 weeks and kept stable in jejunum.Moisture of chyme in jejunum,gizzard andproventriculus kept stable with age.Moisture in jejunum obviously higher than that ingizzard and proventricul
10、us.The small intestine has developed steady and no changes withage.The content of TBA increased gradually with age.Between 24 and 44 weeks thecontent of TBA was higher and stable,but droped rapidly after 44 weeks.Pepsinum activities in adult layers decreased with age but kept stable between 24 to 34
11、weeks and droped rapidly after 44 weeks.Lipase,trypsin and chymase activities keptstable in 24 to 44 weeks.Chymase and amylase activities droped rapidly after 44 weeks.Experiment 2 Digestive and metabolic trial for adult layers in vivoIn this experiment，240 35-weeks healthy layers were randmly assig
12、ned to 3 groupswith 2 repeats 20 each which were fed corn-soybean meal diet with chromiumoxide asindicator.It lasted 4 weeks.Feaces were collected for three days and dried at 65oC.Thedigestibility of crude protein,energy and amino acid of adult layers were determined.The result showed that the diges
13、tibility of crude protein,energy and amino acid of adultlayers kept higher and stable relatively.Experiment 3 Establish of digestion method in vitro for layerIn vitro digestion method includes four parts:establishment of digestive parameters,design of bioreactor,establishment of digestive steps and
14、optimization of in vitro digestioncondition.Establishment of digestive parameters：In this stage,pH,moisture,digestive enzymeslevel and chyme retention time in crop,proventriculus,gizzard and small intestine weredetermined respectively according to the results of experiment 1.Commercial digestiveenzy
15、mes(pepsin,pancreatin,trypsin,amylase and lipase)were used to imitate that of adultlayers gastric-intestinal tract respectively.Design of bioreactor：according to the principle of bionics,bioreactor of layergastric-intestinal tract has the following several parts:digestion device,constanttemperature
16、control device,flow speed control device and digestive juice receivers.Establishment of digestive steps:digestive steps of layer were the crop digestion phase,stomach digestion phase and intestine digestion phase.Optimization of in vitro digestion condition:test showed that the optimal feed size was60 mesh and dialysate flow speed was 1.5ml/min.Experiment 4 Test for in vitro digestive methodAccording to the result of Experiment 3,the digestibility of amino acid of the feed were
