模拟鸭肠液中消化酶的批次来源与活性贡献对饲料原料消化能力的影响

本试验旨在研究模拟鸭肠液中鸭肠液酶粉剂的批次来源与活性贡献对玉米、豆粕、小麦麸消化能力的影响,为模拟鸭肠液中鸭肠液酶粉剂的适宜添加量提供参考。采用嵌套设计,其中独立变量为鸭肠液酶粉剂的批次来源,设3个处理水平,分别为鸭肠液酶粉剂批次1、2、3;嵌套变量为模拟鸭肠液中鸭肠液酶粉剂提供的消化酶活性比例(以胰蛋白酶为基础),设4个处理水平,即0(共用)、25%、50%、75%,分别测定10种模拟鸭肠液对玉米、豆粕、小麦麸3种饲料原料的干物质消化率和酶水解物能值。结果表明:1)3个批次的鸭肠液酶粉剂制备的模拟鸭肠液对玉米、小麦麸的干物质表观消化率、真消化率及酶水解物表观能值、真能值均无显著影响(P>0.05);对豆粕的干物质表观消化率及酶水解物表观能值、真能值无显著影响(P>0.05),但对其干物质真消化率(71.75%～72.24%)有显著影响(P<0.05)。2)同一鸭肠液酶粉剂批次内,酶粉剂提供的消化酶活性的比例从25%增加到75%时,玉米、豆粕、小麦麸的干物质表观消化率和酶水解物表观能值均显著降低(P<0.05),但干物质真消化率相对稳定(最大绝对差值0.95%,相对差值0.95%),酶水解物真能值在鸭肠液酶粉剂提供的消化酶活性的比例从25%增加到50%的范围内也相对稳定(最大绝对差值0.17 MJ/kg,相对差值0.89%)。综合上述结果,不同批次来源的鸭肠液酶粉剂制备的模拟鸭肠液在消化能力上是相等的,模拟鸭肠液中鸭肠液酶粉剂对消化酶总活性的贡献在25%～50%消化能力比较稳定。     

饲喂2种日粮条件下鸭小肠各段肠液组成差异的研究

通过研究在饲喂小麦-豆粕型日粮和玉米-豆粕型日粮条件下,北京鸭小肠各段肠液组成沿肠道纵向长度的差异,为模拟鸭小肠液的设计提供参考。试验采用完全随机设计,将30只成年北京公鸭随机分配到2个处理中,每个处理5个重复,每个重复3只鸭,分别随机饲喂小麦-豆粕型日粮和玉米-豆粕型日粮,在试验期的第19天屠宰后取十二指肠、空肠前段、空肠后段和回肠的食糜,离心后取上清液分析消化酶活性、离子浓度及pH。研究结果表明,十二指肠肠液与空肠前段肠液的淀粉酶和脂肪酶活性无显著差异(P>0.05),且显著地高于空肠后段肠液和回肠肠液的相应值(P<0.05)。空肠前段肠液与空肠后段肠液的胰蛋白酶活性无显著差异(P>0.05),且显著高于十二指肠肠液和回肠液的相应值(P<0.05)。空肠前段肠液的糜蛋白酶活性最高,其后依次为十二指肠肠液、空肠后段肠液和回肠液,且4种肠液中两两间差异显著(P<0.05)。沿小肠纵向长度,鸭肠液的pH从6.22至7.94逐渐升高,Na+和Ca2+浓度先升后降,K+浓度逐步下降,Mg2+浓度在十二指肠肠液中最低,显著地低于其他肠段肠液的相应值(P<0.05)。日粮组成对肠液中4种消化酶的活性及K+和Mg2+的浓度有显著的影响。由此可见,沿鸭小肠长度的纵向分布中,空肠液的4种主要消化酶活性最高,不同肠段肠液在离子浓度上存在显著差异。     

日粮类型及肠液储存条件对鸭空肠液组成与特性的影响

本试验旨在通过研究日粮类型及肠液的体外储存条件对鸭空肠液组成的影响,为人工鸭小肠液的制备提供参考.试验一探讨日粮类型对鸭空肠液组成的影响,采用完全随机设计,将36只安装有空肠T型套管的成年公鸭随机分成2组,每组6个重复,每个重复3只鸭,分别饲喂玉米-豆粕型日粮和玉米-豆粕-菜粕-棉粕型日粮,试验期35 d.试验二利用2×3(2个储存温度:-20和-70℃,3个储存时间:30、60和90 d)完全随机设计,研究鸭空肠液有效生物学活性的适宜储存条件.结果表明,2种日粮条件下鸭空肠液在胰蛋白酶、糜蛋白酶的活性及Mg2+和Cl-浓度上有显著差异(P<0.05),而在淀粉酶和脂肪酶活性,K+、Na+和Ca2+浓度及pH上无显著影响(P>0.05).肠液的储存温度对鸭空肠液的pH有显著影响(P<0.05),而对消化酶活性无显著影响(P>0.05).肠液的储存时间对玉籽豆粕-菜粕-棉粕型日粮条件下鸭空肠液胰蛋白酶和淀粉酶活性以及2种日粮条件下空肠液pH有显著或极显著影响(P<0.05或P<0.01).由此可见,日粮类型是影响鸭空肠液生物学特性的主要因素之一,储存条件对鸭空肠液生物学特件的影响因日粮类型的不同而有所差异.     

鸭空肠液中消化酶粗提纯方法的比较研究

本试验旨在比较硫酸铵沉淀-透析-冻干-脱脂法与低温浓缩-透析-冻干-脱脂法制备鸭空肠液消化酶粉剂的差异。采用两样本完全随机设计,将8 L鸭空肠液随机分成2组,每组4个重复,每个重复1 L肠液。第1组采用硫酸铵沉淀-透析-冻干法,第2组采用低温浓缩-透析-冻干法,分别制备消化酶粉剂,然后对2组制备的粉剂进行脱脂,比较脱脂前和脱脂后2种方法制备消化酶粉剂的消化酶活性与回收率、总蛋白浓度与回收率及化学成分含量的差异。结果表明:1)低温浓缩-透析-冻干法制备的消化酶粉剂中淀粉酶、胰蛋白酶、糜蛋白酶的活性比硫酸铵沉淀-透析-冻干法分别高34.8%、27.9%和12.1%(P<0.05);相应地,3种消化酶回收率及总蛋白回收率比硫酸铵沉淀-透析-冻干法分别高34.8%、35.2%、15.3%和12.6%(P<0.05);粗蛋白质及粗灰分含量显著低于硫酸铵沉淀-透析-冻干法(P<0.05),而粗脂肪含量差异不显著(P>0.05)。2)经脱脂处理后,低温浓缩-透析-冻干-脱脂法制备的消化酶粉剂中淀粉酶、胰蛋白酶活性比硫酸铵沉淀-透析-冻干-脱脂法分别高11.5%和7.9%(P<0.05),而糜蛋白酶活性差异不显著(P>0.05);淀粉酶和胰蛋白酶回收率比硫酸铵沉淀-透析-冻干法分别高39.4%和43.9%(P<0.05),而糜蛋白酶回收率差异不显著(P>0.05);总蛋白回收率显著高于硫酸铵沉淀-透析-冻干-脱脂法(P<0.05),而总蛋白浓度差异不显著(P>0.05);粗蛋白质及粗灰分含量显著低于硫酸铵沉淀-透析-冻干-脱脂法(P<0.05),而粗脂肪含量差异不显著(P>0.05)。由此可知,从纯化过程的全程看,低温浓缩-透析-冻干-脱脂法中淀粉酶、胰蛋白酶活性和回收率均显著高于硫酸铵沉淀-透析-冻干-脱脂法。     

鸭空肠液中淀粉酶、胰蛋白酶、糜蛋白酶活性变异的研究

本试验旨在通过研究鸭空肠套管中食糜流量及空肠液中消化酶活性的变异,探讨获取相对可比的空肠液样品的适宜采样方案,为鸭小肠中消化酶酶谱的研究提供依据.采用3×6(日期×时间)完全随机设计,每4h采集1次空肠食糜,每采集1h后间隔3h,隔日重复采样过程,共采集3d.试验1,随机选择15只荷术鸭,分成5个重复,每个重复3只鸭,测定空肠套管中食糜的流量.试验2,从鸭群中随机选择24只荷术鸭,分成6个重复,每个重复4只鸭,测定空肠液中淀粉酶、胰蛋白酶、糜蛋白酶的活性.结果表明:空肠套管内的食糜流量呈现出日间及日内变异,日内食糜流量呈现出先升后降的总体规律.日内采样时间对空肠液中淀粉酶、胰蛋白酶、糜蛋白酶活性有极显著的影响(P<0.01).不同日间,淀粉酶、糜蛋白酶的日平均活性有显著差异(P<0.05),而胰蛋白酶日间平均活性没有显著差异(P=0.28).3种消化酶活性均呈现出同一日内随采样时间而逐渐降低的总体现象.鉴于上述现象,通过套管获取反映鸭空肠中消化酶活性生理水平的采样方案为:白天采集3次样品,每次采集1h间隔3h,隔日重复采样,共采集3d.     

仿生消化法中消化酶与消化时间对评定生长猪常用植物性饲料磷体外消化率的影响

本试验旨在探讨仿生消化过程中生长猪体内4种小肠消化酶以及胃期和小肠期消化时间对植物性饲料磷体外消化率的影响,为确定仿生消化法评定生长猪常用植物性饲料磷体外消化率时模拟小肠消化液的组成与最佳消化时间提供参考。试验在SDS-Ⅰ型单胃动物仿生消化系统中进行,以玉米、豆粕和麦麸为测试原料,分3个试验进行。试验1,设置5个处理,1个不添加小肠消化酶的处理(对照)和4个添加不同小肠消化酶的处理,分别添加胰蛋白酶、胰蛋白酶+糜蛋白酶、胰蛋白酶+糜蛋白酶+淀粉酶、胰蛋白酶+糜蛋白酶+淀粉酶+脂肪酶,胃期消化时间为1.25 h,小肠期消化时间为4.00 h;试验2,确定小肠消化液主要消化酶组成后,设置5个不同的胃期消化时间的处理,分别为0.50、0.75、1.00、1.25、1.50 h,各处理的对应小肠期消化时间均设置为4.00 h;试验3,确定胃期消化时间后,设置6个不同的小肠期消化时间的处理,分别为1.00、2.00、3.00、4.00、5.00、6.00 h。以上各处理均设3个重复,每个重复5根消化管,分别测定3种饲料原料的磷体外消化率。结果表明:1)胰蛋白酶、淀粉酶和脂肪酶均可显著提高玉米、豆粕和麦麸磷体外消化率(P<0.05),糜蛋白酶可显著提高豆粕和麦麸磷体外消化率(P<0.05),却显著降低了玉米磷体外消化率(P<0.05)。2)胃期消化时间由0.50 h增加到1.00 h,玉米和豆粕磷体外消化率均无显著性变化(P>0.05);1.25 h时玉米和豆粕磷体外消化率显著降低(P<0.05);消化时间由0.50 h增加到1.00 h,麦麸磷体外消化率显著升高(P<0.05),1.25 h时达到稳定。3)小肠期消化时间由1.00 h增加到6.00 h,玉米、豆粕和麦麸磷体外消化率均显著增加(P<0.05),并分别在3.00、4.00、5.00 h达到稳定。分析以上结果得出:1)可采用胰蛋白酶、糜蛋白酶、淀粉酶和脂肪酶模拟小肠液。2)确定胃期消化时间为1.00 h,小肠期消化时间为5.00 h。     

饲粮蛋白质来源对蛋鸡小肠液组成的影响

本试验旨在通过研究饲粮蛋白质来源对鸡肠液中消化酶活性及离子浓度的影响,为鸡饲料酶学生物学效价评定方法中小肠液的仿生酶谱设计提供决策依据.试验采用2×2完全随机没计,分别选用健康、体重相近的十二指肠瘘、空肠瘘成年海兰褐壳蛋公鸡各24只,将每种类型的荷术鸡随机分成2组,每组4个重复,每个重复3只鸡,分别饲喂玉米-豆粕型饲粮和玉米-豆粕-棉籽粕型饲粮.在试验期第31天、第33天、第35天的09:30至18:30间每隔3 h收集1 h十二指肠和空肠食糜,通过低温离心的方法制备肠液.结果表明,玉米-豆粕型饲粮条件下十二指肠液脂肪酶活性,Cl-的浓度及空肠液胰蛋白酶的活性显著地高于玉米-豆粕-棉籽粕型饲粮条件下的相应值(P<0.05),而十二指肠液Mg2+浓度和空肠液K+的浓度显著地低于玉米-豆粕-棉籽粕型饲粮条件下的相应值(P<0.05).从不同肠段肠液组成的差异看,十二指肠液中淀粉酶和胰蛋白酶的活性,Na+、Mg2+的浓度及pH显著地低于空肠液中的相应值(P<0.05),而脂肪酶的活性,K+、Cl-的浓度显著地高于空肠液中的相应值(P<0.05).这表明饲粮蛋白质来源对鸡肠液蛋白酶活性及电解质离子浓度有显著影响,不同肠段的肠液在组成上存在较大差异.     

不同酶制剂在模拟胃肠道环境因素下对玉米皮粉降解的影响

本试验考察了不同酶制剂在模拟胃肠道环境因素下对玉米皮粉降解的影响,试验分为4个部分,首先考察了低pH值对2种不同的酶制剂降解玉米皮粉的影响,结果表明各处理组的干物质消失率没有达到显著性差异(P0.05),但低pH值条件下真菌复合酶组的还原糖含量显著高于其他各组(P0.05);接着考察了胆盐对2种不同的酶制剂降解玉米皮粉的影响,结果表明酶加佳组的还原糖含量及干物质消失率均显著高于其他各组(P0.05);然后按照食糜从胃到小肠的消化次序,先用低pH值处理过后用胆盐处理,考察低pH值和胆盐对2种不同的酶制剂降解玉米皮粉的影响,结果表明真菌复合酶仍具有一定降解淀粉多糖或非淀粉多糖的能力,但酶加佳组的还原糖含量与对照组没有显著性差异(P0.05);最后,试验在发酵体系中按消化次序分别添加胃蛋白酶和胰蛋白酶,考察模拟胃液和小肠液对2种不同的酶制剂降解玉米皮粉的影响,结果表明胃液和小肠液使各复合酶的酶活受到严重抑制。     

小鼠输卵管上皮细胞的原代培养及纯化方法研究

建立小鼠输卵管上皮细胞原代培养及纯化方法.小鼠输卵管上皮细胞原代培养采用组织块培养法和酶消化法.酶消化法于37℃分为4个处理组进行.处理1以2.5 g/L胰酶+0.4 g/L EDTA消化5、10、20 min;处理2以0.5 g/L胰酶+0.08 g/L EDTA消化35、50、75 min;处理3以0.3 g/L的Ⅰ型胶原酶消化60、90、240 min;处理4以2.5 g/L胰酶+0.4 g/L EDTA和0.3 g/L Ⅰ型胶原酶(1∶2)消化60 min,150 min.原代细胞纯化采用差速贴壁和反复差速贴壁法.传代采用胰酶两步消化法进一步纯化输卵管上皮细胞.组织块法原代培养成纤维细胞生长优势明显,传代纯化细胞效果不佳.用酶消化法原代培养时,处理1效果不理想;处理2采用3个消化时间时均取得比较理想的结果;处理3消化240 min时结果较好;处理4消化150 min效果较好.原代细胞纯化,反复差速贴壁得到的上皮细胞较纯,进一步传代纯化细胞取得了理想的结果.小鼠输卵管上皮细胞原代培养采用酶消化法结合反复差速贴壁分离纯化细胞,传代采用两步消化法,可以成功地进行小鼠输卵管上皮细胞的分离纯化培养.     

用绵羊小肠液冻干粉评定瘤胃非降解精饲料残渣的有机物于小肠消化率方法的研究

本试验旨在筛选用绵羊小肠液冻干粉评定瘤胃非降解精饲料残渣的有机物于小肠消化率的最佳培养条件。试验包括三部分 :第一个试验研究了小肠液冻干粉用量 ( 0 .2、0 .3、0 .4与 0 .5g)与缓冲液种类(McDougall缓冲液与磷酸盐缓冲液 )对 1 2h瘤胃非降解玉米与豆粕的有机物于小肠消化率的影响 ;第二个试验研究了缓冲液pH值 ( 7.0、7.5与 8.0 )与Ca2 + 浓度 ( 3 4 0、680与 2 0 0 0 μmol/L)对 1 2h瘤胃非降解玉米与豆粕的有机物于小肠消化率的影响 ;第三个试验研究了离体培养时间 ( 3、6、9、1 2、1 5、1 8、2 1与 2 4h)对1 2h瘤胃非降解玉米与豆粕的有机物于小肠消化率的影响。筛选的用绵羊小肠液冻干粉评定瘤胃非降解精饲料残渣的有机物于小肠消化率的适宜条件为 :0 .4 5g小肠液冻干粉 / 0 .56g饲料 ,McDougall缓冲液 ,pH =7.5,Ca2 + =680 μmol/L ,3 9℃ ,瘤胃非降解玉米与豆粕的最佳培养时间不同 ,分别为 1 2与 1 8h     

The influence of grinding and pelleting of feed on the microbial composition and activity in the digestive tract of broiler chickens

1. The influence of feed grinding (coarsely or finely ground feed) and feed form (mash or pellets) on the intestinal environment was investigated in a growth experiment with broiler chickens taking the intestinal microflora, intestinal viscosity, and the activities of pancreatic digestive enzymes into consideration. 2. As compared to mash the feeding of pellets was associated with a significantly higher body weight due to increased feed intake and improved feed utilisation. 3. Pellet-fed birds had significantly decreased gizzard weights, a higher gizzard pH and a lower intestinal pH than mash-fed birds. 4. Pellet-fed birds had significantly lower relative pancreas weights and lower activities of pancreatic digestive enzymes (amylase, lipase, chymotrypsin), which indicates the existence of a feedback mechanism, which may have been triggered by the intestinal concentration of enzymatically hydrolysed products or of the respective digestive enzymes. 5. Pellet-fed birds had larger numbers of coliform bacteria and enterococci in the ileum and a reduced number of Clostridium perfringens and lactobacilli in the distal end of the digestive tract (caeca and rectum). Microbial fermentation in terms of volatile fatty acid (VFA) concentration was found to be significantly higher in the caeca of pellet-fed birds than in mash-fed birds.     

单宁酸对生长猪胃-小肠仿生消化中消化酶活性及饲粮粗蛋白消化率的影响

本试验旨在探讨单宁酸对生长猪胃、小肠仿生消化中消化酶活性及玉米-豆粕型饲粮干物质和粗蛋白消化率的影响，为评价单宁酸的生物学效应提供参考。试验一采用单因素完全随机设计，考察在无饲粮下2种单宁酸对猪模拟胃液、模拟小肠液消化酶活性的影响。设5个处理，单宁酸添加量分别为0 mg （胃液体积为20 mL，小肠液体积为22 mL）；单宁酸1，10 mg；单宁酸1，20 mg；单宁酸2，10 mg；单宁酸2，20 mg。测定各处理的胃蛋白酶、淀粉酶、胰蛋白酶和糜蛋白酶的活性。试验二考察玉米-豆粕型饲粮添加单宁酸对猪仿生消化中胃、小肠阶段消化酶活性及养分消化率的影响。采用单因素完全随机设计，设5个处理，单宁酸在饲粮中的含量分别为0 mg·（2 g）^-1；单宁酸1，10 mg·（2 g）^-1；单宁酸1，20 mg·（2 g）^-1；单宁酸2，10 mg·（2 g）^-1；单宁酸2，20 mg·（2 g）^-1。测定仿生消化中胃阶段0.5和4 h时胃蛋白酶活性，小肠阶段0.5、4和8 h时淀粉酶、胰蛋白酶和糜蛋白酶活性及生长猪胃-小肠仿生消化测定饲粮的干物质和粗蛋白消化率。结果表明：1）无饲粮的情况下，和空白对照组相比，2种单宁酸对模拟胃液中胃蛋白酶活性无显著影响（P>0.05），单宁酸1比单宁酸2更高地降低了模拟小肠液中淀粉酶、胰蛋白酶和糜蛋白酶的活性（P<0.05）。2）在饲粮进行仿生消化的胃消化0.5～4 h内，除4 h时10 mg·（2 g）^-1添加量外，添加单宁酸1时胃蛋白酶的活性均显著高于添加单宁酸2时的相应值（P<0.05），除单宁酸2在消化0.5 h外，2种单宁酸在添加10 mg·（2 g）^-1时胃蛋白酶活性均显著高于20 mg·（2 g）^-1添加量的相应值（P<0.05）。在小肠仿生消化0.5 h时，饲粮中添加单宁酸1、2的2个水平对消化液中淀粉酶活性无显著影响（P>0.05），但均显著降低了糜蛋白酶的活性（P<0.05）；单宁酸1的消化液中胰蛋白酶活性高于单宁酸2的相应值（P<0.05）。在小肠仿生消化4 h时，除添加水平为20 mg·（2 g）^-1时的糜蛋白酶活性外，饲粮中添加单宁酸1消化液中淀粉酶、糜蛋白酶活性高于添加单宁酸2的相应值，而胰蛋白酶活性低于添加单宁酸2的相应值（P<0.05）。单宁酸1、2的两个添加量均降低了胰蛋白酶和糜蛋白酶的活性（P<0.05）。在小肠仿生消化8 h时，饲粮中单宁酸的添加量影响了淀粉酶的活性，但单宁酸1和单宁酸2各两个添加量在淀粉酶的平均活性上无显著差异（P>0.05）。单宁酸1、2的两个添加量均降低了胰蛋白酶、糜蛋白酶的活性（P<0.05）。3）与对照组相比，两种单宁酸在两种添加水平下均显著降低了饲料粗蛋白消化率（P<0.05），且单宁酸2比单宁酸1更多地降低了饲粮粗蛋白的消化率（P<0.05）。综上所述，在有、无饲粮条件下，单宁酸对消化酶活性呈现不一致影响。单宁酸影响饲粮粗蛋白的消化率可能主要与消化液中糜蛋白酶活性降低以及单宁酸与饲粮中的化学成分形成螯合物降低了小肠消化酶的水解效率有关。     

Enzyme digestion in the proximal digestive tract of the pig: A reviewLa digestion enzymatique dans la partie proximale du porc une revue bibliographiqueEnzymatiche verdauung im proximalen verdauungstrakt beim schwein ein ubersichtsreferat

Studies on enzyme digestion in the precaecal part of the digestive tract show that the pig posesses digestive enzymes that can completely break down dietary substrates to absorbable nutrients. Gastric pepsins, pancreatic proteolytic enzymes and intestinal peptidases are responsible for the hydrolysis of dietary proteins; salivary and pancreatic α-amylases start the hydrolysis of starch, its products being broken down by intestinal carbohydrases; dietary lipids, mainly triglycerides, are hydrolyzed in the intestinal lumen by the complex lipase—colipase—bile salts. Hydrolysis of food components may be complete, depending upon different factors such as the composition of the diet or the nature of the substrate.     

Effect of Different Weaning Ages on Main Digestive Enzymes Activities in the Small Intestinal Contents of Lamb

The objective of this study was to determine the effects of different weaning ages on pH and the main digestive enzymes activities in the small intestinal contents of lamb. Fifty-five male lambs of Gansu modern breeding sheep group with(3.43±1.15)kg initial body weight were divided into 3 treatments randomly that were control group (sucking,25 lambs), group Ⅰ (weaning at 28 days old, 15 lambs), and group Ⅱ(weaning at 42 days old,15 lambs).5 lambs from each group were slaughtered at 12 h,7 d and 14 d after weaning,respectively,and the the change of pH and activities of α-amylase,trypsin,chympotrypsin and lipase were measured in the small intestinal contents. The results showed that the effects of pH and the main digestive enzymes activities could be expressed sensitively in the contents of duodenum. From duodenum to ileum,the effects of weaning turned weakening gradually,and it did not show a high-impact on pH,trypsin and lipase activities. There was no significant influence in the recovery time to the normal levels of the main digestive enzymes activities in the small intestinal contents by different weaning ages,the recovery time of α-amylase in group Ⅰ was shorter than group Ⅱ. In this trail condition,it was feasible to wean at 28 days of age,and it had no significant difference in the recovery ability of main digestive enzymes in the small intestinal contents weaning at 28 and 42 days old.     

断奶日龄对舍饲羔羊小肠内容物中主要消化酶活性的影响

为研究早期断奶日龄对羔羊小肠各段pH及主要消化酶活性的影响,选用55只初生重为（3.43±1.15）kg的甘肃现代肉羊育种群哺乳公羔,按同质原则分成3组,即对照组（正常吮乳组,25只）、Ⅰ组（28日龄断奶组,15只）和Ⅱ组（42日龄断奶组,15只）。在断奶12 h、7 d和14 d后从每个处理中随机抽取5只羔羊屠宰,测定小肠各段pH、α-淀粉酶、胰蛋白酶、糜蛋白酶和脂肪酶活性变化。结果显示,十二指肠食糜能够更为敏感地表达断奶对小肠pH及主要消化酶活性的影响。从小肠近端至远端,断奶对各肠段内容物pH及主要消化酶活性的影响逐渐减弱;断奶对小肠内容物pH、胰蛋白酶活性和脂肪酶活性影响较小;断奶日龄对羔羊小肠主要消化酶活性恢复所需要的时间影响不大,28日龄断奶组小肠α-淀粉酶活性恢复时间较42日龄断奶组短。本试验条件下,对羔羊实施28日龄断奶可行,且羔羊小肠主要消化酶活性恢复能力不逊于42日龄断奶羔羊。     

Metabolic and anatomical adaptations of heavy-bodied chicks to intermittent feeding. 2. Pancreatic digestive enzymes.

1. Activities of digestive enzymes in meat-type chickens under ad libitum or alternate-day feeding were determined from 14 to 83 d of age. 2. Final body weight of intermittently fed birds attained 75% of that of the ad libitum-fed controls. 3. When compared with the ad libitum-fed counterparts, a marked increase in the relative weight of the pancreas and intestinal contents were found on repletion days. On depletion days the relative weights of the pancreas and of the intestinal contents were about half those found in ad libitum-fed birds. 4. The activity of the digestive enzymes in the pancreas, expressed as U/g pancreas or U/kg body weight, was not affected consistently by the feeding regime. In the small intestine a marked increase in relative activity (U/kg body weight) was observed on repletion days and a marked decrease on depletion days as compared with ad libitum-fed controls. The activities per g intestinal contents following food restoration did not differ significantly from those of ad libitum-fed controls except for trypsin, which was higher in the former. On depletion days the activities per g intestinal contents were lowest, lipase excepted.     

The Prenatal Development and Histochemistry of the Ileal Mucins in the Bovine Fetuses

Few studies exist regarding the distribution of intestinal mucins in fetuses of mammalians such as cattle and sheep. In this study, we aimed to describe the changes in the mucin production by ileal epithelium of bovine fetuses during their prenatal development. The goblet cells showed heterogeneity in mucins and the apical cytoplasm of the enterocytes demonstrated Periodic acid Schiff‐positive reaction which declined gradually towards the birth. Moreover, the number of the goblet cells containing acidic and mixed mucins augmented, whereas those containing neutral mucins decreased with advancing gestational age. After sixth month of gestation, with the initiation of the ileal Peyer patches and follicle‐associated epithelium development, a gradual increase in the number of goblet cells containing sulfomucins was also noticed towards the birth. The presence of different mucins in the ileum of bovine fetuses throughout prenatal development might play a role in the protection of the intestinal mucosa against urinary waste products in swallowed amniotic fluid and bile. Furthermore, mucins can also contribute for the formation of meconium in intra‐uterine life and building of strong intestinal barrier with predominating sulfomucins, protecting the intestine against potential pathogens and digestive enzymes after birth.     

Binding of lipase, amylase and protease to intestinal epithelium as affected by carbohydrates and lectins in vitro

Intraluminal digestive enzymes were shown to bind to chick intestinal epithelial surface (glycocalyx). Affinity of the intestinal epithelium for the enzymes decreased in the order, lipase > amylase > protease. The plant hemagglutinins, Con A, phytohemagglutinin, pokeweed mitogen and raw soybean effectively released lipase and amylase from the glycocalyx. Based on specific inhibition of binding by sugars, such as fucose and N-acetylated sugars, lipase and amylase appeared to be bound to blood group antigen-like sugar moieties on the glycocalyx of the microvilli.     

Growth and development of the digestive organs and some enzymes in broiler chicks after hatching.

1. Body weight and the weight of the digestive organs and activities of some digestive enzymes were determined from hatching to 23 d of age. 2. Relative daily growth rate peaked at 11 d of age (22% gain/d) and then decreased gradually. 3. The vitelline residue was decreased rapidly from 4.6 g at hatching to negligible values from 4 d of age. 4. Maximal allometric growth of the pancreas and small intestine was 4-fold and that of liver 2-fold greater than that of the body. 5. Activities (units/kg body weight) of the digestive enzymes measured in the pancreas and intestinal contents increased with age. In the pancreas maximal values were attained on day 8 for amylase and lipase and 11 for trypsin and chymotrypsin. In the small intestine maxima were attained on day 4 for lipase, 11 for trypsin and chymotrypsin and 17 for amylase. 6. The development of secretion of digestive enzymes in the post-hatched chick could be a limiting factor in digestion and subsequently in food intake and growth.     

断奶应激引发仔猪肠道损伤及重建机制研究进展

肠道的发育与成熟状况是制约幼畜快速生长的关键因素。断奶是仔猪必须经历的一个应激过程,而断奶应激主要的靶点就是仔猪的肠道,特别是小肠的损伤尤为严重。因此,本文从仔猪肠道的形态和结构、肠道消化和代谢相关酶活性、肠道黏膜屏障、肠道功能基因和蛋白的表达及调控、断奶激活的肠道应激信号通路、应激蛋白家族在肠道中的差异表达等多个层面探讨断奶应激导致仔猪肠道损伤及重建的机制。为今后采用各种营养调控手段改善仔猪肠道健康、促进其快速生长提供理论基础和支持。