【作者】 蒋正宇；

【导师】 王恬；

【作者基本信息】 南京农业大学 ， 动物营养与饲料科学， 2006， 硕士

【摘要】 本研究的目的在于探讨外源淀粉酶与内源酶之间的互作关系，着重研究添加外源淀粉酶对胰腺淀粉酶合成和分泌活性的影响及其后续效应，为进一步深入研究酶制剂作用机理及其合理应用提供参考依据。论文共分两个部分： 第一部分，研究了添加不同剂量外源a-淀粉酶对肉鸡生长、消化器官发育和内源酶活性变化、胰腺mRNA表达的影响。选用1日龄AA肉鸡440羽，随机分成4组，每组5个重复，每个重复22羽，分别饲喂基础日粮(对照组)和在基础日粮中分别添加1，000LU／kg(250mg／kg)、3，000LU／kg(750mg／kg)、9，000LU／kg(2250mg／kg)微生物a-淀粉酶的试验日粮，至21日龄取样，并测定21日龄和42日龄生产性能。结果表明：(1) 添加淀粉酶均能提高了肉鸡前期和后期增重，促进前期肉鸡采食，而且肉鸡增重与添加剂量呈明显的线性关系(P＜0.01)，但饲料转化率未受影响，添加2250mg／kg淀粉酶对肉鸡增提高作用最大，添加750mg／kg淀粉酶对饲料转化率改善效果最佳；(2) 淀粉酶不同程度地降低了肉鸡肝脏、肌胃、前肠相对重量和前肠相对长度(P＞0.05)，增加了腺胃、胰腺相对重量(P＞0.05)；(3) 淀粉酶不同程度地提高了肉鸡前肠内容物淀粉酶、总蛋白酶(P＜0.05)和胰蛋白酶(P＜0.05)活性，但未影响脂肪酶活性，而且高剂量(2250mg／kg)添加组的总蛋白酶(P＜0.05)和淀粉酶活性有下降趋势；(4) 肉鸡空肠黏膜DNA、RNA、蛋白质含量及淀粉酶、蔗糖酶、麦芽糖酶活性未受淀粉酶水平影响，但高剂量降低了蔗糖酶和麦芽糖酶活性(U／g黏膜)(P＜0.05)；(5) 不同剂量的淀粉酶对肉鸡胰腺蛋白含量、淀粉酶、总蛋白酶、胰蛋白酶、脂肪酶活性均无明显影响，但胰腺淀粉酶活性(U／g胰腺)，随着外源淀粉酶添加量增加而线性下降(P=0.022)；(6) 随着淀粉酶添加水平的提高，胰腺淀粉酶mRNA表达量呈线性下降(P=0.002)，添加2250mg／kg淀粉酶显著降低了胰腺淀粉酶mRNA的表达量(P＜0.05)。 第二部分，研究了肉鸡日粮中添加a-淀粉酶至1周龄后，停止饲喂加酶日粮，改喂不添加酶的对照组日粮至21日龄，分别考察在停喂淀粉酶后的第3、7、14天肉鸡消化器官增重及小肠和胰腺消化酶活性的变化。结果表明：添加淀粉酶对7日龄肉鸡更多还原

【Abstract】 The purpose of this work was to investigate the interrelation between supplementary exogenous a-amylase of microbial origin and the development of broilers’ endogenous enzymes. It focused on the major influence of exogenous a-amylase on the synthesis and secretory activity of pancreatic amylase as well as possible carry-over effects. Some referenced information of this field was provided for further exploration of the action mechanism and reasonable application of enzyme inclusion in poultry diets.This study included two parts and the general results were presented as follows:In the first part, an experiment was designed to study the effects of supplementary a-amylase of different levels on the growth, development of digestive organs, endogenous enzyme activities and expression of a-amylase mRNA level within pancreas. Four hundred and forty 1-day-old AA broiler chickens were randomly allocated to four groups of 22 chicks to 10 cages for 5 replicates, and fed a commercial starter diet and the same diets with l,000LU/kg (250mg/kg), 3,000LU/kg (750mg/kg), 9,000LU/kg (2250mg/kg) of a-amylase inclusion up to 21 day of age. Performance of 21-day-old and 42-day-old broilers were also determined. The results showed: (1) Body weight gain was improved in both starter and growth phase, and average feed intake of starter birds was enhanced with amylase inclusion. On day 21 and 42, there was a positive linear relationship (P<0.01) between increasing amylase inclusion and weight gain. Feed conversion ratio (FCR), however, was not affected by amylase supplementation. Optimum enzyme supplementation was 2250 mg/kg for weight gain and 750mg/kg for FCR, respectively. (2) Relative weights of liver, gizzard, and anterior intestine and relative length of anterior intestine tended to decrease (P>0.05), but proventriculus and pancreas tended to increase with increasing levels of supplementary amylase (P>0.05). (3) The activities of amylase, protease (P<0.05), and trypsin (P<0.05) in anterior intestinal contents apparently increased. Lipase was unaffected by amylase supplementation of all levels (P>0.05). Some high-dosage-depression responses were observed with the amylase supplementation of 2250mg/kg. (4) DNA, RNA, protein content更多还原