蛋白酶和木聚糖酶对肉仔鸡生长性能、血液指标和消化机能的影响

Effects of Protease and Xylanase on Performance,Blood Parameters and Digestive Function of Broilers

以蛋白酶和木聚糖酶分别作为消化酶（或内源酶）和非消化酶（或外源酶）的代表,研究小麦型日粮中添加不同水平蛋白酶和木聚糖酶对1~21日龄肉仔鸡生长性能、血液指标、消化器官指数及肠道组织学形态的影响,为酶制剂在家禽日粮中的合理使用提供理论依据。1日龄健康肉仔鸡972只,随机分为9个处理,每处理9个重复,每重复12只,采用双因子完全随机试验设计,分别饲喂在基础日粮中添加不同水平蛋白酶（0、4 000、32 000 U/kg）和木聚糖酶（0、1 000、8 000 U/kg）的试验日粮,试验期21 d。结果表明,4 000 U/kg蛋白酶＋1 000 U/kg木聚糖酶组显著降低肉仔鸡采食量（P〈0.05）,32 000 U/kg蛋白酶添加水平趋于提高采食量（P=0.080）,但对饲料转化率无显著影响（P〉0.05）。32 000 U/kg蛋白酶添加水平显著降低血糖含量（P〈0.05）。1 000 U/kg和8 000 U/kg木聚糖酶水平均趋于提高回肠指数（P=0.051）。32 000 U/kg蛋白酶组趋于降低空肠绒毛高度（P=0.081）。与8 000 U/kg木聚糖酶组相比,32 000 U/kg蛋白酶组显著增加十二指肠和回肠隐窝深度、显著增加空肠肌层厚度,并显著降低十二指肠和回肠绒毛高度与隐窝深度比值（P〈0.05）。8 000 U/kg木聚糖酶添加水平显著提高空肠绒毛宽度（P〈0.05）。肉仔鸡小麦型日粮中添加高剂量木聚糖酶显著改善肠道组织学形态,而高剂量蛋白酶显著降低血糖含量,小肠绒毛高度与隐窝深度之比,并提高隐窝深度和肌层厚度。

With protease and xylanase as the representative of digestive enzymes and indigestive enzymes,this experiment was conducted to investigate the effects of different levels of protease and xylanase on performance,blood parameters,development of digestive organs and intestinal morphology of broilers from 1 to 21 d of age,in order to provide theoretical foundation of reasonable application for enzymes in poultry diets.Nine hundred and seventy two 1-day-old Cobb 500 broilers were randomly divided into 9 treatments,with 9 replicates of 12 broilers each.The wheat-based diets were supplemented with 0,4 000,32 000 U/kg protease and 0,1 000,8 000 U/kg xylanase using a 3x3 factorial design.The experiment lasted for 21 d.The results showed that supplementation of 4 000U/kg protease ＋1 000U/kg xylanase significantly decreased the feed intake（P0.05）.Level of 32 000 U/kg protease tended to increase the feed intake（P=0.080） but still had no effects on FCR（feed conversion rate）（P0.05）.Supplementation of 32 000 U/kg protease significantly decreased the content of blood glucose（P0.05） and level of protease（32 000 U/kg） significantly decreased the content of blood glucose（P0.05）.Level of 1 000U/kg and 8 000 U/kg xylanase tended to increased the index of ileum（P=0.051）.Supplementation of 32 000 U/kg protease tended to decrease villus height of jejunum（P=0.081）.Supplementation of 32 000 U/kg protease significantly increased the crypt depth of duodenum and ileum and the muscle thickness of jejunum,and decreased the ratio of villus height to crypt depth of duodenum and ileum compared with 8 000 U/kg xylanase（P0.05）.Level of 8 000 U/kg xylanase significantly increased the villus width of jejunum（P0.05）.It can be concluded that excess level of xylanase（8 000 U/kg） had no negative effect on performance,blood parameters and digestive organs,and even had significantly positive effect on intestinal morphology while excess level of protease（32 000 U/kg） significantly decreased the ratio of villus height to crypt depth and increased the crypt depth and muscular thickness.