摘要
为了研发有效预防鸡坏死性肠炎(necrotic enteritis,NE)的微生态制剂,选用1日龄817雏鸡120只,随机分为4个处理组,其中,空白对照(Control)组和坏死性肠炎(NE)组(用G型产气荚膜梭菌感染肉仔鸡建立NE模型)饲喂基础日粮、预防1(Prob1)组在基础日粮中添加0.2%的微生物制剂1、预防2(Prob2)组在基础日粮中添加0.2%的微生物制剂2;试验第14~16 天Prob1组、Prob2组和NE组肉鸡连续灌胃产气荚膜梭菌(Clostridium perfringens,CP),探究在饲料中添加不同的枯草芽孢杆菌复合微生物制剂对该病的预防作用。结果显示:NE组肉鸡体质量低于Control组,试验第17、23天Prob1组、Prob2组体质量显著高于NE组(P<0.05)。NE组肉鸡空肠上皮细胞坏死脱落、绒毛变短、隐窝加深、绒隐比降低,使用枯草芽孢杆菌复合微生物制剂后肉鸡空肠绒毛结构较完整、绒毛长度和绒隐比显著高于NE组。NE组肉鸡空肠黏膜T-SOD、T-AOC、AKP活性低于Control组;试验第17天Prob1组、Prob2组肉鸡空肠黏膜T-AOC、AKP活性显著高于NE组,Prob1组肉鸡空肠黏膜T-SOD活性显著高于NE组;试验第23天,Prob1组、Prob2组肉鸡空肠黏膜T-SOD、T-AOC、AKP活性高于NE组,无显著差异; NE组肉鸡空肠黏膜MDA含量高于Control组,试验第17、23天Prob1组、Prob2组肉鸡空肠黏膜MDA含量低于NE组。NE组肉鸡的肠道紧密连接蛋白CLDN1、ZO-2基因表达量低于Control组,在试验第17天有显著差异;试验第17、23天,Prob1组、Prob2组肉鸡肠道紧密连接蛋白CLDN1、ZO-2基因表达量高于NE组,试验第23天Prob1组、Prob2组ZO-1基因表达量显著高于NE组。研究表明,日粮中添加枯草芽孢杆菌复合微生物制剂可以改善坏死性肠炎鸡的生长发育、提高肉鸡抗氧化能力以及肠道紧密连接蛋白基因表达量,且枯草芽孢杆菌复合微生物制剂1对鸡坏死性肠炎有较好的预防作用。
关键词
鸡坏死性肠炎(necrotic enteritis,NE)是由产气荚膜梭菌(Clostridium perfringens,CP)毒素引起的一种以空肠组织病变为主的肠道疾病,产气荚膜梭菌毒素主要有α、β、ε、ι、肠毒素、坏死性肠炎B样毒
1日龄健康817雏鸡120只(购自襄阳正大农牧有限公司),随机分成4个处理组,每组3个重复,每个重复10只:空白对照(Control)组、预防1(Prob1)组、预防2(Prob2)组、坏死性肠炎(NE)组。试验第1~16天 Control组、NE组肉鸡饲喂基础日粮,Prob1组肉鸡饲喂基础日粮和微生物制剂1,Prob2组肉鸡饲喂基础日粮和微生物制剂2;试验第14~16 天,Prob1、Prob2、NE组每只肉鸡灌胃CP(3×1
基础日粮为510肉小鸡饲料,购自襄阳正大农牧有限公司,饲料组成:粗蛋白质≥20%、粗纤维≤6%、粗灰分≤8%、钙0.6%~1.2%、总磷≥0.5%、氯化钠0.2%~0.8%、蛋氨酸和胱氨酸≥0.74%、水分≤14%。G型产气荚膜梭菌由华中农业大学基础兽医病理实验室分离鉴定保存,攻菌前用FTG(液体硫乙醇酸盐培养基)增菌培养至3×1
主要试剂:总超氧化物歧化酶(SOD)、总抗氧化能力(T-AOC)、碱性磷酸酶(AKP)、丙二醛(MDA)检测试剂盒购自南京建成生物工程研究所;RNA Isolater Total RNA Extraction Reagen、HiScript II Q RT SuperMix for qPCR(+gDNA wiper)、ChamQ Universal SYBR qPCR Master Mix购自南京诺唯赞生物科技有限公司。
主要仪器:ELX800酶标仪(BIO-TEK公司);Step One Plus荧光定量PCR仪(美国ABI公司);Nano-300超微量分光光度计(杭州奥盛仪器有限公司)。
1)肉鸡体质量和平均日增重的测定。于试验第14、23天对肉鸡称质量并计算平均日增重(average daily gain,ADG)。
2)肉鸡空肠形态观察。于试验第17、23天,每个处理组随机选取10只鸡进行屠宰,剪取空肠部位2 cm于4%甲醛中固定后制成石蜡切片,用轮式切片机制作成4 μm切片,常规苏木精-伊红(HE)染色后观察各组肉鸡肠道组织形态结构。采用Nikon 80i生物光学显微镜及高清晰度彩色图文分析系统测量肉鸡空肠绒毛长度(villus length,VL)和隐窝深度(crypt depth,CD),并计算绒隐比。选取5张切片进行测定,取平均值。
3)肉鸡空肠黏膜抗氧化指标的测定。采用试剂盒测定总超氧化物歧化酶(SOD)、总抗氧化能力(T-AOC)、碱性磷酸酶(AKP)活性、丙二醛(MDA)含量。
4)肉鸡空肠紧密连接蛋白基因表达的测定。根据Trizol法提取肠道黏膜RNA,采用超微量分光光度计测定RNA浓度和纯度。采用荧光定量RT-PCR(qRT-PCR)检测各组肉鸡空肠紧密连接蛋白闭合蛋白(claudin,CLDN)-1、闭合小环蛋白(zonula occludens,ZO)-1和ZO-2的基因表达。参照文献[
基因Gene | 上游引物Forward primer | 下游引物Reverse primer |
---|---|---|
Claudin-1(CLDN-1) | GTGTTCAGAGGCATCAGGTATC | GTCAGGTCAAACAGAGGTACAA |
Zonula occluden-1(ZO-1) | GGAGTACGAGCAGTCAACATAC | GAGGCGCACGATCTTCATAA |
Zonula occluden-2(ZO-2) | GCGTCCCATCCTGAGAAATAC | CTTGTTCACTCCCTTCCTCTTC |
根据反转录试剂盒操作说明将总RNA反转录为cDNA。qRT-PCR扩增体系(10 μL):cDNA模板0.5 μL,上下游引物各0.2 μL,2×chamQ Universal SYBR qPCR Master Mix 5 μL,ddH2O 4.5 μL。反应程序为 95 ℃预变性 5 min; 95 ℃ 5 s,56 ℃ 45 s,共40个循环;95 ℃ 15 s。采用
由
时间/d Time | 指标Index | Control | Prob1 | Prob2 | NE |
---|---|---|---|---|---|
14 | 体质量/g BW | 131.83±13.15b | 137.40±14.34ab | 144.15±17.45a | 129.224±12.22b |
平均日增重/g ADG | 7.54±1.05b | 7.25±1.40b | 8.62±1.28a | 6.94±1.44b | |
23 | 体质量/g BW | 282.88±23.04bc | 307.68±20.61a | 292.68±14.03ab | 270.16±20.95c |
平均日增重/g ADG | 17.03±2.52bc | 20.28±1.07a | 18.82±2.91b | 15.06±2.36c |
注: 同行数据标注不同字母表示差异显著 (P<0.05),相同或无字母表示差异不显著(P>0.05),下同。Note:Different letters in the same column indicate significant difference (P<0.05), while the same or no letters indicate no significant difference (P>0.05), the same as below.
由

图1 肉鸡空肠的组织病理学变化(10 ×)
Fig.1 The histopathological lesions of jejunum of broilers (10 ×)
由
时间/d Time | 指标Index | Control | Prob1 | Prob2 | NE |
---|---|---|---|---|---|
17 | 绒毛长度/μm VL | 517.64±4.01b | 690.70±9.51a | 558.06±22.57b | 275.53±18.69c |
隐窝深度/μm CD | 84.37±3.10b | 99.82±6.81a | 96.82±2.65ab | 97.90±2.90a | |
绒隐比VL/CD | 6.17±0.25a | 6.74±0.47a | 5.79±0.33a | 2.82±0.20b | |
23 | 绒毛长度/μm VL | 650.20±25.63a | 679.77±9.74a | 672.36±13.22a | 453.11±12.38b |
隐窝深度/μm CD | 115.67±9.14 | 120.16±5.39 | 116.98±4.40 | 112.77±4.09 | |
绒隐比VL/CD | 5.72±0.37a | 5.70±0.25a | 5.78±0.21a | 4.03±0.13b |
由
时间/d Time | 指标Index | Control | Prob1 | Prob2 | NE |
---|---|---|---|---|---|
17 | T-SOD/(U/mg) | 298.82±60.80a | 351.37±82.84a | 142.26±40.94b | 116.17±12.24b |
T-AOC/(mmol/L) | 0.85±0.03a | 0.76±0.05ab | 0.73±0.06ab | 0.67±0.05b | |
AKP/(U/mg) | 398.99±105.43a | 492.77±187.10a | 291.87±46.70ab | 186.41±89.97b | |
MDA/(nmol/mg) | 3.67±0.67 | 4.62±0.91 | 3.97±1.75 | 5.21±0.38 | |
23 | T-SOD/(U/mg) | 258.38±23.73a | 197.88±45.62b | 196.75±12.14b | 183.63±42.77b |
T-AOC/(mmol/L) | 0.53±0.05 | 0.60±0.08 | 0.36±0.09 | 0.35±0.07 | |
AKP/(U/mg) | 564.13±82.18 | 575.89±243.68 | 742.02±223.44 | 536.31±216.88 | |
MDA/(nmol/mg) | 4.88±0.69 | 5.16±0.60 | 4.40±1.06 | 6.49±1.90 |
由
时间/d Time | 基因Gene | Control | Prob1 | Prob2 | NE |
---|---|---|---|---|---|
17 | CLDN-1 | 1.00±0.19a | 0.31±0.08b | 0.39±0.17b | 0.32±0.13b |
ZO-1 | 1.00±0.11 | 1.05±0.25 | 1.50±1.20 | 0.31±0.34 | |
ZO-2 | 1.00±0.14a | 0.32±0.25b | 0.39±0.04b | 0.25±0.02b | |
23 | CLDN-1 | 1.00±0.37 | 1.34±0.77 | 1.58±0.56 | 0.84±0.16 |
ZO-1 | 1.00±0.22abc | 1.11±0.60ab | 0.69±0.17abc | 0.42±0.18c | |
ZO-2 | 1.00±0.21 | 1.18±0.91 | 0.85±0.12 | 0.78±0.28 |
自畜禽饲料中禁止添加抗生素以来,益生菌、植物精油等抗生素替代品在养殖业尤其是预防畜禽胃肠道疾病中逐步受到重
通常情况下,肉鸡感染CP会引起肠道黏膜受损,导致鸡生长迟缓和饲料转化率降
小肠是机体营养物质吸收的主要场所,绒毛(VL)越长、隐窝(CD)越浅、VL/CD值越大,代表小肠吸收能力越
CLDN、ZO是紧密连接蛋白,紧密连接蛋白对维持肠道屏障功能至关重要,具有调节免疫、转运物质、防止病原体入侵等作
MDA是脂质过氧化产物,而SOD是一种抗氧化物酶,高活性SOD可以清除氧自由基,减少脂质过氧化的发
碱性磷酸酶(alkaline phosphatase,AKP)是广泛分布于机体组织器官的单磷脂水解酶,主要分为组织非特异性和组织特异性AKP,如肠碱性磷酸酶(intestinal alkaline phosphatase,IAP
综上,日粮添加枯草芽孢杆菌复合微生物制剂可以促进肉鸡生长、改善肠道形态、提高肠道紧密连接蛋白基因表达和机体抗氧化能力,其中枯草芽孢杆菌复合微生物制剂1的预防效果更好。
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