【作者】 杨彩梅；

【导师】 刘建新； 陈安国；

【作者基本信息】 浙江大学 ， 动物营养与饲料科学， 2007， 博士

【摘要】 本研究以半胱胺(CS)为材料,以Avian肉鸡为对象,研究日粮中添加CS对肉鸡生长性能、消化功能的影响,并探讨其作用机理。研究分为两个部分：第一部分研究日粮中添加不同剂量的CS对肉鸡生长性能、消化功能、血清相关代谢参数的影响(试验一)。第二部分研究日粮中添加适宜剂量的CS对肉鸡不同生长阶段的生长性能、小肠绒毛形态、抗氧化功能、血清生长抑素(SS)和胰岛素样生长因子-Ⅰ(IGF-Ⅰ)含量的影响(试验二),同时研究CS对肉鸡下丘脑、腺胃、十二指肠和肝脏中SS基因表达量的影响(试验三)。第一部分选择600羽1日龄Avian公鸡,随机分为5组,每组各设4个重复,每个重复30羽,对照组饲喂基础日粮,试验组分别添加60、90、120、150mg/kgCS。在21日龄和42日龄时每只试鸡空腹称重,测定平均日增重(ADG)和饲料转化率;同时每组随机选取12只鸡采血,测定血清相关代谢参数,随后屠宰,收集胰腺及十二指肠内容物,测定蛋白酶、淀粉酶和脂肪酶的活性。主要研究结果如下：1.1-21日龄阶段,日粮中添加60 mg/kgCS可显著提高肉鸡ADG,而添加120mg/kg和150mg/kgCS可使ADG显著降低;22-42日龄阶段,添加90mg/kgCS可使ADG显著提高,而添加150mg/kgCS使ADG显著下降,在肉鸡整个生长阶段,150mg/kgCS组的ADG和饲料转化率均显著低于其它各组。结果提示：肉鸡日粮中添加CS可提高生长性能,但高剂量的CS对肉鸡生长具有抑制作用;1-21日龄日粮中添加60mg/kgCS,22-42日龄添加90mg/kg CS是适宜的剂量。2.1-21日龄阶段,日粮中添加50mg/kgCS组的胰腺和十二指肠内容物蛋白酶、淀粉酶和脂肪酶活性均显著高于对照组、120mg/kgCS和150mg/kgCS组。22-42日龄阶段,添加90mg/kgCS使胰腺和十二指肠蛋白酶和淀粉酶活性比对照组显著提高,添加150mg/kgCS使胰腺和十二指肠内容物蛋白酶活性显著下降,试验结果提示：日粮添加CS对消化酶活性的影响与生长性能具有相关性。3.在1-21日龄阶段,日粮添加60mg/kgCS可显著提高血清总蛋白和碱性磷酸酶含量,降低血清尿素氮含量,而添加150mg/kgCS显著降低血清总蛋白和碱性磷酸酶含量。22-42日龄阶段,添加60mg/kgCS、90mg/kgCS和120mg/kgCS可使血清总蛋白含量显著提高,而添加150mg/kgCS显著降低总蛋白。4.在1-21日龄阶段,日粮中添加不同剂量CS均可使肉鸡T3和T4水平显著提高,日粮中添加120mg/kg和150mg/kgCS可使胃泌素水平显著提高。22-42日龄阶段,添加90mg/kg、120mg/kg和150mg/kgCS可使血清T4水平显著高于对照组。添加150mg/kgCS可使血清胃泌素水平显著提高。结果提示：日粮添加CS均可提高血清相关代谢激素水平。第二部分选择472羽1日龄Avian公鸡,随机分为2组,每组设8个重复,试验分1-21日龄和22-42日龄两个阶段进行,对照组饲喂基础日粮,试验组日粮添加适宜剂量CS(1-21日龄阶段添加60mg/kg,22-42日龄阶段添加90mg/kg),在1、7、21、28、35和42日龄时每只试鸡空腹称重,测定平均日增重,同时收集十二指肠、空肠、回肠样品,测定小肠绒毛形态,采集血样,测定抗氧化功能和血清中SS与IGF-I含量,同时取下丘脑、腺胃、十二指肠和肝脏样品,用半定量RT-PCR法测定不同组织中SS基因表达量,主要研究结果如下：1.日粮中添加适宜剂量CS,可显著提高肉鸡21、28、35和42日龄的体重,并使14-21日龄阶段和21-28日龄阶段试验鸡的ADG分别比对照组提高9.48%(P<0.05)和8.42%(P<0.05)。试验结果提示：日粮中添加适宜剂量CS促进肉鸡生长的效果在14-28日龄更明显。2.在21日龄阶段,日粮中添加CS显著降低了十二指肠绒毛高度和隐窝深度,对空肠、回肠的绒毛高度和隐窝深度无显著影响；在42日龄阶段,添加CS对十二指肠、空肠和回肠绒毛高度均无显著影响。添加CS可显著提高7日龄、14日龄和21日龄肉鸡血清谷胱甘肽过氧化物酶的活性,提高7日龄肉鸡总抗氧化能力。在7、14、21和28日龄,日粮中添加CS可显著降低肉鸡血清SS水平,显著提高血清IGF-Ⅰ水平。3.日粮中添加CS对7-28日龄阶段下丘脑SSmRNA的表达无显著影响,在35日龄时显著降低下丘脑SSmRNA的相对表达量,在42日龄时则显著升高；添加CS可显著降低28日龄肉鸡腺胃SS mRNA表达量；CS可促进整个生长期间肉鸡十二指肠SSmRNA的表达,在21日龄、28日龄时达到显著水平。CS对肝脏中SS基因的表达则有抑制作用,在35日龄时能显著降低肝脏SSmRNA的表达量。试验结果提示：日粮中添加CS对1-14日龄阶段肉鸡SS基因的表达无显著影响,而对22-42日龄阶段SS基因的表达有显著影响,日粮CS对SS基因表达的影响具有组织和生长阶段特异性。综上所述：肉鸡日粮中添加CS可促进生长,提高消化酶活性,但高剂量的CS则抑制生长,降低消化酶的活性。日粮中适宜的CS添加量为1-21日龄阶段60mg/kg,22-42日龄阶段90mg/kg。添加CS可提高血清代谢激素水平。日粮中添加适宜剂量CS可提高肉鸡生长前期的抗氧化能力和血清IGF-Ⅰ水平,降低血清SS水平。添加CS对1-14日龄阶段肉鸡SS基因的表达无显著影响,而对22-42日龄阶段SS基因的表达有显著影响,日粮CS对SS基因表达的影响具有组织和生长阶段特异性。试验结果提示日粮中添加CS促进肉鸡生长主要是通过提高消化酶活性和IGF-Ⅰ水平,降低血清中SS水平来实现的。更多还原

【Abstract】 The study was conducted to determine the effects of cysteamine (CS) on growth performance, digestive function and approach to the mechanism in broilers. It included two parts. In partⅠ:the effects of CS on growth performance, digestive enzyme activities and serum parameter in broilers were investigated (Experiment 1). In partⅡ: the effects were studied of optimal level of CS on small intestinal villous morphology, antioxidation function, serum somatostatin (SS) and insulin-like growth factor-Ⅰ(IGF-Ⅰ) level in the development of broilers (Experiment 2), and SS gene expression were analyzed in hypothalamus, proventriculus, duodenum and liver tissue (Experiment 3).In partⅠ:600 male broiler chickens at the age of 1 d were randomly divided into five equal groups of 120 birds each, and each of these groups was then assigned to one of five treatments. All birds were offered the same basal diets with addition of CS at levels of 0 (Control),60,90,120 and 150 mg/kg. Chickens were weighed individually at the age of 1,22 and 42 d to determine average daily weight gain (ADG) and feed conversions. On d 22 and d 42 of the feeding trial,12 chickens per treatment were chosen to collect pancreatic tissue, small intestinal digesta and blood samples. The activities of amylase, lipase and protease in pancreatic tissue and small intestinal digesta were determined. The serum concentration were analyzed for total protein, albumin, urea N, triglyceride, alkaline phosphatase (AKP), thyroxine (T4), triiodothyronine (T3), insulin and gastrin. The main results obtained were as followes.1. Compared with the control, the ADG during d 1-21 was significantly higher in the birds adding 60 mg CS/kg, but lower in those with 120 or 150 mg CS/kg; and the ADG during d 22-42 was significantly higher with 90 mg CS/kg, but lower with 150 mg CS/kg. Over the experiment, chickens fed on 150 mg CS/kg had lower ADG and feed conversions than those in other groups. The results indicated that 60 mg CS/kg during d 1-21 and 90 mg CS/kg during d 22-42 might be the optimal dose in broilers.2. The activities of protease, amylase and lipase were higher in broilers fed 60 mg CS/kg than fed 0 (control),120 and 150 mg CS/kg during d 1-21. Chickens fed with 90 mg CS/kg had higher activities of protease in pancreas as well as protease, amylase and lipase in the small intestinal digesta, compared with the control during d 22-42. Adding 150 mg CS/kg resulted in lower activities of protease than other groups during d 22-42. The results indicated that the effects of CS on digestive enzyme activities were consistent with the growth performance.3. During d 1-21, adding 60mg CS/kg significantly increased the serum concentrations of total protein and AKP as well as decreased urea N, while adding 150 mg CS/kg significantly decreased total and AKP. During d 22-42, adding 60,90 and 120 mg CS/kg significantly increased the concentration of total protein, while adding 150 mg CS/kg significantly decreased total protein.4. During d 1-21, adding 60,90,120 and 150 mg CS/kg significantly increased the serum concentrations of T4 and T3, while adding 120 and 150 mg CS/kg significantly increased the serum concentrations of gastrin. During d 22-42, adding 90,120 and 150 mg CS/kg significantly increased T4, while gastrin was significantly increased with addition of 150 mg CS/kg. The results suggested that adding CS in dietary increased the serum concentrations of metabolic hormones.In Part II:472 Avian male broilers at the age of 1 d were randomly divided into a control and a treatment group. Birds in each group were kept in 8 pens. Birds in control group were offered basal diets, while birds in treatment group were offered basal diets with addition of CS at levels of 60 mg/kg into a starter diet (d 1-21) and 90 mg/kg into grower diet (d 22-42). Chickens were weighed individually at the age of 1, 7,14,21,28,35 and 42 d, respectively, to determine ADG. At the same time,12 chickens per group were used to obtain blood, duodenum, jejunum, ileum, hypothalamus, proventriculus and liver tissue. The villous morphology in duodenum, jejunum and ileum were analyzed. The serum concentrations of glutathione peroxidase (GSH-Px), total antioxidation capability, SS and IGF-Ⅰwere determined. The SS gene expression level in hypothalamus, proventriculus, duodenum and liver tissue were determined. The main results were as described below.1. The body weight of broilers added optimal level of CS was significantly greater than that fed control on d 21,28 35 and 42. The ADG during d 14 to 21 and d 21 to 28 were increased by 9.48 (P<0.05) and 8.42%(P<0.05) compared to the control, respectively. 2. Adding 60mg CS/kg significantly decreased the duodenum villus height of broilers on d 21. No significant differences were found in intestinal villus height in d42. Addition of optimal level of CS significantly increased activity of GSH-Px on d7,14 and 21 and serum total antioxidation capability on d7. The broilers with addition of optimal level of CS had significant lower concentration of serum SS but higher IGF-I at the age of d 7,14,21 and 28 than those in control.3. No significant differences were found in hypothalamus SS mRNA level on d 7, 14,21 and 28. Hypothalamus SS mRNA of CS-added broilers were higher on d 35, while lower on d 42 than those in control. The CS-added diets significantly decreased SS mRNA level in proventriculus on d 28. The CS depressed liver SS mRNA level on d 35 while increased duodenum SS mRNA level on d 21 and 28. The results indicate the time and tissue specific of SS gene expression.In summary, dietary CS improves the growth performance and enhances the activities of digestive enzymes in broilers, but higher doses of CS appears to decrease the activities of digestive enzymes and hence inhibits growth performance. The optimal dose may be 60mg CS/kg during d 1-21 and 90mg CS/kg during d 22-42. Adding optimal level of CS decreases the concentration of serum SS but increases IGF-I. The SS mRNA level of broiler indicates the time and tissue specific. These results suggest that the CS may improve growth performance by mean of the regulation of SS and IGF-I and the activity of digestive enzyme.更多还原