热应激条件下内毒素对肉鸡免疫功能影响的研究

发布时间：2018-09-17 09:00

【摘要】：动物热应激病是一种常发疾病。国内外的研究报道表明,热应激可以对家禽的生长性能、产蛋性能造成严重影响,特别是对机体的免疫功能也会造成严重影响。急性热应激的发病机理一直是研究热点。我们参照已报道的急性热应激模型,以肉鸡为试验对象设置热应激条件。通过临床症状观察、血液常规指标和生化指标检测、鲎试剂法检测内毒素、组织病理学及分子生物学等实验方法,研究热应激对肉鸡免疫功能的影响。主要研究结果如下:1临床症状及病理学检查结果:随着热应激时间的持续,肉鸡出现精神沉郁、呼吸困难、腹泻等症状。病理学检查结果表明,热应激初期肉鸡小肠绒毛、黏膜和黏膜下层未见明显变化,后期小肠绒毛发生断裂、毛细血管淤血、黏膜上皮细胞发生脱落。热应激初期肉鸡的脾脏、胸腺和法氏囊出现毛细血管扩张,充血,到后期免疫器官的淋巴细胞减少,细胞核裂解,说明热应激对机体免疫器官损伤随时间持续逐渐加剧。2鲎试剂试验结果:热应激初期试验组肉鸡血清内毒素含量呈极显著的升高,随着热应激持续血清内毒素含量明显升高,热应期后期试验组内毒素含量几乎是对照组的7倍。在肉鸡热应激期间热应激组和VC组内毒素含量虽有差异但差异均不显著。3血常规试验结果:热应激初期肉鸡血液红细胞数目轻微升高,到后期显著降低,并且与对照组相比呈差异显著;在热应激各时间段,VC组与试验组红细胞数目相比呈差异不显著。血液白细胞在热应激初期显著降低,而后显著升高。说明红细胞和白细胞在热应激期间受到明显的影响,VC对于缓解热应激的影响效果不明显。4动物生化试验结果:试验组肉鸡肝脏功能相关指标ALT、AST持续升高,与对照组相比,呈差异极显著,说明肉鸡热应激条件下肝脏组织受到损伤,肝脏功能受到影响。肾脏功能相关指标CREA在热应激初期呈显著升高,随着热应激时间的持续升高也越明显;BUN在热应激初期升高不明显,随着热应激时间的持续BUN呈显著性升高;TP、GLOB、ALB在热应激初期,试验组与对照组相比差异显著,随着时间持续差异不显著。说明肉鸡在热应激过程中,肝肾受到损伤的同时,机体的免疫功能也受到抑制。5 RT-PCR法对脾脏内毒素受体检测结果:与对照组相比,试验组肉鸡脾脏中TLR4受体m RNA的相对表达量呈先降低后持续升高的变化趋势,并且随着肉鸡热应激时间的持续TLR4受体m RNA的相对表达量也越明显,10 h时,热应激组的相对表达量急速升高约为对照组的1.778倍;而VC组肉鸡脾脏中TLR4受体m RNA的相对表达量呈持续下降的变化趋势。这说明大量的内毒素进入血液对肉鸡免疫功能产生一定的影响。综上所诉,持续的热应激能够引起肝脏细胞的清除机能下降,肉鸡的肠道损伤,大量的肠道内毒素进入血液系统,形成内毒素血症,随着血液循环进入机体的免疫器官,并且随着热应激时间的持续对机体的红细胞、白细胞数目及免疫器官损伤程度加剧;肠源性内毒素血症的发生导致脾脏内毒素受体TLR4 m RNA的表达上调,说明热应激条件下内毒素对肉鸡免疫器官具有损伤功能。而VC在缓解热应激所致内毒素对肉鸡免疫功能损伤方面有一定的作用,但作用不是很明显。
[Abstract]:Animal heat stress disease is a common disease. Domestic and foreign research reports show that heat stress can seriously affect the growth performance and egg production performance of poultry, especially the immune function of the body. The effects of heat stress on the immune function of broilers were studied by observing clinical symptoms, testing blood routine and biochemical indexes, testing endotoxin by limulus test, histopathology and molecular biology. The results of pathological examination showed that the intestinal villi, mucosa and submucosa of broilers did not change significantly in the early stage of heat stress, but the intestinal villi ruptured, capillaries congested and mucosal epithelial cells shed. Thymus and bursa of Fabricius appeared capillary dilatation, congestion, lymphocyte reduction and nuclear lysis in the immune organs at the late stage, indicating that heat stress on the body's immune organ damage with time continues to intensify. 2 Limulus amebocyte lysate reagent test results: heat stress early experimental group broilers serum endotoxin content showed a very significant increase, with heat stress continued to blood. The content of endotoxin in serum increased significantly, and the content of endotoxin in the late heat stress group was almost 7 times that of the control group. Compared with the control group, there was a significant difference in the number of red blood cells between the VC group and the experimental group at different time points of heat stress, but there was no significant difference in the number of red blood cells between the VC group and the experimental group. The results of biochemical test showed that ALT and AST of broilers in the experimental group increased continuously, which showed that liver tissue was damaged and liver function was affected under heat stress. CREA of kidney function increased significantly in the early stage of heat stress, and increased with the time of heat stress. BUN was not significantly elevated at the initial stage of heat stress, but increased significantly with the duration of heat stress; TP, GLOB, ALB in the initial stage of heat stress, the experimental group was significantly different from the control group, with no significant difference over time. Inhibition.5 RT-PCR assay of spleen endotoxin receptor: Compared with the control group, the relative expression of TLR4 receptor m RNA in the spleen of broiler chickens in the experimental group decreased at first and then continued to increase, and the relative expression of TLR4 receptor m RNA in the broiler chickens increased with the duration of heat stress. The relative expression of TLR4 receptor m RNA in the heat stress group increased at 10 h. The amount of TLR4 receptor m RNA in the spleen of VC broiler chickens showed a decreasing trend, which indicated that a large amount of endotoxin had an effect on the immune function of broiler chickens. Intestinal injury, a large number of intestinal endotoxins into the blood system, forming endotoxemia, with the blood circulation into the body's immune organs, and with the duration of heat stress on the body's red blood cells, white blood cells and immune organ damage increased; intestinal endotoxemia caused the occurrence of splenic endotoxin receptor TLR4 m R The up-regulated expression of NA indicated that endotoxin could damage the immune organs of broilers under heat stress, while VC could alleviate the injury of endotoxin induced by heat stress, but the effect was not obvious.
【学位授予单位】：河南农业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：S858.31

【相似文献】