红景天提取物改善西藏高原地区肉鸡缺氧应激效果及其作用机理研究

The poultry production in Tibet, China is increasing rapidly. It is well known that indigenous Tibet chickens are well adapted to a high altitude environment, and have low production performance. So it has been a common practice for most poultry farms in Tibet to raise commercial broiler chickens presumably due to fast growth after intensive selection of production traits. But these chickens are not well adapted to hypoxia, a main ecological factor which has a negative impact on animal welfare and threatens the survival of poultry in high altitude areas. Rhodiola,which was found to possess increase resistances to a variety of stressors, anti-oxidant anti-hypoxia activities,growing at an high altitude. In addition, R. crenulata has been successfully cultivated by a botanist of Tibet Agricultural and Animal Husbandry College.In preliminary experiment our results suggest that supplementation withlow level Rhodiola might reduce the effects of hypoxia on broilers and consequently decrease mortality rate, but had no significant effect on ascites mortality. This may be due to low level of active components of Rhodiola powder. But high does of Rhodiola powder could reduced the feed intake and growth performance decreased. Therefore we intend to solve this problem by addition of Rhodiola extract, study on the effect of different level Rhodiola extract on growth performance, ascites susceptibility, anti-oxidative, immune funtion and gene expression of EPO, ET-1 and its receptor in broiler reared at high altitude, and explore the mechanism. Although more research needs to be carried out before R. crenulata can be used in poultry production in Tibet, our findings lay a significant foundation for future studies.

目前西藏的家禽生产发展迅速，由于西藏藏鸡生产性能低，当地家禽养殖户开始尝试饲养生产性能更高的肉鸡品种。当地的缺氧环境对引入肉鸡品种的生存和健康都有很大的负面影响，为了缓解高原缺氧对肉鸡的负面影响就需要肉鸡快速适应缺氧环境。藏药红景天已人工种植成功，具有增加机体应激适应性、抗氧化和抗缺氧等作用。在预实验中我们发现：添加低剂量红景天粉能够缓解缺氧应激从而降低死亡率，但对腹水症死亡率无显著影响，这可能是由于低剂量红景天粉中某些药物活性成分太低所引起的，而高剂量红景天粉会显著降低肉鸡采食量。因此我们拟通过添加红景天提取物来解决这一问题，通过添加不同浓度红景天水提物研究其对高原缺氧条件下肉鸡生产性能、腹水敏感性，抗氧化，调节免疫机能和EPO、ET-1及其受体基因表达的影响，探讨红景天的作用机理和腹水症的发生机理，为红景天在肉鸡中的使用奠定基础。

西藏缺氧环境对引入肉鸡品种的生存和健康都有很大的负面影响，为了缓解高原缺氧对肉鸡的负面影响，本试验通过添加不同浓度红景天水提物研究其对高原缺氧条件下肉鸡生产性能、腹水敏感性、抗氧化、免疫机能和EPO、ET-1及其受体基因表达的影响。试验选用900只1日龄雄性AA肉仔鸡，随机分为5处理，每处理6个重复，每个重复30只鸡，分别在基础日粮（对照组）中添加0.1%、0.15%、0.2%和0.4%红景天水提物干粉，试验期42 d。结果表明：（1）0.2%和0.4%红景天提取物处理组显著提高肉鸡的平均日增重和平均日采食量；（2）添加0.2%和0.4%红景天提取物在14、28和42d显著提高肉鸡红细胞数量、血红蛋白浓度和红细胞压积；（3）0.2%和0.4%红景天组显著降低14、28和42d血清中丙二醛和蛋白质羟基含量；显著提高了28和42d血清过氧化氢酶、谷胱甘肽过氧化物酶、超氧化物歧化酶活性和总抗氧化能力；（4）0.2%和0.4%红景天组显著降低肉鸡28和42d血清ET-1水平，并显著降低右心指数。0.2%和0.4%红景天组显著减低28和42d肉鸡左右心室中ET-1的mRNA表达量，显著提高28和42d肉鸡右心室ERAR的mRNA表达量。在28和42d，0.2%和0.4%红景天组肉鸡血清ET-1含量和右心室ETAR的mRNA表达量显著高于0.1%和0.15%红景天提取物组，0.2%和0.4%红景天组肉鸡右心指数和ET-1 mRNA表达量显著低于0.1%和0.15%红景天提取物组。（5）0.2%和0.4%红景天提取物处理组显著降低了肉鸡早期死亡率，并且在14天0.2%和0.4%红景天提取物处理组相比于对照组显著提高血浆中IgA、IgG的水平和BSA抗体滴度。（6）红景天提取物能够肉鸡外周血白细胞免疫球蛋白和细胞因子（NF-α、IL-1β和IL-6）的产生，改善肉鸡的免疫机能；（7）免疫接种法氏囊后于对照组，0.2%和0.4%红景天处理组显著提高了法氏囊病毒抗体水平和绵羊红细胞抗体水平。综上所述，日粮中添加红景天提取物能够通过提高提高高原缺氧环境下肉鸡红细胞生成、免疫机能和抗氧化性能，从而提高生产性能，减低死亡率和腹水敏感性，但存在剂量依赖性，0.2%添加效果最佳，这为藏药红景天在家禽生产中的应用提供理论和实践依据。