以基因表达评价肉仔鸡实用饲粮中锰的适宜水平

EVALUATION OF OPTIMAL DIETARY MANGANESE LEVEL FOR BROILERS FED CONVENTIONAL DIET BY USING GENE EXPRESSION

目的寻找快速、敏感、恒定的评价肉仔鸡饲粮Mn适宜水平的指标。方法给0～3w龄肉仔鸡饲以不同水平无机锰(Mn)饲粮,检测生长性能、组织Mn含量、心肌细胞线粒体中MnSOD活性及基因表达水平,分析各指标随饲粮Mn水平的线性或曲线反应,并拟合相应的数学模型估测肉仔鸡饲粮中Mn的适宜水平。结果各处理组间生长性能均无显著差异;组织Mn含量、心肌MnSOD活性及其MnSODmRNA水平有显著差异;除7d龄肝脏中Mn含量呈线性上升,其它各日龄组织Mn含量、心肌MnSOD活性及其mRNA水平均可与饲粮Mn含量拟合成相应的渐近线或二次曲线模式(P<0.01)。结论1.实用饲粮条件下体增重、采食量、料重比和腿病发生率等表观生长指标均不是评价肉仔鸡饲粮Mn需要量的敏感指标。2.心肌细胞线粒体中MnSODmRNA水平指标评价肉仔鸡体内的Mn营养状况能比其酶活性等其它指标更快、更敏感、更恒定,且可缩短实验期,减少实验动物数,节省费用,是评价肉仔鸡饲粮Mn营养需要量的最敏感指标,根据该指标所得肉仔鸡饲粮Mn适宜水平为130mg/kg。

Objective To find the quick, sensitive and stable criterion to evaluate the optimal dietary manganese （Mn） level for broilers. Method Broilers aged 0-3 w were fed diets supplemented with different levels of Mn as inorganic Mn. Growth performance, tissue Mn contents, and MnSOD activity and MnSOD mRNA level in heart mitochondria of broilers were determined. Linear and quadratic responses of indices to dietary Mn level were analyzed, and mathematical models were used to evaluate the optimal dietary Mn level for broilers. Results Growth performance were not significantly different among treatments. Tissue Mn concentrations, MnSOD activity and MnSOD mRNA of heart mitochondria were all significantly different among treatments. Except that liver Mn contents increased linearly at 7 d of age, quadratic or asymptotic models （P〈0.01） of MnSOD activity and MnSOD mRNA level at other ages to dietary Mn level were acquired. Conclusion Heart MnSOD mRNA level was quicker, more sensitive and stable in detecting Mn nutritional status in broilers than other criteria such as MnSOD activity, and so it was a sensitive criterion for evaluating dietary Mn requirement of broilers. With this criterion, 130 mg/kg Mn in diet would be an optimal dietary level for broilers from 0 to 3 w of age.