中文摘要：

【目的】模拟中国棉区传统饲喂模式，应用富含磷、钾、镁的棉饼稻草日粮饲喂阉割山羊，继而比较分别在添加高钾、磷和高镁在诱发尿石症时的作用差异。【方法】18只山羊均分为A、B、C3组，饲喂3个月含磷、钾、镁分别为0.40%、1.24%、0.32%的试验日粮，从第3个月开始在B组山羊饮水中添加钾、磷，相当于日粮中钾、磷含量分别提高到1.74%和0.75%；在C组饮水中加氧化镁，相当于镁含量提高到0.56%。观察参试山羊临床症状和病理变化，记录尿石症发病率；定期采集血液和尿液，检测血液和尿液中钾、镁、磷、钙离子含量变化以及尿液磷酸钾镁离子积变化。应用化学定性分析、X-射线衍射分析、X-射线能谱和红外光谱方法分析尿沉渣晶体和结石的主要组分。【结果】A、B、C组分别有1、1、6只山羊发生尿石症，χ^2检验表明C组与A、B组发病率差异显著（χ^2=5.49，P＜0.05）。结石主要组分是磷酸氨镁和磷酸钾镁，尿液磷酸钾镁离子积在结石发生后显著降低。【结论】相对于日粮中的高磷、高钾来说，日粮中过量的镁是采食棉饼饲料的山羊尿石症发生的重要因素。高镁诱发尿石症的原因可能与尿液中结石抑制因子的抑制能力降低有关。

英文摘要：

【Objective】 The effect of high dietary magnesium on urolithiasis in feedlot wethers was compared with high potassium and phosphate under the Chinese traditional feeding style with cotton seed meal and rice straw diet. 【Method】Eighteen wethers of 3-4-months-old were randomly allotted to A, B, C three groups, and they were feeding for three months with cotton seed meal and rice straw diet comprised of P 0.40%, K 1.24%, Mg 0.32%, respectively. From the third month, KH2PO4 and K2HPO4 were provided to goats in group B via drinking water and so did MgO to goats in group C, goats in group A still drank tap water, which means dietary P, K in group B was added up to 1.74% and 0.75%, and dietary Mg in group C to 0.56%. The clinical signs and postmortem were observed and incidence of urolithiasis was recorded. Blood and urine samples were collected to analyze the concentration of P, K, Mg and Ca ions, and the activity product of potassium magnesium phosphate was calculated to evaluate the supersaturation of urine before and after urolith formation. The composition of urinary sediments and stones was studied by chemical qualitative analysis, X-ray diffraction, X-ray energy dispersive spectrometry （EDS） and fourier transform infrared （FTIR） spectroscopy. 【Result】 The urolithiasis was found on day 5-8 in all 6 goats of group C after drinking water contains MgO, one urolithiasis case was found in groups A and B on day 25, 28 of the third month, respectively. The aggregate analysis showed that the chemical composition of urinary stones and urinary sedimentary crystals was magnesium ammonium phosphate and potassium magnesium phosphate and P, K, Mg ion concentrations of urine decreased significantly, so did the activity product of potassium magnesium phosphate. 【Conclusion】High dietary level of magnesium is a more important factor of urolithiasis in wethers compared with feeding with high P, K containing diets, and the effect of magnesium induced urolithiasis might be associated with the change of inhibitor