持续性高铁摄入对放牧绵羊铁吸收和母子代健康影响的研究

Iron(Fe) is one of the essential trace elements in animal body, which has important physiological function. Lack or excess of Fe can produce adverse effects on animal. Based on the existing data of iron content in soil and forage as well as the long-term monitoring results of fecel Fe content in sheep, the grazing sheep in northern grassland take risk of the iron excess all year round. however, a systematic study of constant high iron uptake on grazing sheep need further investgation. So in the project, Songnen grassland is selected as test location and the morphology and availability of Fe in sheep gastrointestinal from forage and soil will be evaluated by means of chemical analysis and simulation test in vitro. Iron intake and absorbstion of grazing sheep in different seasonal as well as iron deposition in tissues and organs of grazing sheep for different age will be evaluated by grazing and slaughter test. Through feeding test indoor, effects of dietary iron sources and levels on mineral deposition of ewes and lambs in serum and organs, rumen fermentation, antioxidant and immune status as well as histopathologically pathological change of sheep will also be evaluated.Our results will systemcally determine the excessive degree and absorption of ingesting iron for sheep grazing Songnen grassland as well as the effect of different levels of iron on rumen fermentation, mineral absorption and health of sheep, and provide theoretical basis for understanding the risk of constantly high Fe intake and mineral nutrition management for grazing sheep.

铁是动物体内必需的微量元素之一，具有重要的生理功能。日粮铁缺乏和过量都会对动物产生不利的影响。已有牧草和土壤铁含量数据以及绵羊长期的粪铁监测结果表明，北方草地放牧绵羊全年都处于铁过量的风险之中，然而有关持续性高铁摄入对放牧绵羊影响还缺乏系统研究。因此本项目选择松嫩草地为研究地点，通过化学分析和体外模拟试验，确定牧草和土壤中铁形态及在绵羊消化道的可利用性；通过放牧和屠宰试验分析不同季节放牧绵羊铁来源、摄入和吸收状态，以及生活周期长短对放牧绵羊组织和器官内铁沉积影响；通过舍饲控制试验研究日粮中不同铁源和水平对妊娠和泌乳母羊、断奶羔羊体内组织中矿物质沉积状况、瘤胃发酵及体内抗氧化、免疫状态以及病理组织学变化的影响。进而系统确定松嫩草地放牧绵羊铁摄入的过量幅度、过量铁在体内吸收状况以及不同水平过量铁对绵羊瘤胃发酵、矿物质吸收和健康的影响，为深入全面认识草地放牧绵羊铁风险和和矿物质营养管理提供理论基础。

铁是动物体内必需的微量元素之一，已有数据表明北方草地放牧绵羊全年处于铁过量的风险之中。本项目通过牧草、土壤化学分析及放牧试验和舍内对比试验，确定了非禾本科牧草及土壤来源铁对放牧家畜的贡献程度。同时评估了高剂量背景下典型牧草铁、化学形态铁及土壤铁的利用效率；评价了高剂量背景下化学形态和土壤中铁对绵羊生产性能、采食代谢、血液中铁代谢指标、瘤胃发酵和微生物群落结构、抗氧化、组织和器官中铁沉积及肝组织细胞形态变化的影响。研究结果表明，化学形态和土壤中铁尽管对绵羊采食和生产性能无显著的影响，但抑制了瘤胃发酵、改变了瘤胃群落结构，增加了在肝、脾等器官的沉积，而且通过电镜扫描，发现了铁过载状态下诱发的肝细胞铁死亡现象，从机理上确定了长期铁过量诱发健康风险的可能性，研究结果为全面深入认识草地放牧绵羊铁风险和和矿物质营养管理提供理论基础。