Department of Animal Science, Texas A&M University, College Station, USA.
J Anim Sci. 2011 Mar;89(3):722-8. doi: 10.2527/jas.2010-2871. Epub 2010 Nov 12.
Studies comparing the absorption and retention of various forms of trace minerals in horses have yielded mixed results. The objective of this study was to compare Cu and Zn absorption and retention in exercising horses where the mineral was supplemented in the sulfate or organic chelate form. Nine mature horses were used in a modified switchback design experiment consisting of seven 28-d periods. Horses were fed a diet consisting of 50% concentrate and 50% hay that was balanced to meet the energy, protein, Ca, and P requirements for horses performing moderate-intensity exercise. Horses were subjected to a controlled mineral repletion-depletion diet sequence before feeding the experimental diet to standardize mineral status across horses. The experimental diet was designed to provide 90% of the 1989 NRC for Cu and Zn, with supplemental mineral provided in the inorganic sulfate form (CuSO(4) and ZnSO(4)) or the organic chelate form (Cu-Lys and Zn-Met). Feed, fecal, urine, and water samples collected during a total collection during the last 4 d of the experimental diet periods were analyzed to determine apparent absorption and retention of Cu and Zn from the 2 mineral forms. A formulation error caused horses receiving the organic chelate diet to consume about 3 times the amount of Cu and Zn compared with those fed the sulfate-supplemented diet. Copper and Zn intake and fecal excretion were greater (P < 0.05) for horses consuming the organic chelate-supplemented diet. Apparent absorption values for all horses were negative. Apparent Cu absorption and retention as a percentage of intake were greater for horses fed the organic chelate diet (P < 0.05). It is unknown why excretion of Cu and Zn by the horses during the total collection exceeded the mineral intake. Although Cu-Lys seemed to be better absorbed than CuSO(4) and absorption of Zn-Met and ZnSO(4) were not different, these results are tempered by the observation of abnormally high fecal and urinary excretion values for Cu and Zn in the present study.
比较不同形式的痕量矿物质在马体内吸收和保留的研究结果不一。本研究的目的是比较以硫酸盐或有机螯合物形式补充矿物质时，运动马对铜和锌的吸收和保留情况。9 匹成熟马参与了一项改良往返设计实验，实验由 7 个 28 天周期组成。马匹被喂食一种由 50%浓缩饲料和 50%干草组成的日粮，这种日粮的营养成分平衡，可满足进行中等强度运动的马匹的能量、蛋白质、钙和磷需求。在给马匹喂食实验日粮之前，先让它们进行控制的矿物质补充-消耗饮食序列，以使所有马匹的矿物质状况标准化。实验日粮的设计目的是提供 1989 年 NRC 规定的铜和锌需求量的 90%，其中补充矿物质以无机硫酸盐形式（CuSO4 和 ZnSO4）或有机螯合物形式（Cu-Lys 和 Zn-Met）提供。在实验日粮期的最后 4 天的全收粪期内收集饲料、粪便、尿液和水样，以确定两种矿物质形式的铜和锌的表观吸收和保留情况。由于配方错误，摄入有机螯合日粮的马消耗的铜和锌比摄入硫酸盐补充日粮的马多约 3 倍。摄入有机螯合日粮的马的铜和锌摄入量和粪便排泄量更大（P < 0.05）。所有马匹的表观吸收值均为负值。摄入有机螯合日粮的马的铜表观吸收和保留率作为摄入量的百分比更高（P < 0.05）。尚不清楚为什么马匹在全收粪期内的铜和锌排泄量超过了矿物质摄入量。虽然 Cu-Lys 的吸收率似乎高于 CuSO4，而且 Zn-Met 和 ZnSO4 的吸收率没有差异，但本研究中观察到铜和锌的粪便和尿液排泄值异常高，这使这些结果的可信度受到影响。
