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Abstract：
Kelp (Ascophyllum nodosum) is rich in iodine and often fed by organic dairy producers as a mineral supplement to support animal health. A commonly held belief is that kelp supplementation decreases susceptibility to infectious bovine keratoconjunctivitis due to increased iodine concentrations in tears. Whereas serum and milk iodine concentrations are positively correlated and modulated by oral iodine supplementation, nothing is known about the iodine concentration of tears. Therefore, the 3 objectives of this pilot study were to determine (1) the iodine content of tears, milk, and serum of cows after being fed kelp for 30d; (2) the trace mineral and thyroid status of cows before (d 0) and after being fed kelp for 30d; and (3) the in vitro growth rate of bacteria in tears (Moraxella bovis) or milk (Staphylococcus aureus, Escherichia coli, Streptococcus uberis) collected from cows fed no kelp (d 0) or kelp (d 30). Cows (n=3/treatment) were individually fed 56g of kelp per day (n=3/treatment) or not (n=3/no treatment) for 30 d. Daily feed intake of the TMR was recorded and weekly TMR, kelp, milk, blood and tear samples were collected and analyzed for iodine. The feed samples were pooled and further analyzed for other minerals. On d 0 and 30, liver biopsies and blood samples were collected and analyzed for mineral content and thyroid hormone concentrations, respectively. An inhibition test used milk and tear-soaked plates from kelp-fed cows (d 0 and 30) as well as 1 and 7.5% iodine as positive and distilled water as negative control. As expected, serum iodine concentrations were positively correlated with milk and tear iodine concentrations. Whereas the iodine concentrations in serum increased significantly in the kelp-fed cows during the 30-d study, milk and tear iodine concentrations increased only numerically in these cows compared with the control group. Liver mineral profiles were comparable between groups and generally did not change over the course of the study. Thyroid hormones remained overall within the reference range throughout the trial. Neither milk nor tears from kelp-fed cows inhibited in vitro growth of any of the plated bacteria. In summary, serum iodine concentration was correlated with the iodine concentration in milk and tears and feeding kelp increased only the serum iodine levels of cows in this trial. Bacterial growth was not inhibited in milk and tears of kelp-fed cattle in vitro, and prevention of infectious bovine keratoconjunctivitis would not be based solely on increased iodine concentrations in tears.
摘要：
海带（Accophyllumnodosum）富含碘，通常由有机乳制品生产商作为矿物质补充剂喂养，以支持动物健康。普遍持有的观点是,由于眼泪中碘浓度增加,海带的补充降低了对感染性牛角膜结膜炎的易感性。而血清和牛奶中的碘浓度呈正相关，并通过口服补充碘进行调节，对眼泪中的碘浓度一无所知。因此,这项初步研究的三个目标是确定(1)眼泪中的碘含量，牛奶，和饲喂海带30d后的母牛血清；（2）饲喂海带前（d0）和饲喂海带30d后母牛的微量矿物质和甲状腺状态；（3）泪液（牛莫拉氏菌）或牛奶（金黄色葡萄球菌，大肠杆菌,赤霉病链球菌）从未饲喂海带（d0）或海带（d30）的母牛中收集。奶牛（n=3/处理）每天单独饲喂56g海带（n=3/处理）或不饲喂（n=3/无处理）30天。记录TMR的每日采食量，每周TMR，海带,牛奶，收集血液和泪液样本并分析碘。收集饲料样品并进一步分析其他矿物质。在第0天和第30天，收集肝活检和血样，分析矿物质含量和甲状腺激素浓度，分别。抑制测试使用来自海带喂养的母牛（d0和30）的牛奶和泪液浸泡板，以及1％和7.5％的碘作为阳性，蒸馏水作为阴性对照。不出所料,血清碘浓度与牛奶和泪液碘浓度呈正相关。尽管在30天的研究中，海带喂养的奶牛血清中的碘浓度显着增加，与对照组相比，这些奶牛的牛奶和泪液碘浓度仅在数值上增加。各组之间的肝脏矿物质分布具有可比性，并且在研究过程中通常没有变化。在整个试验中，甲状腺激素总体保持在参考范围内。牛奶和海带喂养母牛的眼泪都不会抑制任何平板细菌的体外生长。总之,血清碘浓度与牛奶和眼泪中的碘浓度相关，饲喂海带仅增加了该试验中奶牛的血清碘水平。在体外，海带喂养的牛的牛奶和眼泪中的细菌生长没有受到抑制，和预防传染性牛角膜结膜炎不会仅仅基于增加眼泪中的碘浓度。
