Redefining trace mineral nutrition in dairy cattle

微量矿物质是奶牛饮食中数量不多但至关重要的组成部分。尽管它很重要，但我们对奶牛吸收和利用微量矿物质的了解有限。在奶牛的日粮中经常添加无机来源的微量矿物质以优化生产性能，但它们的吸收受到胃肠道（GIT）内拮抗相互作用的影响，从而降低了它们的生物利用度。动物饲料公司已经开发出将无机元素与有机分子复合的技术，这些微量矿物质的有机来源将免受GIT中大多数拮抗相互作用的影响，从而有可能提高吸收的生物利用度并改善动物生产性能。尽管如此，关于有机微量矿物质与无机微量矿物质作为奶牛饲料补充来源的优势，尚无结论性数据。本研究旨在研究奶牛日粮中添加有机或无机微量矿物质的来源对1)胃肠道吸收和矿物质综合利用的影响；2)瘤胃微生物群多样性与生物学；3)饲料效率、代谢和产奶量；4)免疫细胞功能、氧化平衡与健康；5)生殖生物学和性能。将按照国家研究委员会的建议，在相同的含量水平下比较有机和无机微量矿物质补充剂。各处理组均饲喂相同的饲粮，但添加钴、铜、锰、硒和锌的来源为无机盐或有机蛋白质。实验将与圭尔夫大学和阿尔伯塔大学的研究小组合作进行。预计项目成果将导致对基本微量矿物质营养的进一步了解，并将确定有机来源完全替代无机微量矿物质是一项有利可图的管理决定。

Trace minerals represent a small but crucial component of a dairy cow's diet. Despite its importance, our knowledge regarding trace mineral absorption and utilization in dairy cattle is limited. Inorganic sources of trace minerals are often supplemented in diets of dairy cattle to optimize performance, but their absorption is compromised by antagonistic interactions within the gastrointestinal tract (GIT) that reduce their bioavailability. Animal feed companies have developed technologies to complex inorganic elements with organic molecules, and these organic sources of trace minerals would be protected from most antagonistic interactions in the GIT, thus potentially increasing bioavailability for absorption and improving animal performance. Nonetheless, conclusive data regarding the superiority of organic compared to inorganic trace minerals as supplemental sources for dairy cattle feeding is not available. Our multidisciplinary research proposal aims to investigate the impact of the source of supplemental trace minerals - organic or inorganic in diets of dairy cows on 1) GIT absorption and overall utilization of minerals; 2) rumen microbiome diversity and biology; 3) feed efficiency, metabolism, and milk production; 4) immune cell function, oxidative balance and health; and 5) reproductive biology and performance. Organic and inorganic trace mineral supplements will be compared at the same inclusion levels, which will follow the recommendation of the National Research Council. Treatments groups will receive the same diet, except for the source of supplemental cobalt, copper, manganese, selenium, and zinc, which will be either inorganic salts or organic proteinates. Experiments will be conducted in collaboration with research groups at the University of Guelph and the University of Alberta. It is anticipated that the project outcomes will lead to an improved understanding of basic trace mineral nutrition, and will establish complete substitution of inorganic trace minerals by organic sources as a profitable managerial decision.