Redefining trace mineral nutrition in dairy cattle

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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.