Interpretive Summary: Source of trace minerals impacts digestibility in steers

By: Anne Kamiya, MS

The source of trace minerals in animal feed may impact its digestibility. In this recent study published in the Journal of Animal Science, researchers compared the neutral detergent fiber (NDF) digestibility of hydroxy trace minerals (HTMs) and sulfate trace minerals (STM) in steers. They hypothesized that the source of trace minerals would impact both digestibility and rumen fermentation. They also hypothesized that ruminal soluble concentrations of minerals would differ based on trace mineral source. 

A total of twelve angus steers were fed a medium-quality grass hay-based diet for 21 days. Steers were fed either STM or HTM with varying concentrations of supplemental copper (Cu), manganese (Mn) and zinc (Zn). The solubility of minerals sourced from HTM were found to be lower in the rumen, indicating that it had higher fiber digestibility. Dry matter, crude protein, NDF and acid detergent fiber (ADF) digestibility were also greater in the HTM-supplemented animals. No differences in ruminal volatile fatty acid (VFA) concentrations were noted based on trace mineral source. 

Overall, the results of this study suggest that source of trace minerals is an important factor to consider in the formulation of rumen feed. The bioavailability of minerals needs to be considered when creating diets that are both cost-effective and optimized for best animal nutrition. More studies into the digestibility and bioavailability of nutrients based on their source in ruminants is justified. 

The original article, Trace mineral source impacts rumen trace mineral metabolism and fiber digestion in steers fed a medium-quality grass hay diet, is viewable in the Journal of Animal Science.