Copper, Mn, and Zn are essential trace minerals (TM) supplemented in cattle to prevent TM deficiencies. Supplemental TM sources can differ in solubility within the digestive tract of cattle, which can impact rumen fermentation and availability for absorption from the small intestine. Rumen fluid (RF) from steers receiving hydroxy or sulfate TM sources of Cu, Mn, and Zn was obtained and subjected to ruminal, abomasal, and small intestine incubation conditions, in vitro, to examine rumen fermentation characteristics and solubility of Cu, Mn, and Zn from each source. In vitro chamber incubated with RF obtained from hydroxy TM supplemented steers had a greater total volatile fatty acid (VFA) concentration and propionic acid molar proportion, but lesser acetic acid molar proportion than in vitro chamber incubated with RF obtained from steers receiving sulfate TM. Following in vitro incubation, the chamber incubated with RF from hydroxy-supplemented steers had greater total VFA concentrations at 24 h compared to the chamber incubated with RF from sulfate-supplemented steers. After simulated abomasal digestion, soluble Mn concentrations in hydroxy-supplemented steers were greater than in sulfate-supplemented steers. These data indicate that the source of TM can influence in vitro rumen fermentation characteristics and TM solubility under simulated abomasal conditions.

Read the full article in the Journal of Animal Science.