Ruminal and postruminal absorption of copper, manganese, and zinc of nonlactating and nonpregnant Holstein cows fed sulfate trace minerals above recommendations.

The objective of this study was to evaluate ruminal and postruminal apparent absorption of Cu, Mn, and Zn with rations containing 2 different concentrations of sulfate Co, Mn, and Zn supplements in nonlactating, nonpregnant Holstein cows. Four multiparous cows with ruminal and duodenal cannulas were used in a double 2 × 2 crossover design. Cows were assigned to the following treatments: (1) mineral supplement providing concentrations of Co, Mn, and Zn at 0.10, 16.7, and 60.8 mg/kg DM, respectively (CON) and (2) mineral supplement providing high concentrations of Co, Mn, and Zn at 0.63, 96.3, and 139.7 mg/kg DM, respectively (HTM). After 20 d of diet adaptation, ruminal, duodenal, and fecal samples were collected during 5 consecutive days to represent every 2 h of the day. Diets and orts were collected daily. All samples were analyzed for Cu, Mn, and Zn concentrations. Two markers (chromic oxide and indigestible NDF) were used to evaluate duodenal digesta outflow and feces output. Dry matter intake was similar between treatments (averaged 17.7 kg/d) and DM digestibility tended to be lower by 3% for HTM than CON cows. Regardless of the marker used, the interpretation of results for ruminal, postruminal, and total apparent absorption remained similar. Ruminal and postruminal absorption of Cu, Mn, and Zn did not differ between treatments. Total apparent absorption of Cu was lower for HTM than CON cows, but no treatment effect was noted for Mn and Zn. Zinc was absorbed both before and after the duodenum cannula. This article gives a useful insight on the potential site of absorption of sulfate Cu, Mn, and Zn in nonlactating and nonpregnant Holstein cows under a nonrestrictive supply of trace minerals.