Effect of Complexed Trace Minerals on the Performance of Lactating Dairy Cows on a Commercial Dairy

On a commercial dairy, 306 Holstein cows were blocked by parity and expected calving date and were used in a randomized complete block design to determine the effect of treatment on claw integrity, lactation, and reproduction. Treatments were 1) all supplemental Zn, Mn, Cu, and Co supplied by sulfates, and 2) 360 mg Zn, 200 mg Mn, 125 mg Cu, and 25 mg Co from sulfates replaced by similar amounts of trace minerals supplied by specific amino acid complexes of Zn, Mn, and Cu and by Co-glucoheptonate [complexed trace minerals (CTM); 4-Plex, Zinpro Corp., Eden Prairie, MN]. All cows were fed inorganic trace minerals for 4 mo before initiation of treatments. Cows received treatments from 21 d prepartum through 250 d postpartum. There was no effect of treatment (P > 0.15) on yields of milk, 3.5% FCM or energy-corrected milk. Cows fed sulfates tended (P = 0.105) to produce more milk fat and milk with a greater fat content (P = 0.045). Cows fed CTM tended to have lower SCC in milk (P = 0.08) and linear SCC score (P = 0.06) than cows fed sulfates. Survival curve analysis indicated feeding CTM tended to generate more pregnancies and at a faster rate (P = 0.08) than cows fed sulfates. Feeding sulfates decreased (P < 0.01) the severity of hemorrhages, whereas feeding CTM decreased (P < 0.01) the incidence of heel erosion. In conclusion, replacing a portion of the inorganic sulfate sources of Zn, Cu, Mn, and Co with those trace minerals supplied by CTM improved some aspects of milk quality and reproductive performance.