Effect of trace mineral source on reproduction and milk production in Holstein cows

A lactation study was conducted to evaluate the effect of increasing the proportion of inorganic versus organic trace minerals (polysaccharides and amino-acid chelates) on reproductive performance and milk production of multiparous and primiparous Holstein cows. Trace minerals evaluated were copper (Cu), manganese (Mn), and zinc (Zn). All minerals were supplemented to meet the NRC (1989) recommended level (10, 40, and 40 mg/kg of Cu, Mn, and Zn, respectively) in diet DM. A total of 101 cows were randomly assigned by expected calving date to 1 of 4 trace mineral treatments: 1) 100% from inorganic sulfate (SULF); 2) 67% SULF:33% polysaccharide complex (SULF-POLY); 3) 67% SULF:33% specific amino-acid complex (SULF-AA); and 4) 100% polysaccharide complex (POLY). Treatments were implemented the day of calving. Number of days open was reduced (P < 0.05) for all cows receiving the POLY versus SULF treatments. Cows receiving the POLY treatment were also more likely (P = 0.008) to become pregnant from the first service than were cows receiving the other treatments. Milk production and composition were not affected by supplements fed. Under the conditions of this study, reproductive performance of cows fed a trace-mineral supplement composed of 100% polysaccharide complexed trace minerals was enhanced versus sulfate, sulfate and polysaccharide, or sulfate and amino acid complexed supplements.