Effect of Replacing Dietary Inorganic Forms of Zinc, Manganese, and Copper with Complexed Sources on Lactation and Reproductive Performance of Dairy Cows

One hundred eighty multiparous Holstein cows (90 cows/treatment) were blocked according to calving date and randomly assigned to a study to determine the effect of trace mineral source on performance. Treatments were 1) all trace minerals supplied by inorganic sources or 2) inorganic minerals (360 mg Zn/d, 200 mg Mn/d, and 125 mg Cu/d) replaced with amino acid complexes of Zn, Mn, and Cu (CTM, Availa-4, Zinpro Corporation). Neither level nor source of Co supplementation differed between dietary treatments. Cobalt was supplemented as Co carbonate to supply 12 and 23 mg Co/d to dry and lactating cows, respectively. Cows received their respective treatments from 60 d prior to calving through 200 d oflactation. Replacing inorganic trace minerals with CTM tended to increase (P = 0.06) milk protein yield (1.09 vs. 1.05 kg/d) and tended to decrease (P = 0.15) linear SCC. There was no effect oftreatment on milk yield and yields of 3.5% fat-corrected milk and energy corrected milk. Feeding CTM increased (P = 0.005) BCS (2.97 vs. 2.86), decreased (P = 0.02) culling rate (13.3 vs. 25.6%) and tended (P = 0.07) to increase incidence of retained placentas (13.3 vs. 6.7%). Feeding CTM also tended to decrease (P = 0.15) incidence of metritis (14.4 vs. 16.7%) and to increase (P = 0.15) first service conception rate (21.9 vs. 19.1%). Replacing inorganic trace minerals with those supplied by CTM tended to improve lactation performance and reduced culling rates.