Inorganic Versus Complexed Trace Mineral Supplements on Performance of Dairy Cows

Abstract

To determine the effects of chemical form of trace mineral supplements on performance of dairy cows, Holstein cows (n = 36) were assigned to dietary treatments of inorganic trace minerals or a combination of inorganic and complexed trace minerals (CTM). Starting at 21 d prepartum, dry cows were fed hay and a grain supplement that contained one of the trace mineral supplements. Cows continued to receive their respective trace mineral treatment from parturition until 150 d in milk (DIM). Cows fed the CTM lost less BW prepartum (P<0.05); however, there was no difference between treatments in postpartum BW change or body condition score (BCS). The DMI of lactating cows were similar between treatments. Actual milk yield (42.2 vs 41.7 kg/d), 3.5% fat-corrected milk (FCM) (42.3 vs 42.3 kg/d), and measures of production efficiency also were similar between treatments. There was a week × treatment interaction (P<0.05) for yield of milk, energy-corrected milk, and 3.5% FCM; the response to CTM was greatest from wk 5 through wk 10 postpartum. Colostrum of cows fed the CTM prepartum had greater IgG (P<0.05) and lesser Zn concentrations. There was no difference between treatments in concentrations of IgM, Co, Mn, or Cu in colostrum. Although there were period effects on serum concentrations of IgG, IgM, nonesterified fatty acids (NEFA), Zn, Co, and Ca, there were no treatment effects. These results indicate that CTM may benefit cows at peak production.