Association between chelated trace mineral supplementation and milk yield, reproductive performance, and lameness in dairy cattle

The objective of this experiment was to evaluate the effects of feeding a ration with partial replacement of chelated trace minerals (CTM; Zn, Cu, and Mn supplied as Mintrex®) compared with a ration containing only inorganic trace minerals (ITM; supplied as sulfates, carbonates, and oxides at a commercial level) on locomotion score, milk production, and reproductive performance of dairy cows in different herds. Twenty-seven dairy herds members of a dairy cooperative (La Pirenaica, La Seu d'Urgell, Spain) that fed the same total mixed ration (TMR), were enrolled in a 6-month study. Fifteen herds continued to receive the same TMR (containing ITM), and the remaining 12 herds fed the same TMR with the only difference being a partial replacement of ITM for CTM. The ITM premix provided 57 ppm of inorganic Zn, 9 ppm of inorganic Cu, and 27 ppm of inorganic Mn, whereas the CTM premix contained 32 ppm of inorganic Zn and 25 ppm of chelated Zn, 3 ppm of inorganic Cu and 6 ppm of chelated Cu, and 17 ppm of inorganic Mn and 10 ppm of chelated Mn. The first month of study was used as a basal period, and then herds were exposed to dietary treatments for 5 months. The total number of lactating cows enrolled in the study was 2880. There were no differences in feed offered (24.1±0.20 kg/d) or milk production (31.4±0.23 kg/d) between treatments. The overall proportion of cows with a lameness score ≥3 (considered lame cows) was not different between ITM and CTM herds, but there was an interaction between treatment and month of experiment due to a numerically greater prevalence of lameness in CTM than in ITM herds during the first 2 months of study, and a lesser prevalence in the last 3 months of study. Cows in ITM herds had a greater risk of being culled due to lameness. A partial replacement of inorganic for chelated forms of Cu, Mn, and Zn (CTM) showed a greater potential for improving hoof health in herds with a relatively low prevalence of lame cows. Lastly, when considering only cows that were exposed to treatments for at least 30 days, cows in CTM herds had greater odds of becoming pregnant at first service and tended to have greater odds of becoming pregnant at second service than cows in ITM herds.