1861
Effect of supplemental chelated Cu, Zn, and Mn on antioxidant status and hoof health of lactating cows
The objective of the study was to evaluate effect of supplemental Cu, Zn, and Mn as chelated trace mineral (CTM) on antioxidant status and hoof health of dairy cows. Forty eight Holstein cows in early lactation (DIM = 65) were randomly assigned into 1 of 2 treatments: 1) basal diet contains 17.2 mg Cu, 70.1 mg Zn, and 63.7 mg Mn/kg dry matter (CON); 2) basal diet supplemented with 150 mg Cu, 320 mg Zn and 130 mg Mn/head/d as CTM (MINTREX®). Cows were gait scored using a 5-point Numerical Rating System where 1 and 2 are considered healthy, and ≥3 lame. Cows in each treatment were blocked as lame cows (n = 12) or healthy cows (n = 12) when data was analyzed. Over the 180 d experiment, DMI, milk yield and milk composition was tested every 10 days. Blood samples and hoof samples were taken at day 0, 90, and 180 to test the blood antioxidant variables and hoof hardness, respectively. There was no difference in DMI, milk yield and milk composition between healthy and lame cows (P > 0.05). Cows receiving CTM had less milk fat concentrations (P < 0.05) than CON, but no difference was observed on milk fat yield or other milk components (P > 0.05). No differences were detected in blood superoxide dismutase (SOD), reduced glutathione (GSH), oxidized glutathione (GSSG), glutathione peroxidase (GSH-Px), catalase (CAT), and malondialdehyde (MDA) between healthy and lame cows (P > 0.05). Compared with CON, blood SOD, GSH, and GSH-Px in CTM cows were significantly increased while MDA and GSSG were significantly decreased (P < 0.05), and blood CAT was not affected by treatments (P > 0.05). Cows receiving CTM did not have hoof hardness that differed from the CON at day 0 and 90, but had significant greater values than CON at day 180 (P< 0.05). There was no interaction between CTM and cows health status. It was concluded that supplemental chelated Cu, Zn, and Mn could improve antioxidant status and hoof hardness regardless of lameness status.
Keywords: chelated trace mineral; antioxidant status; hoof health