Effect of trace mineral form in supplements on first-calf heifer status, immunity, reproduction and calf performance.

摘要

Three trials were conducted to evaluate effects of trace mineral form on immune response, reproduction and trace mineral status in first-calf heifers and their calves. Sulfate (S) and complexed (CX) supplements were formulated to provide 25 ppm Cu, 60 ppm Zn, 40 ppm Mn and 2 ppm Co of total daily DM. Control (CON) supplements contained no additional Zn, Cu, Mn or Co. In Trial 1, supplements were fed free-choice 90 d, beginning 45 d prior to the calving season. On d 30, CX fed heifers had an improved (P < .05) cell-mediated immune response to phytohemmaglutinin compared to S and CON. Heifer and calf serum mineral levels were similar among groups. However, Cu levels in calves at birth (.33 mg/dL) were below those considered adequate. Antagonists (Mo, 5 ppm; S, 2500 ppm; and Fe, 1000 ppm of daily DM) were included in Trial 2 supplements. Supplements were individually fed alternate days for 130 d, beginning 30 d prior to calving. Hepatic Zn status was increased (P < .01) in CX heifers at calving and breeding. Copper status was improved (P < .01) for CX and S compared to CON at calving and remained elevated in CX heifers 150 d after supplementation ended. Serum levels were similar among treatments. Maternal supplementation did not influence mineral status in calves. Higher (P < .05) percentage of CX heifers were bred Al than other groups. Trial 3 supplements were fed in a similar manner with the exception of no additional S or Fe. Liver Cu status increased in CX and S heifers and remained higher than CON 150 d after supplementation ended. Liver Zn levels, cell-mediated immune response and IgG colostrum levels were similar among treatments. The CX heifers had improved (P = .05) E. coli antibody titers compared to S with CON intermediate. Milk production was increased (P = .06) for mineral supplemented groups; however, weaning weights were similar. Post-partum d to first service were decreased (P = .05) for CX heifers compared to CON and S. Results of these studies indicate that supplementing complex trace minerals can change hepatic trace mineral status, enhance immune responses, increase milk production and impact reproduction in first-calf heifers.