Effect of dietary zinc levels on mineral concentration in milk.

Effects of supplemental dietary Zn levels of 0, 50, 500 and 5,000 ppm on the mineral concentration in milk of first- and second-parity sows were evaluated. Colostrum from sows fed 5,000 ppm of supplemental Zn contained less Cu and P than colostrum from sows on the other treatments. Calcium was reduced in the colostrum from sows fed 0 or 5,000 ppm Zn. Copper was reduced and Zn increased in milk from sows fed the highest Zn level compared with the other treatments during wk 1, 2 and 3 of lactation. Iron was lower in the 2nd wk milk from sows supplemented with 50 ppm Zn compared with sows on the other treatments. Copper and Zn concentrations were reduced in the 1st, 2nd and 3rd wk milk from sows fed 0, 50 or 500 ppm additional Zn compared with colostrum, but only Zn was reduced in milk from sows supplemented with 5,000 ppm Zn compared with colostrum. Calcium concentrations were increased in milk for all treatments compared with colostrum, and Mg was increased in 1st, 2nd and 3rd wk milk from sows fed 0, 50 or 500 ppm Zn and in 2nd and 3rd wk milk from sows fed 5,000 ppm Zn compared with colostrum. Phosphorus was higher in 2nd wk milk from sows fed 0 or 500 ppm Zn and higher in 3rd wk milk for sows fed 0, 500 or 5,000 ppm Zn compared with colostrum. The Fe concentration in 1st wk milk from the second-parity sows was increased compared with that from the first-parity sows for all treatments. Magnesium was reduced in second-parity colostrum compared with first parity for all treatments except the unsupplemented group.