Abstract

Iodine (I) concentrations in New Zealand pastures are low and may be inadequate to meet the I requirements of lactating dairy cows. A trial was undertaken with 400 cows to determine the effects of a single intra-muscular injection of 2000 mg I (in popyseed oil) given at the beginning of lactation on cow performance. The pasture I concentration ranged between 0.17-0.26 mg I/kg DM during of the trial and the supplement increased serum thyroxine (T4) and milk I concentrations for 76 (P<0.05) and 170 (P<0.01) days respectively. Iodine supplementation did not affect milk yield milk composition or number of services per conception. To increase I status and maintain milk I concentrations at or above 40

ND, Grace, GC Waghorn, AR Mills, and AF Death

Proceedings of the New Zealand Society of Animal Production, Volume 56, , 143-145, 1996