Evaluation of an intraruminal device to provide an iodine supplement for sheep

Abstract

Commercially manufactured intraruminal devices providing iodine supplementation for grazing sheep were tested for three years in a flock of 200 ewes, and iodine release rates and accumulation in tissues were measured in a small flock of first cross ewes and wethers. Retention of the device exceeded 99.5%. The rate of iodine release increased from about 500 µg/d during the first few months to about 1100 µg/d resulting in an effective life of almost three years. The ewes were not iodine deficient, and supplementation by this device did not improve reproductive performance. Thyroxine levels in plasma, and iodine concentrations in tissue, were not elevated to levels which might be considered toxic, confirming the safety of the device.