Livestock farmers are being advised by Animax that it is possible to over-supplement pregnant ewes and cows with iodine, increasing the risk of poor absorption of colostrum antibodies and ill health or death in new born lambs and calves, after an investigation by The Vet Record of 100 ewes.
The investigation found that of 100 ewes, 40 live lambs died within a few days of birth, and concluded that some ewes ingested sufficient iodine to cause a reduction in colostrum absorption by their lambs.
Vet Dr Elizabeth Berry of Animax said: “Once the daily supply of iodine is in the target zone, more is certainly not better.”
In the same Vet Record report, another investigation of multiple lamb deaths at two to three days old found that hygiene and colostrum quality were good. Lamb post mortems identified normal milk clotting in the abomasum (stomach), but low levels of immunoglobulins in blood plasma, indicating “failure of maternal colostral antibody transfer.” The report suggested this was due to high levels of iodine supplementation in the ewes’ feed.
Maximum iodine levels to aim for are 9.9mg/kg of dry matter feed intake for ewes, and 4.4mg/kg DM for cows. For guidance on hitting these targets, farmers should contact their own vet or a livestock specialist .