Effect of cobalt supplementation on lamb growth rates in the face of cobalt deficiency

A hill farm in eastern Scotland had noted poor lamb growth rates since 2014. Cobalt, selenium and copper deficiencies were reported from historical blood sample results, and trace element supplementation had been administered to the ewes, but not the lambs. A supplementation trial was undertaken in 2018 to compare the daily liveweight gain (DLWG) between lambs supplemented with trace elements and unsupplemented lambs. The trace element supplements used were intraruminal boluses containing 51-mg cobalt, 10-mg selenium and 60-mg iodine (Downland Essential Lamb bolus, Downland). Blood samples taken two months postsupplementation showed that unsupplemented lambs had cobalt-deficient status, but not selenium deficiency. Lambs supplemented with the trace element boluses had an increase in DLWG of 49 g/day compared with unsupplemented lambs. This case confirms that cobalt supplementation on deficient farms can be associated with a significant improvement in growth rates of growing lambs on Scottish hill farms