Evaluation of cobalt pellets for sheep

Abstract

Vitamin B12 concentrations were measured in plasma and liver, and cobalt (Co) concentrations determined in faeces, of sheep given intraruminal Co pellets with or without steel grub screws (grinders). The Co pellets contained 30 or 60% by weight Co oxide (Co3O4). Sheep were maintained on pasture at 2 sites in the South East of South Australia in an area where sheep have been shown to respond to Co supplementation. All pellets, apart from one given without a grinder, maintained above-adequate vitamin B12 concentrations in liver (>200 nmol/kg wet weight) and plasma (>400 �mol/L) for 1 year. In the second year, some pellets containing 30% Co3O4 failed to maintain adequate vitamin B12 concentrations in the liver of sheep at 1 site when untreated sheep were at risk of seasonal Co deficiency (liver vitamin B12 concentrations <100 nmol/kg wet weight). Under these circumstances, a more recently formulated pellet containing 30% Co3O4, when given with a grinder, maintained adequate vitamin B,? status of sheep for 3 years. The 'traditional' pellet containing 60% Co3O4 increased vitamin B12 concentrations to high normal values (in plasma >I500 pmol/L, in liver >200 nmol/kg wet weight) for at least 3 years. Pellets containing 30% Co3P4 may only prevent Co deficiency for 1 year, depending on the source of the pellets.