Abstract:
Proc. Aust. Soc. Anim. Prod. Vol. 19 THE RESPONSE IN SHEEP OF PLASMA AND LIVER VITAMIN B12 CONCENTRATIONS TO COBALT PELLETS CONTAINING VARIOUS AMOUNTS OF COBALT OXIDE J. D. McFARLANE, G. J. JUDSON, T. WOONTON, A. H. GOOD and A. MITSIOULIS South Australian Dept of Agriculture, GPO Box 167 1, Adelaide, S.A. 5000. A pellet containing 60% cobaltic oxide (COO) and 40% iron powder was found to be effective in preventing vitamin Blz (VB,,) deficiency for the productive life of a sheep (Dewey et al. 1969). In 1979, the formulation of the commercial pellet was reduced to 30% COO. In recent years the effective life of the 30% Co0 pellet has been questioned by veterinarians and primary producers. An experiment was conducted near Beachport in S.A. on a property where marginal VB12 deficiency occurs. Experimental Co pellets were made to contain 30%, 50% and 70% Co0 (supplied by Top Australia Ltd). These were administered with a grinder and compared with a nil treatment and the original 60% SIROCO pellet in 2 year old Merino wethers. The wethers were allocated on the basis of liveweight to 1 of 5 groups, each of 10 sheep. There was no liveweight response to treatment. Mean plasma and liver VB,, concentrations are presented in Table 1. The plasma VB12 concentrations reflect the increase in Co contents of the pellets when the untreated sheep had low plasma VBr2 concentrations. The exception to this was the SIROCO group which after week 26 had significantly higher plasma VB12 concentrations than all the other groups. The liver VB12 concentrations were significantly higher in the SIROCO group than other treatment groups after week 38. 1. vitamin B12 concentrations in plasma (pmol/L) and liver (nmolkg wet wethers given cobalt pellets of different formulations Merino Mean values are for810 sheep (plasma) and 5 sheep (liver) Means not followed by the same letter within each column are significantly different 0.05) As low VB12 concentrations (plasma ~400 pmol/L, liver <200 nmol/kg) were not maintained throughout the experiment, the practical implications of severe Co deficiency are not clear. However, the experiment demonstrates that the 30% formulation does not maintain VB12 concentrations to the same levels as the SIROCO pellet and it does not significantly raise liver concentrations above those of untreated sheep. The 70% formulation was not as effective as the 60% formulation of the SIROCO pellet in increasing plasma or liver VB12 concentrations. The source of the SIROCO Co0 was Tasmania. This source is now unavailable and the 30%, 50% and 70% pellets were made from South American or African COO. This evidence would indicate that the crystalline form of the Co0 is important in the solubility and longer term availability of Co from pellets. DEWEY, D. W., LEE, H. J. and MARSTON, H. R. (1969). Aust. .I. Agric. Res. 20: 1109-16. 390
