The effect of sporidesmin toxicity on ovine serum vitamin B12 levels

Major trace elements limiting livestock performance in New Zealand

Abstract Extract • Many New Zealand soils are naturally deficient in cobalt and/or selenium and/or copper, or are naturally high in molybdenum. livestock granng pasture grown on such soils may be deficient in one or more of these trace elements. • In the 1940s and 1950s, New Zealand researchers were at the forefront of research to define the cause of trace-element related ill-thrift and clinical diseases like white muscle disease, peat scours and enzootic ataxia. • New Zealanders have devised production-related reference ranges for blood and liver copper, vitamin B(12) and selenium that are used for the diagnosis and prevention of deficiencies. • A range of supplementation procedures has been devised, from topdressing or spraying pasture to direct animal supplementation, to suit the range of livestock management systems found in New Zealand. • Trace-element monitoring programmes are now a routine procedure for farmers grazing cattle, sheep, and deer on trace-element deficient land. • Copper deficiency is the main trace-element deficiency diagnosed in deer.

Reference curves to diagnose cobalt deficiency in sheep using liver and serum vitamin B12 levels

Reference curves demonstrating the relationship between serum or liver vitamin B12 and weight gain were derived from the examination of 16 published and 48 unpublished N.Z. trials. From these curves probability of obtaining an economic reponse (>10g/day body weight increase) for any serum or liver vitamin B12 can be determined. No significant (P<0.05) weight gain responses occurred to vitamin B12 or cobalt treatment in trials with mean serum vitamin B12 levels above 500 pmol/l or liver vitamin B12 levels greater than 500 nmol/kg. The reference curves were therefore derived from trials with vitamin B12 levels below these levels; 36 trials with serum vitamin B12 and 19 trials with liver vitamin B12 data. The mean vitamin B12 level at the mid point of the weight gain response period was selected from each trial. Examination of serum vitamin B12 reference curves for spring, summer, autumn and winter indicated that curves derived from data closest to the middle of January (summer) adequately reflected response to treatment at any time during the first year of life. Reference curves for liver vitamin B12 also used data closest to middle of January. This was partly because insufficient liver data was available to compare seasonal variations. The fitted response curve approached 0 gram/day at 500 pmol/l for serum vitamin B12 and 375 nmol/kg for liver vitamin B12. The minimum vitamin B12 level at which an economic response to treatment (>10 g/day) is not likely was 336 pmol/l for serum and 282 nmol/kg for liver.