Serum vitamin B₁₂ and methylmalonic acid determinations in the diagnosis of cobalt deficiency in pregnant ewes

Serum vitamin B₁₂ and methylmalonic acid (MMA) concentrations were used to monitor the development of cobalt (Co) deficiency and repletion from the deficient state in housed pregnant hill sheep. Serum MMA concentrations were less variable and provided a more accurate diagnosis of Co deficiency than serum vitamin B₁₂. This was particularly the case for subclinical disease. However, unlike serum MMA, concentrations of the vitamin in serum could be used prognostically. The most precise diagnosis was provided by serum vitamin B₁₂ and MMA data used in conjunction, but where one technique is to be used, serum MMA determinations are preferred.