Vitamin B12 is a so-called cobalamin. Cobalamins are co-enzymes and play an important role in the formation and functioning of, among others, the nerve system. Cobalamins are also important for the formation of blood cells, for DNA synthesis, and in the regulation of that formation5. Also, Vitamin B12 is – as a co-enzyme in methyl malonyl-CoA mutase – required for the metabolism of propionic acid. Eventually, this leads to the formation of glucose, an important source of energy4.
Cobalt is needed for Vitamin B12 synthesis, illustrating the importance of a good cobalt supply. Next to the Co functions mentioned above, anaerobic bacteria in the rumen also require cobalt for their multiplication4, and these bacteria are essential for the fermentation of feed in the rumen. Cobalt as well as Vitamin B12 are, therefore, important for wellbeing and performance of sheep in general.
A cobalt deficiency in sheep occurs in different countries, it is, therefore, considered an international problem. The extent to which forages contain cobalt depends on the cobalt concentration in the soil, the pH of the soil, and the type of soil.
In The Netherlands, cobalt shortages are especially seen in lambs that are kept on pasture, without additional nutrition, particularly towards the end of summer and in the fall. The reason for this is, that ewes that suffer or have suffered from a lack of cobalt, will also excrete less cobalt in their colostrum. In that case, lambs have not had the opportunity to build up any cobalt reserves. Towards the end of summer, these lambs will show signs of cobalt deficiency.
A shortage of cobalt will lead to the same symptoms as a lack of Vitamin B12. The following symptoms (alone or combined) may be seen: decline in appetite, underdeveloped rumen, growth retardation, decline in body condition, decreased production performance, and listless animals standing lethargically in the meadow. In the long run, fertility will diminish and stillborn lambs are more often encountered6.
Unfortunately, it is not always easy to point at cobalt deficiency as the cause of the problems mentioned above. A lack of Vitamin B12 leads to a decline in activity of the methyl malonyl-CoA mutase enzyme, and secretion of more metabolites – like methyl malonic acid (MMA) in the urine. Analysis of urine is a means to detect Vitamin B12 deficiency. Also, a blood test (MMA and Vitamin B12 content in serum or plasma) can be performed to determine a deficiency4. However, the most practical method to determine cobalt deficiency is simply administering cobalt when the above-mentioned symptoms are seen: The animal will quickly recover if a lack of cobalt was causing the problems.