Question

The signs and biochemical lesions that are manifested in Cobalt deficiency are referable to deficiency of which vitamin ?

• A. Vitamin B$_1$
• B. Vitamin B$_6$
• C. Vitamin B$_{12}$
• D. Vitamin C

Hint:

Remember:
- Cobalt is a structural component of Cobalamin (Vitamin \(\mathbf{B_{12}}\)).
- Non-ruminant animals must ingest pre-formed Vitamin \(\text{B}_{12}\) in their diet.
- Ruminants can synthesize it internally, but they require dietary Cobalt to do so.

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
Cobalt is an essential trace mineral in animal nutrition, particularly in ruminants.
Its primary physiological role is to serve as a core structural component of a vital water-soluble vitamin.

Step 2: Detailed Explanation:
Cobalt is the central metallic ion in the corrin ring structure of Vitamin \(\mathbf{B_{12}}\) (cobalamin).
In ruminants (such as cattle and sheep), the active ruminal microflora require a constant dietary source of inorganic cobalt to synthesize cobalamin endogenously.
If the soil and pasture are deficient in cobalt, the ruminal microbes cannot synthesize sufficient quantities of Vitamin \(\text{B}_{12}\).
This leads to a secondary, systemic Vitamin \(\text{B}_{12}\) deficiency in the animal.
The biochemical lesions of cobalt deficiency are directly related to the loss of activity of the two major \(\text{B}_{12}\)-dependent enzymes:
1. Methylmalonyl-CoA mutase: This enzyme is critical in ruminants for converting propionate (their primary gluconeogenic precursor) into succinyl-CoA.
Loss of this activity leads to impaired gluconeogenesis, severe ketosis, and emaciation.
2. Methionine synthase: This enzyme is required for folate recycling and myelin maintenance.
Its deficiency causes anemia and neurological dysfunction.
Therefore, the symptoms of cobalt deficiency are clinically identical to, and referable to, a deficiency of Vitamin \(\text{B}_{12}\).

Step 3: Final Answer:
The signs and biochemical lesions of Cobalt deficiency are referable to a deficiency of Vitamin B\(_{12}\).