Which fungus is responsible for ergot on grasses and is associated with agalactia?

• A. Aspergillus
• B. Penicillium
• C. Claviceps
• D. Fusarium

Answer: (C)

Ergot on grasses is caused by a Claviceps species that infects the flowering heads and replaces the grain with dark, hard sclerotia known as ergot bodies. These ergot sclerotia contain ergot alkaloids, which, when ingested by animals, can cause ergotism. A key effect is on milk production: ergot alkaloids act as dopamine agonists, inhibiting prolactin release from the pituitary and leading to agalactia (failure to lactate). The vasoconstrictive properties of these alkaloids also contribute to other signs, but the connection to reduced milk yield is the important link for agalactia.

Among the fungi listed, Claviceps is the one specifically associated with ergot on grasses. The other genera produce different toxins and diseases (for example, Aspergillus and Penicillium are linked to various mycotoxins like aflatoxins and ochratoxins, and Fusarium toxins have their own distinct effects). Therefore, the fungus responsible is Claviceps.