Which forage grass is associated with agalactia?

• A. Timothy
• B. Bermuda grass
• C. Orchardgrass
• D. Tall fescue

Answer: (D)

Agalactia linked to fescue toxicosis comes from tall fescue that is infected with a endophyte. The endophyte produces alkaloids, notably ergovaline, which act on the animal’s physiology in two ways: they mimic dopamine and suppress prolactin release from the pituitary, and they cause vasoconstriction. The drop in prolactin reduces milk production, while reduced blood flow to the mammary gland (and to the placenta in late gestation) can worsen lactation and pregnancy outcomes. This combination makes tall fescue the classic forage associated with agalactia. The other grasses listed do not have this well-established endophyte–alkaloid effect driving milk production failure.