Which plant example is associated with methemoglobinemia from nitrates?

• A. Redroot Pigweed (Amaranthus)
• B. Beets (Beta)
• C. Oats (Avena)
• D. Corn (Zea)

Answer: (B)

Nitrate in certain forages can be converted to nitrite in the rumen, and nitrite then oxidizes the iron in hemoglobin from Fe2+ to Fe3+, forming methemoglobin which cannot effectively carry oxygen. This creates a functional oxygen deficit known as methemoglobinemia. Beets (Beta vulgaris) are a classic nitrate accumulator, so when animals graze on beets, especially under conditions that favor nitrate buildup, enough nitrite can form to cause methemoglobinemia. Clinically, you’d expect signs of hypoxia such as rapid breathing and weakness, and the blood may appear chocolate-brown. Management focuses on removing the source of nitrates, providing supportive care, and, in severe cases, using methylene blue as an antidote.