What organ system is impacted by Senecio in cows?

The correct answer is the liver. Senecio, commonly known as ragwort, contains pyrrolizidine alkaloids that are highly toxic to the liver in various animals, including cows. When ingested, these alkaloids cause liver damage that can lead to severe health issues, including liver cirrhosis and liver failure. The liver plays a critical role in detoxifying harmful substances and producing essential proteins, so damage to this organ can have widespread effects on an animal's overall health.

In contrast, while other organ systems, such as the heart, kidneys, and lungs, may be affected by various toxins or diseases, they are not specifically impacted by exposure to Senecio. This makes liver toxicity the hallmark of poisoning from this plant in cattle, further emphasizing the importance of avoiding such toxic plants in their grazing areas.