Will rat poison kill cows

Answer 1

You've asked an interesting question here -- let me try and address it properly.

Toxicology defines a toxin by what it is and how it acts, and also by dosage. Elements like selenium, for instance, are needed by the human body in trace amounts, but larger amounts are toxic. So what we use to attack the rat population may well be toxic for cows in a certain dosage. But this leaves the fundamental questions, How do they get that toxin?, and Would they obtain a sufficient dosage to be dangerous?

Rats are omnivorous, and they're especially drawn to rich sources of Kcals and proteins. So rats will go for meats, cheese, peanut butter, etc. Cows, being vegetarian, are not typically drawn to the scents we use for rat bait, so it's unlikely they'd seek out baited traps containing rat poison. And in the case of a chance encounter, it's unlikely that they'd uptake a dosage sufficient to cause harm.

That said, in sufficient amounts, rat poison can and will kill or injure cows (usually -- depends on the rat poison), as they're both mammalian and subject to a lot of the same vulnerabilities. Is it likely that a cow would, under normal circumstances, be exposed to that large a dose of rat poison and want to eat it? To that, I have to say, Very Unlikely.