I've come to find that people with those kind of extreme views have not actually fully thought out where it begins and where it ends. If she were comfortable in her knowledge of why she believes what she believes then she would not get defensive. Defensiveness is a hallmark of insecurity. This applies to ANY lifestyle choice from religion to diet to politics.

Some people just believe that using animals for any purpose is wrong. I disagree, but it's their prerogative to believe it. But the deeper you dig into the whole cycle of life, the more you find that for any animal to eat SOMETHING has to die. Hell, for any life form to eat, something has to die whether it be a bacteria or a blade of grass or a cow. The soil microbes can't eat unless plants and animals die to feed the soil. No organic matter, no soil life. Organic matter=dead things and poop. Plants and plant tissues die so cows can eat. Bugs die so chickens can eat, not to mention the bugs unlucky enough to be on the grass the cow is eating. Even raising crops, they have to die so we can eat. Any modification you make to the environment kills something. Planting an apple tree? You're displacing and perhaps killing plants, insects, and even ground dwelling rodents to plant your tree. Or is that okay b/c they're not cute? Where does it end? I put my trust into the system nature designed, where plants and animals (people included) exist together in a complex and frankly sometimes brutal cycle.