Frankly, my response would be "so what?"
All of the animals we breed are kept in captivity and abused in various ways until they are killed, wild animals would be unaffected, so what is the net impact on the earth? If anything, a positive one.
Deforestation, which cattle ranching is a large driver of, is causing 100s or 1000s of species to go extinction every year, way more than might be lost if we all stopped eating farmed animals.
I would say… we are not eating animals because they are roaming around freely, we breed them into existence to fatten up and eat or take their produce ie eggs and milk. As the demand to eat them and their produce declines so will the need to breed them into existence. Many farmers are turning their animals over to sanctuaries and many have been rescued and are in sanctuaries so they are not going to go extinct. We don’t eat rhinos, giraffes and elephants which are also not extinct.
I would relate that to how dogs are bred in other countries just for food. If a dog is bred and raised with the knowledge that it will be food, does that make this alright? Or is this not alright solely because in our society we view dogs as pets? It would be better to have no animal suffering and no animals bred than to have billions tortured and killed every year.
Hey, make your dad watch Earthling Ed videos on Youtube, trust me.