@ Bine: In practice, I agree with everything you say, but in theory you and I are not yet "holy" enough. :-)
I have had the same thoughts throughout my life. I always realized that chickens would not live very long without us providing them with food (very difficult to come by during WWII and the years following) and protection. (My father, a construction engineer, had built our chickens a deluxe home with material that had also been very difficult to come by.)
Our hens were slaughtered (by someone other than our family members) after 3 or 4 years of laying (when they started to "retire"). This happened, of course, one at a time because there was no fridge, and even less a freezer. It was always a very sad event, with everyone, except my father, crying, and me pleading for the life of the chicken (even though poultry has always been my very favorite food). I always watched the slaughtering (which I found horrifying) because I wanted to be with my beloved chicken to the very end. And I ate the chicken with tears running in streams down my face. (I consoled myself a bit, telling myself that it wouldn't help the chicken if I didn't eat eat, as it was better for it to be reunited with my body than to have its body decaying in the soil. This logic wouldn't quite hold, especially because there was no danger that my part of the chicken would not get eaten by another family member, but it was the best "philosophy" I could come up with. :-))
We raised chickens (from eggs we hatched in the kitchen) only once (or possibly twice). There, we had, of course, about half of them roosters, and they did get slaughtered (again by a stranger) when they "came of age". I felt so terribly sorry for them because they only had such a short life. Even my father, who had bonded with one in particular, named "Teufelchen", was close to tears when Teufelchen's time came.
Btw, all our hens were roasted like the young roosters, and they tasted just as good. (I think they were all leghorns.) I tried to roast 2 "soup chickens", I had obtained from our egg supplier, a few years ago. They were inedible. (Even our cats weren't exited about the tough meat, and only a few not-so-fussy cats eventually and reluctantly ate the roasted "soup chickens".) I don't know the breed of these chickens.
I did not know that roosters would kill each other in the wild. I had always wondered what happened to them and had hoped that they lived in a happy monogamic relationship with just one chicken, as swans, geese, and ducks do.
You write: "They [farm animals] live better and longer lifes in our backyards than in the wild and we have a protein source." This only holds true for humane family farming, certainly NOT for cruel factory-farming. This is why I keep praising family farming, even though that the farmers (just as those of us who are not all vegan) are "not quite holy enough". Nature is cruel, and mankind, as a whole, is even more cruel (just look at the Holocaust, look at ISIS, ... ... ... and look at factory-farming--all cruelty NOT subscribed by nature!)
And because nature (and our species in particular) is so cruel, I don't give a hoot about any of the species on our planet becoming extinct. "Nach mir die Sintflut!". Well, don't take me all seriously, but there is definitely some truth in it.--If the particularly loud-mouthed GOP candidate for the American presidency should win the elections, his belligerence and lack of intelligence might anyway start a war, which due to his "greatness" might become the greatest war of all times. In such case, only cockroaches (which I hear are very resistant to radiation) might survive, and then, we can only hope that they will eventually develop a more "humane" culture. Forget it! I'll take everything back. I remember reading that cockroaches are no kind creatures either. So let's stick with what we have and only hope for humane family farming getting a bigger chunk out of the food economy.
And now I'll have vegetarian lunch (I really miss the meat) and console myself with ice cream for dessert, which, regrettably, comes from factory-farming. (The humanely produced cream I can obtain locally (and tried to use for making ice cream), unfortunately tastes "like cow" and also usually goes sour before I find time to use it. Sigh!