Something to think about....

[Gizabelle]

With something as rapidly producing as chickens, yes you want the most resilient birds to reproduce. But then the caveat of "purpose" in modern times comes into play. If you're breeding for specific breed traits, then it doesn't matter how robust that extra bym rooster may be, you can't use him. I think it all comes down to intent. If your intentions are to make money or keep pets, then you do the best you can with what you've got, and make breeding and vaccination decisions accordingly.
You will likely not end up with birds that are as resilient as landrace breeds developed solely through natural selection, but that's the price you pay for throwing human intent into the mix.

 

[Gizabelle]

One other thing to consider is global commerce today is light-years beyond where it was 100 years ago. With increased movement between countries and across oceans, diseases that may have been just a regional problem a century ago are now everywhere. So 100 years ago farmers may have had only one or two major diseases to concern themselves with. Now... well, there are far more.
Bottom line: vaccines play an important role in protecting pets and financial investments in livestock.

 

[TheOddOneOut]

 

[TheOddOneOut]

It’s true that the Mareks vaccine can be redundant. But if you have a pet flock, don’t you want them to stay alive? Or if it was your dog. You want them to get all their shots so they don’t suffer from traumatic illnesses. But I understand your point of the whole “survival of the fittest.”
It all depends on perspective.

 

[Weeg]

It’s true that the Mareks vaccine can be redundant. But if you have a pet flock, don’t you do any them to stay alive? Or if it was your dog. You want them to get all their shots so they don’t suffer from traumatic illnesses. But I understand your point of the whole “survival of the fittest.”
It all depends on perspective.

Agreed 100%. I would do the same for my pet flock. I am doing the same. Its just another way to look at it.