Cannot imagine Purina causing such issues.
Rather than just speculate widely about such things, I prefer to read, study and digest the research. It is plentiful. In a nutshell, there are two main issues with reproductive failures in high wire layers. First, they are bred for this. The envelope has been pushed to an extreme and there is always a backlash in nature when you do these things. The poultry genetics corporations have pushed these birds to extremes in the last 50 years. Note the CX commercial broiler. Well, the same kind of research and selective breeding has produced these layers.
Secondly, they get pushed to early point of lay. Whenever someone gets excited that their 15 or 16 week old RSL is laying, I wince, quite frankly. A BYCer would be much better to slow down the pullet's growth rate, ihmo. Yes, I've kept these birds for years. Slow it all down is a better way to go. These birds are pushed with 15 or 16 hours of artificial lighting and never given down times, even by BYCers. Push, push. Again, nature pushes back. The layers spit out enormous, brown eggs. Scary big. Is that a good thing? Hmmmmm. It is what it is. That's what these birds do.
The old line breeds are also not immune. They too have been pushed by the hatcheries into becoming production type fowl. Their true bred, heritage counterparts are incredibly slower to feather, develop, reach point of lay at 30 weeks, not 18 weeks and rarely lay at the same rate as the hatchery bred birds that bear the same name.
Blame Purina? I doubt it. BTW, I'm no Purina fanboy, if that helps.
