I come at this question from a non commercial perspective.
My limited reading and listening has indicated to me that nutrients/toxins in the meat are closely tied to the diet eaten a few weeks up to slaughter.
So claim that grass fed beef, finished on corn, loses most of the benefits of grass fed.
For personal use, what would be the outcome of feeding conventional until say 12 weeks and finishing on organic?
Can anyone point me to resources on this topic for chickens and I’d love to hear personal opinions or experiences.
The outcome would be that your chicken meant would be more expensive than if you didn't finish it on organic. Organic / Not Organic is not necessarily better - or worse - from a nutritional standpoint, but you can bet that the mix of ingredients necessary to make an organic feed substantially identical, nutritionally, to a non-organic feed WILL change. Certain amino acids are extremely hard to provide in quantity by way of organic feeding. Fortunately for your question, the need for those high quantity (as % of total diet) amino acids drop as the bird ages, so its less critical than it could be.
the mention of "toxins" presumes:
A) that a given toxin is present in your non-organic feed
B) that the toxin survives a chicken's digestive system, rather than being broken down into safer components
C) that the toxin moves unchanged into the chicken, rather than being excreted
D) that the toxin is concentrated in a part of the chicken you eat (if you don't eat liver and kidneys, you eliminate concentrations of numerous chemicals, some of which are both life
CRITICAL *and* concerning in high quantity. Many trace metals fall into this category.)
So, step away from the generic, and talk specifics. Otherwise, its just fear mongering. Yes, SOME things a chicken eats can concentrate in the meat, much as mercury concentrates in certain fish species - but if those things aren't present in your feed, and they aren't present in your grounds, they aren't a cause for concern. Even if they are present, the dosage is the poison - how concerning the chemical is depends on concentration, frequency of consumption, expected remaining lifespan.
Note that, for many of these chemicals, "organic" says nothing about their presence or absence.