Best conversion time is going to depend on your birds. Typically it would be pushing 14 weeks and you have the advantage of tossing them on the grill. Some breeds/lines are really putting on weight at that time so 16 weeks might be a better conversion rate time. If you're already at 5 months I'd probably wait a few more weeks. There is usually a last bit of growth spurt in ending around 6 months. After that it's another year of very slow growth to full adult size with stew to show for it. There is absolutely no conversion rate gain waiting much past 6 months.
With a bird consuming almost 1/3 pound of feed a day and feed averaging $16 a bag you're spending 75 cents per week to grow that bird. Sounds like a pittance. But if we look at what it costs to grow a bird from 4 months to 6 months that's $6 dollars. You'd be fortunate if they gained 2 lbs in that time meaning you are paying $3 per pound minimum of gain when you keep birds past 16 weeks.
Hatchery birds don't grow large, different breeds and lines have different growth rates, times of rapid gain. I grow breeder stock and can say my Plymouth Rock would be most economical butchering just before 14 weeks. The up side of that is they are tender enough to cook any method you want. Now that I have breeder stock Wyandotte I'm thinking they are still in rapid growth at that time and probably would benefit to let most of them go to 16 or even 18 weeks. Cull a few for grilling then let the others age into fryer as it would be economical to do so. I'd have to study them more and nobody in this house but me will eat the birds so I'm nowhere exacting on the Wyandotte.
Getting to know growth characteristics of the birds you have (varies by breed and source of birds) and paying attention to how you'll be able to cook those birds will be your deciding factors of butcher time. Most people have the mind set that a bird is not ready until it nears the size of a grocery store bird. Don't get me wrong, a bigger roasted bird is nice but it's also the least economical time to butcher. For those getting to roaster age you know are invited to dinner don't send their invitation late.
With a bird consuming almost 1/3 pound of feed a day and feed averaging $16 a bag you're spending 75 cents per week to grow that bird. Sounds like a pittance. But if we look at what it costs to grow a bird from 4 months to 6 months that's $6 dollars. You'd be fortunate if they gained 2 lbs in that time meaning you are paying $3 per pound minimum of gain when you keep birds past 16 weeks.
Hatchery birds don't grow large, different breeds and lines have different growth rates, times of rapid gain. I grow breeder stock and can say my Plymouth Rock would be most economical butchering just before 14 weeks. The up side of that is they are tender enough to cook any method you want. Now that I have breeder stock Wyandotte I'm thinking they are still in rapid growth at that time and probably would benefit to let most of them go to 16 or even 18 weeks. Cull a few for grilling then let the others age into fryer as it would be economical to do so. I'd have to study them more and nobody in this house but me will eat the birds so I'm nowhere exacting on the Wyandotte.
Getting to know growth characteristics of the birds you have (varies by breed and source of birds) and paying attention to how you'll be able to cook those birds will be your deciding factors of butcher time. Most people have the mind set that a bird is not ready until it nears the size of a grocery store bird. Don't get me wrong, a bigger roasted bird is nice but it's also the least economical time to butcher. For those getting to roaster age you know are invited to dinner don't send their invitation late.
