Protein and weight gain

[OHSpartan]

I know most places commend 18-20% protein for Cornish cross meat birds. Would feeding 22-25% cause them to grow faster or would the extra protein just pass through in the poo? Lets say I could put them in a support to keep them from breaking their legs and could keep them from having a heart attack would a diet of 28%,game bird starter cause them to grow higher in less time. (Note I don't advocate unethical treatment, I'm trying to understand nutrition and physiology).



Conversely if I planned to raise them for several weeks to a finish dressed weight of 12-15 lbs could I feed them layer pellets to slow their growth and strengthen their bones in anticipation of a 16-20 week life span?

 

[AgroUrica]

I know most places commend 18-20% protein for Cornish cross meat birds. Would feeding 22-25% cause them to grow faster or would the extra protein just pass through in the poo? Lets say I could put them in a support to keep them from breaking their legs and could keep them from having a heart attack would a diet of 28%,game bird starter cause them to grow higher in less time. (Note I don't advocate unethical treatment, I'm trying to understand nutrition and physiology).



Conversely if I planned to raise them for several weeks to a finish dressed weight of 12-15 lbs could I feed them layer pellets to slow their growth and strengthen their bones in anticipation of a 16-20 week life span?

I'm no expert with these birds though I have now raised a few hundred. From what I understand, that 18-20% protein diet is what the birds are bred for. They're also bred to generally reach a slaughter weight of 6-8 lbs in about 6 to 8 weeks. Can't say I've ever heard of one reaching 12 - 15 lbs though I'm sure it's possible. I'd think shear stress on the heart and other organs would probably be too much for the average Cornish X.

 

[OHSpartan]

I bred two CX's last year that made it almost 20 weeks. After I dressed them, the combined weight was 25 lbs.

Now, these birds were allowed to free range very early. When the rest of the flock met mr plucky at 8 weeks, they were only 5 lbs (live weight). They were the two most active in the flock and lived on layer pellets after 8 weeks. Our layers even taught them to roost. I kept expecting them to break their legs when they got up in the morning but they never did.

we watched them closely and would have taken them if they showed signs of distress.

While not cost effective, I'd like to try this again and was wondering if layer pellets would help them grow slower with better bone. Likewise, if I get part of my flock that isn't growing fast enough, I wondered if a protein boost would help juice them a bit. Or...would it just be expensive poo.