Feeding my dog

[MAiton]

Currently I'm feeding my 9 month old Saint Bernard Multi-Menu large breed dog food but after some more in depth reading I'm considering switching to Orijen. Just by looking at the ingredients, I can tell there's quite a difference. The protein from one to the other is 24%(MM) to 40%(Or). Now, I was once told that with a large breed dog, if fed a lower protein %, it would make them grow slower with less risk to joint problems. I imagine there's some truth to it but how much? If that were a concern with Orijen, would I just feed my dog smaller amounts? If not a concern or even a farce I would like some more info.

Thanks,
Mike