[Monica]

You misunderstand the directions... When switching to Harrison's, they recommend feeding the High Potency pellets first, for 6 months (doesn't matter the age of the bird), before switching them to a Lifetime (or other type) formula.

You can feed them, but if you were to speak with someone from Harrison's they'd recommend to feed the High Potency first.... here's some information from their website...

Why should birds all birds start out on the High Potency formulas?

ANSWER: Most all birds undergoing diet changes are malnourished from their previous diets. All the body's systems have been somewhat compromised. To heal this as fast as possible we use High Potency. It promotes a healthy molt the quickest. The sooner the bird has recovered from malnourishment, the less likely the chances of other illnesses.

Mind you, I don't exactly agree with their view on diet...