'豆腐', by itself, contains plant hormones. As far as reproductive behaviour is concerned, the plant hormones in the '豆腐' has lesser effect than the parrot's own animal hormones. Hence, when a parrot eats the '豆腐' and obtains the plant hormones, the parrot's body mistreats the plant hormones as its own animal hormones and, by regulating its own hormone production mechanism, the parrot's body produces lesser amount of its own animal hormones. As a result, the parrot produces smaller amount of its own hormones and therefore its reproductive behaviour becomes less. As noted earlier, the plant hormones has lesser effect on reproductive behaviour, it will not worsen the the parrot's reproductive behaviour as long as the parrot does not eat too much '豆腐'. Of course, if the parrot eats too much '豆腐', the parrot will obtain too much plant hormones, which will then give rise to the same effect as the parrot's own animal hormones.
Thanks JoeLee very much for the detailed explanation. I am sorry that I didn't write it clearly and caused some misunderstanding here.
In my previous thread I explained that I mistaken "吃豆腐" with its second meaning. and with this second meaning, parrot (projecting this from human, just for fun) should get aroused and its courtship ritual should be encouraged.
Anyways, thanks a lot for the info. I've learnt something new today!