I agree with Tom, power feeding is bad. Infact Christian Elowsky, chairman of the American Tarantula Society suggested over-feeding is the biggest issue concerning tarantula. That was the joint decision of a number of arachnologists and there's a good basis for such a statement.
Tarantula are opportunistic feeders. They don't eat til they're full, they eat when the food is available, and that amount of food is usually dictated by the seasons. The rains arrive, the plants grow, the bugs eat the plants. But when the winter or dry periods arrive food is scarce and naturally all animals will eat less. With tarantula the opportunistic feeding covers it for those leaner times. The Chilean Rose (G. rosea) is a prime example. During the winter months frosts and snow on the ground means it will go into an almost hibernating state, but the food it ate during the summer months carry it through this period quite easily. Infact, those who have tried to emulate this cold period, without food, have had better success with breeding.
There are reports that suggest animals do better with an occassional fast from food. They are more healthy and live longer.
There are also reports that suggest that animals power fed have a shorter life, males have a lower sperm count, and possible links to moulting problems.
In my opinion there are 2 periods when power feeding is acceptable. As slings to get them to the less fragile stages as juveniles. And, as gravid females when an increase in food will help to create the eggs and tied the mother over the period looking after the sac.
