I have been breeding ASF rats for about six years now, and use them as just an additional food source to the mice and rats that I also breed for the snakes. Some of the snakes will go from eating mice to eating rat weaners, some won't - so I use ASF rats as an intermediary, and eventually onto rats.
I feed a 50/50 mix of rabbit food and wild bird seed, supplemented with a 'stir fry' and salad mix once per week.
Feeders are around the 60 - 70 gramme mark when fed to the snakes, with ex-breeders reaching 120 - 130 grammes.