Guinea pig food should be served in a flat-bottomed bowl. Scattered loose on the grass or floor of the hutch is not a good idea, as it quickly spoils. Any spilled food should be cleared away on a daily basis.
The exception to this rule is when hiding food as treats, for the GPs to hunt down and sniff out. This is a great source of mental stimulation for them, but if done too often it may attract unwanted mice and rats.
Guinea pigs need a special bowl to eat from - such as the ones includes with the Eglu hutch
An ideal guinea pig stainless steel food bowl is supplied with the Eglu Go Guinea Pig Hutch. Other suitable vessels can be purchased from your local pet store. The dish should be flat-bottomed, shallow and quite weighty, to make it hard to tip over. Guinea pigs like to climb inside their bowls when eating. Shallow, weighty bowls prevent this enthusiasm from turning the whole thing over and spilling the food.