Oaten is an ideal food for rabbits and guinea pigs due to it high fibre content. Perfect as a long-term feed option. Grass hay, such as Peckish Small Animal Oaten Hay should make up approximately 75% of your small animal’s diet. As your rabbit or guinea pig grazes on the hay, they are benefitting their dental health as chewing wears down their growing teeth and keeps them physically and mentally stimulated.