The most commonly used and accessible is wheat straw. Most pet stores and farmers co-op stores, stock wheat straw. Choose good quality straw, there should be no odours or mouldy growth. It is important to chop it as finely as possible, the optimum is an average particle size of 10mm. We have seen multiple ways of chopping straw from brushcutters to upside down lawnmowers. If doing on a small-scale people often cut by hand. Once chopped as finely as possible, bag it ready for pasteurization.