Identify a single lot of hay to sample. Lots must be from the same cutting, variety, field, stage of maturity and all must be harvested within 48 hours. Do not mix lots, and a lot should not exceed 200 tons. Choose a good, sharp coring device. The cutting edge should be sharp.
Dull probes cause material to be pushed out of the core, altering the composition of the sample.
Do not use an auger or corkscrew-type device which selectively samples leaves. Sample at random. Walk around the entire stack and sample bales at various heights. Do not bias the sample by avoiding some bales or choosing others. Take enough cores.