Both variability and sample size can be reduced by using a core sampler. Core samplers usually have sharpened or serrated tips. Keep tips sharp to cut through hay to prevent selective sampling. Many core samplers can be operated with an electric drill or a hand brace. Run the drill at slow speeds.
High speeds heat the probe and can damage samples.
Square or round bales. Collect one sample from each bale by coring straight in from the center of the end of square bales and from the wrapped circumference of round bales. When sampling hay to be fed on your farm, avoid sampling decayed or moldy hay or other portions of hay that will be discarded or would likely be refused when fed to animals free choice. However, include deteriorated materials if the hay will be ground, sold or purchased in order to best describe all the hay. Place the entire sample into a plastic bag and seal tightly.