TSI (%DM) stands for Total Soluble Index percentage of Dry Matter or Total Sugars Index as a percent of Dry Matter. It is a measure of the soluble carbohydrates present in a feed or forage sample, expressed as a percentage of the dry matter in the sample. TSI (%DM) is used as an indicator of the fermentability of a feed, with higher TSI (%DM) values indicating that a feed is more easily fermentable and can provide more energy to livestock during digestion. TSI (%DM) is calculated based on analysis of various components of the forage. In the United States, some labs that offer TSI testing include Cumberland Valley Analytical Services and Dairyland Laboratories. Contact you lab directly to confirm testing capabilities and pricing.