This work aims to evaluate the enzymatic system defense of forages exposed to low temperatures. The forage plants alfalfa, sorghum, black oat, marandu grass, pearl millet, mombasa grass, and Bermuda grass were subjected to temperatures of 0.2; -0.9; -1.8; -2.7; -4.1; -4.6 and -6.2 oC for 1 h in a growth chamber in a completely randomized design with six replicates for each species. From the crude leaf extracts were evaluated the enzymes ascorbate peroxidase (APX), catalase (CAT), and superoxide dismutase (SOD) activities. Regression analyses compared the treatments. The biochemical responses of forage species to cold stress are different. The enzymes APX and SOD would play an important role in the response to oxidative stress in the forage species black oat and mombasa grass. In marandu grass and sorghum, SOD was the main cell protector. Pearl millet had a positive stimulus in CAT production, Bermudagrass increases the protein content and SOD activity, and alfalfa increases the protein content and APX activity.
