Effect of cutting height of plants on dry matter yield and on bromatologic characteristics of corn forage

This work was conducted with the purpose of evaluating dry matter yield and the chemical nutritive composition of forage of corn cultivars submitted to cutting heights of the plants (height 1 - 0,1 m, and height 2 - 0,8 m) in three growing years. The experiments were set up in an experimental area of the Agriculture Department of the Federal University of Lavras (UFLA) in the agricultural crops of 1998/1999, 1999/2000 and 2000/2001, where five corn cultivars were utilized in the first year and six corn cultivars in the following years. The experiments were conducted in the randomized block design in a 5 x 2 and 6 x 2 factorial scheme, where as five and six corn cultivars and two cutting height, with three replications. The characteristics of dry matter yield (DMY), crude protein (CP), neutral detergent fiber (NDF) and acid detergent fiber (ADF) were evaluated. A significant effect was found for cutting heights in all characteristics evaluated. Crude protein contents increased and NDF and ADF contents decreased with the increase of the cutting height of the plants. Comparing the two cutting heights, it was found that there was a reduction in yield of 3.3 ton. ha(-1) for DMY, an increase of 0.6% in crude protein content, a reduction of 4.4% in the percent of NDF and a decrease of 3.9% in the percent of ADF. The results obtained allowed to conclude that the elevation of the cutting height, although had contributed to the decrease of dry matter yield provided, an improvement in forage quality, due to the most fibrous and least digestible part of the corn plant have not been harvested.