Production and bromatologic composition of Tanzania grass (Panicum maximum) at different regrowth ages

Abstract

The effect of different regrowth ages on the production and nutritional value of grass Tanzania were evaluated in ecological conditions of the coastal plains of Piauí. The experimental design was a randomized complete block with five replications, with treatments consisting of five ages of regrowth (7, 14, 21, 28 and 35 days), making a total of twenty-five plots or experimental units of 6 m2 each. The evaluations were two experimental periods, the first of 02/09/2008 to 16/12/2008 and the second from 01/09/2009 to 15/12/2009. In both periods the nutritional values were evaluated in three cuts, 10 cm of soil, with an interval of 35 days, in the five ages of regrowth. The experimental area received the fertilization of 340 kg ha-1 N and 252 kg K2O ha-1 in the first year and 420 kg ha-1 N and 336 kg K2O ha-1 in the second year, plus 70 kg ha-1 P2O5 in the foundation. Irrigation was applied through a sprinkler system, low pressure and low flow. The dry matter yield increased proportionally with age of regrowth reached a value of 5.7 t ha-1 in 35 days. The dry matter content increases with age of regrowth, ranging from 15.64% to 20.14% from 7 to 35 days. The crude protein content showed an opposite behavior, decreasing linearly from 17.0 to 7.8% from 7 to 35 days. The neutral detergent fiber content also linearly, reaching the critical limit of less than 60% from 24 to 28 days of regrowth and the acid detergent fiber content, using a quadratic behavior estimated values close to 35% by the age of 28 days. Considering together the critical limits for crude protein, neutral detergent fiber and acid detergent fiber, and an appropriate value for the dry matter content is recommended for the grass-Tanzania, in the ecological conditions of the coastal plains of Piauí, observe a rest period between 21 and 28 days.