Características estruturais e valor nutritivo de Brachiaria brizantha cv. Piatã em diferentes idades e alturas de corte

Abstract

The study was conducted in greenhouse at the Center for Experiment Stations to the Center Agricultural sciences, the UNIOESTE - Campus Marechal Cândido Rondon, in Oxisoil, with evaluate the structural and quality of Brachiaria brizantha cv. Piatã in different ages and heights of cut. The experimental design was a randomized block in factorial arrangement of 4x4 (21, 28, 35 and 42 days regrowth and 5, 10, 15 and 20 cm cutting height), with triplicates. The experiment was installed in January 2009, being conducted by October of the same year. The structural characteristics and production were assessed at the time of the cuts and the composition was determined in the material sampled by when felled. The effects of age of regrowth and cutting heights were compared by analysis regression and the sections were compared using the test Tukey a 5% probability. The highest density of tillers culminated with a higher proportion of leaves in relation to the rods obtained from the fourth cut. Increased issue of tillers with the passage of the cuts generated tiller less vigorous, less height, length and thickness of the pseudostem. For leaf / stem significance was found between the variables, the greater respect leaf / stem was obtained at the age of 35 days from the which possibly had a higher rate of senescence leaves, reducing leaf / stem. At the time of sward there was significance between the interactions; The unfolding of the interaction time and age showed a quadratic positive at 5 cm and linear negative at 10, 15 and 20 cm high in interaction between age and height of cutting was observed quadratic positive the first cut, quadratic negative to the second cut and a positive linear for the fourth cut. For plant height was interaction between cutting height and the number of court where the maximum height observed in this interaction occurred at 10 cm cutting the first cut, which was obtained when 42 cm plant height. The length of stem decreased as the ages of regrowth in relation to cutoffs, where the largest length was obtained to 21 days for the first cut. Was no effect significant interactions of age and height of regrowth cut, regrowth age and time of cutting and cutting and cutting for the variable thickness of stem, generating higher thicknesses in frequent cutting and advanced age. Between nutritional characteristics resulted in higher production dry matter for the second cut in the age 28 and 35 days of growth at 5 and 10 cm cutting height. In levels of mineral matter observed significant differences between interactions height and age, age and height and cutting and cutting; can be observed variation between the levels. Also reported an increase in the FDN in the highest 10 and 15 cm and a decrease in content in the highest 5 and 20 cm. To the ADF was observed between the variables fall studied, with lower production at 42 days, with 20 cm cutting height and the fourth cut. The protein were significantly influenced by interactions age and height, age and height and cut and cut, there higher levels at 21 days of age, between 5 and 10 cm cutting height and the first cut. The ages and heights cutting influence on the structural and nutrition, suggesting that the correct management of Brachiaria brizantha cv. Piatã can be beneficial to increase animal performance and improve the quality nutrition of pastures