Frações proteicas do capim-mombaça submetido a doses de nitrogênio em duas alturas de corte

The protein fractions of mombaca grass submitted to four nitrogen doses (0, 100, 300, and 500kg.ha-1) at two cutting heights in dry and rainy periods were characterized and identified. A completely randomized block design, in 2x4 factorial scheme with four repetitions, was used. The crude protein (CP) and A, B1, B2, B3, and C protein fractions of mombaca grass cut at 0.20 and 0.40m were evaluated by the Cornell Net Carbohydrate and Protein System. There was significant difference (P<0.05) for CP according to the nitrogen (N) dose. The CP percentage increased as the N dose increased, in rainy period, averaging around 10%. There was difference for CP in function of season and cutting heights. The B1 and C fractions did not significantly differ concerning N dose and cutting heights. The A + B1 fractions were higher in the dry period in both heights (P<0.05). The N dose and cutting heights influenced in protein fractions composition.