The effects of cutting frequency of guinea grass (Panicum maximum Jacq.) at 30, 45, 60, and 75 days, on the dry matter production, digestibility and mineral contents.

Young Guinea grass plants were transplanted to a soil of the series "Luiz de Queiroz", belonging to Terra Roxa Estruturada (Alfisol) group at Piracicaba, SP, Brasil. On the forthcoming day after planting, each plant received by dressing 2.4 g N (ammonium sulphate), 3.2 g P2O5 (normal superphosphate) and 1.9 g K(2)0 (potassium chloride). The plants were cut at the height of 10 cm from the ground and divided into leaves and stems. The dry matter contents were obtained at 609C. Digestibility was determined in vivo by the nylon bag technique. The mineral contents were determined by conventional laboratory methods for N, P, K, Ca, Mg, S, Cu, Mn, and Zn. The experimental designed was randomised blocs with three replications. CONCLUSIONS Dry matter production The relation steii/Leaf was altered by the aging of the plant. The dry matter contents were higher in the stems than in the leaves. A linear positive relation was observed between dry matter production and age of the plants. Digestibility This decreases with aging of the grass. No differences among leaves and stems were observed. Minerals The concentration of N, P, Cu and Zn decreased with aging of the grass. Concentrations of K, Ca, Mg, S and Mn were not affecred by aging of the grass. Animal nutrition The minimum mineral nutrient requiriments for large animals were not affected by cutting frequency of the grass.Mudas de capim colonião (Panicum maximum Jacq.) foram transplantadas para uma Terra Roxa Estruturada, serie "Luiz de Queiroz", em Piracicaba, SP, e adubadas na razão de 2,5 g de N (sulfato de amônio), 3,2 g de P2O5 (superfosfato simples) e 1,9 g de K2O (cloreto de potássio) por muda. Cortes foram efetuados aos 35, 45, 60 e 75 dias a 15 cm de altura do solo. No material coletado foram separadas hastes e folhas e determinado o peso da matéria seca, o coeficiente de digestibilidade in vitro e as concentrações de N, P, K, Ca, Mg, S, Cu, Fe, Mn e Zn. O delineamento estatístico foi de blocos ao aca so, com três repetições. Concluíram os autores: 1. a relação haste/folha varia com o envelhecimento da planta. A produção de matéria seca e maior nas hastes do que nas folhas. Há uma relação linear positiva entre o aumento de peso da matéria seca e a idade da planta; 2. o coeficiente de digestibilidade da matéria seca diminui com a idade da planta, não havendo diferenças entre haste e folha; 3. a concentração de N, P, Cu, Fe e Zn diminui com o aumento da idade da planta; 4. a idade da planta não afeta os teores mínimos exigidos pelo animal