This study evaluated the biomass flow of massai grass in regrowth subjected to different nitrogen levels (control - no fertilization; 400; 800; and 1200 N kg ha-1year-1) and under rotational stocking with sheep, in a completely randomized design with repeated measures over time. The leaf elongation rate increased with increasing nitrogen levels (N) and the fourth grazing cycle presented a lower value compared with the others. The stem elongation rate responded linearly with increasing levels of N, but it was not influenced by grazing cycles. The senescence rate of leaves remaining before grazing and after grazing were not influenced by the nitrogen fertilization or amended with successive grazing cycles. The phyllochron was influenced only by the nitrogen fertilization, with a decreasing linear response with nitrogen levels. Quadratic response was observed for the average length of leaves with increasing N levels and the grazing cycle 4 presented the lowest value for this variable. For each kilogram N ha-1 year-1, increases of 0.161 and 0.1604 kg ha-1 day-1 were verified in the herbage growth and accumulation rates, respectively. Nitrogen fertilization favors the biomass flow of massai grass, promoting an expressive increase in the production and accumulation of forage.

A ovinocaprinocultura possui elevada importância socioeconômica no Nordeste, entretanto, o baixo potencial genético dos rebanhos, associado à escassez de pastos na estação seca, condiciona baixos índices de produtividade e rentabilidade. A formação de pastagem cultivada é uma forma de nivelar a capacidade de suporte durante o ano. O trabalho proposto objetiva aumentar a produtividade, expandir a renda e incentivar o produtor a investir em novas técnicas produtivas. Foram utilizados 100 ovinos mestiços (Santa Inês x SRD) e empregados três períodos de descanso do pasto: tratamento 1 - tempo para formação de 1,5 folha por perfilho em média; tratamento 2 - tempo para formação de 2,5 folhas, e tratamento 3 - tempo para formação de 3,5 folhas. A análise foi feita com base em 1,3 e 5 hectares com utilização de cerca de tela e elétrica. Foram utilizadas como medidas de eficiência: relação benefício custo, valor presente líquido, taxa interna de retorno, e análise de sensibilidade. O tratamento com 2,5 folhas com exploração de no mínimo 5 hectares apresentou o melhor resultado econômico, biológico e ambiental. Para que haja retorno econômico há necessidade de utilização de animais de ótimo potencial genético e de se explorar áreas superiores a 5 hectares.

The breeding of ovine and caprine possess high partner-economic importance in the Northeast, however, the low genetic potential of the herds, as well as the scarcity of pastures during the dry season, limits the productivity and lucrativeness indices to a low level. The use of cultivated pastures is a way to maintain in high level the carrying capacity of the pasture over the year. This work was conducted with the aim of increase the productivity, expand the income and stimulate the producer to invest in new productive techniques. 100 Sem Raça Definida sheep and three periods were used. The rest period consisted of: treatment 1 - time for expansion of 1.5 new leaves per tiller; treatment 2 - time for expansion of 2.5 new leaves per tiller and treatment 3 - time for expansion of 3.5 new leaves per tiller. The analysis considered the use of 1, 3 or 5 hectares of pasture, fenced by campestre screen or electric fence. The efficiency indices adopted were: benefit cost relation, liquid present value, return internal tax, and sensitivity analysis. The 2.5 leaves rest period exploring at least 5.0 hectares presented best performance, in terms economics, biological and environmental. So, to promote economic return, it is necessary to use sheep of higher genetic potential and pastures areas above 5.0 hectares.