Avaliação da produção e da qualidade do capim Panicum maximum cv. Massai

EVALUATION OF PRODUCTION AND QUALITY OF PANICUM MAXIMUM CV. MASSAI GRASS Rômulo Rocha Caldeira 1 , Clayton Quirino Mendes 1 1 School of Agronomy and Veterinary Medicine – University of Brasilia, DF. The objective of this trial was to evaluate the production and quality of the grass Panicum maximum cv Massai harvested at different cutting ages (21, 38, 35, 42 and 49 days) in four periods of growth. Were evaluated the production, chemical composition, in vitro dry matter digestibility and the percentage of tillers survivors. The average dry matter production was 1.87 ton DM/ha, which was higher in the growth period 1 (2.58 ton DM/ha). There was an increasing linear behavior for the production of dry matter with the advance in cutting age, being higher from 42 days. The cutting age of 21 days showed lower production of DM, whereas the ages of 28 and 35 days were equal and intermediate. The dry matter content was lower for periods of growth: 1 and 4, intermediate for 3 and higher for the 2 period. There was no change on the crude protein, ash, lignin and total carbohydrates in response to periods of growth or harvest ages. An effect of cutting age and interaction between growth period and cutting age for the total digestible nutrients (TDN) (P<0,01), which average value of 48.9% and decreasing linearly for all periods of growth in dates of the cuts evaluated. The TDN value was higher in the growth period 1 compared to the 3 and 4 periods. As for cutting ages TDN value reduced with cutting age increase, being higher for cuts in 21 and 28 days, intermediate for 35 and lower for 42 days and 49 days. A decreasing linear effect was verified with cutting age advance for in vitro dry matter digestibility (R2 = 0.859) and for non-fiber carbohydrate contents (CNF, R2=0,981). The highest CNF values were observed for growth periods 1 and 2 in relation to the 3 and 4. Forage harvested at 21 and 28 days showed higher CNF content compared to other evaluated ages, with the lowest value obtained for the cut time of 49 days. At 49 days old the massai grass showed higher percentage of apical meristems survivors compared to 21 and 35 days. Was observed also higher amount of apical meristems survived for 3 and 4 growth periods (P<0,01). The best combination among production and quality is achieved with 21 or 28 days of the cutting age in situations with high temperature and radiation. Key-words: chemical composition, in vitro digestibility, forage, apical meristems