-This study was carried out to evaluate the nutritive value of elephant grass (Pennisetum purpureum, Schum.) silages with the addition of 0, 4, 8, 12 and 16% dehydrated mango (Mangifera indica, L.) by-product (DMB), on the fresh matter basis. A randomized complete design with four replications was used. As experimental silos, 210L plastic drums were used. Dry matter (DM), organic matter (OM), crude protein (CP), neutral detergent fiber (NDF), acid detergent fiber (ADF), hemicellulose (HCEL), ether extract (EE), total carbohydrates (TC), non-fibrous carbohydrates (NFC), neutral detergent insoluble nitrogen (NDIN, % total N), acid detergent insoluble nitrogen (ADIN, % total N), pH values, ammoniacal nitrogen (% total N), lactic acid, acetic acid, butyric acid and propionic acid levels were determined. The DM, OM, CP, EE, NFC, NDIN, lactic acid and propionic acid levels increased with the DMB addition while the NDF, ADF, hemicellulose, N-NH 3 /ammoniacal nitrogen levels and the pH values decreased with the DMB addition. The addition of DMB had a quadratic effect on the acetic and butyric acid levels but there was no effect with the addition of DMB on TC and ADIN. The DMB can be used at the ensiling of the elephant grass, because the addition of 8.6% improves the silages fermentative process. However, these silages have low crude protein levels and high contents of ether extract and nitrogen compounds mixed with the fiber (NDIN and ADIN) in the silages, that may damage their use by animals.

Avaliou-se os efeitos de diferentes lâminas de irrigação e doses de nitrogênio (N) sobre as características morfogênicas e estruturais do capim-Marandu (Brachiaria brizantha cv. Marandu). O estudo foi conduzido na área experimental da EMBRAPA Meio-Norte, em Parnaíba, Piauí, Brasil. Em delineamento em blocos casualizado, esquema fatorial 2 x 4, foram testadas lâminas de irrigação (equivalente a reposição de 50% e 80% da Evaporação do Tanque Classe “A”) x doses de nitrogênio (16,7; 33,3; 50,0 e66,7 kg de N/corte), com três repetições. Os cortes foram realizados a cada 30 dias, totalizando quatro cortes. A redução da lâmina de irrigação proporcionou decréscimos nas taxas de alongamento da folha, aparecimento de folha, comprimento final da folha e número de folhas vivas, enquanto que a taxa de senescência aumentou. A adubação nitrogenada incrementou as taxas de alongamento e aparecimento de folha, e o comprimento final da folha, no entanto, provocou redução do número de folhas vivas e a ampliação da taxa de senescência.

The sustainability of animal production on pasture is based on improving the management of forage species used, which ensures increase in animal productivity, pasture perenniality and cost reduction. The objective was to characterize productive, structural, physiological and normalized difference vegetation index (NDVI) responses of Brachiaria decumbens Stapf 'Basilisk' over the flexibilization of the grazing management adopted. Four defoliation combinations were evaluated, which consisted of the arrangement of two (85% and 95%) light interceptions (LI) and two (1.3 and 1.8) residual leaf area indexes (RLAI), as parameters of entry and exit of the animals from the pasture, respectively. Higher total forage biomass was observed (TFB, kg DM ha -1 ) 18.82%, when the canopy was managed at the lowest defoliation frequencies (95% LI), but with a higher morphological composition of the stem component and dead material. The 95% LI produced an extra layer of leaves than the canopy managed at 85% LI. The physiological variables were affected by the higher frequency of defoliation (85% LI), with lower photosynthetic rates. NDVI was higher in the canopy managed in the pre-grazing condition at 95% LI (0.88) and residual condition at 1.8 RLAI (0.49), when compared to 85% LI (0.86) and 1.3 RLAI (0.44). For greater production per animal, managing at 85% LI × 1.8 RLAI with pre-grazing and residual NDVI of 0.85 and 0.49, respectively, is the most suitable while for greater animal production per area, managing at 95% LI × 1.3 RLAI with pre-grazing and residual NDVI of 0.88 and 0.44, respectively, becomes more efficient.