SUMMARY This study aimed to evaluate the agronomic, structural traits and chemical composition of andropogon grass subjected to different defoliation intensities and rest periods. Two defoliation intensities (15 and 30 cm) and four rest periods (25; 35, 45 and 55 days) were evaluated in a factorial completely randomized design, with four replications. The rest period promoted a linear decreasing effect (P <0.05) on the dry biomass of leaf blades in the two defoliation intensities. The dry biomass of stems showed an increasing linear effect (P <0.05) according to the rest periods in the two defoliation intensities. Production was recorded at 2427.71; 2907.39; 3325.72 and 3749.45 kg ha−1 for the periods of 25; 35; 45 and 55 days, respectively. The dry matter content showed an increasing linear effect (P <0.05) as a function of the rest periods evaluated in the two defoliation intensities. The rest period indicated a decreasing linear trend (P <0.05) for the crude protein content in the two defoliation intensities. A decrease of 0.9 and 0.7 g kg−1 was verified for each day of the rest period. For each additional day in the rest period, there was an increase of 1.2 and 1.5 g kg−1 DM in the neutral detergent fiber content at intensities of 15 and 30 cm. The andropogon grass pasture managed with a 25-day rest period and defoliation intensity of 30 cm showed high leaf/stem ratio and good nutritional value.

SUMMARY This study aimed to evaluate the chemical composition and in situ degradation dry matter of maize straw ammoniated with urea. This was a completely randomized design with five levels of ammoniation (0; 2; 4; 6 and 8% dry matter), with five repetitions. There was effect (P<0.05) of the ammoniation process on the retention of nitrogen in maize straw. For each 1% utilization of urea, we observed a reduction of 1.57% nitrogen retention. The dry matter content was not influenced (P>0.05) by the ammoniation; straw presented a mean value of 75%. In turn, the crude protein content increased (P<0.05) with ammoniation, increasing from 2.74% in the straw without treatment to 10 and 11% with the levels of 6 and 8% urea, respectively. For each 1% urea used, we found a reduction (P<0.05) of 0.65% in the neutral detergent fiber content of maize straw. The acid detergent fiber presented effect (P<0.05) in response to ammoniation. The technique provided a reduction of 0.69% acid detergent fiber for each 1% urea used. For dry matter degradation, we observed an increase in the soluble fraction up to the level of 6% urea. The ammoniation process favored the increase in the dry matter degradation rate of maize straw. It is recommended to conduct the ammoniation process in maize straw with 6% urea.

The objective of this study was to evaluate the morphogenic and structural characteristics, and demographic patterns of Andropogon gayanus subjected to different cutting frequencies and intensities. A completely randomized design was adopted in a 3 × 2 factorial arrangement, corresponding to three cutting heights (50, 70, and 90 cm), and two cutting intensities (50 and 70%) with four repetitions, totaling 24 plots of 7.50 × 6.25 m. For morphogenesis, there was no interaction effect (P ≤ 0.05) of treatments on stem elongation rate, leaf appearance rate, and phyllochron rate. The highest rate of leaf elongation was observed at a height of 90 cm and cut intensity of 50%, with 1.69 and 0.84 cm tiller-1 d-1 of leaf elongation at heights of 50 and 70 cm, respectively. For forage production, there was no interaction (p > 0.05) between cutting intensity and cutting height. When the pasture was managed to a cutting height of 90 cm, there was a greater increase in dry leaf mass, stalk dry mass, dead forage dry mass, and total dry forage mass, which was 50.89% and 53.29% higher than pasture heights of 50 and 70 cm, respectively. There was no interaction between factors on demographic characteristics (p > 0.05). A cutting height of 70 cm with a cutting intensity of 50% is recommended when handling this grass.

he aim of this study was to evaluate fermentation and chemical characteristics and the in situ degradability of sorghum silages enriched with dried Leucaena. The experiment was conducted as completely randomized design with four treatments (0 - control silage, silage without leucaena; 10.0, 20.0, or 30.0% inclusion of Leucaena) and five replicates, totaling 20 experimental units. The inclusion levels of leucaena influenced (P 0.05), with all silages having values above 90%. Gas loss decreased (P < 0.05) as the level of leucine increased in sorghum silage. A linear increase was observed for dry matter (P ? 0.0001) and crude protein (P = 0.0008) contents in response to Leucaena inclusion. There was a linear (P < 0.05) linear effect on neutral detergent fiber, hemicellulose and acid detergent fiber. As leucaena inclusion levels increased, for each 1% inclusion a reduction of 0.179 was observed; 0.059 and 0.119% for the values of neutral detergent fiber, hemicellulose and acid detergent fiber respectively. The inclusion of leucaena influenced (P < 0.05) the increase of silage lignin levels, probably due to the higher lignin content of the legume. The soluble fraction (a) of the silages increased along with the Leucaena inclusion levels, with highest values observed at the inclusion of 20 and 30% of the legume, respectively. Potential degradation (A) increased linearly with the levels of Leucaena added to the silage; the highest value for this variable was observed at 30% inclusion. Effective degradability (ED) increased up to the inclusion level of 20% (46.77%). Degradation rate (c) decreased markedly with the use of 30% Leucaena. The use of the forage part of Leucaena dried for three hours leads to reduced gas production, increased dry matter and crude protein contents, and decreased fiber contents. The degradability of dry matter increases up to the inclusion level of 20%.

The intercropping of corn and grass allows for the production of grains, and simultaneously, the recuperation and renovation of pastures. This study aimed to evaluate the effects of N doses on the yield, structure, chemical-bromatological characteristics, and the N use efficiency of Brachiara brizantha cultivars in an integrated crop-livestock system. The experimental design was completely randomized, with four replications, in a slip-plot scheme. The plots were formed of two grass plants, Marandu and Paiaguás, intercropped with corn and subplots composed of nitrogen doses (70, 100, and 130 kg N ha-1). During the system’s establishment (1st cycle), the Paiaguás grass presented higher values for all morphogenic and structural characteristics and higher forage yield when compared to Marandu grass. After the corn harvest, the interaction effect of the N doses and the cultivars for the foliar structure emergence and the number of living leaves was observed. The variables foliar elongation rate, stem elongation rate, and phyllochron were not influenced by any of the investigated factors (P>0.05). The highest DM content was obtained with the application of 100 kg ha-1 of N, whereas, for the other chemical characteristics, there was only an effect among the cultivars. Paiaguás grass exhibited the highest levels of NDF, ADF, lignin, and MM. CP levels were not influenced by the factors studied. Marandu grass and the use of 70 kg N ha-1 are recommended for intercropping with corn