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The aim of this study was to evaluate different levels of feed restriction in the diet for F1 Holstein x Zebu cows during the winter on performance and economic viability. Data from Zootechnical book keeping, and from experiments conducted in the Experimental Field of Felixlândia, belonging to EPAMIG, were used. Total lactation of sixty F1 Holstein x Zebu cows receiving different diets was analyzed, by 2.00%, 2.25%, 2.50%, 2.75% body weight (BW), and a control group (3.4%; no feed restriction), allowing 5% leftovers in relation to the dry matter supplied, distributed in a completely randomized design. Data on milk production and feed cost were collected, evaluating the different periods that characterize the lactation of an animal. The highest milk production was found in the diet levels 3.4 %, and 2.75% BW, 3,636.00, and 3,271.50 kg, respectively. Lower milk production was observed at levels of 2.50%; 2.25%; 2.00% BW, respectively. The highest feed cost was verified without feed restriction followed by the levels of 2.75%, 2.50%, 2.25%, and 2.00% BW. The supply of the no feed restriction diet resulted in a performance superior to levels 2.75; 2.50; 2.25; 2.00% BW. The items profit, profitability were similar between all treatments, indicating that, when there is occasional feed shortage, a restriction in the diet supply of up to 2% BW provides economic security to the rural producer.

The Agricultural Research Company of Minas Gerais (EPAMIG) has developed a wheat cultivar, MGS Brilhante, which does not have an awn and adapts well to different regions of the state. Thus, it is being evaluated as an alternative for the production of silage in the offseason, so far proving to be quite promising. Thus, the objective of this work was to evaluate the productive response of the wheat cultivar MGS Brilhante submitted to different levels of nitrogen fertilization. The study was conducted in the Experimental Center of Vale do Piranga, of EPAMIG, in the municipality of Oratorios, Minas Gerais. Four levels of nitrogen fertilization as topdressing, in the form of agricultural urea, were tested: 50, 100, 150 and 200 kg N ha-1, in addition the control, without the covering fertilization. The design adopted was in randomized blocks, with five treatments and four replications per treatment, totaling 20 experimental plots. These plots were planted on May 10, 2022, re3ceived topdressing fertilization on June 15, 2022, and were harvested and evaluated for yield on August 1, 2022. Dry matter content, dry matter productivity, plant height and lodging rate were evaluated. All data were submitted to analysis of variance and were considered significant at 5% probability. The yield and plant height data were submitted to linear regression analysis. For the average dry matter content, analysis was performed based on the Tukey test. All statistical analyses were performed using the SISVAR 5.6 software. No lodging was observed in any experimental plot. There was a significant difference (P=0.015) in the dry matter contents between the treatment that did not receive any top dressing and the treatments that received doses of 150 and 200 kg N ha-1, and the control treatment had the highest dry matter content (31.42%, 26.75% and 26.55%, respectively). Regarding dry matter productivity and plant height, both variables showed high positive correlation coefficients with fertilizer doses (R²=86.95% and R²=98.21%, respectively). Average yields of 4.77, 6.00, 6.52, 6.54 and 7.10 tons DM ha-1 and average plant height were found of 1.15, 1.17, 1.22, 1.25 and 1.28 meters in the treatments with 0, 50, 100, 150 and 200 kg N ha-1, respectively. Nitrogen is a macronutrient that is used in the plants’ photosynthesis process and stimulates increased solar radiation absorption. This means that the greater supply of this nutrient to the plant leads to higher biomass production, because it stimulates the tillering of plants and also increases leaf area. This is the explanation for the increase in plant size and wheat crop productivity with higher doses of nitrogen. The higher dry matter content found in the control treatment, even with all the experimental plots having the same cultivation period, can be explained by the lower leaf area index produced, which caused the proportions of stems and ears, which have lower moisture content, to be higher in these plants. Based on the edaphoclimatic conditions of the region, wecan conclude that the MGS Brilhantecultivarresponds linearly in productivity with the increase in the nitrogen dose, but the cost-benefit ratio of the increment of these doses applied to the crop for silage production should be considered.

The Agricultural Research Company of Minas Gerais (EPAMIG) has developed a wheat cultivar, MGS Brilhante, which does not have an awn and adapts well to different regions of the state. Thus, it is being evaluated as an alternative for the production of silage in the offseason, so far proving to be quite promising. Thus, the objective of this work was to evaluate the productive response of the wheat cultivar MGS Brilhante submitted to different levels of nitrogen fertilization. The study was conducted in the Experimental Center of Vale do Piranga, of EPAMIG, in the municipality of Oratorios, Minas Gerais. Four levels of nitrogen fertilization as topdressing, in the form of agricultural urea, were tested: 50, 100, 150 and 200 kg N ha-1, in addition the control, without the covering fertilization. The design adopted was in randomized blocks, with five treatments and four replications per treatment, totaling 20 experimental plots. These plots were planted on May 10, 2022, re3ceived topdressing fertilization on June 15, 2022, and were harvested and evaluated for yield on August 1, 2022. Dry matter content, dry matter productivity, plant height and lodging rate were evaluated. All data were submitted to analysis of variance and were considered significant at 5% probability. The yield and plant height data were submitted to linear regression analysis. For the average dry matter content, analysis was performed based on the Tukey test. All statistical analyses were performed using the SISVAR 5.6 software. No lodging was observed in any experimental plot. There was a significant difference (P=0.015) in the dry matter contents between the treatment that did not receive any top dressing and the treatments that received doses of 150 and 200 kg N ha-1, and the control treatment had the highest dry matter content (31.42%, 26.75% and 26.55%, respectively). Regarding dry matter productivity and plant height, both variables showed high positive correlation coefficients with fertilizer doses (R²=86.95% and R²=98.21%, respectively). Average yields of 4.77, 6.00, 6.52, 6.54 and 7.10 tons DM ha-1 and average plant height were found of 1.15, 1.17, 1.22, 1.25 and 1.28 meters in the treatments with 0, 50, 100, 150 and 200 kg N ha-1, respectively. Nitrogen is a macronutrient that is used in the plants€™ photosynthesis process and stimulates increased solar radiation absorption. This means that the greater supply of this nutrient to the plant leads to higher biomass production, because it stimulates the tillering of plants and also increases leaf area. This is the explanation for the increase in plant size and wheat crop productivity with higher doses of nitrogen. The higher dry matter content found in the control treatment, even with all the experimental plots having the same cultivation period, can be explained by the lower leaf area index produced, which caused the proportions of stems and ears, which have lower moisture content, to be higher in these plants. Based on the edaphoclimatic conditions of the region, wecan conclude that the MGS Brilhantecultivarresponds linearly in productivity with the increase in the nitrogen dose, but the cost-benefit ratio of the increment of these doses applied to the crop for silage production should be considered.

The Agricultural Research Company of Minas Gerais (EPAMIG) has developed a wheat cultivar, MGS Brilhante, which does not have an awn and adapts well to different regions of the state. Thus, it is being evaluated as an alternative for the production of silage in the offseason, so far proving to be quite promising. Thus, the objective of this work was to evaluate the productive response of the wheat cultivar MGS Brilhante submitted to different levels of nitrogen fertilization. The study was conducted in the Experimental Center of Vale do Piranga, of EPAMIG, in the municipality of Oratorios, Minas Gerais. Four levels of nitrogen fertilization as topdressing, in the form of agricultural urea, were tested: 50, 100, 150 and 200 kg N ha-1, in addition the control, without the covering fertilization. The design adopted was in randomized blocks, with five treatments and four replications per treatment, totaling 20 experimental plots. These plots were planted on May 10, 2022, re3ceived topdressing fertilization on June 15, 2022, and were harvested and evaluated for yield on August 1, 2022. Dry matter content, dry matter productivity, plant height and lodging rate were evaluated. All data were submitted to analysis of variance and were considered significant at 5% probability. The yield and plant height data were submitted to linear regression analysis. For the average dry matter content, analysis was performed based on the Tukey test. All statistical analyses were performed using the SISVAR 5.6 software. No lodging was observed in any experimental plot. There was a significant difference (P=0.015) in the dry matter contents between the treatment that did not receive any top dressing and the treatments that received doses of 150 and 200 kg N ha-1, and the control treatment had the highest dry matter content (31.42%, 26.75% and 26.55%, respectively). Regarding dry matter productivity and plant height, both variables showed high positive correlation coefficients with fertilizer doses (R²=86.95% and R²=98.21%, respectively). Average yields of 4.77, 6.00, 6.52, 6.54 and 7.10 tons DM ha-1 and average plant height were found of 1.15, 1.17, 1.22, 1.25 and 1.28 meters in the treatments with 0, 50, 100, 150 and 200 kg N ha-1, respectively. Nitrogen is a macronutrient that is used in the plants’ photosynthesis process and stimulates increased solar radiation absorption. This means that the greater supply of this nutrient to the plant leads to higher biomass production, because it stimulates the tillering of plants and also increases leaf area. This is the explanation for the increase in plant size and wheat crop productivity with higher doses of nitrogen. The higher dry matter content found in the control treatment, even with all the experimental plots having the same cultivation period, can be explained by the lower leaf area index produced, which caused the proportions of stems and ears, which have lower moisture content, to be higher in these plants. Based on the edaphoclimatic conditions of the region, wecan conclude that the MGS Brilhantecultivarresponds linearly in productivity with the increase in the nitrogen dose, but the cost-benefit ratio of the increment of these doses applied to the crop for silage production should be considered.

The Agricultural Research Company of Minas Gerais (EPAMIG) has developed a wheat cultivar, MGS Brilhante, which does not have an awn and adapts well to different regions of the state. Thus, it is being evaluated as an alternative for the production of silage in the offseason, so far proving to be quite promising. Thus, the objective of this work was to evaluate the productive response of the wheat cultivar MGS Brilhante submitted to different levels of nitrogen fertilization. The study was conducted in the Experimental Center of Vale do Piranga, of EPAMIG, in the municipality of Oratorios, Minas Gerais. Four levels of nitrogen fertilization as topdressing, in the form of agricultural urea, were tested: 50, 100, 150 and 200 kg N ha-1, in addition the control, without the covering fertilization. The design adopted was in randomized blocks, with five treatments and four replications per treatment, totaling 20 experimental plots. These plots were planted on May 10, 2022, re3ceived topdressing fertilization on June 15, 2022, and were harvested and evaluated for yield on August 1, 2022. Dry matter content, dry matter productivity, plant height and lodging rate were evaluated. All data were submitted to analysis of variance and were considered significant at 5% probability. The yield and plant height data were submitted to linear regression analysis. For the average dry matter content, analysis was performed based on the Tukey test. All statistical analyses were performed using the SISVAR 5.6 software. No lodging was observed in any experimental plot. There was a significant difference (P=0.015) in the dry matter contents between the treatment that did not receive any top dressing and the treatments that received doses of 150 and 200 kg N ha-1, and the control treatment had the highest dry matter content (31.42%, 26.75% and 26.55%, respectively). Regarding dry matter productivity and plant height, both variables showed high positive correlation coefficients with fertilizer doses (R²=86.95% and R²=98.21%, respectively). Average yields of 4.77, 6.00, 6.52, 6.54 and 7.10 tons DM ha-1 and average plant height were found of 1.15, 1.17, 1.22, 1.25 and 1.28 meters in the treatments with 0, 50, 100, 150 and 200 kg N ha-1, respectively. Nitrogen is a macronutrient that is used in the plants€™ photosynthesis process and stimulates increased solar radiation absorption. This means that the greater supply of this nutrient to the plant leads to higher biomass production, because it stimulates the tillering of plants and also increases leaf area. This is the explanation for the increase in plant size and wheat crop productivity with higher doses of nitrogen. The higher dry matter content found in the control treatment, even with all the experimental plots having the same cultivation period, can be explained by the lower leaf area index produced, which caused the proportions of stems and ears, which have lower moisture content, to be higher in these plants. Based on the edaphoclimatic conditions of the region, wecan conclude that the MGS Brilhantecultivarresponds linearly in productivity with the increase in the nitrogen dose, but the cost-benefit ratio of the increment of these doses applied to the crop for silage production should be considered.

The Agricultural Research Company of Minas Gerais (EPAMIG) has developed a wheat cultivar, MGS Brilhante, which does not have an awn and adapts well to different regions of the state. Thus, it is being evaluated as an alternative for the production of silage in the offseason, so far proving to be quite promising. Thus, the objective of this work was to evaluate the productive response of the wheat cultivar MGS Brilhante submitted to different levels of nitrogen fertilization. The study was conducted in the Experimental Center of Vale do Piranga, of EPAMIG, in the municipality of Oratorios, Minas Gerais. Four levels of nitrogen fertilization as topdressing, in the form of agricultural urea, were tested: 50, 100, 150 and 200 kg N ha-1, in addition the control, without the covering fertilization. The design adopted was in randomized blocks, with five treatments and four replications per treatment, totaling 20 experimental plots. These plots were planted on May 10, 2022, re3ceived topdressing fertilization on June 15, 2022, and were harvested and evaluated for yield on August 1, 2022. Dry matter content, dry matter productivity, plant height and lodging rate were evaluated. All data were submitted to analysis of variance and were considered significant at 5% probability. The yield and plant height data were submitted to linear regression analysis. For the average dry matter content, analysis was performed based on the Tukey test. All statistical analyses were performed using the SISVAR 5.6 software. No lodging was observed in any experimental plot. There was a significant difference (P=0.015) in the dry matter contents between the treatment that did not receive any top dressing and the treatments that received doses of 150 and 200 kg N ha-1, and the control treatment had the highest dry matter content (31.42%, 26.75% and 26.55%, respectively). Regarding dry matter productivity and plant height, both variables showed high positive correlation coefficients with fertilizer doses (R²=86.95% and R²=98.21%, respectively). Average yields of 4.77, 6.00, 6.52, 6.54 and 7.10 tons DM ha-1 and average plant height were found of 1.15, 1.17, 1.22, 1.25 and 1.28 meters in the treatments with 0, 50, 100, 150 and 200 kg N ha-1, respectively. Nitrogen is a macronutrient that is used in the plants€™ photosynthesis process and stimulates increased solar radiation absorption. This means that the greater supply of this nutrient to the plant leads to higher biomass production, because it stimulates the tillering of plants and also increases leaf area. This is the explanation for the increase in plant size and wheat crop productivity with higher doses of nitrogen. The higher dry matter content found in the control treatment, even with all the experimental plots having the same cultivation period, can be explained by the lower leaf area index produced, which caused the proportions of stems and ears, which have lower moisture content, to be higher in these plants. Based on the edaphoclimatic conditions of the region, wecan conclude that the MGS Brilhantecultivarresponds linearly in productivity with the increase in the nitrogen dose, but the cost-benefit ratio of the increment of these doses applied to the crop for silage production should be considered.

his study aimed to evaluate the effect of different doses of nitrogen fertilization on the morphogenic, structural, productive and chemical composition of Urochloa decumbens (Stapf) R. D. Webster cv. Basilisk in a silvopastoral system with eucalyptus. The experimental treatments consisted of pastures of Basilisk cultivar, fertilized with 0, 100, 200, 300 and 400 kg ha-1 year-1 of N, and intercropped with eucalyptus, clone GG 100 (Eucalyptus grandis x E. urophylla). The experimental arrangement followed a randomized block design with four replicates. The evaluated characteristics were: foliar appearance rate, phyllochron, leaf length, leaf elongation rate, leaf life span, foliar senescence rate, number of green leaves per tiller, number of senescent leaves per tiller, daily dry matter accumulation, dry matter production, crude protein, and neutral detergent fiber. In the conditions of the established silvopastoral system, nitrogen fertilization did not influence (p > 0.05) the morphogenic and structural characteristics of Basilisk cultivar, except for height (p < 0.01) and leaf: stem ratio (p = 0.02). The nitrogen fertilization of the Brachiaria grass with eucalyptus in the proposed structural arrangement does not modify (p > 0.05) the morphogenic characteristics. However, in ration to dry matter production, doses of up to 400 kg of N ha-1 are recommended.

An experiment was carried out to assess rates and nitrogen fertilization strategies on the forage yield using irrigation to supply the water deficit during the dry season. The grasses Cynodon spp cv. tifton 85 and Brachiaria brizantha cv. Xaraés were cultivated with nitrogen (N) at levels of 200 and 400 kg/ha according to strategies: 1) half dose applied during the rainy season (RS) and half during the dry season (DS); 2) 1/3 during the RS and 2/3 during the DS; 3) 2/3 during the RS and 1/3 during the DS; 4) all doses applied during the DS. In each season the dose was divided in three applications. Eleven harvests were conducted: six in the RS and five in the DS. When 2/3 of N was applied in the DS, forage yield in this period was statistically equivalent to those obtained in the RS in three of the five harvests for both 200 and 400 kg/ha of N. With 100% of N applied in the DS, the yield of four of five cuts of forage was similar to that obtained in the RS for both rates of N. The strategy of applying more N in the DS rather than in the RS was effective, keeping the yield steadily throughout the year. The application of 100% of the dose of 200 kg/ha N and 2/3 of the dose of 400 kg/ha N both in the dry period, under irrigation, promote uniform productions per harvest throughout the year.

The present study aimed to estimate the basal temperature and thermal sum for the following tropical forage plants: Brachiaria decumbens, cultivar Basilisk; Brachiaria brizantha, cultivar Marandu; Brachiaria brizantha, cultivar Xaraes; Panicum maximum, cultivar Mombaça; Panicum maximum, cultivar Tanzania; and Cynodon spp, cultivar Tifton 85, in ten cutting seasons, under irrigation. The climatic data were collected in an automatic weather ministration installed in the experimental area and used for irrigation management. The relative development or regression equation method was used to calculate the basal temperature. The estimated basal temperature values were 15.4; 10.5; 14.2; 13.4; 12.4 and 15.1 ºC and the demands were of 2,088.1; 3,542.5; 2,486.5; 2,838.5; 2,701.7 and 2,134.5 degree days for cultivars Basilisk, Marandu, Mombaça, Tanzania, Xaraes and Tifton 85, respectively. The relative development method revealed linearity between plant development and room temperature. Basal temperature can help elaborate climatic zoning for forage species in Brazil and allow the selection of the best suited species for each region in Brazil.

The present study aimed to estimate the photosynthetically active radiation of tropical forage grasses in ten cutting dates, under irrigation. The following treatments were used: Brachiaria decumbens grass (Brachiaria decumbens cultivar Basilisk), Marandu grass (Brachiaria brizantha cultivar Marandu), Xaraes grass (Brachiaria brizantha, cultivar Xaraes), Mombaça grass (Panicum maximum cultivar Mombaça), Tanzania grass (Panicum maximum, cultivar Tanzania) and Tifton 85 grass (Cynodon spp cultivar Tifton 85). The weather parameters were collected by an automatic meteorological station installed in the location and used for irrigation management. The experiment was arranged in a split-plot completely randomized block design, considering the grasses as plots and cutting seasons as subplots, with four replications in a 6 × 10 factorial arrangement, six grasses and ten cutting seasons. The results indicated increased use of photosynthetically active radiation in the wet season, in relation to the dry-wet season transition. Basilisk presented the highest values of photosynthetically active radiation (1,648.9 mE). The variables studied were affected by photosynthetically active radiation. The grass cultivars presented different light interceptions. The values of 87; 90; 90; 88; 92 and 77% were found for grass cultivars Basilisk, Marandu, Mombaça, Tanzania, Xaraes and Tifton 85, respectively. Differences were observed in forage accumulation rates for the grass plants studied. The grasses with the best productive performance were Brachiaria decumbens cultivar Basilisk and B. brizantha cultivar Xaraes. The highest values of crude protein and neutral detergent fiber were observed for Tifton 85. The use of photosynthetically active radiation was different among the grasses evaluated. There is a positive association between photosynthetically active radiation and dry matter production. Besides, photosynthetically active radiation indirectly affects crude protein and forage neutral detergent fiber.

Objetivou-se com este trabalho avaliar a disponibilidade de forragem, a composição morfológica e química do pasto, a capacidade de suporte do pasto e a produção de leite de vacas em três gramíneas forrageiras sob lotação contínua e taxa variável em solo de várzea. O delineamento experimental foi inteiramente casualizado com três tratamentos e três repetições. Os tratamentos constituíram-se das gramíneas Paspalum atratum cv. Pojuca, Brachiaria humidicola cv. Llanero e capim-tangola, híbrido natural de Brachiaria arrecta e Brachiaria mutica. A taxa de lotação foi ajustada para manter a forragem disponível entre 2.000 e 3.000 kg de massa seca por hectare. O período avaliado foi de novembro de 2003 a maio 2004. Não houve diferença significativa entre as espécies quanto à disponibilidade de massa seca de forragem verde, com valor médio de 2.902 kg/ha. O capim-pojuca apresentou 62% de lâminas foliares e 38% de colmo + bainha na massa seca de forragem verde, seguido pelo capim-humidícola com 49 e 51% e o capim-tangola com 18 e 82%, respectivamente. O capim-tangola apresentou teor mais alto de proteína bruta na lâmina foliar (15,41%) que os capins humidícola (9,98%) e pojuca (8,74%) e menores de fibra (FDN e FDA). A produção individual das vacas refletiu o melhor valor alimentício do capim-tangola, cuja média diária (10,27 kg/vaca) foi maior que no capim-pojuca (7,80 kg/vaca) e semelhante ao obtido com capim-humidícola (9,16 kg/vaca). A produção de leite por área não foi afetada pela gramínea forrageira, com média de 27,8 kg/ha × dia-1, uma vez que a taxa de lotação um pouco mais alta no capim-pojuca, apesar de não apresentar diferença significativa, compensou a menor produção individual das vacas.The objective of this study was to evaluate the forage availability, pasture morphological and chemical composition, pasture carrying capacity and the milk production of cows on three forage grasses under continues stocking and the variable rate on lowland soil. The experimental design was completely randomized with three treatments and three replicates. The treatments were the Paspalum atratum cv Pojuca grass, Brachiaria humidicola cv Llanero grass and tangola grass (natural hybrid of Brachiaria arrecta and Brachiaria mutica). The stocking rate was adjusted to maintain the forage available between 2.000 and 3.000 kg dry matter per hectare. The period evaluated was from November 2003 to May 2004. There was no significant difference between the species when the dry matter availability of green forage was evaluated, with mean value of 2.902 kg/ha. The pojuca grass had 62% of leaf blade and 38% of stem + sheath in green forage dry mass, followed by humidícola grass with 49 and 51% and tangola grass with 18 and 22%, respectively. The tangola grass showed higher level of crude protein on the leaf blade (15.41%) than humidícola (9.98%) and pojuca (8.74%) grasses and lower levels of fiber (NDF and ADF). The individual production of cows was affected by the better nutritional value of the tangola grass. The average daily production of this grass was higher (10.27 kg/cow) than the pojuca grass (7.8 kg/cow) and had similar value to humidícola grass (9.16 kg/cow). The milk production per area, with had mean of 27.8 kg/ha × day-1, was not affected by the forage grasses because the more high stocking rate of pojuca grass, although not significant, compensated the lower individual production.

Objetivou-se avaliar o efeito da aplicação de fósforo na implantação de estilosantes Mineirão em consórcio com capim-xaraés. O experimento foi instalado em uma área de 8.000 m², dividida em 24 parcelas experimentais de 333,3 m². As doses de fósforo utilizadas no estabelecimento da pastagem foram 25, 50, 100 e 200 kg/ha de P2O5. As avaliações foram feitas aos 65 dias após a semeadura. Utilizou-se o delineamento em blocos casualizados com três repetições e duas repetições do tratamento dentro de cada bloco. As maiores taxas de aumento no comprimento da lâmina foliar e perfilhamento do capim-xaraés, comprimento de folíolo, largura de folíolo e altura do estilosantes Mineirão foram observadas com a aplicação de 25 a 50 kg/ha de P2O5. As maiores taxas de aumento na largura da lâmina foliar e altura de perfilho do capim-xaraés foram obtidas com aplicação de 25 a 100 kg/ha de P2O5. O número de plantas de estilosantes Mineirão foi maior com a aplicação de 44 kg/ha de P2O5 e reduziu de forma acentuada com o aumento da adubação fosfatada. A adubação fosfatada de estabelecimento de 44 kg/ha de P2O5 garante maior população inicial de plantas de estilosantes Mineirão em consórcio com o capim-xaraés. Todavia, mais estudos são necessários para se verificar o grau de compatibilidade entre as duas espécies e a viabilidade da consorciação. A aplicação de doses crescentes de fósforo em consórcio proporciona aumento nas taxas de acúmulo de matéria seca do capim-xaraés e de acúmulo de matéria seca total durante o primeiro período seco pós-estabelecimento da pastagem.The objective of this study was to evaluate the effect of the application of phosphorus on the establishment of Stylosanthes guianensis cv. Mineirão and Brachiaria brizantha cv. Xaraés mixed. The experiment was installed in an area of 8,000 m², divided into 24 plots of 333.3 m². The phosphorus doses utilized in the establishment of pasture were 25, 50, 100 and 200 kg/ha of P2O5. The evaluations were made 65 days after sowing. The experimental design was a randomized blocks design with three replications and the treatment with two replicates per block. The highest rates of increase in the length of the leaf blade and tillering of Xaraés grass, leaflet length, leaflet width and height of the legume occurred from 25 to 50 kg/ha of P2O5. The highest rates of increase in the width of the leaf blade and tiller height of Xaraés grass occurred from 25 to 100 kg/ha of P2O5. Number of plants of Mineirão stylo was higher with fertilization with 44 kg/ha of P2O5 and decreased drastically with phosphate. Phosphate fertilizers establishing 44 kg/ha P2O5 provide better establishment of the intercropped pasture. Nevertheless, further studies are required to determine the degree of compatibility between the two species and the viability of intercropping. Application of growing levels of phosphorus in an intercropping system provides increase in the rates of accumulation of dry matter of Xaraés grass and accumulation of total dry matter during the first dry period post-establishment of the pasture.

Este trabalho foi realizado com o objetivo de identificar estratégias eficazes de manejo do pastejo de Brachiaria decumbens cv. Basilisk, sob lotação contínua, com base em avaliações das suas características morfogênicas e estruturais. Duas estratégias de manejo do pastejo foram estudadas: em uma, o pasto foi mantido com 25 cm de altura média durante todo o período experimental e, na outra, foi mantido em 15 cm de altura média durante o inverno, com aumento para 25 cm a partir do início da primavera. Adotou-se o delineamento de blocos casualizados em esquema de parcelas subdivididas com quatro repetições. Consideraram-se, como fator primário, as estratégias de manejo do pastejo, caracterizadas pelas alturas médias dos pastos durante as estações do ano (inverno, primavera e verão), e, como fator secundário, as estações. O rebaixamento do pasto para 15 cm no inverno resultou em maior taxa de aparecimento foliar (0,02 folha/perfilho.dia) e maior número de folhas vivas (4,5 folhas por perfilho) no inverno, mas provocou redução, no inverno, da duração de vida da folha (66 dias), da taxa de senescência foliar (0,22 cm/perfilho.dia) e dos comprimentos da lâmina foliar (11 cm) e pseudocolmo (15,2 cm) em relação ao pasto com 25 cm. Nesta estação, foram menores os valores observados para as taxas de aparecimento foliar (0,06 folha/perfilho.dia), alongamento foliar (0,110 cm/perfilho.dia) e alongamento de pseudocolmo (0,008 cm/perfilho.dia), número de folha viva (2,9 folhas por perfilho) e comprimentos da lâmina foliar (8,6 cm) e do pseudocolmo (13,5 cm). Por outro lado, a duração de vida da folha (139 dias) e o número de folhas mortas (2,0 folhas por perfilho) foram maiores. O maior valor de taxa de senescência foliar ocorreu na primavera (0,40 cm/perfilho.dia). O pasto de B. decumbens cv. Basilisk sob lotação contínua pode ser manejado de forma sazonal, com rebaixamento para 15 cm no início do inverno e posterior aumento para 25 cm no início da primavera.This study was conducted to identify effective strategies for grazing managing of Brachiaria decumbens cv. Basilisk, under continuous stocking, based on assessments of their morphogenetic and structural characteristics. Two strategies of grazing management were studied: in one, the grass was maintained with 25-cm mean height throughout the experimental period, and in the other, it was 15 cm during the winter, rising to 25 cm from the beginning of spring. The split-plot in randomized block design with four replications was adopted. The strategies of grazing management responded to primary factor, characterized by average heights of pastures during the seasons (winter, spring and summer). The seasons corresponded to secondary factor and consisted of measures over the experimental period. Pasture's lowering to 15 cm in the winter resulted in higher leaf appearance rate (0.02 leaves/tiller.day) and higher number of live leaves (4.5 leaves/tiller) in the winter. However, this management strategy lowered leaf lifespan (66 days), leaf senescence rate (0.22 cm/tiller.day), and length of leaf lamina (11 cm) and stem (15.2 cm) in winter months, in relation to pasture with 25 cm. During this season, rates of leaf appearance (0.06 leaves/tiller.day), leaf elongation (0.110 cm/tiller.day) stem elongation (0.008 cm/tiller.day), live leaves (2.9 leaves/tiller), length of leaf lamina (8.6 cm) and stem (13.5 cm) lowered. On the other hand, leaf lifespan (139 days) and number of dead leaves (2.0 leaves/tiller) were higher. The highest leaf senescence rate occurred in the spring (0.40 cm/tiller.day). The B. decumbens cv. Basilisk pasture under continuous stocking can be managed on a seasonal basis, with decrease to 15 cm in early winter, and further increase to 25 cm in early spring.

Avaliaram-se os índices de crescimento taxa de crescimento relativo (TCR), taxa assimilatória líquida (TAL), razão de área foliar (RAF), índice de área foliar (IAF) e a interceptação luminosa do capim-elefante 'Napier' após pastejo. O trabalho consistiu de dois experimentos, com quatro tratamentos de adubação de N e K, em kg/ha (T1: 100 kg de N e 80 kg de K, T2: 200 kg de N e 160 kg de K, T3: 300 kg de N e 240 kg de K e T4: 400 kg de N e 320 kg de K), sendo um irrigado e outro sem irrigação, segundo o delineamento de blocos ao acaso com três repetições. A análise estatística observou um esquema de parcela subdividida, tendo nas parcelas as doses de N e K e nas sub-parcelas as idades de rebrotação após pastejo (2, 8, 15, 45 e 123 dias), para IAF e interceptação de luz. O IAF na área irrigada aumentou de 0,28 para 8,27, média dos quatro tratamentos de N e K, entre a menor e maior idade de rebrotação. Na área não irrigada, também ocorreu um aumento no IAF, embora de menor magnitude que na área irrigada, de 0,16 para 7,76. Os valores médios de TCR, TAL e RAF foram 0,0083 g/g.dia, 3,57 g/cm².dia e 0,0021 m²/g, respectivamente. A interceptação de luz aumentou com o aumento do IAF, estabilizando-se no 51,5º dia. Já a penetração de luz no interior do dossel diminuiu assintoticamente em função do IAF. O coeficiente de extinção variou de 0,29 na maior combinação de N e K, para 0,53 nas doses de 200 kg/ha de N e 160 kg/ha de K.The growth indexes were evaluated: relative to growth rate (RGR), net assimilation rate (NAR), leaf area ratio (LAR), leaf area index (LAI) and the luminous interception of the 'Napier' elephant grass after graze. The work consisted of two experiments for the study of four manuring treatments of N and K, in kg/ha (T1: 100 kg of N and 80 kg of K, T2: 200 kg of N and 160 kg of K, T3: 300 kg of N and 240 kg of K and T4: 400 kg of N and 320 kg of K), being an irrigated and other without irrigation, according to the randomized block desing, with three replicates. The statistical analysis was donne in outline of split plot, tends in the portions the doses of N and K, and in the sub-portions the regrowth ages after graze (2, 8, 15, 45 and 123 days) for LAI and interception of light. The LAI in the irrigated area increased from 0.28 to 8.27, average of the four treatments of N and K, between the smaller and larger regrowth ages. In the not irrigated area also was verified an increase in LAI, although in smaller magnitude that in the irrigated area, of 0.16 for 7.76. The medium values of RGR, NAR and LAR were 0.0083 g/g.day, 3.57 g/cm².day and 0.0021 m²/g, respectively. The light interception increased with the increase of the LAI, stabilizing in the 51.5th day. therefore, the light penetration inside the dossel reduced asymptotically in function of LAI. The extinction coefficient varied of 0.29 in the largest combination of N and K for 0.53 in the doses of 200 kg/ha of N and 160 kg/ha of K.

Objetivou-se avaliar a dinâmica do aparecimento, do alongamento e da senescência de folhas do capim-elefante ‘Napier’ após pastejo de uniformização. O trabalho consistiu de dois experimentos, para o estudo de quatro tratamentos de adubação (T1: 100 kg de N e 80 kg de K, T2: 200 kg de N e 160 kg de K, T3: 300 kg de N e 240 kg de K e T4: 400 kg de N e 320 kg de K), sendo um irrigado e outro sem irrigação, segundo o delineamento de blocos ao acaso com três repetições. As plantas da área irrigada atingiram um maior número de folhas verdes (5 folhas) em um menor intervalo de crescimento (51,5 dias) do que as plantas não irrigadas (4,3 folhas em 68 dias). As taxas médias de aparecimento foliar foram 0,14 e 0,07 folhas/dia para os perfilhos basilares e aéreos, respectivamente. Observou-se resposta linear e positiva entre acúmulo de graus-dia (GD) e o índice de Haun, estimando-se filocronos de 84,0 e 150,8 GD para os perfilhos basilares e aéreos, respectivamente, na área irrigada. Para a área não irrigada os valores foram de 105,4 GD para os perfilhos basilares e 173,3 GD para os perfilhos aéreos. A taxa de alongamento foliar nos perfilhos basilares variou com a adubação; seu maior valor foi de 11,6 cm/dia referente à combinação de 200 kg/ha de N e 160 kg/ha de K. As plantas da área irrigada apresentaram maior taxa de alongamento foliar (11,58 cm/dia) em relação às da área não irrigada (7,99 cm/dia). A irrigação resultou em maior senescência foliar em ambos os tipos de perfilhos.The objective of this study was evaluate the leaf appearance, extension and senescence rates in ‘Napier’ elephant grass after uniformized graze. The study consisted of two experiments, for the evaluate the effect of four manuring treatments (T1: 100 kg of N and 80 kg of K, T2: 200 kg of N and 160 kg of K, T3: 300 kg of N and 240 kg of K and T4: 400 kg of N and 320 kg of K), on the an irrigated and no irrigated area , in a randomized block desing, with three replicates. The plants of the irrigated area reached a larger number of green leaves (5 leaves) in a smaller growth interval (51.5 days) that the plants not irrigated (4.3 leaves in 68 days). The average leaf appearance rates were 0.14 and 0.07 leaf/day for the basal and aerial tillers, respectively. Linear and positive answer was observed among degrees-day (DD) accumulation and the index of Haun, being considered phyllochron of 84.0 and 150.8 DD for the basal and aerial tillers, respectively, in the irrigated area. For the area not irrigated the values were of 105.4 DD to the basal tillers and 173.3 DD for the aerial tillers. The leaf extension rate in the basal tillers varied with the manuring; his largest value was of 11.6 cm/day regarding the combination of 200 kg/ha of N and 160 kg/ha of K. The plants of irrigated area shown a larger leaf extension rate (11.58 cm/day) in relation to that of the area not irrigated (7.99 cm/day). The irrigation resulted in larger leaf senencence in both types of tillers.

Este trabalho foi realizado com o objetivo de determinar o efeito do fornecimento de suplementos sobre o desempenho de 40 tourinhos F1 Limousin X Nelore, em fase de terminação, inicialmente com 17 meses de idade e 367 kg de peso, em pastagem diferida de Brachiaria decumbens. Foram testados cinco tratamentos; em um deles os animais receberam apenas mistura mineral; nos outros quatro, os animais receberam concentrados constituídos por 1,49% de mistura mineral, 1,99% de uréia e diferentes proporções de milho quebrado, farelo de soja e farelo de trigo, com média de 24% de proteína bruta na matéria seca e diferentes teores de carboidratos não-fibrosos e de fibra em detergente neutro. Os concentrados foram fornecidos ad libitum em quantidades equivalentes, em matéria original, a 1% dos pesos dos animais. Utilizou-se delineamento inteiramente casualizado, com cinco tratamentos e oito repetições. Estudou-se, também, a influência de características do relvado sobre o GPD dos animais suplementados. Os resultados demonstraram que a terminação de bovinos para abate precoce, entre 22 e 24 meses de idade, em pastagens tropicais durante a época seca, é tecnicamente viável com a utilização de suplementos. Os animais suplementados apresentaram ganhos de peso (GPD) semelhantes entre si e superiores aos dos animais não-suplementados, em média, respectivamente, 915 e 104 g/dia. No mês de setembro, os animais não-suplementados perderam, em média, 292 g/dia. O GPD dos animais suplementados correlacionou-se linear e negativamente com disponibilidade de forragem morta e linear e positivamente com disponibilidade de forragem verde e com as seguintes razões: forragem verde/forragem morta, forragem verde/forragem disponível, folha verde/(caule verde + material morto) e folha verde/forragem disponível.The experiment was performed to determine the supplements effects in the animal performance of forty crossbred Limousin-Nelore young bulls, aging 17 months and 367 kg average live weight, in Brachiaria decumbens postponed pasture, and during the dry season. The animals were distributed in five treatments: T1, control, the animals received only mineral complex; and the others were constituted by 1.49% of mineral complex, 1.99% of urea, and cracked corn, soybean meal and wheat bran in different percentages. The treatments had 24% crude protein of the dry matter, and different non-fibrous carbohydrates (NFC) and neutral detergent fiber (NDF) contents. The concentrates were offered in amount equivalent to 1% of animal live weight on original matter basis. The experiment was analyzed in completely randomized design, with five treatments and eight replications. The influence of pasture characteristics over the supplemented animals performances were studied. The results showed that young bulls can be finished on tropical pastures during dry season using supplements. The animals with supplements exhibited similar average daily gains (ADG), but showed higher ADG than the control animals, respectively, 915 and 104 g/d. In September, the control animals loosed 292 g/d. ADG was linearly and negatively correlated with availability of dead forage dry matter, and it was linearly and positively correlated with availability of green forage dry matter, and availability of green forage dry matter/dead forage dry matter ratio, green forage dry matter/total forage dry matter ratio, green leaf dry matter/dead forage dry matter plus green stem dry matter ratio, and green leaf dry matter/total forage dry matter ratio.

Este trabalho foi realizado com o objetivo de estudar a influência de concentrados com diferentes teores de energia sobre consumo, digestibilidade aparente da matéria seca, pH e concentração de amônia do líquido ruminal em cinco tourinhos F1 Limousin-Nelore, com 18 meses e 286 kg de peso médio, fistulados no esôfago e rúmen. Os animais foram mantidos em pastagem de Brachiaria decumbens, durante a seca, e receberam apenas sal mineralizado, ou um dos tratamentos constituídos de 1,49% de mistura mineral completa, 1,99% uréia e diferentes proporções de milho quebrado, farelo de soja e farelo de trigo, com média de 24% de PB e diferentes teores de carboidratos não fibrosos e de fibra em detergente neutro. Os suplementos foram fornecidos em quantidades equivalentes, em matéria original, a 1% do peso vivo (PV). O consumo de matéria seca (CMS) dos animais suplementados, média de 2,05% do PV (84,5 g MS/kg PV0,75), foi 42% maior que o CMS dos animais não suplementados, média de 1,44% do PV (57,7 g MS/kg PV0,75). O fornecimento de concentrados elevou em 55,4% a digestibilidade da MS e em 60,4% a concentração de energia digestível na dieta. O pH do líquido ruminal foi linear e negativamente influenciado pelo tratamento mais rico em milho quebrado, e linear e positivamente influenciado (PThe experiment was carried out to determine the supplements effects in the voluntary intake, digestibility, rumen pH and ammonia content of five 18 months old and 286 kg of live weight Nelore-Limousin young bulls, that received rumen and esophageal fistula. The treatments were: control, the animals received only mineral complex; and the others four were constituted by 1,49% of mineral complex, 1,99% of urea, and cracked corn, soybean meal and wheat bran different percentages. The treatments had 24% average crude protein, and non-fibrous carbohydrates and neutral detergent fiber different contents, and were provided on original matter basis, in amount equivalent to 1% of the weight. The animals that were submitted to the supplementary treatments exhibited similar DM intake and digestibility, and showed higher DMI and digestibility than the control group. The average dry matter intakes (DMI) were 2.05% live weight (LW) (84.5 g DM/kg LW.75) and 1.44% LW (57.7 g DM/kg LW.75) for supplemented animals and non-supplemented animals, respectively. The supplementation increased 42% the DMI, 55.4% the dry matter digestibility and 60.4% the digestible energy content, in respect the non-supplemented animals diet. The ruminal fluid pH was influenced linear and positively by treatment with wheat bran amount, and linear and negatively by treatment with 75% cracked corn. The concentration of ruminal ammonia stayed above 5 mg of nitrogen/100 ml of ruminal fluid, except for control treatment.

Verificaram-se, durante o período seco, as composições químico-bromatológicas da forragem colhida em pastagem diferida de Brachiaria decumbens por dois métodos, forragem total (FT) e extrusa (EXT); as composições químico-bromatológicas; e as frações de proteína e carboidratos dos componentes folha verde (FV), caule verde (CV), folha seca (FS) e caule seco (CS). A FT apresentou proteína bruta (PB) inferior a 2,5%; a fibra em detergente neutro (FDN), superior a 78%; a lignina, superior a 8,7% na MS; e a digestibilidade in vitro da matéria seca (DIVMS), de 43,5%. A EXT apresentou maior DIVMS e maiores teores de PB, proteína insolúvel em detergente neutro e ácido, cinzas e fósforo e menores teores de fibras, carboidratos totais (CHT) e magnésio, quando comparado com FT. Verificaram-se maiores DIVMS e teores de PB, carboidratos não fibrosos (CNF), fósforo e potássio no componente FV e maiores teores de CHT e FDN nos componentes CV, FS e CS. Observaram-se altos valores da fração A da PB nos componentes FV e CV, baixos valores em FS e CS e altos valores da fração C da PB em CV, FS e CS. As concentrações das frações potencialmente digestíveis da PB, com exceção da fração B1, e de CNF, correlacionaram-se com o teor protéico nos componentes FV, CV, FS e CS. Em relação aos CHT, verificaram-se baixos valores de CNF e altos da fração C nos componentes CV, FS e CS.The chemical-bromatological characteristics of forage sampled for two methods, available herbage (AH) and extrusa (EXT), and green leaf (GL), green stem (GS), dead leaf (DL) and dead stem (DS) dry matter (DM) components were evaluated in the Signalgrass postponed pasture, during the dry season, from July to October 1997. Protein and carbohydrate fractions of the Cornell system were also evaluated. AH sampled was characterized as low quality, with low crude protein (CP) concentration (78% DM) and lignin (>8.7% DM) contents, and 43.7% in vitro dry matter digestibility (IVDMD). Higher IVDMD and higher contents of CP, neutral detergent and acid detergent insoluble proteins, ash and phosphorus and smaller contents of fibers, total carbohydrates (TC) and magnesium were observed in the EXT, when compared to AH. Higher IVDMD and higher contents of CP, non-fibrous carbohydrates (NFC), phosphorus (P) and potassium (K) were observed in the GL component and higher TC and NDF contents were observed in the GS, DL and DS components. High values of crude protein A fraction were observed in the GL and GS components, while low values were observed in the DL and DS components. High values of crude protein C fraction were also verified in the GS, DL and DS components. The potentially digestible CP fractions, except for B1 fraction, and NFC contents, were correlated with the CP contents in the forage components. Concerning the carbohydrates, low values of NFC (A+B1) and high values of C fraction were observed in the GS, DL and DS components.

Verificaram-se as disponibilidades de forragem total, forragem verde e morta e dos componentes folha verde, caule verde, folha seca e caule seco em pastagem diferida de Brachiaria decumbens. A pastagem foi vedada à entrada dos animais de dezembro de 1996 a junho de 1997 e avaliada, sob pastejo contínuo, durante a estação seca, nos meses de julho a outubro de 1997. Também foram estudadas correlações entre características do relvado e ganho de peso de tourinhos Limousin-Nelore com 19 meses e 374 kg de peso. O diferimento da pastagem de Brachiaria decumbens proporcionou disponibilidade média de forragem (DMST) de 7.568, forragem verde (DMSV) de 3.834 e morta (DMSM) de 3.734 kg de matéria seca (MS)/ha em julho, antes do período de pastejo. A utilização contínua da pastagem diferida durante o período seco, com lotação animal de 0,75 UA/ha, não afetou a DMST, média de 7.902, e DMSM, média de 4.637 kg/ha, mas afetou a DMSV e a disponibilidade de folhas verdes (DMSFV). A DMSV e a DMSFV apresentaram taxas crescentes em julho e outubro e diminuíram a taxas crescentes em agosto e setembro. No final de setembro, as pastagens apresentaram a menor DMSV, 2.540 kg/ha. A DMSFV e a proporção de folhas verdes no relvado foram maiores no início de agosto, respectivamente, 1.517 kg/ha e 18,5%, e menores no final de setembro, 480 kg/ha e 5,7%, respectivamente. O diferimento da pastagem permitiu a manutenção dos animais e apenas pequeno ganho de peso durante a seca, média de 104 g/dia. Em setembro, os animais nas pastagens perderam peso. O ganho de peso vivo médio diário correlacionou-se linear e negativamente com DMSM e linear e positivamente com as relações [DMSV/DMSM] e [DMSFV/(DMSM + DMSCV)], em que DMSCV é a disponibilidade de matéria seca de caule verde. Não foram verificadas correlações entre ganho de peso e as variáveis DMSV, DMSFV, pressão de pastejo e oferta diária de forragem.The availability of herbage, green herbage, dead herbage, green leaf, green stem, dead leaf and dead stem components was evaluated in the Signalgrass (Brachiaria decumbens) pasture during the dry season, and after postponement period, from July to October 1997. The pasture characteristics were correlated with the average daily weight gain (ADG) of crossbred Limousin-Nelore males, aging 19 months and 374 kg body weight on average, from July to September 1997. The average availability of herbage was 7.568 kg dry matter (DM)/hectare (AH), green herbage (AGH) 3,834 kg DM/ha, and dead herbage (ADH) 3,734, in early July, after the postponement period of the Signalgrass pasture. The continuous utilization during the dry period of the postponed pasture, and stocking rate .75 animal units, did not affect AH and ADH, respectively, 7,902 and 4,637 kg/ha on average; nevertheless, diminished the availability of green herbage and green leaf dry matter (AGL). The availability of green herbage and of green leaf component increased in July and October, and reduced at crescent rate from August to September. In late September, the average availability of green herbage reached least value, 2,540 kg DM/ha. The availability and proportion of green leaf component in total herbage were greatest in early August, respectively, 1,517 kg DM/ha and 18.5%, and were least in late September, respectively, 480 kg DM/ha and 5.7%. The tropical pasture postponement warranted the maintenance of the animals, and leaded at a minimum average daily gain (ADG) (104 g/d), during the dry season. In September, the animals loosed body weight. ADG was linearly and negatively correlated with availability of dead dry matter, and it was linearly and positively correlated with the availability of green dry matter/dead dry matter ratio and green leaf dry matter/dead dry matter plus green stem dry matter ratio. Had no correlation between the ADG and availability of green leaf, and between the ADG and availability of green herbage. ADG did not correlated with grazing pressure or with herbage availability.

A pesquisa foi conduzida na Fazenda Experimental da EPAMIG-Leopoldina, MG, onde foram avaliados o consumo de capim-elefante, a efetividade da limitação do tempo de pastejo a quatro horas diárias, para manter o consumo próximo à mantença e o ganho de peso de 36 novilhos ¾ Gir-Holandês, em cinco períodos sucessivos de 36 dias, na estação chuvosa. Os tratamentos foram: livre acesso ao pasto (pastejo irrestrito) e pastejo restrito. A disponibilidade de matéria verde seca do capim-elefante nos cinco períodos variou de 4,0 a 7,8 kg/100 kg PV. Os animais com livre acesso ao pasto consumiram o equivalente a 1,61 vezes o dos animais de pastejo restrito e tiveram ganho de peso de corpo vazio médio diário de 516,4 g, com um ganho estimado de 432,5 kg por hectare, estando dentro da faixa de ganho de peso verificada para capim-elefante no Brasil. O consumo de energia metabolizável por unidade de tamanho metabólico manteve-se estável nos três primeiros períodos, elevando-se nos dois últimos períodos, em que ocorreram os maiores ganhos de peso dos animais. Quatro horas diárias de pastejo garantiram consumo próximo à mantença.

O experimento foi realizado com o objetivo de avaliar o efeito da idade sobre o potencial de degradação dos diferentes tecidos da lâmina foliar e do colmo de capim-braquiária (Brachiaria decumbens), capim-gordura (Melinis minutiflora) e capim-tifton 85 (Cynodon sp). Foram amostradas a 7ª (capim-braquiária e capim-gordura) e a 11ª (capim-tifton 85) lâminas foliares, no dia da exposição da lígula e 20 dias após. Por meio de observações ao microscópio foram estimadas a extensão da digestão in vitro dos tecidos da lâmina e do colmo e a redução na espessura da parede de células do esclerênquima do colmo. Lâminas foliares e segmentos de colmos jovens apresentaram maiores áreas digeridas. Permaneceram intactos os tecidos com células de parede espessada e lignificada, a bainha parenquimática dos feixes, o esclerênquima, o xilema e a epiderme do colmo. Tecidos com células de parede delgada, normalmente não-lignificada, o mesofilo, o floema e o parênquima, desapareceram completamente. O avanço na idade reduziu a digestão do mesofilo, em lâminas de capim-braquiária e capim-gordura, e do parênquima em colmos, principalmente de capim-gordura. A epiderme na lâmina foliar foi parcialmente digerida, independentemente da idade e da espécie. Embora aparentemente intactas, células esclerenquimáticas do colmo sofreram redução da espessura da parede com a incubação em líquido ruminal. A porcentagem de redução variou de 7 a 37% e a taxa de redução da espessura de 0,007 a 0,018 µm/h.

Foram avaliados os efeitos da idade, do nível de inserção da folha no perfilho e da estação de crescimento (verão ou outono), sobre a proporção de tecidos e a espessura da parede celular em lâminas foliares e segmentos de colmo de capim-braquiária (Brachiaria decumbens), capim-gordura (Melinis minutiflora) e capim-tifton 85 (Cynodon sp). Lâminas foliares das posições inferior e superior do perfilho foram colhidas no dia da exposição da lígula e 20 dias após. Foram determinadas as proporções relativas de epiderme, xilema, floema, bainha parenquimática dos feixes, esclerênquima, parênquima no colmo e mesofilo na lâmina foliar. Foram medidas as espessuras das paredes dos vasos de metaxilema e do esclerênquima da lâmina e do colmo. A proporção de tecidos em lâminas foliares não foi alterada pela idade nem pela estação de crescimento, sendo a espessura da parede de células do esclerênquima da lâmina a única característica modificada pela idade. Lâminas do nível de inserção superior apresentaram mais elevadas proporções de esclerênquima, bainha parenquimática dos feixes e xilema e células do esclerênquima e do metaxilema com paredes mais espessas, enquanto as lâminas do nível de inserção inferior se destacaram por apresentar mais elevada proporção de mesofilo e paredes celulares mais delgadas. Enquanto a proporção de parênquima decresceu, a área relativa de esclerênquima e as espessuras das paredes celulares variaram diretamente com a idade do colmo e foram maiores, em geral, no verão.

Lâminas foliares e segmentos de colmo das gramíneas forrageiras capim-braquiária (Brachiaria decumbens), capim-gordura (Melinis minutiflora) e capim-bermuda Tifton 85 (Cynodon sp) foram analisados quanto aos teores de proteína bruta (PB), fibra em detergente neutro (FDN), fibra em detergente ácido (FDA), celulose, hemicelulose e lignina e aos coeficientes de digestibilidade in vitro da matéria seca (DIVMS), em duas estações de crescimento: verão e outono. As lâminas, amostradas no momento da exposição da lígula e 20 dias após, situavam-se nas posições inferior e superior do perfilho. Os segmentos de colmo avaliados foram os situados imediatamente abaixo da lâmina da posição superior. O colmo de capim-bermuda Tifton 85 apresentou 8,5 unidades percentuais a menos de FDA que os das outras duas gramíneas, que não diferiram entre si. Os teores médios de PB de lâminas foliares exibiram pequena variação entre as espécies e diminuíram de 18,8 para 14,6%, após 20 dias de expansão, e de 18,9 para 14,5%, entre as lâminas das posições inferior e superior do perfilho. Lâminas da posição superior apresentaram mais elevados teores de FDN e lignina, independente da espécie, da estação e da idade. Os coeficientes de DIVMS reduziram a partir do momento da expansão da lâmina foliar e foram maiores em lâminas situadas no nível inferior e colhidas no outono. Entre as espécies, a DIVMS não variou em lâminas recém-expandidas, mas foi mais elevada em capim-bermuda Tifton 85 e mais baixa em capim-braquiária em lâminas com 20 dias após completa expansão. A DIVMS do colmo foi mais baixa em capim-braquiária (56,9%) e mais elevada em capim-bermuda Tifton 85 (59,6%) e capim-gordura (60,5%), que não diferiram entre si.

Lâminas foliares e segmentos de colmo das gramíneas forrageiras capim-braquiária (Brachiaria decumbens), capim-gordura (Melinis minutiflora) e capim-bermuda Tifton 85 (Cynodon sp) foram amostradas em dois níveis de inserção no perfilho (inferior e superior), em duas idades (momento da exposição da lígula da folha e 20 dias após) e em duas estações de crescimento (verão e outono). Amostras dos segmentos de colmo e lâminas foliares foram submetidas à determinação de sua composição química, composição anatômica e digestibilidade in vitro. Após obtenção dos dados, foram estabelecidas as correlações entre os componentes químicos e anatômicos e entre estes e a DIVMS, na lâmina, no colmo e no agrupamento dos dados das duas frações. A espessura da parede celular foi a característica anatômica a se correlacionar mais fortemente com todos os componentes químicos, independente da fração considerada. Suas correlações foram positivas com os teores de fibra em detergente neutro, fibra em detergente ácido e lignina e negativa com os de proteína bruta. A proporção de mesofilo se correlacionou positivamente com os teores de proteína bruta e negativamente com os de fibra em detergente ácido, enquanto a proporção de esclerênquima apresentou correlação positiva com os teores de fibra em detergente neutro. Os componentes químicos se correlacionaram fortemente entre si e com a DIVMS. Entre as características anatômicas, somente a espessura da parede celular mostrou correlação significativa com a DIVMS, independente da fração. O mesofilo se correlacionou positivamente e o xilema negativamente com a DIVMS, respectivamente, na lâmina e no colmo.Leaf blades and stem segments at two stages of development (day of leaf ligule exposure and 20 days thereafter) and two insertion levels on tillers (lower and upper) of signalgrass (Brachiaria decumbens), molassesgrass (Melinis minutiflora) and tifton 85 bermudagrass (Cynodon sp), were sampled in two seasons of the year (summer and autumn). The anatomical and chemical traits, and in vitro dry matter digestibility of blades and stems segments were evaluated. The correlations among these variables were established to associated values observed in leaf blade and stem, and to each fraction. The cell wall thickness was the anatomical trait to exhibit the highest correlation with all the chemical components, being positive with neutral detergent fiber, acid detergent fiber and lignin contents and negative with crude protein content. The proportion of mesophyll correlated positively with crude protein and negatively with acid detergent fiber content, while the proportion of sclerenchyma showed positive correlation with neutral detergent fiber content. The chemical components showed strong correlation among themselves and with the IVDMD. From the anatomical traits, the cell wall thickness was the only one to exhibit a significant correlation with the IVDMD, independent of fraction. The IVDMD correlated positively with leaf blade mesophyll and negatively with stem xylem.

RESUMO - A proporção de tecidos, o grau de correlação linear desta característica com a digestibilidade in vitro da matéria seca (DIVMS) e sua composição química foram determinadas em seções transversais das frações botânicas, lâmina e bainha foliares e colmo, amostrados no topo e na base de perfilhos de capim-elefante (Pennisetum purpureum, cv. Mott), capim-setária (Setaria anceps, cv. kazungula) e capim-jaraguá (Hyparrhenia rufa). O capim-jaraguá, com maior proporção de bainha parenquimática dos feixes (BPF) na lâmina foliar e de tecido vascular lignificado (TVL) e esclerênquima (ESC) na lâmina e bainha foliares, apresentou proporção de tecidos menos compatível à de uma forrageira de alto valor nutritivo, em comparação ao capim-elefante e capim-setária. As lâminas foliares caracterizaram-se por apresentar alta proporção de epiderme e baixa proporção de ESC, TVL e células parenquimáticas (CPA) em relação à bainha foliar e ao colmo. A proporção de ESC mostrou correlação negativa com a DIVMS da lâmina foliar de topo, do colmo e do total das frações do perfilho. A proporção de CPA correlacionou positivamente com a DIVMS da bainha foliar, r = 0,68, enquanto a proporção de TVL apresentou correlação positiva com a DIVMS, quando todas as frações do perfilho foram consideradas, r = 0,31. As proporções de BPF, TVL e ESC correlacionaram positivamente com os teores de fibra em detergente neutro e fibra em detergente ácido das forrageiras, enquanto as proporções de mesofilo e epiderme apresentaram correlação negativa.ABSTRACT - The tissue proportions, the degree of simple linear correlation of this characteristics with the in vitro dry matter disappearance (IVDMD) and their chemical composition were determined in transversal sections of the botanical fractions, leaf blades and sheath and stem sampled from the top and bottom tillers of dwarf elefantgrass (Pennisetum purpureum, Schumach cv. Mott, setariagrass (Setaria anceps, Stapf ex Massey cv. Kazungula)) and jaraguagrass (Hyparrhenia rufa, Nees Stapf). The jaraguagrass, with high percentage of parenchyma bundle sheath (PBS) in its leaf blade and lignified vascular tissue (LVT) and sclerenchyma (SCL) in the leave blades and sheath, presented a less compatible proportion of tissues with a high nutritive forage value, as compared with dwarf elefantgrass and setariagrass. The leaf blades characterized by showing higher epidermis proportion, lower proportion of SCH, LVT and parenchymal cells (PCA) in relation to leaf sheath and stem. The proportion of SCH negatively correlated with IVDMD of the leaf blade from the top of the tiller, stem, and the total tiller fractions. The proportion of PCA positively correlated with IVDMD of the leaf sheath, r = 0,68, while the proportion of LVT presented a positive correlation with IVDMD, when all tiller fractions were considered, r = 0.31. The proportions PBS, LVT and SCH positively correlated with the neutral detergent fiber and acid detergent fiber content of the forages, while the proportions of mesophyll and epidermis showed a negative correlation.

RESUMO - Foi avaliado o grau de correlação linear simples entre a digestibilidade in vitro da matéria seca (DIVMS) e a composição química de lâminas e bainhas foliares e, do colmo, amostrados no topo e na base de perfilhos de capim-elefante (Pennisetum purpureum, cv. Mott), capim-setária (Setaria anceps, cv. Kazungula) e capim-jaraguá (Hyparrhenia rufa, Nees Stapf ). Os valores de DIVMS e os teores de proteína bruta (PB) e parede celular (FDN) exibiram gradiente ao longo do perfil do perfilho e diferença entre as frações do perfilho. As folhas situadas no topo do perfilho mostraram maior conteúdo de PB e digestibilidade, apesar dos mais altos teores de FDN, que as folhas situadas na base dos perfilhos. As lâminas foliares mostraram valores relativamente mais altos de DIVMS, PB e FDN que a bainha foliar. Nenhuma correlação foi observada entre os componentes químicos e a DIVMS da lâmina foliar do topo do perfilho. Apenas o teor de lignina apresentou correlação significativa (r = - 0,53) com a DIVMS, quando dados das lâminas foliares de topo e base do perfilho foram agrupados. Os teores de fibra em detergente neutro, fibra em detergente ácido, proteína bruta e lignina propiciaram correlações com a DIVMS da lâmina foliar de base, da bainha foliar e do colmo.

Este trabalho foi conduzido em Leopoldina-MG, com o objetivo de se avaliar os efeitos da combinação de doses de N e K na disponibilidade e composição química da forragem e da capacidade de suporte da pastagem de capim-elefante (Pennisetum purpureum Schum. cv. Napier) sob pastejo rotativo. Numa área de 4,5ha estudou-se a combinação fatorial de três doses de N (100, 200 e 400kg/ha/ano) e três doses de K2O (50, 100 e 200kg/ha/ano), durante 4 períodos chuvosos (1997/98 a 2000/01). O delineamento experimental utilizado foi o de blocos casualizados, com duas repetições espaciais. Não foi constatado efeito da adubação potássica sobre a produção vegetal, composição química da forragem e produção animal. Por outro lado, a disponibilidade de matéria seca total, matéria seca de lâmina foliar, matéria seca de colmo e teor de proteína bruta foram proporcionais às doses de N e variaram com os períodos chuvosos. A adubação nitrogenada aumentou a disponibilidade de MS total, de lâminas foliares e de colmo no capim-elefante, assim como contribui para elevar a taxa de lotação e os ganhos de peso por animal e por área.

Este trabalho foi conduzido em Leopoldina-MG, com o objetivo de se avaliar os efeitos da combinação de doses de N e K na disponibilidade e composição química da forragem e da capacidade de suporte da pastagem de capim-elefante (Pennisetum purpureum Schum. cv. Napier) sob pastejo rotativo. Numa área de 4,5ha estudou-se a combinação fatorial de três doses de N (100, 200 e 400kg/ha/ano) e três doses de K2O (50, 100 e 200kg/ha/ano), durante 4 períodos chuvosos (1997/98 a 2000/01). O delineamento experimental utilizado foi o de blocos casualizados, com duas repetições espaciais. Não foi constatado efeito da adubação potássica sobre a produção vegetal, composição química da forragem e produção animal. Por outro lado, a disponibilidade de matéria seca total, matéria seca de lâmina foliar, matéria seca de colmo e teor de proteína bruta foram proporcionais às doses de N e variaram com os períodos chuvosos. A adubação nitrogenada aumentou a disponibilidade de MS total, de lâminas foliares e de colmo no capim-elefante, assim como contribui para elevar a taxa de lotação e os ganhos de peso por animal e por área.

Este trabalho foi conduzido em Leopoldina-MG, com o objetivo de se avaliar os efeitos da combinação de doses de N e K na disponibilidade e composição química da forragem e da capacidade de suporte da pastagem de capim-elefante (Pennisetum purpureum Schum. cv. Napier) sob pastejo rotativo. Numa área de 4,5ha estudou-se a combinação fatorial de três doses de N (100, 200 e 400kg/ha/ano) e três doses de K2O (50, 100 e 200kg/ha/ano), durante 4 períodos chuvosos (1997/98 a 2000/01). O delineamento experimental utilizado foi o de blocos casualizados, com duas repetições espaciais. Não foi constatado efeito da adubação potássica sobre a produção vegetal, composição química da forragem e produção animal. Por outro lado, a disponibilidade de matéria seca total, matéria seca de lâmina foliar, matéria seca de colmo e teor de proteína bruta foram proporcionais às doses de N e variaram com os períodos chuvosos. A adubação nitrogenada aumentou a disponibilidade de MS total, de lâminas foliares e de colmo no capim-elefante, assim como contribui para elevar a taxa de lotação e os ganhos de peso por animal e por área.

The use of optical sensors to identify the nutritional needs of agricultural crops has been the subject of several studies using precision agriculture techniques. In this work, we sought to overcome the lack of research evaluating the use of these techniques in the management of nitrogen (N) fertilizer in pastures. We evaluated the methodology of the nitrogen sufficiency index (NSI) in N management at variable rates (VR) using a portable chlorophyll meter. In addition, the use of color vegetation indices generated from a digital camera was evaluated as a low-cost alternative. The work was conducted in four management cycles at different times of year, evaluating the productivity and quality of Brachiaria brizantha cv. Xaraés grass. Three NSIs (0.85, 0.90 and 0.95) were evaluated, applying complementary doses of N according to the response of monitored plots using a chlorophyll meter and comparing the productivity and leaf N content of these treatments to the reference treatment (TREF), which received a single dose of N (150 kg ha-1). Together with these treatments, plots without N application (control) were analyzed, totaling five treatments with six replications in a completely randomized design. The dry mass productivity and N leaf concentration of the VR treatments were statistically equal to TREF in all management cycles (P < 0.05). Most color vegetation indices correlated significantly (P < 0.05) to the chlorophyll readings. The use of NSI methodology in pastures allows the same productivity gains, with significant input savings. In addition, the use of digital cameras presents itself as a viable alternative to monitoring the N status in pastures.