-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 -1 year -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.

Resumo -Objetivou-se com esse estudo avaliar trocas gasosas e índices de crescimento no capim-braquiária manejado sob cinco lâminas de irrigação (3,84; 4,39; 6,19; 8,62 e 10,46 mm dia -1 ) e quatro idades, num delineamento inteiramente casualizado em arranjo de parcelas subdivididas, sendo as lâminas de irrigação estudadas nas parcelas e as idades (10, 17, 24 e 31 dias) nas subparcelas, com quatro repetições. Constatou-se interação entre lâminas de irrigação e idades nas variáveis: transpiração foliar, temperatura da folha, taxa de fotossíntese e razão de peso foliar. Verificou-se resposta quadrática com ponto de mínimo para a concentração interna de CO 2 e área foliar específica (0,0055 m² de folha g -1 de folha) em função do avanço nas idades. A concentração interna de CO 2 apresentou valores estimados em 220,09 e 176,20 ppm aos 10 e 31 dias de crescimento, respectivamente, com valor mínimo (173,68 ppm) aos 27 dias. Verificou-se resposta quadrática com ponto de máximo (25,04 g m -2 de folha dia -1 ) para a taxa de assimilação líquida com o aumento nas idades. Observou-se resposta linear decrescente para taxa de crescimento relativo e razão de área foliar com aumento nas idades. A taxa de crescimento relativo revelou valores de 0,097 e 0,048 g g -1 dia -1 , com 10 e 31 dias de crescimento, respectivamente. As idades de crescimento proporcionam mudanças nas trocas gasosas e nos índices de crescimento do capim-braquiária, porém, tais variáveis são pouco influenciadas pelas lâminas de irrigação nas condições do presente estudo.Palavras-chave -Taxa de assimilação líquida. Taxa de crescimento relativo. Taxa de fotossíntese foliar. Transpiração foliar. Temperatura da folha.Abstract -This research aimed to evaluate the gas exchange and growth index of Brachiaria decumbens under five water supply (3.84, 4.39, 6.19, 8.62 and 10.46 mm day -1 ). A completely randomized with split-plot design with five irrigation depth being the parcels and ages (10, 17, 24 and 31 days), the subparcels, with four replicates. It was observed interaction between irrigation depth and ages for leaf transpiration, leaf temperature, rate of photosynthesis and leaf weight ratio. Quadratic responses with minimum values were observed to the internal CO 2 concentration and specific leaf area (0.0055 m² leaf g -1 leaf) with advance in ages. The internal concentration of CO 2 revealed values of 220.09 and 176.20 ppm to 10 and 31 days, respectively, with minimum (173.68 ppm) to 27 days. It was observed quadratic response with maximum value (25.04 g m -2 leaf day -1 ) to the net assimilation rate with increasing ages. Decreasing linear responses were observed to the relative growth rate and leaf area ratio with increasing ages. The relative growth rate presented values of 0.097 and 0.048 g g -1 day -1 , with 10 and 31 days, respectively. The growth ages provided changes on gas exchange and growth index of Brachiaria grass, however, these characteristics are little influenced by irrigation depth under the conditions of this study.

RESUMO-Objetivou-se avaliar a influência de quatro níveis de substituição (0; 33; 67 e 100%) do farelo de soja pela torta de mamona destoxificada em rações sobre o desempenho produtivo e as características de carcaça de ovinos mestiços de Morada Nova. Utilizaram-se 20 machos não-castrados, com peso vivo médio de 18,7 kg, em delineamento de blocos ao acaso com cinco repetições. Foram avaliados o desempenho, o peso, o rendimento e a composição regional das carcaças. A substituição do farelo de soja pela torta de mamona destoxificada não teve efeito sobre o peso vivo ao abate e o ganho de peso total durante o confinamento, entretanto teve efeito linear decrescente sobre o ganho médio diário e a conversão alimentar dos animais. Não foi observado efeito dos níveis de substituição do farelo de soja pela torta de mamona destoxificada sobre o peso vivo final, o peso vivo ao abate em jejum, o peso corporal vazio, o peso da carcaça quente e o peso da carcaça fria. O rendimento de carcaça quente foi afetado pelos níveis de substituição do farelo de soja pela torta de mamona, mesmo comportamento observado para o rendimento de carcaça fria. O peso da costela e os rendimentos da costela e da paleta também foram influenciados pelos níveis de substituição do farelo de soja pela torta de mamona destoxificada. O peso e o rendimento das demais regiões, no entanto, não apresentaram diferenças entre níveis de substituição. A torta de mamona destoxificada pode ser utilizada em níveis de até 67% de substituição ao farelo de soja em dietas para ovinos. Palavras-chave: borregos, rendimento de carcaça, Ricinus communis, subproduto do biodiesel Performance and carcass traits of sheep in feedlot and fed diets containing detoxified castor cake replacing soybean meal ABSTRACT-The objective of this study was to evaluate the influence of four substitution levels (0; 33; 67 and 100%) of soybean meal by detoxified castor cake on performance and carcass characteristics of 20 non-castrated male crossbred Morada Nova lambs, with mean body weight of 18.7 kg, in a randomized blocks design with four treatments and five replicates. Performance, carcass weight, carcass yield and relative composition of the commercial cuts were evaluated. The substitution levels of soybean meal by detoxified castor cake had no effect on final live weight or total weight gain in feedlot, but it caused decreasing linear effect on average daily gain and feed conversion ratio was observed. There was no effect of the substitution levels of soybean meal by detoxified castor cake on final body weight, live weight at fasting, empty body weight, hot carcass weight or cold carcass weight. The hot carcass yield was affected by substitution levels; the same behavior was observed for cold carcass yield. Rib weight and yield and shoulders yield had linear decrease of substitution levels of soybean meal by detoxified castor cake, whereas weight and yield of other regions did not present any effect for the substitution levels. Detoxified castor cake can be utilized in levels of up to 67...

Resumo -Objetivou-se avaliar os componentes da biomassa do resíduo pós-corte em capim-massai submetido a cinco doses de nitrogênio (0; 150; 300; 450 e 600 mg N dm -3 de solo) num delineamento inteiramente casualizado, com cinco repetições (vasos) em casa de vegetação. Avaliaram-se a altura residual, a densidade populacional de perfilhos (DPP), a massa seca de forragem total residual (MSFTr), de forragem verde residual (MSFVr), de forragem morta residual (MSFMr), de lâmina foliar verde residual (MSLVr), de colmo verde residual (MSCVr), relação lâmina foliar/ haste (LF/C), a massa seca radicular (MS radicular) e a relação parte aérea/raiz. Observou-se efeito quadrático dos níveis de adubação nitrogenada sobre a altura residual. As variáveis MSFTr, MSFVr e MSCVr responderam positivamente, enquanto a MSLVr revelou comportamento quadrático com os níveis de N. Constatou-se valores estimados de 13,35 e 39,73 g MS/vaso para MSFTr, de 9,71 e 24,69 g MS/vaso para MSFVr e de 3,65 e 15,07 g MS/vaso para MSFMr nas doses de 0 a 600 mg N dm -3 de solo, respectivamente. A MS radicular respondeu positivamente às doses de N. A adubação nitrogenada proporciona resultados positivos sobre as características estruturais do resíduo pós-corte do capim-massai. Palavras-chave -Adubação nitrogenada. Massa seca de lâmina foliar residual. Panicum maximum x Panicum infestum.Abstract -After cut residue of Massai grass under five nitrogen fertilized levels were evaluated. A completely randomized design with five nitrogen levels (0; 150; 300; 450 and 600 mg N dm -3 of soil) and five replicates (plots) in greenhouse was used. It was evaluated the residual canopy height (RCH), the tiller population density (TPD), the total residual forage dry mass (TFDM), the residual green forage dry mass (GFDM), the senescent forage dry mass (SFDM), the residual green leaf dry mass (GLDM), the residual green culm dry mass (GCDM), leaf/culm ratio (L/C), root dry mass (RDM) and above ground/root ratio (A/R). There was square effect of nitrogen fertilization on RCH. There were crescent and linear effect of nitrogen fertilization on TFDM, GFDM and GCDM. There was square effect of nitrogen fertilization on GLDM. The values were estimated in 13.35 and 39.73 g DM/plot to TFDM; 9.71 and 24.69 g DM/plot to GFDM and 3.65 and 15.07 g DM/plot to SFDM on 0 and 600 mg N dm -3 of soil, respectively. The RDM presented positively response to the N levels. It was concluded that the nitrogen fertilizing brought benefits for all structural characteristics after cut of Massai grass.

Response of biomass flow in Massai grass to nitrogen fertilization during the establishment and regrowthThe use of fertilizers, especially nitrogen, can increase significantly the biomass production of a pasture. The objective of this study was to evaluate the biomass flow of Massai grass produced in greenhouse during the establishment and regrowth under five nitrogen fertilization levels. The experiment was arranged in a completely randomized split-plot design with five nitrogen levels (0; 150; 300; 450 e 600 mg de N dm -3 of soil) and five replications (plots) .The leaf elongation rate was increased with the nitrogen fertilization levels and the establishment growth presented higher values in relation to the regrowth. The culm elongation rate was not influenced by N levels. The A produção de biomassa em uma pastagem pode ser incrementada com o uso de fertilizantes, principalmente os nitrogenados. Diante disso, objetivou-se, com este trabalho, avaliar o fluxo de biomassa do capim-massai, durante o estabelecimento e a rebrotação, em casa de vegetação, sob cinco doses de nitrogênio (0; 150; 300; 450 e 600 mg de N dm -3 de solo), em delineamento inteiramente casualizado, com medidas repetidas no tempo, e cinco repetições. A taxa de alongamento foliar foi incrementada pelas doses de nitrogênio (N) e o crescimento de estabelecimento apresentou maior valor, em relação ao das rebrotações. A taxa de alongamento das hastes não foi influenciada pelas doses de N. O crescimento de estabelecimento apresentou maior valor para esta variável, em relação ao das rebrotações. A taxa de senescência foliar anterior não sofreu influência das doses de N, porém, foi alterada entre os ciclos de crescimento. O número de folhas vivas por perfilho foi superior, para as maiores doses e no estabelecimento, o inverso ocorrendo para o filocrono. A dose aplicada de 600 mg dm -3 de N proporcionou um incremento de 448%, na taxa de produção de forragem, e de 455%, na taxa de acúmulo de forragem, em relação àquelas do manejo sem N. A adubação nitrogenada proporciona respostas positivas nas variáveis do fluxo de biomassa do capim-massai.Palavras-chave: filocrono, morfogênese, nitrogênio, Panicum maximum.

-To evaluate biomass components of Massai grass under five doses of N (0, 150, 300, 450 and 600 mg N/dm 3 soil) during three cycles of growth (establishment, regrowth 1 and regrowth 2) this study was carried out.The experiment was carried out in a greenhouse, in a completely randomized design with measures repeted over time and five replications. In the three cycles, nitrogen doses had increasing linear effect on green herbage dry matter (GHDM), green leaf dry matter (GLDM), on the tiller population density (TPD) and on forage density. Canopy height and foliage height were the highest ones in establishment of regrowth 2, respectively, and they decreased at the highest doses of nitrogen.Irrigation depth was the greatest at the highest doses and in regrowth 1. Water use efficiency responded positively to the doses, being the regrowth 2 the highest values were obtained at the highest doses of nitrogen. Nitrogen use efficiency by Massai grass is influenced by fertilizantion as well as by the cycles. Nitrogen fertilization has positive effects on the components of Massai grass biomass.

-The objective of this study was to evaluate gas exchange in the massai grass during establishment and regrowth cycles in a greenhouse, using five nitrogen (N) fertilization levels. A completely randomized split-plot design of five nitrogen levels (0; 150; 300; 450 and 600 mg N•dm -3 of soil) was employed with the N levels as plots, and the cycles (establishment, regrowth 1 and 2) as subplots, evaluated with five replicates. We evaluated leaf transpiration (E), leaf temperature (TFOL), leaf photosynthesis rate (A), leaf carbon dioxide concentration (Ci), stomatal conductance (gs), photosynthesis/transpiration ratio (A/E), photosynthesis/conductance ratio (A/gs), chlorophyll relative index (CRI), and nitrogen sufficiency index (NSI). Growth cycles influenced all physiological characteristics, except for NSI. N fertilization levels affected TFOL, A, CRI and NSI variables, whereas for gs, E, Ci, A/E and A/gs it did not occur. A increased from 6.38 to 10.33 μmol•m -2. s -1 , at levels 0 and 600 mg N•dm -3 of soil, respectively. Gas exchange in the massai grass was favored by nitrogen fertilization, since the cycles amended these characteristics of the grass.

This study aimed to evaluate the growth index of massai grass during two regrowth cycles in a greenhouse under five levels of nitrogen (0, 150, 300, 450 and 600 mg N/dm³ of soil) and eight growth ages (5, 8, 11, 14, 17, 20, 23 and 26 days) in a split-plot design with five replications. The following variables were evaluated: net assimilation rate, herbage growth rate, relative growth rate, leaf area ratio, leaf weight ratio and specific leaf area. The effect of nitrogen was detected on the variables net assimilation rate (regrowths 1 and 2), leaf area ratio (regrowth 1), leaf weight ratio (regrowths 1 and 2), specific leaf area (regrowths 1 and 2) and herbage growth rate (regrowths 1 and 2). The growth ages influenced the relative growth rate (regrowth 2) and the net assimilation rate (regrowth 2). The net assimilation rate presented linear effect, estimated in 0.70 and 2.86 g/m² leaf.day-1 for the 0 and 600 mg N/dm³ soil, respectively (regrowth 1). For each milligram of N/dm³ added, the leaf area ratio was reduced in 0.0000258 m² leaf/g plant (regrowth 1). The herbage growth rate was estimated in 1.38 and 37.02 g/m².day-1 (regrowth 1), and 4.37 and 32.20 g/m².day-1 (regrowth 2) for the 0 and 600 mg N/dm³ soil, respectively. The massai grass' growth is favored by nitrogen fertilization, and little do the growth ages affect the growth index of the plants