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There is limited information regarding both nitrogen (N) and energy partitioning of dairy cows grazing well­managed tropical pastures. The objective of this study was to investigate the N and energy partitioning of mid­lactation dairy cows on rotationally grazed elephant grass using two pre­grazing targets: 95 % or maximum canopy light interception (LI95% or LIMax) during regrowth. The study used 26 Holstein × Jersey dairy cows arranged in a randomized complete block design with three 40­day periods of sampling. Grazing at LI95% increased organic matter and crude protein intake by 20 % (p ≤ 0.05) which resulted in a 9 % increase in fat corrected milk yield (p ≤ 0.05) relative to LIMax. Cows grazing at LI95% had greater concentration of total volatile fatty acids, butyrate and valerate (p ≤ 0.05), and smaller acetate (p ≤ 0.05) than those grazing at LIMax. Intake of net energy for lactation (NEL) and NEL secreted in milk were greater (p ≤ 0.05), while partitioning of NEL towards maintenance tended to be greater (p = 0.07) for cows grazing at LI95% than those grazing at LIMax. Milk urea nitrogen and both urine and fecal N excretion were greater for cows grazing at LI95% (p ≤ 0.05), but N excretion intensity was lower than in cows grazing at LIMax (p ≤ 0.05). Strategic grazing management using the LI95% pre­grazing target increases N losses through both urine and feces; however, it reduces N excretion intensity of dairy cows by 9 %.

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This study evaluated the leaf area index (LAI) recovery mechanisms and forage accumulation rates on the regrowth of different grass species subjected to different defoliation intensities. For that purpose, plots of Pennisetum clandestinum (kikuyugrass), Lolium multiflorum (annual ryegrass), and Avena strigosa (black oats) were defoliated from 20 to 80 % of their initial heights (25, 20, and 25 cm, respectively). At different increments in height, forage samples were collected to ground level and used to estimate tiller population density (TPD), leaf area per tiller (LA), and forage mass. From these data, we calculated the leaf area index (LAI), average leaf area index (aLAI), and average and instantaneous forage accumulation rate (FAR and IFAR, respectively). Data were plotted over time (days) to describe LAI recovery and forage accumulation rates. As the defoliation intensity increased, greater canopy heights were needed for pastures to achieve their maximum forage accumulation rates, which required longer regrowth intervals. The need for high tiller recruitment after defoliation, which delayed canopy LAI recovery, seemed to be one of the main cause. Thus, grazing management strategies that involve costly tiller recruitment could decrease both overall forage production and sward persistence over time. However, the plant ability to recover LAI after successive intense defoliations seems to be species-dependent and related to their phenotypic plasticity.

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This article aims to determine the adequate pasture height and the nitrogen dose at the beginning of the deferral period for Urochloa brizantha cv. Marandu (Marandu palisade grass). Two pasture heights (15 and 30 cm) and four nitrogen doses (0, 40, 80, and 120 kg ha-1) were evaluated in a completely randomized factorial (4x2) design with three replications. A linear increase in the number of vegetative tillers was observed with the application of nitrogen in the 15-cm deferred pasture. The lengths of stem and leaf blades of tillers increased linearly with the application of nitrogen. The weight of the vegetative tillers was greater in the 30-cm deferred pasture, compared to the 15-cm one when the pasture was fertilized with 0 and 40 kg ha-1 of N. The nitrogen fertilization linearly increased the weight of both the vegetative tillers in the 15-cm deferred pastures and the reproductive tillers in the 30-cm deferred pastures. The recommendation is that Marandu palisade grass be deferred with 15 cm and fertilized with 80 kg ha-1 of N at the beginning of the deferment period.

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The aim of this study was to relate the occurrence of visible losses in silage (effluent, spoiled top-layer and during feedout) with silage-making practices, physical and chemical characteristics of silage, and milk composition in Brazilian dairy herds. One-hundred and eight silos from 95 farms, in the State of Parana, were visited for data collection. Data were analyzed by Fisher's Exact and Pearson Correlation Test. Effluent loss was higher in silages with the lowest dry matter content. Using unwalled clamp (drive-over piles) silos, neglecting a protection over the plastic film, and unloading silage with a bucket increased the occurrence of top spoilage. Feedout losses were higher in farms where: the crop was harvested with self-propelled machines; the particle size was larger, and the silage density was lower. There was no relationship between visible losses and silage composition or milk composition, except for milk fat content that, unexpectedly, there was a positive correlation with spoiled silage in the top-layer. Silage losses are reduced by adopting good practices during silage production and feedout.

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This study evaluated the leaf area index (LAI) recovery mechanisms and forage accumulation rates on the regrowth of different grass species subjected to different defoliation intensities. For that purpose, plots of Pennisetum clandestinum (kikuyugrass), Lolium multiflorum (annual ryegrass), and Avena strigosa (black oats) were defoliated from 20 to 80 % of their initial heights (25, 20, and 25 cm, respectively). At different increments in height, forage samples were collected to ground level and used to estimate tiller population density (TPD), leaf area per tiller (LA), and forage mass. From these data, we calculated the leaf area index (LAI), average leaf area index (aLAI), and average and instantaneous forage accumulation rate (FAR and IFAR, respectively). Data were plotted over time (days) to describe LAI recovery and forage accumulation rates. As the defoliation intensity increased, greater canopy heights were needed for pastures to achieve their maximum forage accumulation rates, which required longer regrowth intervals. The need for high tiller recruitment after defoliation, which delayed canopy LAI recovery, seemed to be one of the main cause. Thus, grazing management strategies that involve costly tiller recruitment could decrease both overall forage production and sward persistence over time. However, the plant ability to recover LAI after successive intense defoliations seems to be species-dependent and related to their phenotypic plasticity.(AU)

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This article aims to determine the adequate pasture height and the nitrogen dose at the beginning of the deferral period for Urochloa brizantha cv. Marandu (Marandu palisade grass). Two pasture heights (15 and 30 cm) and four nitrogen doses (0, 40, 80, and 120 kg ha-1) were evaluated in a completely randomized factorial (4x2) design with three replications. A linear increase in the number of vegetative tillers was observed with the application of nitrogen in the 15-cm deferred pasture. The lengths of stem and leaf blades of tillers increased linearly with the application of nitrogen. The weight of the vegetative tillers was greater in the 30-cm deferred pasture, compared to the 15-cm one when the pasture was fertilized with 0 and 40 kg ha-1 of N. The nitrogen fertilization linearly increased the weight of both the vegetative tillers in the 15-cm deferred pastures and the reproductive tillers in the 30-cm deferred pastures. The recommendation is that Marandu palisade grass be deferred with 15 cm and fertilized with 80 kg ha-1 of N at the beginning of the deferment period.(AU)

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The aim of this study was to relate the occurrence of visible losses in silage (effluent, spoiled top-layer and during feedout) with silage-making practices, physical and chemical characteristics of silage, and milk composition in Brazilian dairy herds. One-hundred and eight silos from 95 farms, in the State of Parana, were visited for data collection. Data were analyzed by Fisher's Exact and Pearson Correlation Test. Effluent loss was higher in silages with the lowest dry matter content. Using unwalled clamp (drive-over piles) silos, neglecting a protection over the plastic film, and unloading silage with a bucket increased the occurrence of top spoilage. Feedout losses were higher in farms where: the crop was harvested with self-propelled machines; the particle size was larger, and the silage density was lower. There was no relationship between visible losses and silage composition or milk composition, except for milk fat content that, unexpectedly, there was a positive correlation with spoiled silage in the top-layer. Silage losses are reduced by adopting good practices during silage production and feedout.(AU)

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This essay aims to evaluate the composition of fiber in neutral detergent, digestibility of plant components, as well as ruminal disappearance rate of fodder dry matter from five ryegrass fields submitted to different cut systems for the production of haylage. The experimental design was the randomized blocks one, at a 5 x 3 factorial scheme, with five cultivars (cv.) of ryegrass Lolium multiflorum (cv. Barjumbo, cv. BarHQ, cv. Ribeye, cv. Potro and cv. Willians) associated with three harvesting management systems: 1- single harvesting system at a pre-floral stage; 2 - double harvesting system, with a cut at vegetative stage and another at pre-floral stage; and 3 - triple harvesting system, with a cut at vegetative stage, a cut at full vegetative stage and a cut at pre-floral stage, with three repetitions each. Similarities were noticed on the results of fodder digestibility of different fields, however, cv. Potro presented a higher ruminal disappearance rate after 48 hours, with 69.27%. Generally, the harvesting management system with the increase of ryegrass cut frequency determined increments on the percentage of lignin and the reduction in the concentration of total nutrients and dry matter digestibility of the resulting hylage.(AU)

O objetivo do presente trabalho foi avaliar a composição da fibra em detergente neutro, digestibilidade dos componentes da planta, bem como a taxa de desaparecimento ruminal da matéria seca da forragem de cinco cultivares de azevém submetidos a diferentes sistemas de cortes para produção de silagem pré-secada. O delineamento experimental foi em blocos ao acaso,, em um fatorial 5 x 3, sendo cinco cultivares de azevém Lolium multiflorum (cv. Barjumbo, cv. BarHQ, cv. Ribeye, cv. Potro e cv. Willians) associados a três sistemas de manejo de colheita: 1 - sistema com única colheita no estádio de pré-florescimento; 2 - sistema com uma colheita no estádio vegetativo e outra no estádio de pré-florescimento; e 3 - sistema com uma colheita no estádio vegetativo, uma no estádio pleno vegetativo e outra no estádio de pré-florescimento, com três repetições cada. Notou-se similaridade entre os resultados de digestibilidade da forragem entre os cultivares, porém o cv. Potro apresentou a maior taxa de desaparecimento ruminal após 48 horas, com 69,27%. De maneira geral, o sistema de manejo de colheita mostrou que o aumento do número de cortes do azevém determinou incrementos nos teores de lignina e redução na concentração de nutrientes digestíveis totais e da digestibilidade da matéria seca nas silagens pré-secadas resultantes.(AU)

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This essay aims to evaluate the composition of fiber in neutral detergent, digestibility of plant components, as well as ruminal disappearance rate of fodder dry matter from five ryegrass fields submitted to different cut systems for the production of haylage. The experimental design was the randomized blocks one, at a 5 x 3 factorial scheme, with five cultivars (cv.) of ryegrass Lolium multiflorum (cv. Barjumbo, cv. BarHQ, cv. Ribeye, cv. Potro and cv. Willians) associated with three harvesting management systems: 1- single harvesting system at a pre-floral stage; 2 - double harvesting system, with a cut at vegetative stage and another at pre-floral stage; and 3 - triple harvesting system, with a cut at vegetative stage, a cut at full vegetative stage and a cut at pre-floral stage, with three repetitions each. Similarities were noticed on the results of fodder digestibility of different fields, however, cv. Potro presented a higher ruminal disappearance rate after 48 hours, with 69.27%. Generally, the harvesting management system with the increase of ryegrass cut frequency determined increments on the percentage of lignin and the reduction in the concentration of total nutrients and dry matter digestibility of the resulting hylage.(AU)

O objetivo do presente trabalho foi avaliar a composição da fibra em detergente neutro, digestibilidade dos componentes da planta, bem como a taxa de desaparecimento ruminal da matéria seca da forragem de cinco cultivares de azevém submetidos a diferentes sistemas de cortes para produção de silagem pré-secada. O delineamento experimental foi em blocos ao acaso,, em um fatorial 5 x 3, sendo cinco cultivares de azevém Lolium multiflorum (cv. Barjumbo, cv. BarHQ, cv. Ribeye, cv. Potro e cv. Willians) associados a três sistemas de manejo de colheita: 1 - sistema com única colheita no estádio de pré-florescimento; 2 - sistema com uma colheita no estádio vegetativo e outra no estádio de pré-florescimento; e 3 - sistema com uma colheita no estádio vegetativo, uma no estádio pleno vegetativo e outra no estádio de pré-florescimento, com três repetições cada. Notou-se similaridade entre os resultados de digestibilidade da forragem entre os cultivares, porém o cv. Potro apresentou a maior taxa de desaparecimento ruminal após 48 horas, com 69,27%. De maneira geral, o sistema de manejo de colheita mostrou que o aumento do número de cortes do azevém determinou incrementos nos teores de lignina e redução na concentração de nutrientes digestíveis totais e da digestibilidade da matéria seca nas silagens pré-secadas resultantes.(AU)

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This study aimed to evaluate the production characteristics of pastures in integrated livestock production systems. For that, an experiment was carried out in São Carlos, SP, Brazil, from 2013 to 2015. Forage development, production and nutritive value were evaluated in five beef cattle production systems: extensive continuous stocking (Urochloa decumbens) = EXT; intensive = INT; crop-livestock = iCL; livestock-forest = iLF and crop-livestock-forest = iCLF. Rotational stocking pastures in INT, iCL, iLF and iCLF systems were established with Urochloa brizantha cv. BRS Piatã. In iCL and iCLF, pastures were renovated by resowing the grass simultaneously with corn. In iLF and iCLF, eucalyptus (Eucalyptus urograndis clone GG100) was planted in Apr 2011 in single rows with 15 × 2 m spacing. In the 2013/2014 crop season, INT, iCL, and iCLF pastures were more productive than in iLF and EXT. Shading increase in the 2014/2015 season reduced pasture production in iLF and iCLF, compared with INT and iCL, but increased crude protein content and digestibility. In the shaded systems, pasture production was affected by proximity to trees, mainly due to reductions in solar radiation transmission. The principal component analyses showed that forage accumulation and leaf area index were associated with the position in the middle of the inter-row, and nutritive value was associated with the position at 1.5 m from the trees. In iCLF, solar radiation transmission greater than 60 % maintained forage accumulation similar to iCL, while in iLF, it reduced forage accumulation, evidencing that pasture renovation minimized shading effects in these systems.

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The Brazilian livestock activity is undergoing constant evolution, and aiming at its maximum efficiency, it is necessary to have available to the animals food in quantity and quality all the year. To this end, the cultivation of winter forage is carried out. The present study aimed to evaluate the productive and qualitative agronomic traits of ryegrass forage. The experiment was a randomized block design in a 3 x 2 factorial arrangement consisting of six treatments, three plant stands (525, 1050 and 2095 plants m-2) associated with two successive cutting times (vegetative and full vegetative), and four repetitions. There was no interaction between population stand and cutting times for the variables studied. The stand of 525 plants m-2 had a higher participation of green leaves (50.52 %), higher digestibility of the whole plant dry matter (84.81 %) compared to the stands of 1.050 and 2.095 plants m-2, and dry biomass production per unit area equivalent to the others (6087, 7243 and 6989 kg ha-1, respectively). The first harvest season presented higher participation of green leaves and better leaf/stem ratio, 58.62 % and 3.41 % respectively, as well as higher digestibility of green leaves (77.26 %) and stem (80.82 %).(AU)

A atividade pecuária brasileira vem passando por constante evolução, visando sua máxima eficiência, ter disponível para os animais alimento em quantidade e qualidade o ano todo se faz necessário, para isso realiza-se o cultivo de forragens de inverno, o presente trabalho objetivou avaliar as características agronômicas produtivas e qualitativas da forragem do azevém. O delineamento experimental foi o de blocos ao acaso, num esquema fatorial 3 x 2, composto por seis tratamentos, sendo três estandes de plantas (525, 1.050 e 2.095 plantas m2 ) associado a duas épocas de corte sucessivas (vegetativo e pleno vegetativo) e quatro repetições. Não ocorreu interação entre estande populacional e épocas de corte para as variáveis estudadas. O estande de 525 plantas m-2 apresentou maior participação de folhas verdes (50,52 %), maior digestibilidade da matéria seca da planta inteira (84,81 %) em relação aos estandes de 1.050 e 2.095 plantas m-2, e produção de biomassa seca por unidade de área equivalente aos demais (6.087, 7.243 e 6989 kg ha-1 respectivamente). A primeira época de colheita apresentou maior participação de folhas verdes e melhor relação folha/colmo 58,62 % e 3,41 % respectivamente, assim como maior digestibilidade das frações folhas verdes (77,26 %) e do colmo (80,82 %).(AU)

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The aim of this experiment was to identify grazing height targets for Alexandergrass pastures under continuous stocking in integrated crop-livestock system (ICLS). For this purpose, twelve pastures were cultivated into an ICLS area, and maintained at 10, 20, 30, or 40 cm using grazing goats. The following variables were analyzed: leaf and herbage mass, accumulation rate, and allowance; leaf:stem ratio; chemical composition of hand-plucked samples; stocking rate; average daily gain and gain per area. The data were submitted to regression and correlation analysis. Significance was set at 5% (P≤0.05). The main results were: i) herbage and leaf lamina mass increased linearly with grazing height, and pastures maintained at 20 cm already presented the minimum amount recommended for soil cover in ICLS; ii) animal performance achieved an upper asymptotic plateau in pastures maintained around 30-40 cm and it was highly correlated with both grazing height and forage availability (mass and allowance). Alexandergrass pastures under continuous stocking in ICLS should be maintained between 30-40 cm to improve both cover crop biomass and animal performance.(AU)

O objetivo deste trabalho foi identificar alturas de manejo para pastos de papuã sob lotação contínua em sistemas de integração lavoura-pecuária (ILP). Para tanto, doze pastos foram cultivados em uma área de ILP e mantidos em 10, 20, 30 ou 40 cm por meio de lotação contínua com caprinos. As seguintes variáveis foram analisadas: massa; taxa de acúmulo e oferta de forragem e de folhas; relação lâmina:colmo; composição química de amostras de simulação de pastejo; carga animal; ganho médio diário e produção animal por área. Os dados foram submetidos a análises de regressão e correlação. A significância adotada foi de 5% (P≤0,05). Os principais resultados foram: i) houve um aumento linear na massa de forragem e folhas com o aumento da altura de manejo e pastos com mais de 20 cm já apresentavam a quantidade mínima recomendada para cobertura de solo em ILP ii) o desempenho animal atingiu um platô assintótico nos pastos manejados entre 30-40 cm e foi altamente correlacionado com a altura de manejo e a disponibilidade de forragem (massa e oferta). Pastos de Papuã manejados sob lotação contínua em ILP devem ser mantidos entre 30-40 cm para favorecer a produção de biomassa de cobertura e o desempenho animal.(AU)

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This study aimed to evaluate the production characteristics of pastures in integrated livestock production systems. For that, an experiment was carried out in São Carlos, SP, Brazil, from 2013 to 2015. Forage development, production and nutritive value were evaluated in five beef cattle production systems: extensive continuous stocking (Urochloa decumbens) = EXT; intensive = INT; crop-livestock = iCL; livestock-forest = iLF and crop-livestock-forest = iCLF. Rotational stocking pastures in INT, iCL, iLF and iCLF systems were established with Urochloa brizantha cv. BRS Piatã. In iCL and iCLF, pastures were renovated by resowing the grass simultaneously with corn. In iLF and iCLF, eucalyptus (Eucalyptus urograndis clone GG100) was planted in Apr 2011 in single rows with 15 × 2 m spacing. In the 2013/2014 crop season, INT, iCL, and iCLF pastures were more productive than in iLF and EXT. Shading increase in the 2014/2015 season reduced pasture production in iLF and iCLF, compared with INT and iCL, but increased crude protein content and digestibility. In the shaded systems, pasture production was affected by proximity to trees, mainly due to reductions in solar radiation transmission. The principal component analyses showed that forage accumulation and leaf area index were associated with the position in the middle of the inter-row, and nutritive value was associated with the position at 1.5 m from the trees. In iCLF, solar radiation transmission greater than 60 % maintained forage accumulation similar to iCL, while in iLF, it reduced forage accumulation, evidencing that pasture renovation minimized shading effects in these systems.(AU)

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This study was carried out to evaluate the effect of nitrogen fertilization on tillering dynamics of Alexandergrass (Urochloa plantaginea (Link) Hitch) grazed by beef heifers in a rotational stocking grazing method. The experiment was conducted in a completely randomized design following a repeated measure arrangement, three levels of nitrogen (Zero, 150 and 300kg ha-1) and two area repetition. The classification of tillers into categories (basal and axillary) showed a greater number of basal tillers, due to their higher appearance rate, in the absence of nitrogen fertilization. Nitrogen fertilization promoted higher axillary tiller density. The use of nitrogen promotes the renewal of axillary tillers of Alexandergrass, without compromising the stability of the tiller population.(AU)

Esse estudo foi conduzido para avaliar o efeito da fertilização nitrogenada no perfilhamento do Papuã (Urochloa plantaginea (Link) Hitch) pastejado por novilhas de corte em um método de lotação rotacionada. O delineamento foi inteiramente casualizado com arranjo de medidas repetidas, três níveis de nitrogênio (Zero, 150 e 300kg ha -1 ) e duas repetições de área. A classificação dos perfilhos em categorias (basais e axilares) mostrou um maior número de perfilhos basais, devido à sua maior taxa de aparecimento, na ausência de adubação nitrogenada. A fertilização nitrogenada promoveu maior densidade de perfilhos axilares. O uso de nitrogênio promove renovação dos perfilhos axilares no Papuã, sem comprometer a estabilidade da população de plantas.(AU)

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The objectives of this study were to determine the rates of plant litter deposition and decomposition in Marandu pastures (Urochloa brizantha cv. Marandu) under a) three forms of nitrogen (N) supply, b) at different stages of rotational grazing and c) to compare the single-exponential decay constant (‘k) derived from litterbags with values derived from estimates of deposited and existing litter (DEL technique). The three N supply treatments were: without or with N fertilization (zero or 150 kg N ha-1 yr-1) or with the legume Desmodium ovalifolium. There were no significant differences (p<0.05) between existing litter and rates of litter deposition and decomposition between the three N supply treatments. The litter decomposition rate was estimated using the DEL technique for the 7-day grazing periods and two subsequent 14-day periods in each 35-day grazing cycle. The litter decomposition rate was (P<0.05) higher for the second rest period (days 21 to 35) at 0.089 g g-1 day-1, than for the grazing period (0.038 g g-1 day-1) and for the first rest period (0.040 g g-1 day-1). The mean half-life of the litter was 12 days using the DEL technique while the estimate from the litterbags was 136 days. Results showed that estimates provided by litterbags severely underestimate the decomposition in relation to the DEL technique and predict a long-term accumulation of litter which is not observed.(AU)

Os objetivos deste estudo foram determinar taxas de deposição e decomposição de serapilheira em pastagens de Marandu (Urochloa brizantha cv. Marandu) sob a) três formas de suprimento de nitrogênio (N), b) em diferentes estágios de pastejo rotativo e c) comparar a constante de decomposição (‘k) derivada de “litterbags” com os valores derivados das estimativas de serapilheira existente e depositada (técnica SED). Os três tratamentos de suprimento de N foram: sem ou com adubação nitrogenada (zero ou 150 kg N ha-1 ano-1) ou com a leguminosa Desmodium ovalifolium. Não houve diferenças significativas (p<0,05) entre a serapilheira existente e as taxas de deposição e decomposição da serapilheira entre os três tratamentos de N. A taxa de decomposição da serapilheira foi estimada usando a técnica SED para os 7 dias de pastejo e dois períodos subsequentes de 14 dias em cada ciclo de 35 dias. A taxa de decomposição da serapilheira foi (p<0,05) maior no segundo período de descanso (dias 21 a 35) em 0,089 g g-1 dia-1, do que no período de pastejo (0,038 g g-1 dia-1) e no primeiro período de repouso (0,040 g g-1 dia-1). A meia-vida média da serapilheira foi de 12 dias pela técnica SED, enquanto a estimativa dos “litterbags” foi de 136 dias. Os resultados mostram que as estimativas fornecidas pelos “litterbags” subestimam severamente a decomposição em relação à técnica SED, e preveem um acúmulo de serapilheira a longo prazo que não é observado.(AU)

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This study was carried out to evaluate the effect of nitrogen fertilization on tillering dynamics of Alexandergrass (Urochloa plantaginea (Link) Hitch) grazed by beef heifers in a rotational stocking grazing method. The experiment was conducted in a completely randomized design following a repeated measure arrangement, three levels of nitrogen (Zero, 150 and 300kg ha-1) and two area repetition. The classification of tillers into categories (basal and axillary) showed a greater number of basal tillers, due to their higher appearance rate, in the absence of nitrogen fertilization. Nitrogen fertilization promoted higher axillary tiller density. The use of nitrogen promotes the renewal of axillary tillers of Alexandergrass, without compromising the stability of the tiller population.(AU)

Esse estudo foi conduzido para avaliar o efeito da fertilização nitrogenada no perfilhamento do Papuã (Urochloa plantaginea (Link) Hitch) pastejado por novilhas de corte em um método de lotação rotacionada. O delineamento foi inteiramente casualizado com arranjo de medidas repetidas, três níveis de nitrogênio (Zero, 150 e 300kg ha -1 ) e duas repetições de área. A classificação dos perfilhos em categorias (basais e axilares) mostrou um maior número de perfilhos basais, devido à sua maior taxa de aparecimento, na ausência de adubação nitrogenada. A fertilização nitrogenada promoveu maior densidade de perfilhos axilares. O uso de nitrogênio promove renovação dos perfilhos axilares no Papuã, sem comprometer a estabilidade da população de plantas.(AU)

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The aim of this study was to evaluate the oxidative and anti-oxidative status of unaged and aged Longissimus dorsi (LD) muscle obtained from a commercial abattoir. Also, fatty acid composition and calculated health lipid indices of meat were compared. Animals slaughtered were Aberdeen Angus steers raised in three typical feeding systems of Uruguay: (1) Pasture (n=10), (2) Pasture + Supplement (P+S) with corn grain (n=10), and (3) Feedlot (n=10). Feeding had no effect on lipid and protein oxidation but the antioxidant enzymes activities were affected as follows: superoxide dismutase (SOD): Pasture, Feedlot > P+S; catalase: Pasture > P+S, Feedlot; glutathione peroxidase (GPx): Feedlot > P+S > Pasture. Total antioxidant potential, determined by Fenton reaction, was higher in aged meat from Pasture compared with aged meat from Feedlot. Meat from Pasture and P+S presented a higher eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA) and total n-3 content and a lower lipid content, n-6/n-3 ratio and trombogenic index compared to meat from Feedlot. In conclusion, Pasture seems to produce a more resistant meat against induced oxidation processes, particularly after ageing, and a healthier meat together with meat from P+S system, regarding fatty acid composition and lipid indices, compared to Feedlot.(AU)

O objetivo deste estudo foi avaliar o estado oxidativo e antioxidante do músculo Longissimus dorsi (LD), sem maturação e amadurecido, obtido de um matadouro comercial. Também foram comparados a composição de ácidos graxos e os índices lipídicos de saúde da carne calculados. Os animais abatidos foram os novilhos Aberdeen Angus criados em três sistemas alimentares típicos do Uruguai: (1) Pastagem (n=10), (2) Pastagem + Suplemento (P + S) com grão de milho (n=10), e (3) Confinamento (n=10). A alimentação não teve efeito sobre a oxidação lipídica e protéica, mas as atividades das enzimas antioxidantes foram afetadas da seguinte forma: superóxido dismutase (SOD): Pastagem, Confinamento > P + S; catalase: Pastagem > P + S, Confinamento; glutationa peroxidase (GPx): Confinamento > P + S > Pastagem. O potencial antioxidante total, determinado pela reação de Fenton, foi maior em carne de Pastagem amadurecida em comparação com a carne amadurecida do Confinamento. Carne de Pastagem e P + S apresentaram maior conteúdo de EPA, DHA e n-3, e menor conteúdo lipídico, razão n-6 / n-3 e índice trombogênico em comparação à carne de Confinamento. Em conclusão, o sistema Pastagem parece produzir uma carne mais resistente contra processos de oxidação induzido, particularmente após o maturação e uma carne mais saudável, juntamente com carne do sistema P + S, em relação à composição de ácidos graxos e índices lipídicos, comparado com o sistema Confinamento.(AU)

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As espécies do gênero Urochloa tem-se destacado na integração lavoura-pecuária, e o tipo de semente utilizada e a profundidade de semeadura são fundamentais para o estabelecimento e produção da forrageira. Objetivou-se nesta pesquisa avaliar a emergência e o crescimento de plantas de Urochloa brizantha cv. Marandu, oriundas de sementes incrustadas ou não, semeadas em diferentes profundidades e solos. O delineamento usado foi o de blocos casualizados, com quatro repetições. Os tratamentos foram arranjados em esquema fatorial 2x5, composto por dois tipos de sementes (incrustadas ou não) semeadas em cinco profundidades (0; 1; 2,5; 5; 10cm) em solos de textura franco argilo arenosa (TFAA) e argilosa (TA). Plantas de U. brizantha oriundas de sementes incrustadas e estabelecidas em solo de TFAA apresentaram maior emergência, mas menor crescimento em relação às plantas provindas de sementes não incrustadas. Em solo de TA, o uso de sementes incrustadas promoveu maior índice de velocidade de emergência, mas menor crescimento das plantas. A semeadura de U. brizantha com sementes incrustadas e não incrustadas a 1,0 e 2,5 cm de profundidade proporcionaram maior velocidade de emergência, independente da textura do solo. Após o corte da forrageira, o maior perfilhamento da rebrota foi observado em plantas oriundas de sementes não incrustadas e semeadas em solo de TA até 2,5 cm de profundidade. Na rebrota, não houve efeito dos tratamentos sobre o rendimento de forragem.

The species of the genus Urochloa has been highlighted in the crop-livestock integration and practices such as the type of seed used, and the depth of sowing are fundamental for the establishment and production of the pasture. The objective of this research was to evaluate the emergence and growth of plants of UrochloaBrizantha cv. Marandu, originating from seeds incrusted or not, sown in different depths and soils. The experimental design was a randomized block design with four replications. The treatments were arranged in a 2x5 factorial scheme, composed of two types of seeds (incrusted or not) seeded in five depths (0; 1; 2.5; 5; 10cm) in medium textured and clayey soils. Plants of U. brizantha from seeds incrusted and cultivated in medium textured soil presented higher emergence, but lower growth in relation to the plants coming from non-incrusted seeds. In soils of clayey texture, the use of incrusted seeds promoted a greater speed of emergency, but less growth of the plants. The sowing of U. brizantha at 1.0 and 2.5 cm depth provided a higher emergence speed, regardless of soil texture and type of seed. After forage cutting, the greatest tillering of regrowth was observed in plants from non-encrusted seeds and sown in soil up to 2.5 cm deep. At regrowth, there was no effect of treatments on forage yield.

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O objetivo deste trabalho foi avaliar a pastagem, o desempenho, o conforto térmico e os parâmetros hematológicos de bovinos Nelore na fase de terminação em sistemas integrados de produção agropecuária com duas densidades de árvores (ILPF-1L= 196 árvores ha-1 e ILPF-3L=448 árvores ha-1) e em pleno sol (ILP). Foram avaliados a massa e a composição morfológica da forragem, o ganho médio diário, o ganho de peso por área e a taxa de lotação no verão e no outono, bem como as variáveis climáticas dos sistemas em três horários e parâmetros hematológicos dos animais (n=60). A massa de forragem foi superior no tratamento ILP e no verão (P<0,05). Porém, a redução da massa de forragem nos sistemas ILPFs não interferiu no desempenho dos animais (P>0,05). A temperatura ambiente, a temperatura do globo e o índice de temperatura e umidade foram melhores nos tratamentos com sombreamento e no período da manhã, proporcionando maior conforto aos animais, sendo ainda confirmado pelo menor volume globular dos bovinos em ILP (P<0,05). Conclui-se que os sistemas com componente arbóreo diminuem a massa de forragem, mas essa redução não altera o desempenho dos animais na fase de terminação. Além disso, os sistemas ILPFs melhoram o conforto térmico, entretanto essa melhora não foi suficiente para favorecer o desempenho.(AU)

The objective of this work was to evaluate pasture, performace, thermal comfort, and haematological parameters of Nellore cattle in the finishing phase in integrated crop-livestock systems with two tree densities (ICLF-1L= 196 ha -1 trees and ICLF-3L= 448 ha -1 trees) and in full sun (ICL). The forage mass morphological composition of the pasture average daily gain, weight gain per area, stocking rate of the animals were evaluated in summer and autumn, and the climatic variables of systems we evaluated at three different times, and haematological parameters of the animals (n= 60). The forage mass was higher in the ICL treatment and summer (P<0.05). However, the reduction of the forage mass in the ILPFs systems did not interfere with the performance of the animals (P>0.05). Ambient temperature, globe temperature and temperature and humidity index were better in shade treatments and in the morning, providing greater comfort to the animals, and was also confirmed by the lower globular volume of the bovines in ICL (P<0.05). It is concluded that the systems with trees reduce the forage mass but this reduction does not alter the animals' performance in the finishing phase. In addition, ICLFs improve the thermal comfort of the animals, however, this improvement was not enough to favor their performance.(AU)

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Este trabalho teve como objetivo avaliar o valor nutritivo e a força de cisalhamento da cultivar de Urochloa brizantha (syn Brachiaria brizantha) cv Xaraés submetida a três intensidades luminosas e quatro cortes. O experimento foi conduzido na FMVZ - Unesp de Botucatu, com delineamento experimental em blocos ao acaso, sendo os tratamentos: luminosidade natural, redução de 30% e 60% de luz, com quatro cortes e três repetições. As análises realizadas foram: composição bromatológica, digestibilidade e a força de cisalhamento. Não houve diferença na digestibilidade entre os tratamentos em nenhum dos cortes, mas a qualidade forrageira foi influenciada pelos níveis de intensidade de luz, tendo o tratamento com 60% de redução de luminosidade apresentado maiores concentrações de proteína bruta e cinzas, menores teores de fibra em detergente neutro, hemicelulose, celulose e força de cisalhamento. Em relação aos cortes estudados, o primeiro teve o menor intervalo de corte e produziu forragem com qualidade superior em comparação ao último, pois obteve menor teor de fibra em detergente ácido, lignina, hemicelulose, celulose e consequente menor força de cisalhamento. Portanto, a redução de 60% de luminosidade é benéfica à qualidade e à força de cisalhamento da cultivar Xaraés.(AU)

This study aimed to evaluate the nutritive value and shear strength of the Xaraés grass (Urochloa brizantha) under the three intensities of light and four cuts. The experiment was conducted at FMVZ - UNESP, Botucatu, with a randomized block design, with the following treatments: natural luminosity, 30% and 60% light reduction, with four cuts and three replications. The analyzes were bromatological composition, digestibility, and shearing strength. There was no difference in digestibility between the treatments in any of the cuts, forage quality was influenced by the light intensity levels, and the treatment with 60% of light reduction produced higher concentrations of crude protein and ash, lower levels of neutral detergent fiber, hemicellulose, cellulose and shear strength. According to the studied cuts, the first one had the lowest cut interval and produced superior forage compared with the last one, as it obtained lower fiber content in acid detergent, lignin, hemicellulose, cellulose and consequent lower shear force. Therefore, the reduction of 60% of luminosity is beneficial to the quality and shear force of the Xaraés palisade grass.(AU)

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