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In grass-legume pastures, grazing management strategies are an essential factor affecting nitrogen (N) cycling. This study assessed the impact of grazing management on N cycling in rotationally-stocked mixed pastures of ‘Marandu’ palisadegrass (Brachiaria brizantha) and ‘Comum’ calopo (Calopogonium mucunoides). Treatments included three grazing management strategies, defined by interruption of the rest period when the canopy reached 90 (90LI), 95 (95LI) and 100% (100LI) of the interception of photosynthetically active radiation. A 2-yr experimental period was adopted. Plant litter responses, forage intake and livestock excretion were evaluated. No differences between grazing management were obtained for existing (294 g OM m−2) and deposited litter (6.7 g OM m−2 d−1, P > 0.10). Compared to the dry season, the litter decomposition rate increased 24.0%, and the half-life decreased 37.8% in the rainy season (P 0.10). Less frequent defoliation (100LI) resulted in reduced proportion of legume intake (P

The study of canopy structures is essential for the precise management of local forage. Although the relationship between the canopy height (CH) and light interception (LI) allows the best use of forage, there are other characteristics of the canopy that, if not observed, can lead to errors in grazing management. This study analyzes the effect of the defoliation frequencies (DF) and season on the productive and structural characteristics of Guinea grass and defines whether tiller population density (TPD) should be considered in the mathematical models that relate CH to LI. The experimental design used includes randomized blocks with six defoliation frequencies (DF) of 14, 21, 28, 35, 42, and 49 days, over three seasons: rainy season 2015 (RS2015), dry season (DS), and rainy season 2016 (RS2016), in the Amazon biome. Yield characteristics and forage structure were evaluated. The interaction between the DFs and seasons in all evaluated variables included forage accumulation, proportions of stem, leaves and dead material, tiller population density (TPD), CH, LI, and leaf area index. The curve steepness constant (CSC) of the nonlinear models between CH and LI was different from that of the DFs. A DF of 14–28 days averaged a TPD of 616 tillers m−2 and CSC of 0.0407, and a DF of 35–49 days averaged a TPD of 496 tillers m−2 and CSC of 0.0368. An agreement index (d) of 0.87, a bias of 1.5 %, and a determination coefficient (R²) of 0.6187 were obtained for the model that estimated a CH with the inclusion of LI and TPD when validated with data from studies published in the literature. TPD associated with CH and LI allowed for more precise management of the ideal defoliation moment.

A well-established canopy is crucial for a stable mixed grass–legume forage pasture. The aim of this study was to assess a defoliation intensity that can ensure the establishment of mixed pasture of brachiaria grass (Brachiaria brizantha) intercropped with forage peanut (Arachis pintoi). The treatments comprised four canopy heights: 10, 20, 30 and 40 cm, maintained throughout the first 3 years of pasture establishment. Canopy structure, morphogenetic and structural characteristics were measured. A block design was used with four replicates, and seasons of the year were considered using repeated measurements over time. Light interception during the experimental period was 86.3%, 95.9%, 97.6%, and 99.1% for 10, 20, 30 and 40 cm of defoliation respectively (p

The objective of this study was to evaluate 2 systems for covering corn silage in bunker silos. The first system consisted of a sheet of 45-μm-thick oxygen barrier film (OB, polyethylene + ethylene-vinyl alcohol) placed along the length of the sidewall before filling. After filling, the excess film was pulled over the wall on top of the silage, and a sheet of polyethylene was placed on top. The second system involved using a standard sheet (ST) of 180-μm-thick polyethylene film. Eight commercial bunker silos were divided into 2 parts lengthwise so that one-half of the silo was covered with OB and the other half with a ST system. During the filling, 3 net bags with chopped corn were buried in the central part (halfway between the top and bottom of the silo) of the bunkers (CCOR) in 3 sections 10 m apart. After filling, 18 net bags (9 per covering system) were buried 40 cm below the top surface of the 3 sections. These bags were placed at 3 distances from the bunker walls (0 to 50 cm, 51 to 100 cm, and 101 to 150 cm). During unloading, the bags were removed from the silos to determine the dry matter (DM) losses, fermentation end products, and nutritive value. The Milk2006 spreadsheet was used to estimate milk per tonne of DM. The model included the fixed effect of treatment (7 different locations in the bunker) and the random effect of the silo. Two contrasts were tested to compare silages in the top laterals (shoulders) with that in the CCOR (CCOR vs. OB and CCOR vs. ST). Three contrasts compared the corresponding distances of the silage covered by the 2 systems (OB50 vs. ST50, OB100 vs. ST100 and OB150 vs. ST150). Variables were analyzed with the PROC MIXED procedure of the SAS at the 5% level. The OB method produced well-fermented silages, which were similar to CCOR, whereas the OB system showed less lactic acid and greater pH and mold counts compared with CCOR. The ST method had 116.2 kg of milk/t less than the CCOR, as the OB system and the CCOR were similar (1,258.3 and 1,294.0 kg/t, respectively). Regarding the distances from the walls, the effects were more pronounced from 0 to 101 cm. The OB50 and OB100 silages had better quality and lower mold counts and DM losses than ST50 and ST100. The OB system reduced DM and nutrient losses at the shoulders in farm bunker corn silages compared with no sidewall plastic. The OB film should lap onto the crop for at least 200 cm so that 150 cm are covered outward from the wall.

A sound understanding of the effects of defoliation management in a grass–legume pasture is key in balancing populations between species. The aim of this study was to quantify the morphogenetic and structural characteristics and forage production of brachiaria grass and forage peanut mixtures under four defoliation strategies. A two-year experiment was carried out in Brazil (Cwa climate), where the following treatments were studied: rest period interruption by cattle grazing when the canopy attained light interception (LI) of 90%, 95% and 100%, and grazing performed every 42 d. Morphogenetic and structural characteristics of both species were measured. The forage and leaf accumulation rates were also quantified. The design was randomised blocks, with three replications, and repeated measurements over time. The 100% LI had greater stem and stolon elongation rates and a lower leaf appearance rate in both species and fewer tillers or stolons when compared with the other strategies. Conversely, rest periods of 90–95% LI promoted an increase of about 30% on forage and leaf accumulation rates of both grass and legume. Therefore, to enhance productivity and stability when these species are associated we recommend defoliating at 90–95% LI, which represents a canopy height ranging from 26 to 32 cm.Keywords: Arachis pintoi, Brachiaria brizantha, palisade grass, warm-season forage legume

The objective of this study was to evaluate forage production and root accumulation in Brachiaria decumbens cv. Basilisk with swine wastewater as a fertilizer. The experiment was conducted into a greenhouse in Federal Institute of Education, Science and Technology of Southeast of Minas Gerais, Rio Pomba Campus. Pots with 6 dm-3 volumes were used as experimental units. Were used a randomized block design with four replications. Were studied four swine waste doses (0, 225, 450 and 675mL pot-1) over four regrowth cycles. The dry matter production of the aerial part, forage accumulation rate, crude protein and dry matter production of roots increased with the highest swine waste doses being around 670, 742, 160 and 465% respectively from lower to higher dose. There was interaction between swine waste and regrowth cycles for plant height and tillering, and in all regrowth cycles responded positively with increasing swine waste doses. Applying swine waste on pastures is therefore a viable alternative to increase productivity of B. decumbens cv. Basilisk, it recommends the use of swine waste corresponding to the dose of 675mL pot-1 to maintenance pastures

Response pattern of grasses as influenced by legume residues after its disappearance in mixed pasture is very limited in the literature. The objective of this study was to evaluate the historical effect of different proportions of Mineirao stylo (Stylosanthes guianensis (Aubl.) Sw. cv. Mineirao) on morphogenetic characteristics and structure of the Xaraes palisadegrass (Brachiaria brizantha (Hochst ex. A. Rich) Stapf cv. Xaraes) under two canopy heights over 2 years. This study used a completely randomized design with a split‐plot arrangement. The historical botanical composition (HBC24, HBC34, HBC45 and HBC52) was allocated in the plots that corresponded to the percentages of legume (24, 34, 45 and 52%) before the experimental period and pre‐grazing heights (30 and 45 cm; CH30 and CH45) in the subplots. The canopies with HBC52 showed greater leaf elongation rate (P = 0.036) and leaf appearance rate (P = 0.0041), 1.6 cm tiller⁻¹ day⁻¹ and 0.053 leaves tiller⁻¹ day⁻¹, respectively, during the growing season. There was an increase in the herbage accumulation rate with the increase of HBC (P = 0.0128). The leaf mass was higher (P = 0.0016) for the CH45 compared with the CH30 (3294 and 2450 kg dry matter [DM] ha⁻¹, respectively). The stem mass was higher (P

Gradual reduction of legumes in mixed tropical pastures requires periodic oversowing. Exploiting the carrying capacity of grass for an extra year after the disappearance of legumes can be economically advantageous to the farmer. This study aimed to evaluate the productivity of Xaraés palisadegrass (Brachiaria brizantha) pastures in response to its historical association with stylo (Stylosanthes guianensis) under two canopy heights to determine whether different grazing management conditions affect the defoliation pattern left by grazing animals. The split-plot experimental design was used, with the historical botanical composition (HBC) (24, 34, 45 and 52 % legume composition) corresponding to the main plots and the canopy frequency of defoliation determined at heights of 30 and 45 cm for Xaraés palisadegrass corresponding to the subplots with two replicates (500 m2) grazed by Tabapuã cows. Pastures with over 34 % stylo in the botanical composition remained productive for one year after legume disappearance, accumulating more than 8 mg ha−1 of forage per year. Xaraés palisadegrass pastures at a height of 30 cm provided better canopy structure, with 64 % less stem production and 43 % less dead material. The 30-cm pre-grazing canopy height provided a grazing environment conducive to forage intake by animals that resulted in efficient use of the pasture. In response to the improved canopy structure, the cows grazed an average of 60 fewer minutes. A HBC greater than 34 % of legumes in the pastures allows for the postponement of legume oversowing until the next growing season.

The objective in this research was to identify photosynthetic responses of three leaf age groups measured in three portions of the leaf blade of two morphologically contrasting genotypes of Panicum maximum. Photosynthetic rate (PR) varied across leaf age groups and among leaf portions. Highest PR (20.6 μmol CO2 m−2 s−1) was recorded on the youngest fully expanded leaf, followed by the oldest green leaf and the expanding leaf. The middle and apical portions of the leaf had, on average, the highest PR (24.2 and 26.3 μmol CO2 m−2 s−1, respectively). In both ‘Massai’ and ‘Tobiata’ cultivars the photosynthetic response was dependent upon leaf age groups and portions of the blade, with highest rates measured on the middle portion of the youngest fully expanded leaf. The P. maximum had similar parameters for the light response curve suggesting similar photosynthetic light response to light intensity across genotypes.

This study evaluated two potassium sorbate (PS) and sodium benzoate (SB) application rates in improving the aerobic stability of maize silage. Treatments included no additive, the addition of PS at 1 and 2 g kg−1 fresh matter (FM) and the addition of SB at 1 and 2 g kg−1 FM. Four replicates of each treatment were ensiled in 15-L plastic jars. The silages were analysed for their fermentative characteristics and were subjected to an aerobic stability test with pH and yeast and mould count measurements. Considering fermentation quality and aerobic stability, both additives were effective. The PS was more active against yeasts during aerobic exposure. When the additives were applied at 2 g kg−1, the silages were more stable (256 h, on average) than those with 1 g kg−1 (119 h, on average) and control (61 h). Aerobic deterioration was more pronounced in the controls than in the treated silages. Silages treated at 2 g kg−1 had consistent effects on pH values and yeast counts over 288 h of aerobiosis. Overall, PS and SB applied at 2 g kg−1 were more effective in improving aerobic stability.

Understanding the morpho-physiological responses of forage plants is critical for successfully managing pastures; however, there is no specific method for morphogenetically assessing Arachis pintoi. The present study aimed to develop and validate mathematical models to estimate leaf area in A. pintoi to enable assessments of leaf elongation and senescence. Two experiments were performed. The first experiment used 500 A. pintoi leaves to model leaf area. Three models were used: correlation, mechanistic and empirical. A total of 336 leaflets were collected to validate the models. For the second experiment, 786 leaflet pairs were collected to test the leaf symmetry. Leaf length (L), width (W) and area (A) were measured for each leaflet in both of the experiments. The model identity test was used. The leaflet area can be estimated using the following formula: Â = W ×L × 0·25 × π. Experiment 2 showed that the initial leaflet pairs were equal, as were the terminal leaflet pairs. In conclusion, the mechanistic model should be used to estimate the leaf area for A. pintoi, and only half of each leaf can be measured.

O objetivo deste trabalho foi quantificar a fotossíntese foliar, durante o período de rebrotação, e estimar a fotossíntese de dosséis de duas espécies e cinco cultivares de braquiária, com base na arquitetura foliar e no ambiente luminoso no verão e inverno. Foram avaliadas quatro cultivares de Urochloa brizantha (Marandu, Xaraés, Arapoty e Capiporã) e uma de U. decumbens (Basilisk). Utilizou-se o delineamento de blocos ao acaso, com quatro repetições. As parcelas foram irrigadas e adubadas com 220 kg ha-1 por ano de N e K2O. Foi avaliada a taxa de assimilação de carbono nas folhas no dossel, o índice de área foliar (IAF) e a interceptação luminosa (IL). A fotossíntese foliar não variou entre cultivares ou estações, e houve assimilação de 0,91 mg m-2 s-1 de CO2 . Na fase inicial de rebrotação, o potencial fotossintético dos dosséis de verão e inverno foi baixo (0,80 mg m-2 s-1 de CO2); entretanto, dosséis forrageiros no inverno apresentaram maior aumento da assimilação de carbono por unidade de IAF. A fotossíntese de dossel, no final do período de rebrotação, foi 15% menor no inverno em comparação ao verão, e as correlações entre fotossíntese foliar e de dossel com a produção de forragem foram baixas. O IAF influencia fortemente os resultados do modelo de simulação da fotossíntese de dossel de espécies de braquiária.

Warm-season grasses are economically important for cattle production in tropical regions, and tools to aid in management and research of these forages would be highly beneficial. Crop simulation models synthesize numerous physiological processes and are important research tools for evaluating production of warm-season grasses. This research was conducted to adapt the perennial CROPGRO Forage model to simulate growth of the tropical species palisadegrass [ Brachiaria brizantha (A. Rich.) Stapf. cv. Xaraes] and to describe model adaptation for this species. In order to develop the CROPGRO parameters for this species, we began with values and relationships reported in the literature. Some parameters and relationships were calibrated by comparison with observed growth, development, dry matter accumulation and partitioning during a 2-year experiment with Xaraes palisadegrass in Piracicaba, SP, Brazil. Starting with parameters for the bahiagrass ( Paspalum notatum Flugge) perennial forage model, dormancy effects had to be minimized, and partitioning to storage tissue/root decreased, and partitioning to leaf and stem increased to provide for more leaf and stem growth and less root. Parameters affecting specific leaf area (SLA) and senescence of plant tissues were improved. After these changes were made to the model, biomass accumulation was better simulated, mean predicted herbage yield per cycle was 3573 kg ha −1 , with a RMSE of 538 kg DM ha −1 ( D -Stat = 0.838, simulated/observed ratio = 1.028). The results of the adaptation suggest that the CROPGRO model is an efficient tool to integrate physiological aspects of palisadegrass and can be used to simulate growth.

Crop models can aid the synthesis and application of knowledge, planning of experiments and forecasting in agricultural systems. Few studies have reviewed the uses and applications of these models for tropical forages. The purpose of this study was to review the information available in this scientific area, highlighting the main models, their applications and limitations. Several empirical models have been developed to predict the growth and biomass accumulation of tropical forages, especially for the genera Cynodon, Paspalum, Panicum and Brachiaria. Their application, however, is often location or region specific. The adaptation of mechanistic models to accurately predict biomass accumulation in tropical grasses is still limited. Recent advances have been made on the plot-scale and farm-scale process-based models ALMANAC, CROPGRO Perennial Forage and agricultural production systems simulator (APSIM), with promising results. In addition, global-scale process-based models, such as the Century Agroecosystem Model and the Orchidee Grassland Management Model, have been tested for tropical grassland areas. A greater number of regionspecific calibrations of empirical models can enhance their use, and improved databases and model parameterizations for a wide range of tropical grasses will enable the continuous improvement of mechanistic models. Made available in DSpace on 2019-12-16T18:10:44Z (GMT). No. of bitstreams: 1 2016cpamtbrunopedreirasimulationtropicalforagegrowthbiomassaccumulationmodeldevelopmentapplication.pdf: 524194 bytes, checksum: 5a0693f09bf6aa966a959c71adef465c (MD5) Previous issue date: 2016

O objetivo do presente estudo foi avaliar o acúmulo de forragem durante o verão agrostológico e a degradabilidade ruminal da matéria seca, fibra em detergente neutro e fibra em detergente ácido da forragem de cinco capins do gênero Panicum (Mombaça, Tanzânia, Massai, Tobiatã e Atlas) em Piracicaba, SP. O período experimental foi de setembro de 2003 a março de 2004. Os intervalos de colheita foram fixados em períodos de 28 dias para Atlas, Massai e Mombaça e em períodos de 35 dias para Tanzânia e Tobiatã, em função de suas características morfológicas e estruturais. Amostras de forragem foram incubadas, adotando-se seis tempos de incubação: 96; 48; 24; 12; 6; 3 e 0 horas. Os cultivares Mombaça (15.500 kg MS ha-1) e Massai (20.400 kg MS ha-1) destacaram-se com as maiores produções de forragem. O estudo da degradabilidade in situ mostrou que, embora sua composição química seja bastante semelhante, alguns fatores importantes como a degradabilidade potencial, tempo de colonização e degradabilidade efetiva diferem entre genótipos, o que sugere diferentes potenciais de produção animal. Palavra-chave: gramínea, in situ, incubação, tempo de colonização. FORAGE YIELD AND RUMINAL DEGRADABILITY OF FIVE Panicum spp GRASSES ABSTRACT The aim of this study was to evaluate the forage yield during the growing season of 2003/2004 as well as the ruminal dry matter degradability, neutral detergent fiber and acid detergent fiber concentration in the forage of five Panicum grasses (Mombaça, Tanzânia, Massai, Tobiatã and Atlas) in Piracicaba, SP. Rest period was fixed on 28 days for Atlas, Massai and Mombaça and 35 days for Tanzânia and Tobiatã, according to their morphologic and structural characteristics. The samples were incubated for 96; 48; 24; 12; 6; 3 and 0 hours. Mombaça (15500 kg DM ha-1) and Massai (20400 kg DM ha-1) were the highest yielding genotypes. Ruminal degradability showed that, although chemical composition is similar across genotypes, some parameters such as potential degradability, lag time and effective degradability are variable, suggesting contrasts in animal production potential. Keywords: grass, in situ, incubation, lag time. DOI: http://dx.doi.org/10.14583/2318-7670.v02n03a03

Produtores de leite de três mesorregiões (Central, Centro-Oeste e Campos das Vertentes) do Estado de Minas Gerais foram convidados a participar do levantamento das práticas de produção e uso de silagens em suas propriedades. Trinta e nove produtores responderam a um questionário durante um dia de campo, realizado no município de Ijaci, Estado de Minas Gerais. O questionário continha 22 perguntas que incluíam informações referentes às seguintes características: os rebanhos utilizados nas propriedades (n=3); o processo de ensilagem (n=9); o desabastecimento do silo (n=4), e o uso da silagem na alimentação animal (n=3), além de mais três questionamentos sobre a atividade. O milho foi a cultura mais citada pelos produtores na produção de silagem, sendo que, dos 39 produtores entrevistados, 38 (97,4%) afirmaram que utilizam tal cultura isoladamente ou com outras forrageiras. A maioria dos produtores no momento da colheita da forragem faz uso de colhedoras tracionadas por trator (92,3%). Lonas do tipo dupla face foram as mais citadas (84,6%) pelos produtores como ferramenta utilizada na vedação dos silos. A maioria dos produtores (61,5%) retira menos de 20 cm de silagem por dia no painel e 87,2% descartam silagem com aspecto deteriorado antes de fornecer aos animais. A maioria (92,3%) dos entrevistados não faz nenhum tipo de análise bromatológica da silagem produzida. O uso de técnicas de manejo consideradas simples – como o tipo de lona usada na vedação, a cobertura utilizada sobre a lona e o correto avanço no desabastecimento do silo – ainda é um entrave na obtenção de silagens menos deterioradas e com menores taxas de descarte.

O objetivo deste trabalho foi avaliar as respostas morfogênicas e estruturais de duas espécies e cinco cultivares de braquiária a intensidades de desfolhação. As cultivares Marandu, Xaraés, Arapoty, Capiporã (Urochloa brizantha) e Basilisk (U. Decumbens) foram desfolhadas mecanicamente a 15 e 7,5 cm de altura, durante o verão e o inverno. Utilizaram-se unidades experimentais de 9x4 m, irrigadas e adubadas com 220 kg ha-1 por ano de N e K2O. As características morfogênicas avaliadas foram: filocrono e senescência, duração de vida e taxas de aparecimento e alongamento de folhas. As características estruturais foram: número de folhas vivas por perfilho, comprimento final das folhas expandidas e de colmos, relação senescência/crescimento e densidade populacional de perfilhos. Variações nas condições meteorológicas, em cada estação, promoveram aumentos nas taxas de aparecimento e alongamento, diminuição do filocrono e duração de vida das folhas. As características estruturais mais responsivas ao gradiente promovido pelas alturas de corte foram o comprimento final de folhas expandidas e a densidade populacional de perfilhos. A altura de corte mais baixa exerceu maior impacto na dinâmica de crescimento do que na senescência, em perfilhos individuais. As cultivares Xaraés e Capiporã foram as mais produtivas, em razão das maiores taxas de alongamento foliar e maior densidade populacional de perfilhos. The objective of this work was to evaluate structural and morphogenetic responses of two species and five cultivars of brachiaria to defoliation intensities. The cultivars Marandu, Xaraés, Arapoty, Capiporã (Urochloa brizantha), and Basilisk (U. decumbens) were mechanically defoliated at 15 and 7.5 cm, in mid-summer and mid-winter. The experimental units (9x4 m plots) were irrigated and fertilized with 220 kg ha-1 per year of N and K2O. Morphogenetic characteristics measured were: phyllochron, leaf senescence and life span, and leaf appearance and elongation rate. The structural characteristics evaluated were: number of leaves per tiller, final leaf length of fully expanded leaves, stems length, senescence/growth ratio, and tiller density. Variations in meteorological conditions of each season promoted increasing of the appearance rates and leaf elongation, and decreasing of the phyllochron and leaf life span. The structural features most responsive to the gradient promoted by harvesting heights were the final leaf length of expanded leaves and tiller density. The lower harvest height had the greatest impact on growth dynamics in comparison to senescence, in individual tillers. The cultivars Xaraés and Capiporã were more productive due to higher leaf elongation rates and higher tiller density.

The objective of this research was to characterize the nutritive value of corn silage made on intensive dairy farms and demonstrate the nutritional variations between silages located at the top and at the center of a bunker silo. Thirty-two dairy farms were visited in four Brazilian states. One corn bunker silo of each farm was chosen and samples were collected from the top and center parts. The nutritive value, fermentation end-products, and microbial counts were assessed. The predicted milk was determined by Milk2006 spreadsheet. The mean, standard deviation, maximum, minimum, and 95% confidence interval of all data were calculated. The ash, neutral detergent fiber (NDF), starch, in vitro NDF, and dry matter (DM) digestibility data were compared with reference value. Both statistical procedures were performed through the PROC MEANS of SAS. The mean values found at the center for NDF, starch, total digestible nutrients (TDN-1x), and estimated milk were 503 g kg−1 DM, 308 g kg−1 DM, 583 g kg−1, and 1,124 kg t−1, respectively. The top silages presented a mean TDN-1x and predicted milk of 559 g kg−1 and 1046 kg t−1, respectively. For NDF digestibility and starch concentration, 53.1% and 62.5% of the center samples presented a value equal to or above the reference value (500 g kg−1 and 300 g kg−1 DM for NDF digestibility and starch concentration, respectively). Overall, the corn silage produced on intensive dairy farms in Brazil has satisfactory nutritive value, especially in terms of starch concentration. Some parameters, such as the concentration of fiber and its digestibility, should be improved. This study also shows that a silo may contain two different types of silage: top and center. This alerts nutritionists and farmers when feeding and sampling corn silage from bunker silos.