This study aimed to evaluate the effects of different grazing intensities on residual straw mass, soil water content, available water between field capacity and the wilting point, and soybean yield. The experiment was conducted in a randomized block design with three replications, on a Typic Hapludox soil under a non-irrigated integrated crop-livestock (ICL) system. The experiment was established in the 2009/2010 season in Xambrê County, in the Northwestern region of Paraná State, Southern Brazil. The treatments consisted of five palisadegrass grazing height treatments: an ungrazed control and grazing heights of 10, 20, 30, and 40 cm, maintained through variable stocking rates. Palisadegrass dry mass was evaluated three times, and soil water content was measured 19 times during soybean cultivation in the 2013/2014 crop season, and soybean grain yield. In this ICL system, managing palisadegrass at a grazing height of 30 cm resulted in greater water availability in the 0-10 cm soil layer during the soybean growing season. However, soybean grain yield was not influenced by grazing heights management, due to severe dry spells between December and February. During this period, soil water content fell below 50% of the available water, coinciding with the critical grain-filling stage of soybean development. Monitoring water availability in sandy soils under ICL systems highlighted the need for supplemental irrigation to improve soybean grain yield under drought conditions.

Soil compaction periodic monitoring through soil penetration resistance (PR) has been a rapid, easy, and economic way to evaluate the different management systems on soil physical attributes effect. The aim was to evaluate the grazing intensities and nitrogen fertilization effect in two winter/summer seasons (black oat/corn/black oat/soybean) on soil PR in an integrated crop-livestock system. The experimental design was in randomized blocks, in a factorial 2×3 [2 black oat pasture residual heights (15 and 7 cm), under rotational grazing × 3 nitrogen rates applied to pasture (0, 75 and 150 kg N ha-1)], with 4 repetitions. Soil PR was measured using an electronic penetrograph to an 80 cm depth. Soil samples were collected to determine gravimetric moisture. In the first year, 75 kg N ha-1 resulted in the highest depth compaction while intensive grazing (7 cm) resulted in the highest PR. In the second year, plots without N resulted in lower PR levels, mainly in the superficial layers. However, the rate of 150 kg N ha-1 presented greater compaction in the 15-20 cm layer after grazing. The high moisture levels in depth reduced PR in all evaluated periods, highlighting the close relationship between both variables. General grazing heights did not affect PR, but the use of systems that increase residues production, as moderate grazing and nitrogen fertilization might be an alternative to mitigate the soil compaction in surface layers effects.

Changes in grazing intensity affect forage production and performance of animal on C4 grass pastures; however, these relationships are not well defined for cattle grazing on limpograss (Hemarthria altissima (Poir) Stapf & C.E. Hubb. cv. Flórida) under continuous stocking. The objective of this study was to quantify plant and animal production from Flórida limpograss pastures, managed at different grazing intensities by beef heifers (i.e. different sward heights) in order to define pasture management outcomes that maximise plant and animal responses. For a 3-year period, the influence exerted by the sward height (10, 20, 30 and 40 cm) was assessed. Greater total herbage accumulation and herbage accumulation rate were observed for the more lenient grazing heights (30 and 40 cm). The 20-, 30- and 40-cm heights revealed similar heifer average daily gain of 0.49 kg liveweight (LW) animal–1 day–1, reducing at the rate of 0.04 kg LW animal–1 day–1, for each cm decrease below 19 cm, according to a segmented equation. LW gain per area showed a quadratic response to the sward height, with optimum values (i.e. 2.1 kg LW ha–1 day–1) achieved at a pasture height of around 21 cm. Therefore, to optimise cattle performance on continuously stocked Flórida limpograss pastures, a sward height of ~20 cm should be maintained.

Sheep production on pasture plays an important role in subtropical climates around the world, with great economic and environmental relevance to those regions. However, this production is much lower than its true potential in subtropical regions, largely due to lack of knowledge of how to feed grazing lambs, and mitigate gastrointestinal parasite infections. Due to weather instability and the high growth rate of tropical grasses, it is difficult to adjust the quality and quantity of feed consumed by lambs. In addition, due to warm, wet weather during spring, summer, and autumn, gastrointestinal parasite infection can be intense on subtropical pastures. Thus, the objective of this paper is to summarize 17 years of research in southern regions of Brazil testing alternative management for sheep farmers under these challenging conditions. Our review indicates that ewes play important roles raising their lambs. Besides protecting and providing milk, they leave a better pasture structure for lamb nutrition. The use of creep feeding and creep grazing are additional alternatives to improve lamb growth. However, feeding supplementation with concentrate can deteriorate pasture quality at the end of the summer–autumn season. Gastrointestinal parasitic infections can be reduced with improved lamb nutrition, although L3 larvae of Haemonchus contortus can be present at various pasture heights. This indicates that it is difficult to control L3 ingestion solely by manipulating grazing heights. We summarize important technologies for raising lambs on pasture-based systems to make the best of high herbage growth and minimize intense parasitic infections common in subtropical regions. We discuss research results in light of the latest studies from other ecoregions and climates, although there is a lack of similar research in subtropical regions of the world.

Effects of Nitrogen fertilisation and stocking rates on soil erosion and water infiltration in a Brazilian Cerrado farm

Abstract It is well reported in the scientific literature that pastures can have similar net forage accumulation when managed with contrasting structures. However, we hypothesized that the dynamics of forage accumulation in grazed swards is linked to seasonal‐environmental conditions. Marandu palisadegrass (Brachiaria brizantha [Hochst. ex A. Rich.] was used as the forage species model. The experimental treatments were four grazing heights (10, 20, 30 and 40 cm) allocated to experimental units according to a randomized complete block design with four replicates and evaluated throughout four contrasting environmental seasons (summer, autumn, winter–early spring and late spring). Under rainy and warm periods, greater net forage accumulation was observed in pastures maintained taller; on the contrary, during the mild and dry periods, net forage accumulation rate reduced as grazing height increased. Such patterns of responses were related to compensations between tiller population density and tissues flows during summer and late spring and the reduced capacity of taller canopies to compensate lower population with greater growth rates during autumn and winter–early spring. Grazed swards changed their patterns of forage growth as they transitioned from favourable to more abiotic stressful conditions, suggesting that seasonal adjustments in grazing intensities are necessary in order to maximize forage production.

ABSTRACT To evaluate the foraging behaviour of yearling bulls grazing on Marandu grass, we conducted two experiments. In the first experiment (Exp. 1), three grazing heights of 15, 25, and 35 cm were evaluated, with bulls receiving 0.3% of body weight (BW) of supplement (161 g kg–1 crude protein (CP) and 20.1 MJ kg–1 gross energy (GE)); in the second experiment (Exp. 2), supplementation levels were decreased as grazing height increased: (1) low height (15 cm) and high supplementation (0.6% BW: 142 g kg–1 CP and 18.9 MJ kg–1 GE (LH-HS)); (2) moderate height (25 cm) and moderate supplementation (0.3% BW: 161 g kg–1 CP and 20.1 MJ kg–1 GE (MH-MS)) or (3) high height (35 cm) without supplementation (HH-WS). Ingestive behaviour was evaluated by direct visual observations, and intake using markers. It was used 9 paddocks each experiment. The experimental design was completely randomized, analysing effects by polynomial orthogonal contrasts (Exp. 1) and Tukey test (Exp. 2). In Exp. 1, a linear decreasing response to daily grazing time (P < 0.01) was observed, whereas a linear increasing response to herbage intake (P < 0.01) was observed with increased grazing height. In Exp. 2, LH-HS bulls had lower herbage intake (P < 0.01) than their counterparts. Bulls from both experiments showed increased grazing activity after 12 PM (P < 0.05). The herbage intake substitution effect of supplements can be explored as a production strategy, as the adjustment of supplementation levels can promote high dry matter intake as well as performance in beef cattle, in conditions of low grazing height or low forage allowance, even with a high stocking rate.

Abstract The ability to quantify forage mass (FM) is needed when budgeting pasture supply. Calibrated sward height is an indirect measure of FM. In a previous study, it was observed that the regression intercept and slope of forage density vs. height (FDint and FDslope, respectively) had a strong linear relation, giving rise to the hypothesis that there is a calibration continuum across pastures. This hypothesis was tested using 121 plate meter calibrations conducted across a range of plant species, defoliation managements, land resource areas, latitude, and elevation. Sward compressed height (CHt) was measured using a resting plate meter. Within calibrations, 30 to 60 paired CHt and FM samples were collected: half pre‐grazing and half post‐grazing. Within calibrations, the linear relation between CHt and forage density (FD) was calculated. Across calibrations, the linear relation between FDint and FDslope was calculated. Forage mass available for grazing (FMAG) was predicted using individual calibrations and the continuum calibration and compared with forage mass grazed (FMG) measured using pre‐ and post‐grazing clipped samples. Across calibrations, there was a strong linear relation between FDint and FDslope (R2 = 0.83). Within calibrations, predicted FMAG vs. FMG was accurate and precise. Across events, predicted FMAG using the continuum was accurate but less precise. Using the continuum to estimate FMAG provided estimates within 10% for recommended grazing heights. Factors that determine the relation between FDint and FDslope include morphology of the dominate grass, species composition, tiller size/density compensation, sward growth to optimize light interception, and tiller dynamics relative to time of year.

Differences in chemical composition and fatty acid profile of Longissimus muscle in Nellore cattle under different grazing heights (15, 30, 45 and 60 cm) of xaraés grass were tested. Longissimus muscle sample was collected 24 h after slaughter and the chemical (moisture, mineral residue, protein and total lipids) and fatty acids composition was quantified. Only fatty acid profiles were different on percentages of lauric (12:0), oleic (18:1n9c) and eicosadienoic acid (20:2), being best in height of 30 cm grazing (0.36%, 0.85% 39.7% and 1.83%, respectively); myristic (14:0) and conjugated linoleic acid (C18:2,c9-t11) presented better value for the height of 60 cm (4.04% and 0.23%, respectively). Percentage of omega-3 (n-3) and omega-6 (n-6) were better at 30 cm grazing, with values of 2.61% and 8.32%, respectively. Grazing height between 30 and 45 cm improves the levels of fatty acids, important to human healthy, in Longissimus muscle of Nellore cattle.

Carcass characteristic and meat quality from bulls and Nellore steers (n = 64 total) subjected to different grazing heights (15, 25, 35, and 45cm) were evaluated isolatedly, under continuous grazing and variable load, in pastures of Convert grass. The experimental period was from May 2015 to June 2017, in an area of 16ha, divided into 16 paddocks of 1ha. The experimental design was randomized blocks with four replications. Each paddock was grazed by three animals and regulators, used to adjust grazing heights. The final slaughter weight, hot carcass, and crude protein in the meat of steers were higher when the pastures were managed at 42cm. When the pasture was managed between 25 and 35cm in height, greater fat thickness, marbling, muscle:bone and muscle+fat:bone ratio and lower color* of the meat and percentage of bone were found. For the steers, the height of 40cm provided higher fat thickness and marbling in the meat. The loss during thawing in meat was greater at 28cm in height. The heights of grazing alter the carcass characteristics and meat of bulls and steers.

A matéria orgânica do solo é essencial dentro do sistema agrícola e seu acúmulo pode ser favorecido pelo aporte de resíduos vegetais sobre o solo. Objetivou-se avaliar o efeito da altura de pastejo de Urochloa ruziziensis nos teores e estoques de carbono orgânico e nitrogênio do solo, em sistema agropastoril, em Latossolo Vermelho Distrófico típico. Para o estudo foram coletadas amostras de solo entre os anos de 2010 e 2012. O delineamento foi em blocos casualizados em parcelas subdivididas no tempo e cinco tratamentos, constituídos pelas alturas de pastejo: 10; 20; 30 e 40 cm e mais uma área não pastejada de Urochloa ruziziensis, e três repetições. Determinou-se nas camadas do solo (0-10, 10-20 e 20-30 cm de profundidade) o teor e estoque de carbono orgânico total, carbono orgânico particulado, carbono orgânico associado aos minerais, teor e estoque de nitrogênio total e o teor de nitrogênio mineral. As variáveis estudadas foram submetidas à análise de variância pelo teste F e as médias foram comparadas pelo teste de Tukey, ambos, ao nível de 5% de probabilidade. Os teores e estoques de carbono orgânico total e suas respectivas frações, os teores de nitrogênio total e mineral do solo, além, dos estoques de nitrogênio total do solo, não foram alterados pelas alturas de pastejo e a área não pastejada. Todavia, na camada 0-10 cm, ocorreu aumento dos teores e estoques de carbono orgânico total, carbono orgânico associado aos minerais e redução do carbono orgânico particulado do solo, e, também, aumento dos teores e estoques de nitrogênio total entre o primeiro e o segundo ano de condução, sob plantio direto. Houve aumento dos teores de nitrogênio mineral após a colheita da soja para todas as camadas do solo.

SUMMARY The objectives were to evaluate the performance of bull calves under two grazing strategies and the use of energy supplementation in a rotational system of marandu palisade grass (Urochloa brizantha) and to assess the morphological and chemical composition of the grass. Eighty eight-month-old bulls of 224 ± 2.4 kg body weight (BW) were used in a completely randomized block design in a 2×2 factorial arrangement of two post-grazing heights (i.e.10 cm or 15 cm) and of a citrus pulp-based supplement (i.e. 72% total digestible nutrients) fed daily at 0 or 6 g/kg BW. Initial grazing height was set at 25 cm with variable grazing intervals and stocking rate adjustments used to control the grazing heights. Statistical analyses were performed using the SAS Mixed procedure. Significance was set at 0.05. Forage data from 12 pre-determined paddocks showed no differences in forage mass (FM) and morphological composition at pre-grazing, but greater post-grazing FM and shorter grazing interval in pastures managed at 15 cm. Higher grazing pressure resulted in lowest BW gains for non-supplemented bulls in the 10 cm treatment. The use of an energy supplement and 15 cm postgrazing height resulted in the greatest BW gains; however, combination of10 cm post-grazing height and energy supplementation allowed greater stocking rates. Under high grazing pressure, supplementary feed overcame the normal limitations, and high gains were achieved.

Abstract The aim of this study was to evaluate some morphogenetic and structural characteristics to explain variations in forage accumulation of Alexandergrass (Urochloa (Syn. Brachiaria) plantaginea) under continuous stocking method. The experimental treatments consisted of four grazing heights (10, 20, 30, and 40 cm), allocated to experimental units following a randomized block design with three replicates. The following variables were analyzed: leaf appearance, elongation, and senescence rates, leaf lamina length, number of leaves per tiller, leaf area index (LAI), and forage accumulation rate. Data were submitted to analysis of variance and means were compared by Student's t-test (P≤0.05). The main results were: i) different grazing heights had different tissue flows; ii) grazing heights between 30-40 cm showed the highest LAI, and produced similar values; iii) forage accumulation rate increased according to grazing height increments, but did not change above 30 cm. In conclusion, Alexandergrass pastures under continuous stocking should not be maintained at grazing heights lower than 30 cm if the objective is to maximize forage production.

For continuously stocked pastures, net forage accumulation is thought to be relatively unaffected across a rather large range of canopy‐based management targets. It is not known whether this is also characteristic of intermittently stocked canopies, and if so, the underlying mechanisms have not been well delineated. We hypothesized that initiation of grazing when canopy heights are shorter than heights corresponding to the critical leaf area index, associated with a moderate intensity of defoliation, do not reduce forage accumulation in pastures under intermittent stocking. Therefore, kikuyugrass (Pennisetum clandestinum Hochst. Ex Chiov) pastures were grazed at four pregrazing heights (10, 15, 20, and 25 cm) with the same proportion of defoliation (50% reduction in pregrazing height; i.e., postgrazing heights of 5, 7.5, 10, and 12.5 cm, respectively) from December 2011 to May 2013. As the canopy height increased, there was an inverse relationship between tiller weight and number; however, heavier tillers presented greater rates of leaf elongation. Pastures grazed at 15 to 25 cm had the same forage accumulation. The same homeostatic mechanisms that keep a constant forage accumulation in different heights when pastures are subjected to continuous stocking also allowed for a similar forage accumulation in pastures under intermittent stocking at different grazing heights.

Influence of post-weaning management system during the finishing phase on grasslands or feedlot on aiming to improvement of the beef cattle production

The objective of this study was to evaluate the agronomic characteristics of corn seed inoculated with Azospirillum brasilense , grown on black oat and ryegrass straw, and managed under different grazing strategies and doses of nitrogen. The experiment was conducted in Santa Maria, Rio Grande do Sul State, Brazil, during two agricultural seasons (2012/2013 and 2013/2014) in a randomized, complete block design with three replications. In the winter period, black oat and ryegrass straw were managed at different grazing heights by sheep (0.30, 0.20, 0.10 m, conventional grazing, and no grazing) with three doses of nitrogen (0, 50, and 100 kg ha -1 , with or without inoculation by A . brasilense ). We used the hybrid Pioneer (P1630H ® ) in 2012 and the hybrid Agroeste (AS 1551 ® ) in 2013. The height of corn plants was greater when they were grown on black oat and ryegrass straw, and the absence of grazing favored productivity. Under drought conditions, the application of nitrogen to the pasture favored corn development, increasing plant height, ear height, and stem diameter. Inoculation with A. brasilense had a positive effect on the characteristics of yield and productivity of corn, independent of growing season and hybrid used.

The aim of this study was to evaluate agronomic and structural traits, as well as root mass, of Panicum maximum cv. Mombasa in different conditions of animal grazing in the same pasture in a monoculture system and a Pasture-Forestry Intercropping System (intercropped with Babassu palm trees). Evaluations were performed from December 2012 to February 2013. The systems were kept under continuous grazing with sheep (20 kg live weight on average) throughout the evaluation period. The design was completely randomised into split plots, in which each plot was the system and the subplots were grazing heights, with three sample cycles. The Babassu palm tree influenced the production of the aerial-part dry matter in the intercropping system due to a decrease in grass tillering caused by shading stress. The root dry matter decreased influenced by shading and intensity of animal grazing in the evaluated heights, leading to a reduction as decreased the grass height. The monoculture system led to better results for the same heights in all parameters in comparison to the intercropping system, including the number of tillers, dry matter production (DM), leaf-area index (LAI) and DM (%), which were higher in the monoculture system regardless of the assessed heights. The natural shade of Babassu palms negatively affected the productive and structural traits of Panicum maximum cv. Mombasa, thereby altering the grass structure and lowering its productive capacity.

Resumo: O objetivo deste trabalho foi avaliar o efeito da altura de pastejo em braquiária (Urochloa brizantha) sobre o carbono orgânico total e a qualidade física de Latossolo Vermelho, após cultivos de soja e períodos de pastejo em braquiária, em sistema integração lavoura-pecuária (ILP). Utilizou-se o delineamento de blocos ao acaso, com quatro tratamentos (alturas de pastejo de 0,10, 0,20, 0,30 e 0,40 m) e três repetições, no quarto e quinto anos após a implantação do ILP. As amostras de solo, coletadas das camadas de 0,00-0,10 e 0,10-0,20 m, apresentaram textura arenosa: 126 e 132 g kg-1 de argila, respectivamente. Foram avaliadas as seguintes variáveis: carbono orgânico total, densidade do solo (Ds), intervalo hídrico ótimo (IHO) e densidade do solo crítica (Dsc). A qualidade física do solo no sistema ILP depende do manejo da altura de pastejo em braquiária no outono-inverno. A altura de pastejo de 0,27 m proporcionou os maiores valores de carbono orgânico total e IHO mais amplo à profundidade de 0,10-0,20 m. O cultivo da braquiária reduz mais a frequência de amostras de solo com Ds&gt;Dsc do que o cultivo da soja, e o manejo da altura de pastejo da braquiária contribui para o aumento da qualidade física do solo.

O manejo da altura de pastejo das forrageiras pelos bovinos pode comprometer os atributos físicos do solo. O objetivo deste trabalho foi avaliar a influência da altura de pastejo de braquiária (Urochloa ruziziensis) e a carga animal média, após três anos de sistema integração lavoura-pecuária com soja, nos atributos físicos de um Latossolo Vermelho distrófico típico. O delineamento experimental foi de blocos casualizados, com três repetições. Cinco tratamentos com 10, 20, 30 e 40 cm de altura de pastejo, após 84 dias de pastejo contínuo mantidos com carga variável de bovinos, e um tratamento testemunha sem pastejo foram avaliados em parcelas experimentais de 1 ha. Em novembro de 2012, após o terceiro período de pastejo, com carga animal média de 1.262, 919, 892 e 724 kg ha-1 de peso vivo, respectivamente, para as alturas de pastejo de 10, 20, 30 e 40 cm, coletaram-se amostras indeformadas de solo nas camadas de 0-10, 10-20 e 20-30 cm, as quais foram utilizadas para determinar as curvas de retenção de água e de resistência do solo à penetração e a densidade do solo (Ds), bem como para calcular o intervalo hídrico ótimo (IHO). A menor Ds ocorreu na camada de 0-10 cm para a altura de pastejo de 31 cm da braquiária que correspondeu a 72 % da carga animal máxima. O maior IHO ocorreu na camada de 10-20 cm para a altura de pastejo de 23 cm da braquiária que correspondeu a 83 % da carga animal máxima. O manejo da altura de pastejo da braquiária foi limitado em 23 cm pela maior carga animal e melhores atributos físicos na camada de 10-20 cm do Latossolo Vermelho distrófico típico.

A presença de animais em áreas de lavoura pode alterar a estrutura física do solo, sendo que a intensidade de pastejo contribui para esse resultado. Este trabalho objetivou avaliar os atributos físicos do solo e a produtividade de soja e braquiária, em sistema integrado de produção agropecuária, sob plantio direto. Os tratamentos foram distribuídos em blocos casualizados, com três repetições, e consistiram de diferentes alturas de manejo do pasto (0,25 m, 0,35 m e 0,45 m) e uma área sem pastejo. Foi determinada a biomassa seca da parte aérea e raiz da soja e braquiária e a produtividade da soja. Amostras de solo foram coletadas nas camadas de 0-5 cm, 5-10 cm e 10-20 cm de profundidade, sendo determinados os seguintes atributos físicos: densidade, porosidade total, macroporosidade, microporosidade, resistência à penetração e diâmetro médio ponderado de agregados. As intensidades de pastejo não interferiram na densidade do solo em nenhuma das camadas. Houve redução da porosidade total após o segundo ciclo de pastejo, na camada de 0-5 cm. O diâmetro médio ponderado de agregados foi menor nas áreas pastejadas nas camadas de 0-5 cm e 10-20 cm e verificou-se aumento da resistência mecânica à penetração em todas as camadas, principalmente para o pastejo a 0,25 m de altura. A quantidade de biomassa seca total (soja + braquiária) e biomassa seca da parte aérea da braquiária foram menores nas áreas pastejadas, no entanto, a produtividade da soja não foi influenciada pelos ciclos de pastejo.