Comparing grazing intensities in crop-livestock systems with STICS

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Diversidade metabólica e atividade microbiana no solo em sistema de integração lavoura‑pecuária sob intensidades de pastejo

The objective of this work was to evaluate the metabolic diversity and the microbial activity in an integrated crop-livestock system under no-tillage, and at different grazing intensities and soybean production. The experiment was carried out in São Miguel das Missões county, in Rio Grande do Sul state, Brazil, in a clayey Rhodic Hapludox (Oxisol), subjected to grazing intensities at 10, 20, 30 and 40 cm‑height of pasture with black oat + italian ryegrass, and a nongrazing treatment, in the winter. The metabolic diversity was evaluated with the Biolog EcoPlate technique, by the Shannon diversity index, and the microbial activity by the fluorescein diacetate hydrolysis method. There was higher functional diversity at the moderate grazing intensities (20 to 40 cm). The highest microbial activity, in the soil, occurred in the nongrazing treatment because of the high quantity of plant residues. Microbial functional diversity and activity had alterations caused by the grazing intensities, which can be used as soil quality indicators on integrated crop-livestock systems under no-tillage.O objetivo deste trabalho foi avaliar a diversidade metabólica e a atividade microbiana, em sistema de integração lavoura-pecuária em plantio direto, sob diferentes intensidades de pastejo e produção de soja. O experimento foi realizado em São Miguel das Missões, RS, em Latossolo Vermelho distroférrico argiloso, submetido ao pastejo a 10, 20, 30 e 40 cm de altura de azevém + aveia-preta, e sem pastejo, no inverno. A diversidade metabólica foi avaliada com microplacas Biolog EcoPlate pelo índice de diversidade de Shannon, e a atividade microbiana pelo método de hidrólise do diacetato de fluoresceína. Houve maior diversidade funcional a intensidades moderadas de pastejo (20 a 40 cm). A maior atividade microbiológica no solo ocorreu no tratamento sem pastejo, em consequência da grande quantidade de resíduos vegetais remanescentes. A diversidade funcional da microbiota e a atividade microbiana tiveram alterações causadas pelas intensidades de pastejo, que podem ser utilizadas como indicadores de qualidade do solo, em sistema de integração lavoura-pecuária em plantio direto

Integrated crop and livestock systems increase both climate change adaptation and mitigation capacities.

peer reviewedIntegrated crop-livestock systems (ICLS) are proposed as key solutions to the various challenges posed to present-day agriculture which must guarantee high and stable yields while minimizing its impacts on the environment. Yet the complex relationships between crops, grasslands and animals on which they rely demand careful and precise management. In this study, from a 18-year ICLS field experiment in Brazil, that consists in annual no-till soybean-pastures grazed by beef cattle, we investigated the impacts of contrasted pastures grazing intensities (defined by sward heights of 10, 20, 30 and 40 cm, plus an ungrazed treatment) on the agroecosystem productivity and soil organic carbon (SOC) under both historical and future (2040-2070, RCP8.5) climatic conditions. We used an innovative methodology to model the ICLS with the STICS soil-crop model, which was validated with field observations. Results showed that the total system production increased along with grazing intensity because of higher stocking rates and subsequent live weight gains. Moderate and light grazing intensities (30 and 40 cm sward heights) resulted in the largest increase in SOC over the 18-year period, with all ICLS treatments leading to greater SOC contents than the ungrazed treatment. When facing climate change under future conditions, all treatments increased in productivity due to the CO2 fertilization effect and the increases in organic amendments that result from the larger stocking rate allowed by the increased pasture carrying capacity. Moderate grazing resulted in the most significant enhancements in productivity and SOC levels. These improvements were accompanied by increased resistance to both moderate and extreme climatic events, benefiting herbage production and live weight gain. Globally, our results show that adding a trophic level (i.e. herbivores) into cropping systems, provided that their carrying capacities are respected, proved to increase their ability to withstand climate change and to contribute to its mitigation

Italian ryegrass management, pasture larval contamination and parasitic infection in sheep

O objetivo deste trabalho foi avaliar o efeito do manejo da pastagem de azevém sobre o risco de reinfecção parasitária. Foram utilizadas duas ofertas (10 e 20 kg de matéria seca por 100 kg de peso vivo)em dois métodos de pastejo (lotação contínua e intermitente). A infestação parasitária no mantilho e nos diferentes estratos da forragem foi avaliada nos estratos: acima de 15, 10–15, 5–10, 2,5–5 e 0–2,5 cm; a carga parasitária no animal foi avaliada por exames coproparasitológicos; e a seletividade da dieta foi avaliada comafi lhos marcados. Independentemente do método, a densidade larval aumentou do topo para a base do dossel forrageiro. No entanto, entre os estratos aptos ao pastejo foram observadas diferenças na oferta de 20% do peso vivo. A oferta infl uenciou o número de larvas recuperadas na forragem e a infecção no animal para ambos os gêneros de parasitas Haemonchus spp. e Trichostrongylus spp. A maior oferta proporcionou maior contaminação larval e infecção nos ovinos, porém na oferta de 10% do peso vivo, a quantidade de larvas presentes no pasto foi menor em lotação contínua, mas a carga parasitária no animal foi semelhante à da lotação rotacionada, independentemente do método de pastejo.The objective of this work was to evaluate the effect of Italian ryegrass management pasture on parasite reinfection risk. The pasture was submitted to two forage offers (10 and 20 kg of dry matter by 100 kglive weight) in two grazing methods (set stocking and rotational). The parasitic infestation was analyzed in litter and in different forage strata: above 15, 10–15, 5–10, 2.5–5, and 0–2.5 cm; parasitic burden in sheep was evaluated through parasitological tests; and marked tillers were used for selective diet evaluation. Independently of the method, larval density increased from the top to the base of sward canopy. However, among grazing strata, differences were observed when forage allowance was 20% of live weight. The offer infl uenced the number of larvae recovered in the pasture and the animal infection for both parasite genera Haemonchus spp. and Trichostrongylus spp. The highest offer provided the highest recovery of infective larvae and animalinfection. However, at low forage offer (10% live weight), infective larva in pasture was lower in set stocking, but the animal parasitic burden was similar to the rotational stocking, independently of the grazing method

In vitro fermentation profile and methane production of Kikuyu grass harvested at different sward heights

Highly digestible forages are associated with an in vitro low-methane (CH4) rumen fermentation profile and thus the possibility of reducing CH4 emissions from forage-based systems. We aimed to assess the in vitro ruminal fermentation profile, including CH4 production, of the top stratum of Kikuyu grass (Cenchrus clandestinus - Hochst. ex Chiov) harvested at different sward heights (10, 15, 20, 25, and 30 cm). Herbage samples (incubating substrate) were analyzed for their chemical composition, in vitro organic matter digestibility (IVOMD), and morphological components. In vitro incubations were performed under a randomized complete block design with four independent runs of each treatment. Gas production (GP), in vitro dry matter digestibility (IVDMD), CH4 production, total volatile fatty acid (VFA) concentration, and their acetate, propionate, and butyrate proportions were measured following 24 and 48 hours of incubation. Herbage samples had similar contents of organic matter, neutral detergent fiber, and crude protein for all treatments. However, a higher acid detergent fiber (ADF) content in taller sward heights than in smaller sward heights and a tendency for metabolizable energy (ME) and IVOMD to decrease as sward height increased were found. Similarly, the stem + sheath mass tended to increase with increasing sward height. Amongst the nutrients, ME (r = –0.65) and IVDMD (r = –0.64) were negatively correlated with sward height (p < 0.001) and ADF was positively correlated with sward height (r = 0.73, p < 0.001). Both the GP and IVDMD were negatively related to the sward height at both incubation times. Sward heights of Kikuyu grass below 30 cm display an in vitro profile of VFAs high in propionate and low in acetate, with a trend toward lower methane production of CH4 per unit of IVDMD. These findings are important to aid decision-making on the optimal sward height of Kikuyu grass and manage animal grazing with the opportunity to reduce CH4 production

Acúmulo de forragem e características morfogênicas e estruturais de Axonopus aureus no cerrado de Roraima

The effects of cutting plant age (21, 28, 35, 42, 49, 56, 63 and 70 days) on dry matter (DM) yield, and morphogenetic and structural characteristics of Axonopus aureus, during rainy season, were evaluated under natural field conditions. The experimental design was a completely randomized, with three replications. Evaluations were carried out during the period of June to August 2009. DM yield, absolute growth rate (AGR), number of tillers plant-1, number of leafs plant-1, leaf area, leaf senescence and elongation rates and blade length increased consistently with growth stage. The relations between DM yield and AGR with cutting plants age were described by the quadratic regression model. The maximum DM yield and forage production rate performance were estimated at 62.7 and 49.4 days of regrowth. The crop growth and relative growth rates, tiller and leaf appearance rates were inversely proportional to cutting plant age. These data suggest that cutting at 49 to 56 days were optimal for obtain maximum dry matter yields and improved the grass morphogenetic and structural characteristics.O efeito da idade de rebrota (21, 28, 35, 42, 49, 56, 63 e 70 dias) sobre a produ&ccedil;&atilde;o de forragem e caracter&iacute;sticas morfog&ecirc;nicas e estruturais de Axonopus aureus, durante o per&iacute;odo chuvoso, foi avaliado em condi&ccedil;&otilde;es de campo. O delineamento experimental foi inteiramente casualizado com tr&ecirc;s repeti&ccedil;&otilde;es. As avalia&ccedil;&otilde;es foram realizadas no per&iacute;odo de junho a agosto de 2009. O aumento da idade de rebrota resultou em maiores rendimentos de forragem, taxa absoluta de crescimento, n&uacute;mero de perfilhos planta-1, n&uacute;mero de folhas perfilho-1, tamanho m&eacute;dio de folhas, &aacute;rea foliar e taxas de expans&atilde;o e senesc&ecirc;ncia foliar. As rela&ccedil;&otilde;es entre idades de rebrota e o rendimento de mat&eacute;ria seca e a taxa absoluta de crescimento da gram&iacute;nea foram ajustadas ao modelo quadr&aacute;tico de regress&atilde;o, sendo os m&aacute;ximos valores registrados aos 62,7 e 49,4 dias de rebrota, respectivamente. As taxas de crescimento da cultura, taxa de crescimento relativo, taxas de aparecimento de perfilhos e de folhas foram inversamente proporcionais &agrave;s idades de rebrota. Visando conciliar produtividade de forragem com a maximiza&ccedil;&atilde;o das caracter&iacute;sticas morfog&ecirc;nicas e estruturais da gram&iacute;nea, o per&iacute;odo de utiliza&ccedil;&atilde;o mais adequado de suas pastagens situa-se entre 49 e 56 dias de rebrota. &nbsp

Atributos físicos de um Argissolo sob pastagem natural após 18 anos sob diferentes níveis de ofertas de forragem

The adjustment of stocking rate to the available forage is one of the most efficient ways to enhance sustainability of production in natural pastures. The definition of the best level of herbage allowance must consider results of animal performance, in association with aspects related to the soil. This research aimed to evaluate the physical attributes of a Paledult soil (300 g kg-1 clay) under natural pasture managed for 18 years with different grazing intensities, represented by daily herbage allowances of 4, 8, 12 and 16 kg dry matter per each 100 kg animal live weight. The effect of trampling and excreta accumulation due to the concentration of animals close to water sources was also evaluated, in comparison with areas regularly grazed. An area without grazing was included as a control. Changes in the soil attributes were observed. They were related to grazing intensity ant to other factors, such as trampling intensity and excreta distribution. Such alterations occurred mainly on the soil surface layer, where the soil density and microporosity increased, and macroporosity decreased in grazing areas compared to the no-grazed control. The diameter of stable soil aggregates was larger on herbage allowances of 8 and 12%. Results indicate that intermediate grazing intensities (8-12%) are more adequate for this environment.O ajuste da carga animal à oferta de forragem é uma das formas mais eficientes de conferir sustentabilidade ao uso de pastagens naturais. A definição do nível de oferta deve considerar, além do desempenho animal, aspectos relacionados à qualidade do solo. Este estudo objetivou avaliar atributos físicos de um Argissolo Vermelho Amarelo (300 g kg-1 argila) sob pastagem natural, manejada por 18 anos com intensidades de pastejo representadas por níveis de oferta diária de forragem de 4, 8, 12 e 16 kg de matéria seca para cada 100 kg de peso vivo animal, equivalentes à ofertas de 4, 8, 12 e 16%. Os efeitos do pisoteio e do acúmulo de dejetos pela concentração de animais nas proximidades de fontes de água foram avaliados, dividindo-se os piquetes em dois ambientes: áreas pastejadas normalmente e áreas de concentração dos animais. Uma área não pastejada adjacente ao experimento foi incluída como testemunha. Verificou-se que as alterações nos atributos do solo estão relacionadas à intensidade do pastejo, além de outros fatores como intensidade de pisoteio e distribuição de dejetos. Tais alterações ocorreram, principalmente, na camada superficial do solo, observando-se aumento da densidade e da microporosidade e redução da macroporosidade, quando comparadas à testemunha. Maior estabilidade de agregados foi observada nas ofertas de 8 e 12%. Os resultados indicam que intensidades de pastejo intermediárias (8-12%) são as mais adequadas para o ambiente estudado

INTEGRAÇÃO LAVOURA-PECUÁRIA: EFICIÊNCIA DE USO DO NITROGENIO NA CULTURA DO MILHO

O aumento da eficiência de produção para a cultura do milho (Zea mays) tem levado os produtores a buscaremalternativas sustentáveis através de sistemas integrados. O objetivo deste trabalho foi determinar o efeito do nitrogênio na produtividade do milho e seus componentes de rendimento, em um sistema de integração lavoura-pecuária. O experimento foi conduzido na fazenda experimental Capão da Onça da Universidade Estadual de Ponta Grossa, Brasil, durante a safra agrícola de 2002/2003. O delineamento experimental foi de blocos completos casualizados com parcelas subdivididas e quatro repetições. Os tratamentos foram duas doses de N (0 e 150 kg ha-1) com e sem pastejo aplicados no inverno sobre aveia preta mais azevém estabelecidas em abril de 2002 e dessecadas para o plantio do milho em outubro do mesmo ano. Sequencialmente, os tratamentos aplicados no milho foram doses de N (0, 75, 150, 225 kg ha-1). O milho apresentou uma resposta de produtividade crescente para o aumento das doses de nitrogênio nas áreas sem pastejo e sem adubação nitrogenada no inverno, no entanto quando há o pastejo é possível alcançar maiores produtividades de milho com menores doses de nitrogênio. ABSTRACT Producers seeking higher corn (Zea mays) production efficiency have pursued more sustainable, integrated systems. The objective of this investigation was to determine the effect of nitrogen fertilization on corn yield and yield components in an integrated crop-livestock production system. The experiment was conducted on the experimental farm Fazenda Capão da Onça of the Universidade Estadual de Ponta Grossa, Brazil during the 2002/2003 harvest. Treatments were replicated four times in a split-plot randomization of a randomized complete block design. Whole plot treatments were two N rates (0, 150 kg ha-1) with and without grazing applied to a winter cover crop of black oat and Italian ryegrass established in April 2002 and desiccated prior to planting the corn in October 2002. Sequentially, treatments were four N rates (0, 75, 150, 225 kg ha-1) applied to the corn. The corn presented an increasing yield in relation to increasing N rates in plots without neither grazing nor N fertilization during winter; however, grazing allows for higher corn yields with lower N rates

FITOMASSA AÉREA RESIDUAL DA PASTAGEM DE INVERNO NO SISTEMA INTEGRAÇÃO LAVOURA-PECUÁRIA

Producers in southern Brazil are seeking to diversify farm income and increase production efficiency by integrating livestock grazing of winter annual forages within rotations of summer grain crops. Our objective was to determine grazing and nitrogen fertilization effects on decomposition of winter annual forage residues in corn. A winter cover of oat (Avena strigosa Shreb) and annual ryegrass (Lolium multiflorum L.) was no-till seeded in April 2002 near Ponta Grossa, PR in southern Brazil. Treatment combinations of N fertilizer (0 or 150 kg ha-1) and grazing (grazed or not grazed) were imposed on the winter forage cover. The grazing period was from June to early October 2002. The winter forage was desiccated on 11 October and corn was no-till planted 20 d later with two N treatments (0 and 150 kg N ha-1). Above ground forage biomass residue was hand-clipped, placed in small nylon bags that were scattered on the soil immediately after corn planting, and recovered after five periods of three weeks each for determination of residual dry matter. Results were submitted to analysis of variance. The loss of residual dry matter followed a quadratic function on time. Decomposition of winter annual forage residue was affected by winter treatment (P<0.02), corn N rate (P<0.01), and by their interaction . At the last collection period (132 days after corn planting) differences (P<0.01) were detected only for the winter treatments. Treatments receiving winter-applied N had greater decomposition of residue regardless of the grazing treatment imposed on the winter forage cover.Produtores no Sul do Brasil estão procurando diversificar a propriedade aumentando a eficiência de produção através da integração lavoura-pecuária. O objetivo foi determinar o efeito do pastejo e da adubação nitrogenada na decomposição dos resíduos da pastagem anual de inverno no milho. A cobertura de Avena strigosa Schreb mais Lolium multiflorum L. foi semeada em abril de 2002, em Ponta Grossa - PR. A combinação de tratamentos com e sem nitrogênio, com e sem pastejo foi aplicada sobre a pastagem de inverno. O período de pastejo ocorreu de junho à outubro de 2002, a pastagem foi dessecada em 11 de outubro e o milho semeado vinte dias depois, tendo sido aplicados duas doses de nitrogênio (0 e 150 kg.ha-1). A pastagem de inverno, cortada, foi colocada em sacos de nylon que foram espalhados sobre o solo, e recolhidos em cinco épocas com intervalos de três semanas para análise de matéria seca residual. Os dados foram submetidos a análise de variância. Ajustes de modelo matemático indicaram que a redução da massa seca ocorreu de acordo com o modelo quadrático em função do tempo. A decomposição dos resíduos da pastagem foi afetada pelos tratamentos impostos (p<0,02), pelas doses de nitrogênio no milho (p<0,01) e suas interações. Na última data de avaliação (132 dias do período experimental) foram verificadas diferenças (p<0,01) apenas para os tratamentos sobre a pastagem de inverno. Tratamentos que receberam adubação nitrogenada no inverno resultaram em decomposição maior nas áreas com e sem pastejo

Carcass characteristics of lambs kept on ryegrass pasture managed at different sward heights

O objetivo deste trabalho foi avaliar as características de carcaça, de cordeiros mantidos em pastagem de azevém anual (Lolium multiflorum Lam.) manejada em diferentes alturas (5, 10, 15 e 20 cm), sob lotação contínua com carga variável, no período de agosto a novembro de 1999. Utilizou-se um delineamento em blocos ao acaso, com três repetições, e as variáveis estudadas foram submetidas à análise de regressão. Os pesos de abate, carcaça quente, filé mignon, paleta e costela diferiram entre os tratamentos e foram inferiores no tratamento relativo à altura de manejo de 5 cm, quando comparados aos tratamentos de 10, 15 e 20 cm, que não diferiram entre si. Não houve diferença entre tratamentos para os pesos de pernil e de carré. O rendimento de carcaça variou entre 42,8±0,29 e 44,1±0,32%. Todas as variáveis apresentaram relação quadrática com os tratamentos. O ganho médio diário influenciou diretamente o peso de abate que, por sua vez, correlacionou fortemente com o rendimento e o peso da carcaça. Os resultados mostram que os melhores rendimentos dos cortes comerciais de cordeiros são obtidos quando a pastagem de azevém é manejada no intervalo entre 12 e 14 cm de altura.The objective of this work was to evaluate the carcass characteristics of lambs maintained on ryegrass (Lolium multiflorum Lam.) pastures managed with different heights (5, 10, 15 and 20 cm), under continuous variable stocking, from August to November 1999. A randomized block design with three replicates was used. The slaughter weight, hot carcass, fillet, palette and rib weights were different among treatments, and those related to the height 5 cm were lower than the ones of 10, 15 and 20 cm, which were not different among them. There were no differences for hind leg and rib loin. Carcass yield ranged from 42.8±0.29 and 44.1±0.32%. All variables showed a quadratic relationship to treatments. The daily liveweight gain determined directly the liveweight at slaughter, the latter being strongly correlated to carcass yield and weight. Better yield of lamb carcass cuts were obtained when ryegrass was managed between 12 and 14 cm height