Greenhouse gas mitigation and carbon sequestration potential in humid grassland ecosystems in Brazil: A review.

Climate change is a major constraint on the sustainability of the humid tropics, maintaining ecosystem services, food production, and social functioning. Humid tropics play an essential role in C storage and greenhouse gas (GHG) emission reduction. Unfortunately, unplanned economic exploration, human occupation, and lack of knowledge of techniques to maintain ecosystem services negatively affect the humid tropics. In this study, we focused on the mechanisms of GHG emissions, C storage, and their mitigation strategies. This review indicated technologies that can be adopted by farmers in humid tropics to maintain or increase their capacity to store C stocks and reduce GHG emissions. The adoption of climate-smart agriculture technologies and the regulation of ecosystem services markets will accelerate the progress of preserving the humid tropics. Improved management practices, such as proper N fertilizer management and the introduction of N2-fixing legumes, can increase soil C sequestration, providing economic and environmental trade-offs associated with these management strategies. Public and private investments toward knowledge dissemination and technology adoption regarding GHG emissions reduction and soil C storage are needed to allow humid tropics to maintain their critical function of generating environmental and societal benefits.

Competitividade de espécies forrageiras do campo nativo com capim-annoni em solo com diferentes níveis de adubação e calagem / Competition between forage species from native grasslands and tough lovegrass in soil under different fertilization and liming regimes / Competitividad de las especies forrajeras del campo nativo con capim annoni en suelos con diferentes niveles de fertilización y encalado

A infestação de capim-annoni (Eragrostis plana Ness) nas áreas de pastejo em campo nativo ameaça a preservação do Bioma Pampa e a atividade pecuária no Rio Grande do Sul (RS). O objetivo deste trabalho foi avaliar a influência de tratamentos de adubação e calagem sobre a competitividade de espécies forrageiras do campo nativo com o capim-annoni, em área infestada pela invasora. Foi realizado um experimento em área de campo nativo infestada com capim-annoni no Centro de Pesquisa do DDPA/SEAPDR em Viamão - RS, sem uso de herbívoros domésticos, para avaliação do efeito dos tratamentos sem interferência do pastejo seletivo. Foram avaliados quatro tratamentos: TO sem adubação e calagem: T1 ­ apenas calagem: T2 - com adubação (nitrogênio, fósforo e potássio) e calagem; T3 - adubação com o dobro da dose de fósforo, mais potássio e calagem. Foram acompanhadas a evolução da composição botânica e o desenvolvimento das espécies do campo nativo e do capim-annoni por dois anos, pela avaliação da cobertura vegetal do solo e da produção de massa seca, como também as modificações da fertilidade do solo. Os resultados de produção de massa seca mostraram que a adubação nitrogenada do tratamento T2 beneficiou o crescimento do campo nativo e desfavoreceu o capim-annoni. Com a adubação nitrogenada do tratamento T2, espécies de gramíneas cespitosas do campo nativo atingiram maior altura e provavelmente competiram com o capim-annoni por meio de sombreamento, resultando na redução do crescimento da invasora.

The invasion of tough lovegrass (Eragrostis plana Ness) in native grassland grazing areas threatens the preservation of the Pampa biome as well as livestock farming in Rio Grande do Sul (RS), Brazil. The objective of the present study was to evaluate the influence of fertilization and liming treatments on the competitiveness of native grassland forage species with tough lovegrass, in an area infested by the invader. An experiment was carried out in a native grassland area infested with tough lovegrass that was not subjected to domestic herbivores at the DDPA/SEAPDR Research Center in Viamão - RS, to evaluate the effects of the treatments without interference from selective grazing. The following four treatments were assessed: TO - no fertilization or liming: T1 - liming only; T2 - fertilization (nitrogen, phosphorus and potassium) and liming; and T3 - fertilization with double the phosphorus dose, plus potassium and liming. The evolution of botanical composition and development of native grassland species and tough lovegrass were monitored for two years, by evaluating soil vegetal coverage and dry mass production, as well as modifications of soil fertility. The dry mass production results showed that nitrogen fertilization from T2 treatment benefited the growth of native grassland species and disfavored tough lovegrass. With nitrogen fertilization from T2 treatment, native grassland tufted grass species grew taller and probably competed with tough lovegrass through shading, resulting in reduced growth of the invader.

La infestación del capim annoni (Eragrostis plana Ness) en áreas de pastoreo en pastizales nativos amenaza la preservación del Bioma Pampa y la actividad ganadera en Rio Grande do Sul (RS), Brasil. El objetivo de este trabajo fue evaluar la influencia de los tratamientos de fertilización y encalado sobre la competitividad de las especies forrajeras del campo nativo con el capim annoni, en un área infestada por el invasor. Se realizó un experimento en un área de campo nativo infestado con capim annoni en el Centro de Investigación del DDPA/SEAPDR en Viamão - RS, sin el uso de herbívoros domésticos, para evaluar el efecto de los tratamientos sin la interferencia del pastoreo selectivo. Se evaluaron cuatro tratamientos: TO sin fertilización y encalado; T1 sólo encalado; T2 con fertilización (nitrógeno, fósforo y potasio) y encalado; T3 - fertilización con doble dosis de fósforo, más potasio y encalado. La evolución de la composición botánica y el desarrollo de las especies del campo nativo y del capim annoni fueron seguidos durante dos años, mediante la evaluación de la cobertura vegetal del suelo y la producción de masa seca, así como las modificaciones en la fertilidad del suelo. Los resultados de la producción de masa seca mostraron que la fertilización nitrogenada del tratamiento T2 benefició el crecimiento del campo nativo y perjudicó al capim annoni. Con la fertilización nitrogenada del tratamiento T2, las especies gramíneas cespitosas del campo nativo alcanzaron una mayor altura y probablemente compitieron con el capim annoni mediante el sombreado, lo que resultó en la reducción del crecimiento de la planta invasora.

Voisin Rational Grazing as a Sustainable Alternative for Livestock Production.

Current livestock practices do not meet current real-world social and environmental requirements, pushing farmers away from rural areas and only sustaining high productivity through the overuse of fossil fuels, causing numerous environmental side effects. In this narrative review, we explore how the Voisin Rational Grazing (VRG) system responds to this problem. VRG is an agroecological system based on four principles that maximise pasture growth and ruminant intake, while, at the same time, maintaining system sustainability. It applies a wide range of regenerative agricultural practices, such as the use of multispecies swards combined with agroforestry. Planning allows grazing to take place when pastures reach their optimal resting period, thus promoting vigorous pasture regrowth. Moreover, paddocks are designed in a way that allow animals to have free access to water and shade, improving overall animal welfare. In combination, these practices result in increased soil C uptake and soil health, boost water retention, and protect water quality. VRG may be used to provide ecosystem services that mitigate some of the current global challenges and create opportunities for farmers to apply greener practices and become more resilient. It can be said that VRG practitioners are part of the initiatives that are rethinking modern livestock agriculture. Its main challenges, however, arise from social constraints. More specifically, local incentives and initiatives that encourage farmers to take an interest in the ecological processes involved in livestock farming are still lacking. Little research has been conducted to validate the empirical evidence of VRG benefits on animal performance or to overcome VRG limitations.

Effects of supplementation with corn distillers' dried grains on animal performance, nitrogen balance, and enteric CH4 emissions of young Nellore bulls fed a high-tropical forage diet.

The inclusion of corn-dried distillers' grains (DDG) could be an alternative supplement to increase animal performance, nitrogen efficiency usage (NEU), and decrease enteric methane (CH4) emissions. Our goal was to determine whether DDG could replace a traditional supplement (cottonseed meal) without affecting animal performance, N balance, and CH4 emissions. The experiment was conducted during the forage growing season (December to April), with 15 d adaptation, and a 112 d experimental period. The experimental design was completely randomized with four treatments: a mineral supplement (MS), cottonseed meal supplement (CS), 50% replacement of CS by DDG (50DDG), and 100% replacement of CS by DDG (100DDG). Cottonseed meal and DDG were used as protein supplement. A total of 12 paddocks, 3 per treatment, were used to measure forage mass: morphological and chemical composition of forage, forage allowance, and animal performance. Six animals per treatment were used to evaluate DM intake, digestibility, CH4 emissions, microbial protein production (MCP), and NEU of each treatment. Eighty-one Young Nellore bulls (48 testers, 12 per treatments and 33 adjusters) with initial BW of 255 ±â€¯5 kg (10-12 months old) were supplemented with each supplement type at a level of 0.3% of BW. Pasture management was continuous stocking with a variable stocking rate (put-and-take). Enteric CH4 was measured using the gas tracer technique. The MCP was quantified using purine derivatives and the NEU mass balance. No differences were found in nutrient intake (P > 0.228). Individual animal performance and gain per area were higher in the treatments with concentrates compared with that of MS; however, there was no difference among treatments CS, 50DDG, and 100DDG. The ADG was 0.83 for MS and 1.08 kg/animal/d when supplemented (P < 0.05). Gain per hectare was 709 kg/ha for MS and 915 kg/ha when supplemented with concentrates (P < 0.05). There was no difference in CH4 production among treatments that average 180 g/animal/d; however, CH4 per kg of gain was reduced with CS. The CH4 conversion factor averaged 5.91%. There was no difference in the synthesis of MCP and NEU. Corn DDG can replace 100% of cottonseed meal as a protein source for supplementation of young Nellore bulls grazing in tropical pastures without affecting animal performance, NEU, MCP, and CH4 emissions.

Effect of pasture management on enteric methane emissions from goats.

The effect of pasture management on CH4 emissions was investigated from goats in a tropical climate. Two experiments were conducted in a "Tanzania Guinea grass" (Panicum maximum Jacq.) pasture to assess enteric CH4 production in a completely randomized design. Emissions from light, moderate, and heavy grazing intensities were analyzed in the first experiment, and variations between grazing days were explored in the second experiment. Grazing intensity was defined as 2.4, 1.6, and 0.8 post-grazing leaf area index. Pasture management employed intermittent grazing with variable stocking rate using Anglo Nubian female adult goats. SF6 tracer gas technique was used to measure CH4 production. Grazing intensity was not found to affect CH4 emissions per animal, dry matter forage intake (DMI), and gross energy (GE) intake. However, the second experiment showed that CH4 production was influenced by the grazing day. CH4 emissions were 18.1 g day-1, and the variables were 0.88 g kg-1 of metabolic weight, 17.45 g kg-1 of DMI, and 5.5% of GE. CH4 production increased linearly with the grazing day, possibly reflecting a reduction in forage quality. These findings suggest that the day of occupation in intermittent grazing has a greater effect on CH4 emissions than that by grazing intensity and that a single day grazing of Tanzania Guinea grass could mitigate CH4 emissions.

Sheep and goat feeding behavior profile in grazing systems

Feeding behavior analysis provides information about the relationships between animals and pastures. Therefore, this review aims to describe some aspects of the feeding behavior profiles of both sheep and goats in grazing systems. The structure of the pasture is a key factor in the feeding behavior of grazing animals. The amount of feed consumed in a given period of time is affected by the number of meals, duration and velocity of swallowing, changes in grazing time, bite rate, bite weight, and quality of ingested forage. The different phenological stages of forage also influence the animals’ strategies to optimize their intake, which consequently changes their behavioral activities. Sheep and goats tend to be more selective than cattle, and young animals are more selective than older animals; this selectivity characteristicis one of the most important aspects to be observed in pasture management. According to the degree of selectivity, the animals will intake forages of higher or lower nutritive quality. In addition, the intensity and distribution of their daily activities (grazing, ruminating, and resting)are influenced by several factors, such as the availability and nutritive value of the pasture, its management, the animal activity in the group, and the predominant climatic conditions of the region.

Sheep and goat feeding behavior profile in grazing systems

Feeding behavior analysis provides information about the relationships between animals and pastures. Therefore, this review aims to describe some aspects of the feeding behavior profiles of both sheep and goats in grazing systems. The structure of the pasture is a key factor in the feeding behavior of grazing animals. The amount of feed consumed in a given period of time is affected by the number of meals, duration and velocity of swallowing, changes in grazing time, bite rate, bite weight, and quality of ingested forage. The different phenological stages of forage also influence the animals strategies to optimize their intake, which consequently changes their behavioral activities. Sheep and goats tend to be more selective than cattle, and young animals are more selective than older animals; this selectivity characteristicis one of the most important aspects to be observed in pasture management. According to the degree of selectivity, the animals will intake forages of higher or lower nutritive quality. In addition, the intensity and distribution of their daily activities (grazing, ruminating, and resting)are influenced by several factors, such as the availability and nutritive value of the pasture, its management, the animal activity in the group, and the predominant climatic conditions of the region.(AU)

Infective larvae of Haemonchus contortus found from the base to the top of the grass sward / Larvas infectantes de Haemonchus contortus são encontradas da base até o topo da forragem

Abstract The resistance of gastrointestinal nematodes (GIN) of sheep to anthelmintic treatment has motivated researchers to seek alternatives to reduce the use of these drugs in sheep farming and decontaminate pastureland based on knowledge about the survival dynamics of larvae. The aim of this work was to evaluate the migration of the infective larvae (L3) of Haemonchus contortus at different times of the day, strata, and sward heights, with and without shade after the deposition of contaminated sheep feces. The grass species used here was Cynodon dactylon cv. Tifton 85 in four treatments: low sward height shade; low sward height sunshine; high sward height shade; and high sward height sunshine. The number of L3 recovered from the pasture at different times of the day did not differ. The highest number of L3 recovered was in shade. The number of L3 at different times and strata occurred uniformly, confirming that L3 remain in the same place after migrating from dung at the hottest times of the day. Infective larvae of H. contortus were able to migrate across all the strata regardless of the time of day in the summer season in humid subtropical climate.

Resumo A resistência dos nematódeos gastrintestinais (NGI) de ovinos aos tratamentos com anti-helmíntico tem estimulado os pesquisadores a buscar alternativas para reduzir o uso desses medicamentos na ovinocultura e descontaminar pastagens com base no conhecimento sobre a dinâmica de sobrevivência das larvas. O objetivo do trabalho foi avaliar a migração das larvas infectantes (L3) de Haemonchus contortus em diferentes horários do dia, estratos, e alturas do pasto, com e sem sombra, após a deposição de fezes de ovinos contaminadas. A espécie forrageira utilizada foi Cynodon dactylon cv. Tifton 85 em quatros tratamentos: pasto baixo sombra; pasto baixo sol; pasto alto sombra; e pasto alto sol. Não houve diferença na recuperação de L3 no pasto nos diferentes horários. As maiores recuperações foram encontradas na sombra. O número de larvas recuperadas nos diferentes horários e estratos ocorreu de forma uniforme, confirmando que as L3 podem permanecer no mesmo local, após migrar do bolo fecal, nos horários mais quentes do dia. Larvas infectantes de H. contortus foram capazes de migrar por todos os estratos, independentemente da hora do dia no verão em clima subtropical úmido.

Management Strategies for Lamb Production on Pasture-Based Systems in Subtropical Regions: A Review.

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.

The effect of different grazing heights on carcass and meat quality characteristics of Nellore cattle fattened in pastures of Convert grass.

Carcass characteristic and meat quality from bulls and Nellore steers (n = 64 total) subjected to different grazing heights (15, 25, 35, and 45 cm) 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 16 ha, divided into 16 paddocks of 1 ha. 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 42 cm. When the pasture was managed between 25 and 35 cm 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 40 cm provided higher fat thickness and marbling in the meat. The loss during thawing in meat was greater at 28 cm in height. The heights of grazing alter the carcass characteristics and meat of bulls and steers.

Milk Production, Milk Quality, and Behaviour of Dairy Cows Grazing on Swards with Low and High Water-Soluble Carbohydrates Content in Autumn: A Pilot Trial.

Grazing ruminant systems can be sustainably intensified by improving efficiency while reducing their environmental impact. The objective of the present study was to examine the potential of pastures differing in water-soluble carbohydrates (WSC) and crude protein (CP) contents to affect milk production and composition as well as the behaviour of cows grazing perennial ryegrass (PRG) swards. By modifying the nitrogen (N) fertilisation rate (83 and 250 kg/ha per year) and the defoliation frequency (two or three leaves per tiller) in combination with cultivar selection (high-sugar vs. standard cultivars), we obtained two swards differing in WSC and CP contents. The two contrasting swards were each grazed by six dairy cows in nine daily strips in autumn. Pasture samples were collected to determine herbage mass and quality. Cow behaviour was recorded by direct observation. Herbage offered and apparently consumed were similar between swards (averaging 37.3 and 18.2 kg/cow, respectively), although the residual was lower in the high-sugar sward (1735 vs. 2143 kg/ha). Cows spent less time grazing in the high-sugar sward (66.9% v. 71.6%), but the rumination times was similar (14.6%). Milk production and composition were similar between groups, suggesting that high-quality pastures would require a greater difference in nutritional composition to affect animal performance.

Herbage accumulation dynamics in digit grass subjected to defoliation frequencies / Dinâmica do acúmulo de forragem do capim faixa-branca submetido a frequências de desfolhação

This study was undertaken to examine the herbage accumulation dynamics and structural characteristics of digit grass subjected to different defoliation frequencies in the period of January 2015 to February2016. Four defoliation frequencies [very high (25 cm), high (35 cm), medium (45 cm), and low (55 cm)] were evaluated in two periods of the year [greater insolation (September to March) and lesser insolation (April to August)]. The experiment was set up as a randomized-block design with four replicates. Overall, the decreasing defoliation frequencies increased the cutting interval; leaf area index; total-herbage, stem, and dead-herbage accumulation rates; and percentages of stems and dead herbage. This reductionin defoliation frequency also resulted in a lower leaf accumulation rate and percentage of leaves. In overall terms, digit grass showed higher total-herbage, leaf, and stem accumulation rates; percentages of stems and dead herbage; stem volume density; and tiller density in the period of greater insolation. In the period of lesser insolation, however, digit grass exhibited a lower dead-herbage accumulation rate and a lower percentage of dead herbage. Less frequent defoliations increase the herbage accumulation rates of digit grass, but result in a less desirable morphological composition.(AU)

Este trabalho foi realizado com o objetivo de avaliar a dinâmica do acúmulo de forragem e as características estruturais do capim faixa-branca submetido a diferentes frequências de desfolhação, no período de janeiro de 2015 a fevereiro de 2016. Foram avaliadas quatro frequências de desfolhação: muito alta (25 cm), alta (35 cm), média (45 cm) e baixa (55 cm), em duas épocas do ano: maior insolação (setembro a março) e menor insolação (abril a agosto). Utilizou-se o delineamento experimental em blocos casualizados com quatro repetições. De maneira geral, a redução na frequência de desfolhação aumentou o intervalo entre cortes, o índice de área foliar, as taxas de acúmulo de forragem total, de colmos e forragem morta e as porcentagens de colmos e forragem morta. Por sua vez, esta redução na frequência de desfolhação diminuiu a taxa de acúmulo de lâmina foliar e a porcentagem de lâmina foliar. De maneira geral, o capim faixa-branca apresentou maiores taxas de acúmulo de forragem total,de lâmina foliar e colmos, porcentagens de colmos e forragem morta, densidade volumétrica de colmo e a densidade populacional de perfilhos no período de maior insolação. Por sua vez, o capim faixa-branca apresentou no período de menor insolação menor taxa de acúmulo de forragem morta e porcentagem de forragem morta. Desfolhações menos frequentes aumentam as taxas de acúmulo de forragem do capim faixa-branca, porém com composição morfológica menos desejável.(AU)

Herbage accumulation dynamics in digit grass subjected to defoliation frequencies / Dinâmica do acúmulo de forragem do capim faixa-branca submetido a frequências de desfolhação

This study was undertaken to examine the herbage accumulation dynamics and structural characteristics of digit grass subjected to different defoliation frequencies in the period of January 2015 to February2016. Four defoliation frequencies [very high (25 cm), high (35 cm), medium (45 cm), and low (55 cm)] were evaluated in two periods of the year [greater insolation (September to March) and lesser insolation (April to August)]. The experiment was set up as a randomized-block design with four replicates. Overall, the decreasing defoliation frequencies increased the cutting interval; leaf area index; total-herbage, stem, and dead-herbage accumulation rates; and percentages of stems and dead herbage. This reductionin defoliation frequency also resulted in a lower leaf accumulation rate and percentage of leaves. In overall terms, digit grass showed higher total-herbage, leaf, and stem accumulation rates; percentages of stems and dead herbage; stem volume density; and tiller density in the period of greater insolation. In the period of lesser insolation, however, digit grass exhibited a lower dead-herbage accumulation rate and a lower percentage of dead herbage. Less frequent defoliations increase the herbage accumulation rates of digit grass, but result in a less desirable morphological composition.

Este trabalho foi realizado com o objetivo de avaliar a dinâmica do acúmulo de forragem e as características estruturais do capim faixa-branca submetido a diferentes frequências de desfolhação, no período de janeiro de 2015 a fevereiro de 2016. Foram avaliadas quatro frequências de desfolhação: muito alta (25 cm), alta (35 cm), média (45 cm) e baixa (55 cm), em duas épocas do ano: maior insolação (setembro a março) e menor insolação (abril a agosto). Utilizou-se o delineamento experimental em blocos casualizados com quatro repetições. De maneira geral, a redução na frequência de desfolhação aumentou o intervalo entre cortes, o índice de área foliar, as taxas de acúmulo de forragem total, de colmos e forragem morta e as porcentagens de colmos e forragem morta. Por sua vez, esta redução na frequência de desfolhação diminuiu a taxa de acúmulo de lâmina foliar e a porcentagem de lâmina foliar. De maneira geral, o capim faixa-branca apresentou maiores taxas de acúmulo de forragem total,de lâmina foliar e colmos, porcentagens de colmos e forragem morta, densidade volumétrica de colmo e a densidade populacional de perfilhos no período de maior insolação. Por sua vez, o capim faixa-branca apresentou no período de menor insolação menor taxa de acúmulo de forragem morta e porcentagem de forragem morta. Desfolhações menos frequentes aumentam as taxas de acúmulo de forragem do capim faixa-branca, porém com composição morfológica menos desejável.

Partial correlation analysis in the study of morphogenesis and herbage accumulation in Panicum maximum cv. Tanzânia / Análise de correlação parcial no estudo da morfogênese e do acúmulo de forragem de Panicum maximum cv. ‘Tanzânia

The objective of this study was to evaluate, through partial correlation analysis, the degree of association between herbage accumulation and morphogenetic traits of Tanzania grass (Panicum maximum Jacq.) defoliated with 95% of light interception and fertilized with nitrogen, under different planting densities. The experiment was carried out in a randomized complete design with 12 treatments and two replicates, in a 4 × 3 factorial arrangement consisting of four nitrogen rates (0, 80, 160, and 320kg ha-1 Yr-1) and three planting densities (9, 25, and 49 plants m-2). Harvests were performed at 25cm above the soil, when the plots intercepted 95% of the incident light. The simple correlation coefficients between herbage accumulation and leaf and stem elongation rates and leaf appearance rate were high and positive. Correlation between herbage accumulation and leaf lifespan; however, was high and negative. The study of partial correlation coefficients revealed considerable changes in the correlation structure, whereby the association with stem elongation had a negative value statistically equal to zero, indicating no relationship between these variables. A similar result was observed for the correlations between herbage accumulation and leaf appearance and leaf lifespan. The partial correlation between accumulation and leaf elongation was different from zero and positive indicating a strong association. In Guinea grass cv. Tanzania canopies defoliated at 95% light interception, leaf elongation is the morphogenetic variable with the highest strength of association with herbage accumulation.(AU)

Objetivou-se avaliar, por meio de correlação parcial, o grau de associação entre o acúmulo de forragem e as características morfogênicas do capim-tanzânia (Panicum maximum Jacq.) desfolhado com 95% de interceptação luminosa e adubado com nitrogênio em diferentes densidades de planta. O delineamento foi em blocos completos casualizados, com 12 tratamentos e duas repetições em esquema fatorial 4 × 3, constituído por 4 doses de nitrogênio (0, 80, 160 e 320kg ha-1 ano-1) e três densidades de plantas (9, 25 e 49 plantas m-2). As colheitas foram realizadas a 25cm do nível do solo quando as parcelas interceptavam 95% da luz incidente. Os coeficientes de correlação simples foram altos e positivos, entre o acúmulo de forragem e as taxas de alongamento de folha e de colmo e aparecimento de folha. Já a associação do acúmulo com a duração da vida das folhas foi alta e negativa. O estudo dos coeficientes de correlação parcial implicou em mudanças consideráveis na estrutura da correlação, onde a associação com o alongamento de colmos assumiu valor negativo e estatisticamente igual a zero, indicando não haver relação de causa e efeito entre estas variáveis. Resultado semelhante foi observado para a associação entre o acúmulo de forragem e o aparecimento de folhas e a duração da vida da folha. á a correlação parcial entre o acúmulo e o alongamento de folhas foi diferente de zero e positiva. Nesse contexto, em dosséis forrageiros de capim-tanzânia desfolhados com 95% de interceptação de luz, a taxa de alongamento foliar é a variável morfogênica que apresenta maior grau de associação com o acúmulo de forragem.(AU)

Soil, water, and nutrient losses from management alternatives for degraded pasture in Brazilian Atlantic Rainforest biome.

The objective of this study was to evaluate sediment, water and nutrient losses from different pasture managements in the Atlantic Rainforest biome. A field study was carried out in Alegre Espiríto Santo, Brazil, on a Xanthic Ferralsol cultivated with braquiaria (Brachiaria brizantha). The six pasture managements studied were: control (CON), chisel (CHI), fertilizer (FER), burned (BUR), plowing and harrowing (PH), and integrated crop-livestock (iCL). Runoff and sediment samples were collected and analyzed for calcium (Ca), magnesium (Mg), potassium (K), phosphorus (P) and organic carbon contents. Soil physical attributes and above and below biomass were also evaluated. The results indicated that higher water loss was observed for iCL (129.90mm) and CON (123.25mm) managements, and the sediment losses were higher for CON (10.24tha-1) and BUR (5.20tha-1) managements when compared to the other managements. Majority of the nutrients losses occurred in dissolved fraction (99% of Ca, 99% of Mg, 96% of K, and 65% of P), whereas a significant fraction of organic carbon (80%) loss occurred in a particulate form. Except for P, other nutrients (Ca, Mg and K) and organic carbon losses were higher in coarse sediment compared to fine sediment. The greater losses of sediment, organic carbon, and nutrients were observed for CON followed by BUR management (p<0.05). Our findings indicated that the traditional pasture management adopted in the Atlantic Rainforest needs to be rethought and burned management should be avoided. Based on the water, soil, and nutrient losses from various practices, to reduce pasture degradation, farmers should adopt edaphic practices by applying lime and fertilize to improve pasture growth and soil cover, and reducing soil erosion in the hilly Brazilian Atlantic Rainforest biome.

Production and nutritional value of the wheat silage managed with different cutting systems / Produção e qualidade nutricional da silagem de trigo manejado em diferentes sistemas de corte

Winter cereals are mainly used for human and animal nutrition and several studies are now exploring their potential as conserved forage (hay and silage). Among the winter cereal species available for cultivation in the south of Brazil, which is major winter cereals producer in the country, the wheat cv. BRS Umbu has attracted special attention. However, few studies have investigated the potential of this cultivar for silage production. The aim of this study was to evaluate the production and quality of silage from the dual-purpose wheat, BRS Umbu, subjected to different cut managements treatments: T1 - without cut (control), T2 - one cut and T3 - two cuts. Each plot represented an experimental unit in a randomized block design, with 5 replicates per treatment. Two representative samples were collected from each plot to determine morphological segmentation (stem, leaf and ear) and dry matter (DM) content of the whole plant and its morphological components. At the time of opening of the silos, food chemical analysis and pH determination were performed. Forage mass production decreased by 26.88% and 67.82%, respectively, with one and two cuts, compared to control. The DM content of the ensiled plant was 49.9 g kg-1 for the control, 54.7 g kg-1 with one cut and 63.2 g kg-1 with two cuts, at the time of ensiling. Management cuts changed the morphological components of the plants, with a lower proportion of stem (28%) in plants subjected to two cuts. The control treatment showed fewer leaves in ensiled plant (9.6%) and intermediate amount of stalk (52.8%), and was significantly different (p < 0.05) to treatment of a cut. Regarding feed chemistry evaluations, no significant difference (p > 0.05) was observed for mineral matter (MM), crude protein (CP) and hemicellulose (HEM) between the different cutting regimens. However, neutral detergent fiber (NDF) and acid detergent fiber (ADF) decreased (p < 0.05) as the number of cuts increased...(AU)

O cultivo de cereais de inverno tem como objetivo suprir a demanda alimentar humana e animal, contudo estudos recentes têm focado no seu uso como alimento conservado (feno e silagem). Dentre as várias opções disponíveis para o plantio o trigo cv. BRS Umbu vem despertando interesse. Contudo, poucos estudos tem avaliado o potencial desta cultivar para produção de silagem. Sendo assim, objetivo deste trabalho foi avaliar a produção e a qualidade das silagens obtidas a partir do trigo de duplo propósito, BRS Umbu, manejado em diferentes manejos de cortes: T1 sem corte (controle), T2 um corte e T3 dois cortes. Cada parcela representou uma repetição em um delineamento em blocos casualizados, com cinco repetições por tratamento. Duas amostras representativas de cada parcela foram coletadas para se determinar a composição morfológica e massa seca dos seus componentes. No momento da abertura dos silos, amostras foram coletadas para determinação do pH e composição nutricional. O aumento no número de cortes proporcionou redução na produção de massa de forragem seca na ordem de 26.88% e 67.82% do manejo com um e dois cortes, respectivamente em relação ao controle. No momento da ensilagem o teor de matéria seca (MS) das plantas ensiladas foi de 49,9 para o tratamento sem corte, 54,7 g kg MS-1 para o tratamento com um corte e 63,2 g kg MS-1 para o tratamento com dois cortes. Verificou-se alterações nos componentes morfológicos das plantas, sendo influenciados pelo manejo de cortes, observando-se menor proporção de colmo nas plantas submetidas a dois cortes (28%), porém, apresentando maior proporção de espigas (59,4%), enquanto o tratamento controle mostrou menor quantidade de folhas nas plantas ensiladas (9,6%) e quantidade intermediária de espigas (52,8%), diferindo (P < 0,05) do tratamento de um corte, que apresentou (42,6%) de espigas na planta...(AU)

Canopy structure and tillering of piatã and marandu grasses under two grazing intensities with sheep / Estrutura do dossel e perfilhamento dos capins-piatã e marandu sob intensidades de pastejo com ovinos

This study aimed to evaluate productive and structural parameters of Piatã and Marandu cultivars submitted to two grazing intensities. The experimental design was in randomized blocks with treatments in a 2 x 2 factorial arrangement (Marandu and Piatã palisadegrass x 25 and 30 cm residual heights). Intermittent stocking grazing method was used. Non-defined breed sheep were used as defoliation agents. Interaction between cultivars and height was not significant for any of the variables. In pastures managed at 25 cm post-grazing, a greater regrowth period was observed. Forage mass was on average 27% higher in Marandu palisadegrass in relation to Piatã palisadegrass, regardless of height. Dead material accumulation was higher in the Marandu cultivar. There was no difference in mass between the cultivars and heights for leaf blade or stem before and after grazing. The highest population density of tillers was observed in pastures lowered to 25 cm post-grazing height, with no difference between cultivars. In the third generation the appearance of tillers was higher in pastures managed at 25 cm. Post-grazing heights of 25 and 30 cm do not change pasture structure in Piatã and Marandu cultivars in pre-grazing; however, it is possible to obtain a shorter regrowth period if managed at 30 cm.

Objetivou-se avaliar parâmetros produtivos e estruturais das cultivares Piatã e Marandu submetidas a duas intensidades de pastejo. O delineamento experimental foi em blocos ao acaso, com os tratamentos em arranjo fatorial 2 x 2 (Marandu e Piatã x 25 e 30 cm de alturas de resíduo). O método de pastejo empregado foi o de lotação intermitente. Como agentes de desfolhação foram utilizados ovinos sem padrão racial definido. A interação entre cultivar e altura não foi significativa para nenhuma das variáveis. Nos pastos manejados a 25 cm de altura no pós-pastejo foi observado maior período de rebrotação. A massa de forragem foi em média, 27% maior no capim-Marandu em relação ao capim-piatã, independentemente da altura. O acúmulo de material morto foi maior na cultivar Marandu. Não houve diferença nas massas entre as cultivares e alturas para de lâmina foliar e colmo no pré e pós-pastejo. A maior densidade populacional de perfilhos foi observada em pastos rebaixados a 25 cm de altura pós-pastejo, sem diferença entre as cultivares. Na terceira geração o aparecimento de perfilhos foi superior nos pastos manejados a 25 cm. As alturas de pós-pastejo de 25 e 30 cm não modificam a estrutura dos pasto das cultivares de Piatã e Marandu no pré-pastejo, porém manejados a 30 cm é possível obter menor tempo de rebrotação.