Forage-based Livestock Research Articles

Current and future trends in managing internal parasites in forage-based livestock

Current and future trends in managing internal parasites in forage-based livestock

451 Establishing producer research sites for the development of beef and bison climate-smart agriculture

Abstract Greenhouse gas (GHG) emissions and livestock production are topics that are increasingly intertwined. While livestock production is frequently presented as harmful to the environment, this perception fails to consider the carbon sequestration that takes place in livestock grazing systems and the role that grazing ruminants have in maintaining healthy grassland ecosystems. Grazing lands, which are often unsuited to row crop agriculture, are estimated to account for 25% of the global soil sequestration potential for soil carbon storage. Grazing livestock producers are often overlooked in the GHG reduction conversation, despite over 70% of beef GHG emissions being attributed to the cow-calf sector, which is primarily grazing. Furthermore, there is a relative lack of data surrounding the implementation of climate-smart agriculture practices on grazing operations and a lack of cost-effective methods to measure carbon/GHG sinks and sources on these landscapes. The potential climate benefits are considerable, with nearly 940 million acres of rangelands in the U.S. supporting forage-based livestock production. South Dakota State University recently received funding to support a large-scale climate-smart project focused on grazing beef and bison. For this project, we are utilizing the Cottonwood Field Station that has over 80 yr of historical grazing data, along with six grazing beef and bison ranching operations in the Northern Great Plains. The work on these ranches will focus on measuring and monitoring the impacts of climate-smart NRCS land practices, including cover crops, improved pasture and range seedings, prescribed grazing, and prescribed burning. A significant focus will be extensive, annual soil sampling across these operations to continuously monitor changes in soil organic carbon, bulk density, texture, pH, and soil microbiome community profiles. Each operation will have GreenFeed methane pasture units deployed for 5 yr to monitor changes in beef cattle and bison methane emissions in response to climate-smart practice adoption. We are also assessing biodiversity pre and post climate-smart practice adoption, as biodiversity improvements may be one of the most overlooked and yet most important responses to climate-smart land practice implementation. Over the duration of this project, a large-scale, comprehensive data collection will be achieved and used to refine GHG and carbon sequestration estimates associated with range livestock systems. Data resulting from this project will be used to inform research protocols and prediction models, fill knowledge gaps, and shape science-based discussions and marketing strategies for climate-smart agricultural commodities.

315 Implementation of Large-Scale Climate-Smart Agriculture Practices and Research on Beef and Bison Grazing Lands

Abstract Today’s livestock producers face increasing public scrutiny because animal agriculture is often cited as a major contributor to greenhouse gas (GHG) emissions. However, this negative perception does not take into account the carbon (C) sequestration benefits of grazing livestock nor that grazing lands account for 25% of the global soil sequestration potential of soil C storage. Grazing beef cattle and bison are key to healthy grassland ecosystems and provide the most nutrient dense source of protein available for human consumption. Beef and bison producers who graze their livestock are widely recognized as environmental stewards because they use sustainable grazing practices that maintain grassland health. These practices are considered climate-smart agriculture (CSA) because they promote soil C sequestration and resilience to increased climate variability. Yet, these same producers are generally overlooked in GHG reduction and C sequestration incentives because of a relative lack of cost-effective methods to measure C and GHG sinks and sources. Emerging technologies are beginning to bridge that gap by paving the way to develop, implement, and monitor CSA practices. Furthermore, rangelands in the U.S. dedicated to supporting forage-based livestock production amount to nearly 940 million acres. This is more than double the acres dedicated to row crops and represents enormous potential to contribute to U.S. climate change commitments. Successful implementation and monitoring of CSA land management practices creates potential to develop climate-smart livestock commodities that sustainably provide economic incentives to producers operating resilient livestock grazing systems. Recently, South Dakota State University, along with ten external partners, was awarded a CSA commodity development grant by the USDA and NRCS focused on CSA-raised grazing beef cattle and bison in the Northern Great Plains. Specific objectives include: 1) developing and implementing existing and novel CSA practices alongside custom grazing plans; 2) measuring, monitoring, reporting, and verifying CSA practice impacts on GHG emissions, C sequestration, and ecosystem biodiversity of plants, arthropods, and wildlife; and 3) creating sustainable, value-added market opportunities for producers using CSA practices. To achieve these objectives, the project team is partnering with producers throughout the Northern Great Plains and beyond and will provide incentives for CSA practice implementation. Additionally, emerging and novel technologies will be used to collect large-scale data across producer operations and test sites to determine and refine GHG and C sequestration estimates associated with range beef cattle and bison systems. The long-term goal of this project is to provide CSA beef and bison producers with sustainable, value-added market opportunities that align with consumer preferences and demand.

415 Awardee Talk: Foraging for Collaboration: Beef-Forage System Strengths Unite Research and Extension Efforts in the Asas Southern Section

Abstract The American Society of Animal Science Southern Section has a rich history of collaboration and hosts an annual professional development meeting for ASAS members. The Section meeting includes scientific presentations, academic quadrathlon, undergraduate and graduate student competitions, symposia, and networking opportunities for its members. The Section has used strategic collaborations to foster multi-state projects and initiatives. One of the key discipline focus areas of the Section is forage-based beef production systems. The Section holds two symposia focused on research, Extension, and industry topics related to beef cattle management. The Bill E. Kunkle Interdisciplinary Symposium was started in 2014 to honor the impact of Dr. Kunkle, University of Florida, and fosters multi-disciplinary communication of beef cattle science. The SERA 41 Symposium is part of the regional NIMSS project focus-group on improving production efficiency of the beef cow herd in the Southeast US. The NIMSS group works collectively to create partnerships and common goal-oriented projects across the Southern Section states. The section is also home to the Randel Physiology Lecture series which was formed in 2016 to highlight Dr. Ron Randel’s commitment to the Southern Section physiology section, and to promote high-quality science for the next generation of physiologists and endocrinologists. More than 25 peer-reviewed publications and several webinars have resulted from these symposia and invited lectureships. This creates a referenceable resource for scientists on emerging topics and identifies potential priority areas of focus for scientists within the Southern region. Another highlight of the Section is the collaborative work of the Extension committee. The Extension committee collaboratively fosters Extension program development across the Southern region. The committee developed a regional webinar series in 2015 for regional training of Extension agents on livestock and forage management topics. Subsequent in-service training courses have emerged through both virtual and in-person delivery. Training is primarily focused on forage-based livestock management systems. Through these opportunities, the Southern Section has remained a gathering point for professional engagement and should continue to evolve to meet the needs of animal scientists.

Crop-livestock-forestry systems as a strategy for mitigating greenhouse gas emissions and enhancing the sustainability of forage-based livestock systems in the Amazon biome

Intensification of livestock systems becomes essential to meet the food demand of the growing world population, but it is important to consider the environmental impact of these systems. To assess the potential of forage-based livestock systems to offset greenhouse gas (GHG) emissions, the net carbon (C) balance of four systems in the Brazilian Amazon Biome was estimated: livestock (L) with a monoculture of Marandu palisade grass [Brachiaria brizantha (Hochst. ex A. Rich.) R. D. Webster]; livestock-forestry (LF) with palisade grass intercropped with three rows of eucalyptus at 128 trees/ha; crop-livestock (CL) with soybeans and then corn + palisade grass, rotated with livestock every two years; and crop-livestock-forestry (CLF) with CL + one row of eucalyptus at 72 trees/ha. Over the four years studied, the systems with crops (CL and CLF) produced more human-edible protein than those without them (L and LF) (3010 vs. 755 kg/ha). Methane contributed the most to total GHG emissions: a mean of 85 % for L and LF and 67 % for CL and CLF. Consequently, L and LF had greater total GHG emissions (mean of 30 Mg CO2eq/ha/year). Over the four years, the system with the most negative net C balance (i.e., C storage) was LF when expressed per ha (−53.3 Mg CO2eq/ha), CLF when expressed per kg of carcass (−26 kg CO2eq/kg carcass), and LF when expressed per kg of human-edible protein (−72 kg CO2eq/kg human-edible protein). Even the L system can store C if well managed, leading to benefits such as increased meat as well as improved soil quality. Moreover, including crops and forestry in these livestock systems enhances these benefits, emphasizing the potential of integrated systems to offset GHG emissions.

Assessment of planting soil temperature and growing degree day impacts on silage corn (Zea mays L.) biomass.

The annual forage crop production system, enclosing silage corn (Zea mays L.) and following cool-season annual forage, can enhance forage production efficiency where available land is limited for pasture production. In this forage production system, successful silage corn cultivation has a significant value due to the great yield of highly digestible forage. However, some untimely planting or harvesting of corn due to changing weather often reduces biomass and feeding values. Therefore, a study was conducted to quantify the corn silage biomass reductions by the deviations from optimum planting soil temperature and optimum growing degree day (GDD). The approximations of maximum corn production were estimated based on field trial data conducted between 1978 and 2018 with early, medium, and late-maturity corn groups. Based on weather data, the recorded planting dates and harvest dates were converted into the corresponding trials' soil temperatures at planting (STP) and the GDD. The silage corn biomass data were regressed against STP and GDD using a quadratic function. The maximum biomass point was modeled in a convex upward quadratic yield curve and the optimum STP and GDD were defined as those values at the maximum biomass for each maturity group. Optimized STP was at 16.6°C, 16.2°C, and 15.6°C for early, medium, and late maturity corn groups, respectively, while optimized GDD at harvest was at 1424, 1363, and 1542°C. The biomass reductions demonstrated quadratic functions by the departures of STP or GDD. The 5% reductions were anticipated when STP departed from the optimum temperature by 2.2°C, 2.4°C, and 1.4°C for early, medium, and late maturity corns, respectively; the same degree of reductions were estimated when the GDD departed by 200, 180, and 130°C in the same order of the maturity groups. This result indicates that biomass reductions of late-maturity corn were more sensitive to the departures of STP or GDD than the early-maturity corn. Therefore, early maturing cultivars are more stable in biomass production in a silage corn-winter annual forage crop production system to enhance forage-based livestock production efficiency.

109 Invited Talk: Grazing Management and Stocking Strategy Decisions for Pasture-Beef Systems: Experimental Confirmation vs Testimonials and Perceptions

Abstract The primary objectives of forage-based livestock grazing systems are to enhance sustainability of pastures and cattle production, and to maintain economic stability in the presence of changes in input costs and returns. Grazing management strategies and implementation vary for adapted forages according to vegetational-hardiness zones, livestock production objectives, and manager preferences for grazing systems, stocking rates, and stocking methods. Stocking methods are strategies or techniques to manipulate grazing animals in space and time and may be considered as variations of continuous or rotational stocking. In many stocking method discussions, the debates are often focused on experimental confirmational data vs testimonials and perceptions. Acceptable methodology and statistical analyses of grazing experimentation on continuous vs rotational stocking provides repeated measures of forage nutritive value, forage mass, grazing intensity, and stocking rate on gain per animal, gain per unit land area. Additional measurements may include effects on forage stand maintenance and soil nutrient analyses-status. Recent adaptations of mob stocking and intensive rotational grazing via popular press and consultants have received acclaims for methods to enhance ecosystem services, soil health, and other non-experimentally documented attributes. Managers may adopt these testimonials of stocking methods of 60 days or more deferment based on their perception of protecting and enhancing the environment rather than logic of seeking experimental evidence. However, when given a choice of forage available for consumption, cattle select more than 80% of their diet as leaves. Thus, with respect to average daily gain per animal (ADG), only a small percentage of pasture studies have shown an advantage for rotational stocking. The lack of ADG was attributed to reduced nutritive value of forage available for selection during the residence time. Selecting management and stocking strategies for optimum utilization for forage produced, individual animal performance, and overall gain per unit land area has led to flexible grazing systems. These grazing systems may not be “hardcore rotationally, time-scheduled stocked,” but they do involve multiple pastures with strategies to incorporate movement of cattle based on current paddock forage status and forage mass estimates for desired animal performance. Grazing management strategies control the degree of intensity of beef cattle production based on level of economic risk and desired-expected environmental stewardship goals. Of all the strategies that management may adopt for grazing, the primary factor that controls resultant sustainability of pastures is that of grazing intensity as measured by stocking rate or forage height-density. Implementing revised or new management strategies requires attention to detail and the use of data-results-recommendations from comparative experiments conducted by a recognized source without conflict of interest in the method promoted.

Forage Mass and Nutritive Value of Grain- and Forage-Type Soybean Cultivars Managed under Different Row Spacings and Clipping Heights

Soybean (Glycine max L.) is a high value crop that has been used as a forage since the early 1900s in the southern U.S. (e.g., Mississippi, Alabama, Georgia, South Carolina, and Florida). Renewed interest has increased the use of soybean as a viable and economical high protein alternative to forage growers in the southern region. The objective of this study was to determine herbage mass (HM) and nutritive value of forage soybean managed under two row spacing (36 and 72 cm) and three stubble heights (10, 15, and 20 cm). Five cultivars were used ‘Stonewall’, ‘Laredo’, ‘Tower of Leaves’, Asgrow® ‘AG64X8’, and Asgrow® ‘AG79X9’ and sown at two locations (Shorter and Headland, AL). Forage was harvested in July and August during both years and HM was determined. Crude protein (CP) and fiber fractions were determined using near-infrared spectroscopy. Years and location did vary, but overall, Stonewall had the greatest (p < 0.026) HM (1706 kg DM ha−1) with a high nutritive value (124 g CP kg−1, 449 g NDF kg−1, and 372 g ADF kg−1). Laredo had the lowest HM (1169 kg DM ha−1; p < 0.025). The 10 cm stubble height resulted in increased HM (1898 kg DM ha−1; p < 0.0001) but decreased nutritive value (149 g CP kg−1; 331 g ADF kg−1; 413 g NDF kg−1; p = 0.001) compared to 20 cm (179, 282, and 375 g kg−1 for CP, ADF, and NDF, respectively). Row spacing did not consistently influence either HM or nutritive values. Due to its relatively good nutritive value and HM, forage soybean should be considered as a monoculture or in a mixed sward with other warm-season annual forages for inclusion in forage-based livestock diets.

58 Development of Forage Establishment and Management Educational Resources for Alabama Farmers

Abstract Forage-based livestock production systems are one of the largest economic drivers for agriculture in the southern USA. There is a strong reliance on forages as the primary feed source due to favorable climatic conditions and wide range of adapted species. Increasing population growth and urbanization has exacerbated the need to enhance productivity per land through improved management strategies of forage systems. An increase in the number of beginning farmers seeking forage-based livestock systems management information has exacerbated educators to improve educational resources available to reach a wide spectrum of Extension clientele. Resources created by the Alabama Cooperative Extension System (ACES) include a new online course, Forage Basics, which was released in September 2021 to provide a broad overview of concepts as forages, soils, weed and insect management in the Southeast region. A sister resource, the Alabama Forages Handbook, was also developed and provides more detailed information on similar topics. This printed resource will serve as a reference guide and curriculum base resource for Extension educators in the Alabama to hold associated trainings. A one-day in-service training was conducted with county and regional extension agents in Alabama to evaluate perceptions of these resources and potential use in Extension programming. There was a 55 % response rate (n = 20 respondents). Using a Likert scale, most respondents indicated that they are very likely to integrate both the coursework (55%) and the handbook (64%) into their programming activities in the next year, and that they often refer to the ACES resources to support their program. Suggested topics for resources included forage system for other animal categories and expansion of some of the forages topics. This information will support upcoming efforts to develop new resources statewide and expand the content for associated trainings to the handbook.

108 Forage Mass and Nutritive Value of Stockpiled Alfalfa-bermudagrass Systems

Abstract The development of newer alfalfa cultivars with improved adaptation to local growing conditions and dual-purpose applications has increased alfalfa incorporation into grass systems in the southern United States. The complementary growth of both species helps to extend the forage production season length, decreasing producer reliance on supplementation. The objective was to determine forage mass (FM) and nutritive value, botanical composition, and structural responses of alfalfa-bermudagrass systems managed under five stockpiling strategies (6-, 8-, 10-, 12- and 14-weeks of accumulation) in Shorter, AL. A randomized complete block design with eight replications was used. Harvested forage samples were manually separated into individual components and placed into 60° C until constant weight, then weighed. Measurements of ground cover, and alfalfa density and persistence were taken prior to plot harvest. There was a treatment × year interaction (P= 0.009) and greater FM was observed for 10- and 12-wks of regrowth (4,279 and 4244 kg DM/ha, respectively) in Year 2. This response was associated with greater (P < 0.001) bermudagrass percentage in the mixture in Year 2 than 1 (averaged 57 vs 23%, respectively). Weeds remained below 4% in both years. There was a direct relationship between increased regrowth period length with leaf shattering and lodging. Over 10-wks of regrowth, percentage of lodging was >30% and rate of leaf shattering doubled. This response directly affected leaf area index observed for the alfalfa-bermudagrass mixtures at 14-wk with a reduction of 30% when compared to 6-wks regrowth (2.6 vs 3.9, respectively). Greater (P < 0.001) digestibility was associated with shorter regrowth period (6-wk), although the values observed ranged from 62 to 87% which represents high nutritive value forage that can meet higher animal requirements. Based on results, stockpiling alfalfa-bermudagrass mixtures using varying accumulation period lengths may be a viable system to provide high quality feed and extend the grazing season length into the fall and winter. This can also be an important strategy aiming to increase diversity and sustainability in forage-based livestock systems.

Woodland Grazing: Untapped Resource to Increase Economic Benefits from Forestland

Abstract The southeastern United States offers a tremendous opportunity for expanding woodland grazing technology for small ruminants in its almost 60 percent woodland. Like in many other states, Alabama alone has 23 million acres of woodland. Conversely, livestock owners face a daunting challenge to forage their animals for about seven lean months each year. Raising animals on concentrates, of course, is economically unfeasible for small-scale producers. Woodland grazing is an untapped practice that boosts economic, social, and environmental benefits to woodland owners. The objectives of this study were to diversify household cash flow for woodland owners and simultaneously promote forage-based livestock production systems. The study was conducted at Tuskegee University from 2017 to 2020 in 6 acres of woodland (southern pines and non-pine species). Meat goats (8 Wethers) and hair sheep (5 Rams) were grazed rotationally for 6 months (May–Oct.) until they consumed 50% of the available foliage. They were not fed any supplement feed while grazing in woodlands. The feeding cost was estimated using four scenarios: sack/pellet, hay, sack/pellet and hay, and woodland grazing holding health, management, minerals and water costs constant. Feeding cost was 58–204% lower, and labor cost was 50–100% less in woodland grazing compared to conventional feeding systems. Extrapolated data reveal that woodland owners may generate about $9,947.00 more cash flow annually from 50 acres with woodland grazing than without grazing. Moreover, the system approach strengthens knowledge, attitude, awareness, skill, and motivation of the family members and community as a percolation effect. Besides, the environmental benefits (controlling unwanted and invading species and aesthetic pleasure) increase the economic value. Results reveal that woodland grazing can open an enormous economic opportunity to all forestland owners by upholding annual cash flow while trees are growing and making the total returns from woodlands much higher than the monocropping-timber.

Agroforestry systems: an alternative to intensify forage-based livestock in the Brazilian Amazon

Brazil is one of the few countries in the world that can produce animal products, grains, fibers, and bioenergy in the same area, either in a consortium, rotation, or succession. Our objective was to compare pasture productivity and animal performance in agroforestry systems with grass monoculture in the Brazilian Amazon Biome. The experiment was carried out in Sinop, MT, Brazil, with Nellore steers in a continuous stocking with variable stocking rate. The experimental design was a randomized complete block, with four systems and four replicates. The palisadegrass [Brachiaria brizantha (Hochst. ex A. Rich.) R. D. Webster cv. Marandu] was planted in the four systems: livestock (grass monoculture); livestock–forestry [eucalyptus trees (Eucalyptus urograndis; hybrid of Eucalyptus grandis W. Hill ex Maiden and Eucalyptus urophylla S. T. Blake) arranged in three-row groves spaced 30 m apart]; crop–livestock (palisadegrass after two years of crops); and crop–livestock–forestry (palisadegrass after two years of crops with single rows of eucalyptus trees spaced 37 m apart). The herbage accumulation was greater in the systems with the two previous cropping years (crop–livestock and crop–livestock–forestry) than in the livestock and livestock–forestry, in both seasons. In the crop–livestock–forestry, the greatest herbage accumulation associated with the modified microclimate supported the greatest average daily gain (0.750 kg BW day− 1), stocking rate in both seasons, resulting in the greatest gain per area (940 kg BW ha− 1). We conclude that agroforestry systems assure pasture productivity and animal performance similar or greater than livestock (grass monoculture). Furthermore, the combination of two previous crop years and the least tree density optimized the synergy between crop, livestock, and forestry components, improving beef cattle productivity in crop–livestock–forestry systems.

ASAS-CSAS ANNUAL MEETING SYMPOSIUM ON WATER USE EFFICIENCY AT THE FORAGE-ANIMAL INTERFACE: Life cycle assessment of forage-based livestock production systems.

Livestock production is increasingly subjected to environmental and economic challenges related to water quantities being utilized, expressed as green (evapotranspiration from rainwater), blue (surface and groundwater), or gray (waste) water footprints at each stage of the product life cycle. Published data indicated that the largest share of water being used for producing beef in the United States can be traced back to growing forage and feed (>90%), whereby the green water footprint was substantially greater (12,933 liters of water per kg of product) than the blue water footprint, as only a small amount of pasture- and cropland is irrigated (525 L/kg). Based on prevailing quantification methods, feed conversion ratios, and grazing land required, water footprints for beef produced through grazing alone can be relatively high. Green water footprints can easily reach more than 19,000 L/kg for beef from grazing compared with a maximum of 1,731 L/kg for chicken under a typical scenario. However, much of the existing grazing land cannot or should not be converted to cropland for various ecological reasons, and large water footprints would remain for the vegetation even if cattle were removed. Life cycle assessments (LCA) were historically developed to provide a framework for evaluation of the full life cycle of a product or service and to ultimately model environmental impacts through life cycle impact assessment methods. Life cycle assessments grew more refined during past years and efforts are being made to reflect the environmental and economic consequences of different livestock and crop production systems more accurately than in the past. Typical beef production systems on natural and naturalized grasslands in North America generate environmental, economic, and societal benefits that should be reflected in future LCA, farm policies, and regulations. To increase the water use efficiency of each segment of the beef supply chain and thereby to reduce water footprints, grazing systems and methods as well as external inputs should be further optimized and integrated toward enhanced ecosystem services, thereby lowering the overall environmental impact of livestock production.

438 Life cycle assessment of forage-based livestock production systems.

438 Life cycle assessment of forage-based livestock production systems.

Multigene synergism increases the isoflavone and proanthocyanidin contents of Medicago truncatula.

Isoflavones and proanthocyanidins (PAs), which are flavonoid derivatives, possess many health benefits and play important roles in forage-based livestock production. However, the foliage of Medicago species accumulates limited levels of both isoflavones and PAs. In this study, biosynthesis of isoflavone and PA in Medicago truncatula was enhanced via synergy between soya bean isoflavone synthase (IFS1); two upstream enzymes, chalcone synthase (CHS) and chalcone isomerase (CHI); and the endogenous flavanone 3-hydroxylase (F3H). Constitutive expression of GmIFS1 alone resulted in ectopic accumulation of the isoflavone daidzein and large increases in the levels of the isoflavones formononetin, genistein and biochanin A in the leaves. Furthermore, coexpression of GmIFS1 with GmCHS7 and GmCHI1A generally increased the available flux to flavonoid biosynthesis and resulted in elevated isoflavone, flavone and PA contents. In addition, down-regulation of MtF3H combined with coexpression of GmIFS1, GmCHS7 and GmCHI1A led to the highest isoflavone levels (up to 2 μmol/g fresh weight in total). Taken together, our results demonstrate that multigene synergism is a powerful means to enhance the biosynthesis of particular flavonoids and can be more broadly applied to the metabolic engineering of forage species.

Soil‐Fertility Principles for Warm‐Season Perennial Forages and Sustainable Pasture Production

Pasture fertilization plays a vital role in the biological and economic successes of forage-based livestock systems. Sustainability of productive, warm-season perennial forage systems depends, to a major extent, on management–utilization strategies and pasture fertilization. As soil nutrient reserves are exhausted, forage production and nutritive value are reduced proportionally. Despite the vast scientific literature suggesting that warm-season forage crops can respond favorably to high levels of N fertilization, the increasing costs of commercial fertilizers and environmental concerns have prompted the need to reexamine optimumefficient fertilizer levels, sources, and methods of application that can sustain economic pasture production. Because the fate of fertilizers applied to grassland systems is extremely complex and is affected by several factors, including application rate and timing, fertilizer source, and soil and environmental characteristics, it is critical to implement management strategies for soil fertility that integrate all the factors that affect fertilizer efficiency, sustainable forage production, and protection of natural resources. The primary objective of this review paper is to present some of the basic principles of soil-fertility management for warm-season perennial forages and fertilization strategies for sustainable

Simulating forage production of Marandu palisade grass (Brachiaria brizantha) with the CROPGRO-Perennial Forage model

Forage-based livestock systems are complex, and interactions among animals, plants and the environment exist at several levels of complexity, which can be evaluated using computer modelling. Despite the importance of grasslands for livestock production in Brazil, tools to assist producers to make decisions in forage–livestock systems are scarce. The objective of this research was to use the CROPGRO-Perennial Forage model to simulate the irrigated and rainfed growth of Marandu palisade grass (Brachiaria brizantha (A. Rich.) Stapf. cv. Marandu), the most widely grown forage in Brazil, by using parameters previously calibrated for the tall-growing cv. Xaraes of the same species, under non-limiting water conditions. The model was calibrated for the irrigated experiment and then tested against independent data of the rainfed experiment. Data used to calibrate the model included forage production, plant-part composition, leaf photosynthesis, leaf area index, specific leaf area, light interception and plant nitrogen (N) concentration from a field experiment conducted during 2011–13 in Piracicaba, SP, Brazil. Agronomic and morpho-physiological differences between the two grasses, such as maximum leaf photosynthesis, N concentration and temperature effect on growth rate, were considered in the calibration. Under rainfed conditions, the simulations using the Penman–Monteith FAO 56 method gave a more realistic water stress response than the Priestley and Taylor method. After model parameterisation, the mean simulated herbage yield was 4582 and 5249 kg ha–1 for 28 days and 42 days irrigated, and 4158 and 4735 kg ha–1 for 28 days and 42 days rainfed, respectively. The root-mean-square error ranged from 464 to 526 kg ha–1 and the D-statistic from 0.907 to 0.962. The simulated/observed ratios ranged from 0.977 to 1.001. These results suggest that the CROPGRO-Perennial Forage model can be used to simulate growth of Marandu palisade grass adequately under irrigated and rainfed conditions.

Nutrient Cycling in Grazed Pastures

Many forage-based livestock production systems in Florida are characterized by extensive grazing with minimal inputs of commercial fertilizer and supplemental feed. In these systems, adequate soil fertility conditions are essential to sustain forage production. If nutrients become deficient, pasture and animal performance is reduced, and the economic returns of livestock operations may decline. This 3-page fact sheet discusses the different nutrient pathways in grazing pastures to help producers better understand how to promote nutrient cycling and pasture sustainability. Written by Maria L. Silveira, Joao M. B. Vendramini, Hiran M. da Silva, and Mariana Azenha, and published by the UF Department of Soil and Water Science, January 2013. 
 http://edis.ifas.ufl.edu/ss578

Challenges and opportunities for improving eco-efficiency of tropical forage-based systems to mitigate greenhouse gas emissions

Forage-based livestock production plays a key role in national and regional economies, for food security and poverty alleviation, but is considered a major contributor to agricultural GHG emissions. While demand for livestock products is predicted to increase, there is political and societal pressure both to reduce environmental impacts and to convert some of the pasture area to alternative uses, such as crop production and environmental conservation. Thus, it is essential to develop approaches for sustainable intensification of livestock systems to mitigate GHG emissions, addressing biophysical, socio-economic and policy challenges. This paper highlights the potential of improved tropical forages, linked with policy incentives, to enhance livestock production, while reducing its environmental footprint. Emphasis is on crop-livestock systems. We give examples for sustainable intensification to mitigate GHG emissions, based on improved forages in Brazil and Colombia, and suggest future perspectives.

Nitrate and fecal coliform concentration differences at the soil/bedrock interface in Appalachian silvopasture, pasture, and forest

A major limitation to efficient forage-based livestock production in Appalachia is asynchrony of forage availability and quality with nutritional requirements of the grazer. Producers require dependable plant resources and management practices that improve the seasonal distribution and persistence of high quality herbage, sustainability and environmental integrity of the agricultural landscape. It was hypothesized that inorganic N and fecal coliform concentrations delivered in leachate to the soil/bedrock interface would be lowest in deciduous forest (HF) and highest in pasture (CP) with HF converted to silvopasture (SP) between the two. Piezometers were used to monitor water quality at the soil/bedrock interface under conventional pasture, SP, and hardwood forest. The pasture and SP were rotationally grazed by sheep during the spring to fall grazing season (2004–2008). Geometric mean fecal coliform bacteria concentrations (FC) were greatest in SP (18 FC 100 mL−1) with no difference between CP (7.5 FC 100 mL−1) and HF (5.6 FC 100 mL−1). Mean NO3-N concentration was lowest in SP (2.3 mg L−1) and greatest in CP (4.4 mg L−1) and HF (4.1 mg L−1), which were not significantly different. Mean NH4-N concentrations showed different trends with the lowest mean concentration in CP (0.5 mg L−1) and the greatest in SP (2.5 mg L−1) and HF (2.6 mg L−1), which were not significantly different. SP was shown to be a management option in the study area that reduces nitrate leaching, but should be considered cautiously in near-stream areas and near wells where fecal bacteria pollution can be problematic. This study makes an important contribution to our knowledge about interactions between landscape management and environmental quality of the Appalachian region. A diversity of land and forage management options are needed to maximize forage and livestock productivity while protecting surface and groundwater quality of the region.