Switchgrass (Panicum virgatum L.)-a perennial, warm-season (C
4
) species-evolved across North America into multiple, divergent populations. The resulting natural variation within the species ...presents considerable morphological diversity and a wide range of adaptation. The species was adopted as a crop-initially as a forage-only in the last 50 yr. Its potential uses have recently been expanded to include biofuels. Management of switchgrass for biofuels is informed by an understanding of the plant's biology. Successful establishment requires attention to seed dormancy and weed control as well as proper depth and date of planting. The plant's growth rate is closely tied to temperature, but timing of reproductive development is linked to photoperiod. Accordingly, the period of vegetative growth can be extended by planting lower-latitude cultivars at higher latitudes. This strategy may provide a yield advantage, but cold tolerance can become limiting. Switchgrass is thrifty in its use of applied N; it appears able to obtain N from sources that other crops cannot tap. The N removed in harvested biomass is often greater than the amount of N applied. In areas with sufficient rainfall, sustainable yields of ∼15 Mg ha
−1
yr
−1
may be achievable by applying ∼50 kg N ha
−1
yr
−1
. Harvesting biomass once per season-after plants have senesced and translocated N into perennial tissues-appears to allow plants to maintain an internal N reserve. Two harvests yr
−1
may increase yields in some cultivars, but a single annual harvest maximizes yields in many cases. If two harvests are taken, more N must be applied to compensate for the N removed in the midseason harvest. Taking more than two harvests yr
−1
often adversely affects long-term productivity and persistence. Switchgrass has potential as a renewable fuel source, but such use will likely require large infrastructural changes; and, even at maximum output, such systems could not provide the energy currently being derived from fossil fuels.
A silvopasture system intentionally integrates trees, forages, and livestock, allowing dual land use. These systems can provide high-quality habitat for broiler chickens; however, such systems have ...not been widely adopted by the broiler industry in the United States. The objective of this study was to examine the effect of silvopasture versus open pasture access on fearfulness and leg health in fast-growing broiler chickens. A total of 886 mixed-sex Ross 708 chicks in Experiment 1 (Exp 1) and 648 chicks in Experiment 2 (Exp 2) were housed in coops and had access to 16 (Exp 1) or 12 (Exp 2) 125m2 silvopasture plots (x̄ = 32% canopy cover) or open pasture plots (no canopy cover) from day 24 of age. Fearfulness was measured using a tonic immobility test (tonic immobility duration), and leg health was assessed by quantifying footpad dermatitis, hock burns, gait, and performing a latency-to-lie test on days 37-39 of age. Birds in the silvopasture treatment were less fearful than birds in the open pasture treatment. Overall, birds in both silvopasture and open pasture systems had excellent leg health. Silvopasture birds had lower footpad dermatitis scores than open pasture birds. Silvopasture birds tended to have worse gait than open pasture birds in Exp 1, but not in Exp 2. Hock burn scores and latency-to-lie did not differ between treatments in Exp 1 or Exp 2. Raising birds in silvopasture reduced fear and improved footpad health compared to birds raised in open pastures, which indicates that silvopasture systems provide some benefits for affective state and leg health in fast-growing broilers.
Pulmonary arterial hypertension (PAH) is a deadly disease with no cure. Alternate conversion of angiotensin II (AngII) to angiotensin-(1-7) (Ang-(1-7)) by angiotensin-converting enzyme 2 (ACE2) ...resulting in Mas receptor (Mas1) activation improves rodent models of PAH. Effects of recombinant human (rh) ACE2 in human PAH are unknown. Our objective was to determine the effects of rhACE2 in PAH.We defined the molecular effects of Mas1 activation using porcine pulmonary arteries, measured AngII/Ang-(1-7) levels in human PAH and conducted a phase IIa, open-label pilot study of a single infusion of rhACE2 (GSK2586881, 0.2 or 0.4 mg·kg
intravenously).Superoxide dismutase 2 (SOD2) and inflammatory gene expression were identified as markers of Mas1 activation. After confirming reduced plasma ACE2 activity in human PAH, five patients were enrolled in the trial. GSK2586881 was well tolerated with significant improvement in cardiac output and pulmonary vascular resistance. GSK2586881 infusion was associated with reduced plasma markers of inflammation within 2-4 h and increased SOD2 plasma protein at 2 weeks.PAH is characterised by reduced ACE2 activity. Augmentation of ACE2 in a pilot study was well tolerated, associated with improved pulmonary haemodynamics and reduced markers of oxidant and inflammatory mediators. Targeting this pathway may be beneficial in human PAH.
Globally, forest ecosystems are shrinking and their health is declining due to a range of biotic and abiotic factors. Forest ecosystems in Pakistan are no exception and the country faces a crisis as ...its growing population (> 208 million) places increasing pressure on the country’s food production systems and forest resources. Effective food systems that enhance productivity, increase economic outputs, improve ecological outcomes and maintain social acceptance are needed. Agroforestry, a traditional land management system in Pakistan, offers the opportunity to meet these goals. Planting trees on private farmland provides clear ownership of any timber resource and well managed systems have great potential both to boost agriculture and reduce wood shortages. Concerted extension efforts have been made to introduce and promote innovative agroforestry practices in Pakistan, but the success of these efforts depends on many factors. This paper reviews some of the current constraints to agroforestry promotion in Pakistan, including attitudes of the extension staff, poor or weak research-extension coordination, lack of trained personnel, lack of farmer response to advice, tree species limitations, and market mechanism as well as wood price challenges. Establishing model agroforestry farms at the village level can be a productive extension approach, but successful extension programming requires partners to share both an appreciation of the problem and a vision of successful outcomes. Successful promotion also requires appropriate choice of message, messenger, target audience and effective use of appropriate communication tools. Remedial measures to streamline the existing systems and devise future sustainable strategies and approaches are suggested to promote agroforestry in Pakistan.
Shade for livestock during periods of heat stress is likely to be one of the biggest drivers for silvopasture adoption by livestock producers, yet the degree of physiological benefit for animals in ...silvopastures is generally unquantified. The greatest challenge for measuring body temperatures and assessing heat stress in animals on pasture is in collecting the data while minimizing disturbance to the animal. In this study, intravaginal temperature sensors were constructed from blank controlled internal drug release devices and small temperature loggers. Body temperatures of ewe lambs (
n
= 9) were recorded within a replicate within a week, and these measures were taken sequentially within each of three experimental periods. During the hottest part of the day (1200–1900 h), ewe lambs in the open pasture had hotter vaginal temperatures than lambs in the black walnut (
Juglans nigra
) silvopastures (P ≤ 0.0338). Ewe lambs in the honeylocust silvopastures (
Gleditsia triacanthos
) had cooler body temperatures than lambs in the open pastures at 1500 h (P = 0.0469). Ewe lambs in the open pasture experienced more fluctuation in day to nighttime core temperature change (P < 0.0001). Ewe lambs in the honeylocust silvopastures and the open pastures exhibited increasing vaginal temperatures each successive month. The trees within these silvopastures moderated the impact of ambient conditions on lamb body temperatures.
Hair cortisol is a relatively non-invasive and reliable measure of chronic stress, but it has received limited use, especially in pasture systems. A two-year study was carried out to compare ...behavioral and physiological (intravaginal temperature, hair, and blood cortisol) responses of ewes (Ovis aries) that grazed black walnut (Juglans nigra) silvopasture (BSP), honeylocust (Gleditsia triacanthos) silvopasture (HSP), or open pastures (OP) treatments. Ewe weights and intravaginal temperatures were recorded once for every 3-week interval. Plasma and hair cortisol concentrations were determined by ELISA. Trail cameras detected animal behavior. Ewe average daily gain was greater in HSP compared with OP (p = 0.0456) but did not differ with BSP (p = 0.4686) across both years. Ewes on OP had higher (p < 0.0001) hair cortisol concentrations than ewes on silvopasture treatments both summers. Ewes on OP had ≥ 0.4 °C higher (p ≤ 0.03) intravaginal temperatures during portions of the afternoon than ewes managed in silvopasture treatments. Ewes on OP spent 500–700% more (p < 0.0001) time standing and 125–150% less (p < 0.0001) time lying down compared with ewes on silvopasture treatments. Hair cortisol measures could be an effective and relatively non-invasive technique for determining long-term chronic stress in grazing animals.
Biofuel production from crop residues is widely recognized as an essential component of developing a bioeconomy, but the removal of crop residues still raises many questions about the sustainability ...of the cropping system. Therefore, this study reviews the sustainability effects of crop residues removal for biofuel production in terms of crop production, soil health and greenhouse gas emissions. Most studies found little evidence that residue management had long‐term impacts on grain yield unless the available water is limited. In years when water was not limiting, corn and wheat removal rates ≥90% produced similar or greater grain yield than no removal in most studies. Conversely, when water was limiting, corn grain yield decreased up to 21% with stover removal ≥90% in some studies. Changes in soil organic fractions and nutrients depended largely on the amount of residue returned, soil depth and texture, slope and tillage. Reductions in organic fractions occurred primarily with complete stover removal, in the top 15–30 cm in fine‐textured soils. Soil erosion, water runoff and leaching of nutrients such as total nitrogen (N) and extractable soil potassium decreased when no more than 30% of crop residues were removed. Stover management effects on soil bulk density varied considerably depending on soil layer, and residue and tillage management, with removal rates of less than 50% helping to maintain the soil aggregate stability. Reductions in CO2 and N2O fluxes typically occurred following complete residue removal. The use of wheat straw typically increased CH4 emissions, and above or equal to 8 Mg/ha wheat straw led to the largest CO2 and N2O emissions, regardless of N rates. Before using crop residues for biofuel production, it should therefore always be checked whether neutral to positive sustainability effects can be maintained under the site‐specific conditions.
Biofuel production from crop residues is widely recognized as an essential component of developing a bioeconomy, but the removal of crop residues still raises many questions about the overall sustainability of the cropping system. Before using crop residues for biofuel production, it should therefore always be checked whether neutral to positive sustainability effects can be maintained under the site‐specific conditions.
Heat stress is of growing concern for producers and costs the livestock industry > $2B annually, with predictions that this cost will increase with climate change. Silvopasture is a potential ...strategy for reducing heat stress in livestock and improving productivity. In this study, we compared heifer performance and body temperatures in open pasture (OP), newly established loblolly pine (
Pinus taeda
) silvopasture, thinned pine silvopasture (PSP), and thinned hardwood silvopasture (HSP). Heifers were weighed at 4-week intervals, and their intravaginal and external hide temperatures were recorded using small temperature loggers and a drone with a thermal camera, respectively. Pre- and post-grazing forage biomass was greater in OP compared to silvopasture treatments in both years (
p
< 0.05). Type of grazing system had no effect on the seasonal weight gains of the heifers (
P
= 0.5764). Heifers in HSP and PSP had cooler intravaginal and hide temperatures (
p
< 0.05) during the afternoon hours (1150–1830 h) compared to heifers in OP, indicating reduced radiant energy loads and improved welfare during summer. Heifers without shade had a larger increase in hide temperature from morning to afternoon than heifers with access to shade (10.7 vs. 3.9 °C). These findings suggest that silvopasture systems can reduce heat stress while maintaining similar levels of livestock productivity. However, animal performance in silvopastures by month was variable. Management strategies that increase forage production in silvopastures may further the value of these systems in terms of greater land-use efficiency relative to open pasture systems.
A silvopasture system intentionally integrates trees, forages, and livestock, allowing dual land use. These systems can provide high-quality habitat for broiler chickens; however, such systems have ...not been widely adopted by the broiler industry in the United States. The objective of this study was to examine the effect of silvopasture versus open pasture access on fearfulness and leg health in fast-growing broiler chickens. A total of 886 mixed-sex Ross 708 chicks in Experiment 1 (Exp 1) and 648 chicks in Experiment 2 (Exp 2) were housed in coops and had access to 16 (Exp 1) or 12 (Exp 2) 125m2 silvopasture plots (x̄ = 32% canopy cover) or open pasture plots (no canopy cover) from day 24 of age. Fearfulness was measured using a tonic immobility test (tonic immobility duration), and leg health was assessed by quantifying footpad dermatitis, hock burns, gait, and performing a latency-to-lie test on days 37-39 of age. Birds in the silvopasture treatment were less fearful than birds in the open pasture treatment. Overall, birds in both silvopasture and open pasture systems had excellent leg health. Silvopasture birds had lower footpad dermatitis scores than open pasture birds. Silvopasture birds tended to have worse gait than open pasture birds in Exp 1, but not in Exp 2. Hock burn scores and latency-to-lie did not differ between treatments in Exp 1 or Exp 2. Raising birds in silvopasture reduced fear and improved footpad health compared to birds raised in open pastures, which indicates that silvopasture systems provide some benefits for affective state and leg health in fast-growing broilers.
Cattle grazing tall fescue (
) infected with wild-type endophytes (WE) leads to a syndrome commonly known as fescue toxicosis. Replacing WE tall fescue with a novel endophyte-infected (NE) tall ...fescue can mitigate this problem but adoption of this technology has been limited. This study measured and determined the physiological and behavioral responses of heifers that grazed either WE or NE tall fescue, utilizing relatively non-invasive techniques including hair cortisol, thermography (for extremity temperatures), small loggers for intravaginal temperature, and remote observation of in-field behavior. Heifers that grazed WE had greater (
< 0.0001) hair cortisol levels, lower extremity temperatures (
≤ 0.0075), and 0.3-0.9 °C greater (
≤ 0.02) intravaginal temperatures (particularly during the daytime) than heifers that grazed NE. From 1200 h-1700 h each day, heifers on WE pastures spent 1.5 more (
= 0.0003) hours standing up and 0.9 fewer (
= 0.0402) hours lying down than heifers on NE pastures. Differences (
= 0.0160) in ADG were small (0.1 kg d
) and were only observed in the first year of these 8-week studies. However, even in the mild environment of the study site, grazing NE tall fescue provided clear welfare benefits as evidenced by heifer behavioral changes, temperature differentials, and hair cortisol levels. This study underscores the potential utility of non-invasive techniques, such as thermographic imaging and hair cortisol analysis, for evaluating animal responses to stress in extensive grazing systems.
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