Shifts in bacterial traits under chronic nitrogen deposition align with soil processes in arbuscular, but not ectomycorrhizal-associated trees

Nitrogen (N) deposition increases soil carbon (C) storage by reducing microbial activity. These effects vary in soil beneath trees that associate with arbuscular (AM) and ectomycorrhizal (ECM) fungi. Variation in carbon C and N uptake traits among microbes may explain differences in soil nutrient cycling between mycorrhizal associations in response to high N loads, a mechanism not previously examined due to methodological limitations. Here, we used quantitative Stable Isotope Probing (qSIP) to measure bacterial C and N assimilation rates from an added organic compound, which we conceptualize as functional traits. As such, we applied a trait-based approach to explore whether variation in assimilation rates of bacterial taxa can inform shifts in soil function under chronic N deposition. We show taxon-specific and community-wide declines of bacterial C and N uptake under chronic N deposition in both AM and ECM soils. N deposition-induced reductions in microbial activity were mirrored by declines in soil organic matter mineralization rates in AM but not ECM soils. Our findings suggest C and N uptake traits of bacterial communities can predict C cycling feedbacks to N deposition in AM soils, but additional data, for instance on the traits of fungi, may be needed to connect microbial traits with soil C and N cycling in ECM systems. Our study also highlights the potential of employing qSIP in conjunction with trait-based analytical approaches to inform how ecological processes of microbial communities influence soil functioning.

Litter and soil biodiversity jointly drive ecosystem functions

The decomposition of litter and the supply of nutrients into and from the soil are two fundamental processes through which the above- and belowground world interact. Microbial biodiversity, and especially that of decomposers, plays a key role in these processes by helping litter decomposition. Yet the relative contribution of litter diversity and soil biodiversity in supporting multiple ecosystem services remains virtually unknown. Here we conducted a mesocosm experiment where leaf litter and soil biodiversity were manipulated to investigate their influence on plant productivity, litter decomposition, soil respiration, and enzymatic activity in the littersphere. We showed that both leaf litter diversity and soil microbial diversity (richness and community composition) independently contributed to explain multiple ecosystem functions. Fungal saprobes community composition was especially important for supporting ecosystem multifunctionality (EMF), plant production, litter decomposition, and activity of soil phosphatase when compared with bacteria or other fungal functional groups and litter species richness. Moreover, leaf litter diversity and soil microbial diversity exerted previously undescribed and significantly interactive effects on EMF and multiple individual ecosystem functions, such as litter decomposition and plant production. Together, our work provides experimental evidence supporting the independent and interactive roles of litter and belowground soil biodiversity to maintain ecosystem functions and multiple services.

Anatomical drivers of stomatal conductance in sorghum lines with different leaf widths grown under different temperatures

Sustaining crop productivity and resilience in water-limited environments and under rising temperatures are matters of concern worldwide. We investigated the leaf anatomical traits that underpin our recently identified link between leaf width (LW) and intrinsic water use efficiency (iWUE), as traits of interest in plant breeding. Ten sorghum lines with varying LW were grown under three temperatures to expand the range of variation of both LW and gas exchange rates. Leaf gas exchange, surface morphology and cross-sectional anatomy were measured and analysed using structural equations modelling. Narrower leaves had lower stomatal conductance (g_s ) and higher iWUE across growth temperatures. They also had smaller intercellular airspaces, stomatal size, percentage of open stomatal aperture relative to maximum, hydraulic pathway, mesophyll thickness, and leaf mass per area. Structural modelling revealed a developmental association among leaf anatomical traits that underpinned g_s variation in sorghum. Growing temperature and LW both impacted leaf gas exchange rates, but only LW directly impacted leaf anatomy. Wider leaves may be more productive under well-watered conditions, but consume more water for growth and development, which is detrimental under water stress.

103 The Economics and Role of Beef X Dairy Calves in the Beef Supply Chain

Utilizing beef genetics in dairy herds to produce terminal beef x dairy (BXD) crosses is a growing trend in the U.S. dairy industry. It has been estimated that more than two million U.S. BXD calves were born in 2020, which is a practice that is expected to continue to grow throughout the foreseeable future. While not a new concept, the widespread adoption, scale, and strategies currently being used to produce BXD calves have recently received considerable industry attention. Although the increased duration of feeding exposes BXD feeders to increased price and production risks when compared to straightbred beef cattle, these risks are met with several potential benefits. A prime example of such benefits includes a consistent supply of uniform, traceable feeder cattle that are easily age and source verified, that also serve as ideal candidates for enrollment in or development of other value-added marketing programs. Current demand, as indicated by newborn calf prices, suggests that the industry perceives BXD calves to be superior when compared to their straightbred dairy breed contemporaries, and at times, suggests that they may be overvalued. Sustaining such demand will require BXD calves to meet or exceed the performance and profitability expectations of the various production sectors of the beef industry. Results of a multi-year analysis of the economics of BXD calves as compared to cattle of straightbred beef or dairy breed composition will be presented. Furthermore, specific factors expected to influence value throughout the production supply chain will be outlined and discussed. Calfhood management practices that promote calf health, paired with genetic selection strategies focused on complementary traits that minimize cost of gain and increase cutability, such as feed efficiency, carcass yield, and muscularity, will play key roles in sustaining the value of BXD calves to all aspects of the beef supply chain.

The temperature sensitivity of soil: microbial biodiversity, growth, and carbon mineralization

Microorganisms drive soil carbon mineralization and changes in their activity with increased temperature could feedback to climate change. Variation in microbial biodiversity and the temperature sensitivities (Q₁₀) of individual taxa may explain differences in the Q₁₀ of soil respiration, a possibility not previously examined due to methodological limitations. Here, we show phylogenetic and taxonomic variation in the Q₁₀ of growth (5-35 °C) among soil bacteria from four sites, one from each of Arctic, boreal, temperate, and tropical biomes. Differences in the temperature sensitivities of taxa and the taxonomic composition of communities determined community-assembled bacterial growth Q₁₀, which was strongly predictive of soil respiration Q₁₀ within and across biomes. Our results suggest community-assembled traits of microbial taxa may enable enhanced prediction of carbon cycling feedbacks to climate change in ecosystems across the globe.

Administration of acetylsalicylic acid after parturition in lactating dairy cows under certified organic management: Part I. Milk yield, milk components, activity patterns, fertility, and health

Parturition is a natural process that gradually progresses from one stage to the next. However, around 5% of dairy cows will experience dystocia, which is considered to be a painful and stressful event. Studies have reported positive effects on cow performance and welfare after treatment with nonsteroidal anti-inflammatory drugs during the first postpartum days. The objectives were to assess the effects of acetylsalicylic acid administration after calving on (1) milk yield and components, (2) daily activity patterns, (3) reproductive performance, and (4) health in lactating dairy cows under certified organic management. Cows from 3 organic herds were enrolled. Within 12 h after parturition, cows were blocked by parity and calving ease and randomly assigned to 2 treatments: (1) aspirin (ASP; n = 278), in which cows received 4 consecutive treatments every 12 h with acetylsalicylic acid (100 mg/kg; 2 boluses) or (2) placebo (PLC, n = 285), in which cows received 4 treatments every 12 h with gelatin capsules (2 capsules) filled with water. Daily milk yield for the first 30 d in milk (DIM) and monthly milk yield, fat, protein, and somatic cell count (SCC) data from the first 5 Dairy Herd Improvement Association tests were collected. Activity patterns were measured using activity data loggers in the first 7 DIM. Clinical disease events (60 DIM) and fertility data were collected from on-farm computer records. Statistical analysis was performed using the MIXED (milk yield, components, and activity), LIFETEST (fertility), and GLIMMIX (health) procedures of SAS (SAS Institute Inc., Cary, NC). Overall, ASP cows produced 1.82 kg/d more milk than PLC cows during the first 30 DIM. Interestingly, cows that experienced dystocia and received ASP produced 4.48 kg/d more milk compared with cows in the PLC group that experienced dystocia. Cows treated with ASP had lower somatic cell count during the first 5 Dairy Herd Improvement Association tests. There were no differences in daily lying time, lying bouts, and lying bout duration between the ASP and PLC groups. However, cows in the ASP group had 587,64 steps/d more compared with PLC cows. In addition, ASP cows tended to require fewer days (ASP = 113.76 ± 4.99 d; PLC = 125.36 ± 4.74 d) and needed fewer services (ASP = 1.86 ± 0.21 services; PLC = 2.19 ± 0.24 services) to become pregnant compared with PLC cows. There were no differences in clinical disease events between treatments. Results from this study suggest that treating cows with ASP after calving may help improve milk yields and udder health, increase activity, and enhance fertility in dairy cattle under certified organic management.

Effects of elevated CO2 on fine root biomass are reduced by aridity but enhanced by soil nitrogen: A global assessment

Plant roots play a crucial role in regulating key ecosystem processes such as carbon (C) sequestration and nutrient solubilisation. Elevated (e)CO2 is expected to alter the biomass of fine, coarse and total roots to meet increased demand for other resources such as water and nitrogen (N), however, the magnitude and direction of observed changes vary considerably between ecosystems. Here, we assessed how climate and soil properties mediate root responses to eCO2 by comparing 24 field-based CO2 experiments across the globe including a wide range of ecosystem types. We calculated response ratios (i.e. effect size) and used structural equation modelling (SEM) to achieve a system-level understanding of how aridity, mean annual temperature and total soil nitrogen simultaneously drive the response of total, coarse and fine root biomass to eCO2. Models indicated that increasing aridity limits the positive response of fine and total root biomass to eCO2, and that fine (but not coarse or total) root responses to eCO2 are positively related to soil total N. Our results provide evidence that consideration of factors such as aridity and soil N status is crucial for predicting plant and ecosystem-scale responses to future changes in atmospheric CO2 concentrations, and thus feedbacks to climate change.

Comparison of montelukast versus budesonide in the treatment of exercise-induced bronchoconstriction

BACKGROUND

Previous studies in which leukotriene-receptor antagonist and corticosteroids were used have suggested a possible role for these anti-inflammatory drugs in the prevention of exercise-induced bronchoconstriction, but no direct comparisons have been made.

OBJECTIVE

A crossover study was undertaken to compare the ability of both montelukast and budesonide to protect patients from exercise-induced bronchoconstriction.

METHODS

A total of 20 patients (median age, 17 years; range, 8 to 36 years), who had clinical exercise-induced bronchoconstriction for 1 year and decreased FEV1 of at least 20% after exercise on two occasions, were enrolled in this study. To compare the therapies in each patient, we administered, consecutively, 10 mg of montelukast once daily at bedtime for 3 days and, later, 400 microg of budesonide twice daily for 15 days, or vice versa, with a 15-day intervening washout period during which no patient received treatment. Exercise challenges were performed at baseline (no therapy) and after each treatment. The percentage of FEV1 declines at 2, 7, and 12 minutes after exercise and the area under the curve (summarizing the extent and modification of FEV1 decreases relative to time) were measured and compared.

RESULTS

Both budesonide and montelukast significantly reduced the decrease in FEV1 (area under the curve) after exercise with respect to the baseline condition of no therapy (P = 0.0001). Overall, budesonide offered better protection (area under the curve) than did montelukast (P = 0.01), particularly in the short-term evaluation (2 minutes after exercise; P = 0.003); however, considerable individual variations in the responses to both budesonide and montelukast were observed. The degree of protection against decreases in FEV1 ranged from 0% to almost 100% for both treatments. In 16 of 20 patients, budesonide therapy offered better protection than did montelukast, and in the other 4 patients, montelukast showed better protection than did budesonide. No side effects of either montelukast or budesonide were detected during the study.

CONCLUSIONS

Treatment with budesonide or montelukast prevents exercise-induced bronchoconstriction. Because substantial variation in the response may be present among patients, both drugs should be tested in each patient before long-term therapy is chosen.