Variation in production of cool-season forages over a typical grazing period increases the risk of failing to meet livestock nutrient needs. The objective of this study was to evaluate the ...risk-buffering capacity of warm-season forages to fill the summer slump in production of cool-season grasses in the Appalachian region. Small-plot experiments were initiated in the summer of 2008 at three sites in Virginia. Treatments included three tall fescue Schedonorus phoenix (Scop.) Hulub types (endophyte-infected KY31 E+, endophyte free KY31 E–, and novel endophyte Max Q), Teff Eragrotis tef (Zucc.) Trotter, bermudagrass Cynodon dactylon (L.) Pers. (BG), and Caucasian bluestem Bothriochloa bladhii (Retz) S.T. Blake (CB). Plots were harvested May through October of 2009 and 2010 at the late boot stage at a cutting height of 10 cm. Subsamples were analyzed for dry matter and nutritive value. To assess risk, bootstrap distributions of biomass and quality data were generated by Monte Carlo simulation and compared against an objective function defined as 59 kg ha-1 d-1 forage yield; 100 g kg-1 crude protein (CP); 600 g kg-1 total digestible nutrients (TDN). The warm-season grasses produced biomass yields and nutritional values adequate to fill the summer slump from cool-season forages and demonstrated a higher probability of meeting the minimum requirements in July, August, and September. Teff was most consistent in meeting the minimum requirements in mid-summer. However, both BG and CB can help to fill the gap in summer months when compared to cool-season tall fescue. Bootstrap distributions provide producers with a tool that links their production goals with a measurable value of production risk.
Pasture lands are an important facet of land use in the northeast United States, yet little is known about their recent diversity. To answer some fundamental questions about the diversity of these ...pasture lands, we designed a broad survey to document plant species richness using an intensive, multi scale sampling method. We also wanted to learn whether environmental (soils or climate) or land management variables could help explain patterns of species richness. A total of 17 farms, encompassing 37 pastures, were sampled in New York, Pennsylvania, Vermont, Maryland, Massachusetts and Connecticut during July and August 1998. We positively identified a total of 161 different plant species across the study region. Species richness averaged 31.7 ± 1.1 on pastures. Infrequent, transient species that were mostly perennial and annual forbs accounted for ∼ 90% of the species richness. Except for a subjective rating of grazing intensity, land management methods were not good predictors of species richness. Over time, it appears that grazing neither reduces nor increases species richness in pastures. Of the environmental variables measured, only soil P explained a significant amount of the variation in species richness. Soil P was inversely related to species richness at the$1\text{m}^{2}$scale. Percent SOM was positively associated with species richness at this scale, although weakly. At larger spatial scales, we suggest that patterns of species richness are best explained by the species diversity of soil seed banks, or seed rain, and stochastic recruitment of these species into existing vegetation.
Endophyte-infected (E+) tall fescue Lolium arundinaceum (Schreb.) S.J. Darbyshire is problematic in pastures because it produces alkaloids that can be toxic to cattle (Bos taurus). Replacement of E+ ...tall fescue pasture with endophyte-free (E-) fescue may effectively eliminate this problem. Endophyte-free cultivars, however, are less competitive than E+ fescue and are usually displaced over time. The main objective of this study was to determine whether E+ fescue would reinfest pastures planted with mixtures of E- fescue and other species and grazed under rotational stocking. In 2001, nine tall fescue pastures in western Illinois were renovated and planted with mixtures that contained E- fescue (Barcel) and two, four, or seven additional species. Pastures were grazed by beef cattle over 3 yr. Tall fescue tillers were collected each September and subjected to microscopic analysis for endophyte presence. After renovation, E+ still accounted for 18 to 38% of tall fescue. Relative to all other species, however, E+ fescue was <10% of pasture communities. The species mixtures sown with E- fescue had little influence on E+ fescue reinfestation (P = 0.70). Contrary to other studies, percentage of E+ fescue in E- pastures did not increase in the 3 yr of this study. Moderate grazing pressure under rotational stocking combined with relatively wet growing seasons likely favored E- fescue and suppressed E+ reinfestation. We also suggest that if pasture renovation can reduce E+ fescue percentage to <10%, it is unlikely that E+ fescue will reinfest pastures to an extent that may cause fescue toxicosis in cattle.
Abstract
Integrating trees into pastures, a practice known as silvopasture, may benefit livestock in the summertime through the provision of shade. The purpose of this project was to compare the ...behavioral patterns of sheep grazing in silvopastures and open pastures. Black walnut (Juglans nigra L.) and honeylocust (Gleditisia triacanothose L.) based silvopasture systems were compared with open pastures in a randomized complete block design with three blocks over two summers. Behavior measures were recorded within a replicate within a week, and these measures were taken sequentially within three experimental periods. Ewe lambs (n = 3) within each experimental unit were equipped with a wideband audio-recording device to detect prehension events. Time-lapse cameras documented sheep behavior every 60 s. In the silvopastures, the lambs spent over 90% of daylight hours within shade from trees. Lambs in silvopastures spent more time lying down than animals in the open pastures (P ≤ 0.01), while lambs in the open pastures spent more than 2 h longer each day standing (P < 0.0001). Lambs in the black walnut silvopastures spent more time grazing (488 ± 14 min · d−1) than lambs in the honeylocust silvopastures (438 ± 14 min · d−1; P = 0.0493) and lambs in the open pastures (417 ± 14 min · d−1; P = 0.0026). There was no difference in grazing time for lambs in the latter two systems (P = 0.5597). Spectral analysis of the imagery revealed that the lambs in the black walnut silvopastures grazed more frequently than the lambs in the other systems for both years. The acoustic analysis, though limited by recorder durability to 47 complete recordings, revealed no difference in total bites taken per day (P ≥ 0.7222) or in the morning (P ≥ 0.2069), afternoon (P ≥ 0.5816), and evening periods (P ≥ 0.9337). Silvopastures provide an opportunity to improve lamb comfort in the summer.
Background:
The phosphorylation of eukaryotic initiation factor 2 (p-eIF2) during dietary amino acid insufficiency reduces protein synthesis and alters gene expression via the integrated stress ...response (ISR).
Objective:
We explored whether a Met-restricted (MR) diet activates the ISR to reduce body fat and regulate protein balance.
Methods:
Male and female mice aged 3–6 mo with either whole-body deletion of general control nonderepressible 2 (
Gcn2
) or liver-specific deletion of protein kinase R-like endoplasmic reticulum kinase (
Perk
) alongside wild-type or floxed control mice were fed an obesogenic diet sufficient in Met (0.86%) or an MR (0.12% Met) diet for ≤5 wk. Ala enrichment with deuterium was measured to calculate protein synthesis rates. The guanine nucleotide exchange factor activity of eIF2B was measured alongside p-eIF2 and hepatic mRNA expression levels at 2 d and 5 wk. Metabolic phenotyping was conducted at 4 wk, and body composition was measured throughout. Results were evaluated with the use of ANOVA (
P
< 0.05).
Results:
Feeding an MR diet for 2 d did not increase hepatic p-eIF2 or reduce eIF2B activity in wild-type or
Gcn2
−/−
mice, yet many genes transcriptionally regulated by the ISR were altered in both strains in the same direction and amplitude. Feeding an MR diet for 5 wk increased p-eIF2 and reduced eIF2B activity in wild-type but not
Gcn2
−/−
mice, yet ISR-regulated genes altered in both strains similarly. Furthermore, the MR diet reduced mixed and cytosolic but not mitochondrial protein synthesis in both the liver and skeletal muscle regardless of
Gcn2
status. Despite the similarities between strains, the MR diet did not increase energy expenditure or reduce body fat in
Gcn2
−/−
mice. Finally, feeding the MR diet to mice with
Perk
deleted in the liver increased hepatic p-eIF2 and altered body composition similar to floxed controls.
Conclusions:
Hepatic activation of the ISR resulting from an MR diet does not require p-eIF2.
Gcn2
status influences body fat loss but not protein balance when Met is restricted.
We studied how ungulates and a large variation in site conditions influenced grassland nitrogen (N) dynamics in Yellowstone National Park. In contrast to most grassland N studies that have examined ...one or two soil N processes, we investigated four rates, net N mineralization, nitrification, denitrification, and inorganic N leaching, at seven paired sites inside and outside longterm (33+ year) exclosures. Our focus was how N fluxes were related to one another among highly variable grasslands and how grazers influenced those relationships. In addition, we examined variation in soil δ15N among grasslands and the relationships between soil15N abundance and N processes. Previously, ungulates were reported to facilitate net N mineralization across variable Yellowstone grasslands and denitrification at mesic sites. In this study, we found that herbivores also promoted nitrification among diverse grasslands. Furthermore, net N mineralization, nitrification, and denitrification (kg N ha-1year-1, each variable) were postively and linearly related to one another among all grasslands (grazed and fenced), and grazers reduced the nitrification/net N mineralization and denitrification/net N mineralization ratios, indicating that ungulates inhibited the proportion of available NH₄+ that was nitrified and denitrified. There was no relationship between net N mineralization or nitrification with leaching (indexed by inorganic N adsorbed to resin buried at the bottom of rooting zones) and leaching was unaffected by grazers. Soil δ15N was positively and linearly related to in situ net N mineralization and nitrification in ungrazed grasslands; however, there was no relationship between isotopic composition of N and those rates among grazed grasslands. The results suggested that grazers simultaneously increased N availability (stimulated net N mineralization and nitrification per unit area) and N conservation (reduced N loss from the soil per unit net N mineralization) in Yellowstone grasslands. Grazers promoted N retention by stimulating microbial productivity, probably caused by herbivores promoting labile soil C. Process-level evidence for N retention by grazers was supported by soil δ15N data. Grazed grassland with high rates of N cycling had substantially lower soil δ15N relative to values expected for ungrazed grassland with comparable net N mineralization and nitrification rates. These soil15N results suggest that ungulates inhibited N loss at those sites. Such documented evidence for consumer control of N availability to plants, microbial productivity, and N retention in Yellowstone Park is further testimony for the widespread regulation of grassland processes by large herbivores.
Although the variation in natural 15N abundance in plants and soils is well characterized, mechanisms controlling N isotopic composition of organic matter are still poorly understood. The primary ...goal of this study was to examine the role of NH3 volatilization from ungulate urine patches in determining 15N abundance in grassland plants and soil in Yellowstone National Park. We additionally used isotopic measurements to explore the pathways that plants in urine patches take up N. Plant, soil, and volatilized NH3 δ 15N were measured on grassland plots for 10 days following the addition of simulated urine. Simulated urine increased 15N of roots and soil and reduced 15N of shoots. Soil enrichment was due to the volatilization of isotopically light NH3. Acid-trapped NH3 δ 15N increased from -28‰ (day 1) to -0.3‰ (day 10), and was lighter than the original urea-N added (1.2‰). A mass balance analysis of urea-derived N assimilated by plants indicated that most of the N taken up by plants was in the form of ammonium through roots. However, isotope data also showed that shoots directly absorbed 15N - depleted NH3-N that was volatilized from simulated urine patches. These results indicate that NH3 volatilization from urine patches enriches grassland soil with 15N and shoots are a sink for volatilized NH3, which likely leads to accelerated cycling of excreted N back to herbivores.
Existing reports show a bidirectional association between type 2 diabetes mellitus (T2D) and pulmonary dysfunction. Obesity, which is causally related to both T2D and pulmonary dysfunction, could ...play an important role in this association. However, this has not been reported.
What are the associations of measures of obesity with pulmonary function in T2D?
This was a cross-sectional study among 464 adults with T2D. Spirometry was performed according to the American Thoracic Society/European Respiratory Society guidelines. The predicted values of the spirometric indices were determined using the Global Lung Function Initiative 2012 equations. The values of FEV1/FVC and FVC were used to categorize pulmonary function patterns as normal, obstructive, restrictive, or mixed. Waist circumference (WC) was measured at the midpoint between the lower margin of the lowest palpable rib and the top of the iliac crest.
The mean age, diabetes duration, and female/male ratio of the participants were 55.09 ± 10.45 years, 10.00 ± 7.36 years, and 2.1, respectively. In a multiple linear regression model, WC was a significant predictor of FVC (P = .018) and FEV1/FVC ratio (P = .005), but not FEV1 (P = .472). BMI was a significant predictor of FEV1/FVC ratio (P = .031), but not FEV1 (P = .802) or FVC (P = .129). In a multivariable logistic regression model adjusted for age, sex, socioeconomic status, diabetes duration, glycated hemoglobin, statin use, and smoking pack-years, increasing z score WC was associated with higher odds of restrictive spirometry (OR, 1.32; 95% CI, 1.05-1.66; P = .019), but not airway obstruction (OR, 0.65; 95% CI, 0.42-1.03; P = .067). There were no significant associations of increasing z score BMI with restrictive spirometry (OR, 1.24; 95% CI, 0.98-1.58; P = .075) or airway obstruction (OR, 0.79; 95% CI, 0.51-1.24; P = .305).
Increasing WC is associated with restrictive spirometry, independent of conventional diabetes and pulmonary risk factors. Future research could explore the role of the reversal of central obesity on pulmonary function in T2D.
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