Our objective was to estimate the effects of changes in feedlot diets and the availability of performance-enhancing technologies on growth performance and the carbon footprint of cattle feeding ...between 1990 and 2020.
A model was developed to represent feedlot diets and technologies used in 1990 versus 2020 and evaluate changes in growth performance and carbon footprint. Byproduct feeds became more common between 1990 and 2020; thus, corn and dry roughage inclusion rates decreased. Estradiol-only implants and monensin were the available technologies in 1990, whereas in 2020 use of implants with combinations of trenbolone acetate and estradiol, monensin, and ractopamine hydrochloride (in the final 28 to 42 d) were common.
In both 1990 and 2020 use of all available technologies increased final BW, ADG, G:F, and hot carcass weight compared with no technology. From 1990 to 2020 initial BW, final BW, ADG, G:F, hot carcass weight, and daily DMI increased. Total days on feed increased by 44 d from 1990 to 2020. Compared with no technology, use of technologies in both 1990 and 2020 decreased total greenhouse gas emissions per animal (CO2 equivalent, CO2e). Because cattle had greater days on feed in 2020, all sources of greenhouse gas emissions per animal increased compared with the values estimated in 1990. However, when expressed as CO2e/kg of BW gain, emissions have decreased by 4.4% because of greater total BW gain in 2020 versus 1990.
Feedlot cattle decreased relative emissions from 4.78 kg of CO2e/kg of BW gain in 1990 to 4.58 kg of CO2e/kg of BW gain in 2020. Overall, feedlots in 2020 produced 47.5% more BW gain with 1.4% less cattle, while only increasing total CO2e by 39.5%. Therefore, changes in available technologies and diet formulations have improved efficiency and reduced the carbon footprint of feedlot cattle production in the past 30 yr.
We evaluated the effects of dietary NDF concentration from alfalfa hay and bulk density of steam- flaked corn (SFC) on growth performance, carcass characteristics, and liver abscesses in finishing ...beef steers.
Crossbred beef steers (n = 214; 60 pens; initial BW = 417 ± 11.9 kg) were blocked by BW and assigned randomly to treatments and fed an average of 112 d. The treatments were arranged as a 2 × 3 factorial with 10 pens per treatment and consisted of 3 NDF concentrations from alfalfa hay (3%, 4.5%, or 6%) and 309 g/L (24 lb/bu) or 412 g/L (32 lb/bu) SFC (69% or 33% starch availability, respectively). Growth performance and carcass data were analyzed with PROC MIXED of SAS with pen as the experimental unit. Quality grades and liver scores were analyzed as binomial proportions using PROC GLIMMIX. Contrast statements were used to separate linear and quadratic effects of increasing roughage NDF.
Dry matter intake responded quadratically from d 0 to 35 as roughage NDF increased from 3% to 6%, and DMI increased linearly as roughage NDF increased on d 70 to 105 and d 0 to final. Otherwise, no differences in growth performance were noted. Marbling score responded quadratically to roughage level and was greater for steers fed 3% than for those fed 4.5% or 6% roughage NDF. Steers fed 309 g/L SFC tended to have a larger LM area than those fed 412 g/L SFC. The total percentage of abscessed livers at slaughter decreased linearly as roughage NDF was increased from 3% to 6% of DM as did the presence of A+ abscesses. In addition, total liver abscesses were 13.9 percentage points less in steers fed 412 versus 309 g/L SFC.
Results suggest that increasing roughage NDF and bulk density of SFC are dietary strategies that can decrease the presence of liver abscesses at slaughter without negatively affecting growth performance.
Our goal was to evaluate the use of a novel direct-fed microbial as an alternative to antimicrobials to decrease liver abscesses in finishing beef cattle.
Beef steers (n = 240; initial BW = 263 ± ...18.0 kg) were used in a randomized complete block design comprising 3 BW blocks and 3 pen replications per treatment during the receiving period and 3 BW blocks and 14 to 15 pen replications per treatment during the finishing phase. Experimental treatments were assigned randomly to pen within BW block and consisted of (1) negative control, dietary supplement with no tylosin phosphate; (2) positive control, dietary supplement formulated to supply 90 mg of tylosin phosphate daily (Tylan-100; Elanco Animal Health); (3) positive control with tylosin phosphate removed the last 65 d of the feeding period; and (4) novel direct-fed microbial Bacillus licheniformis fed daily at 1 × 1011 cfu/steer.
From d 0 to 59, ADG, DMI, DMI as a percentage of BW, and G:F did not differ. During the finishing period, live- and carcass-adjusted final BW did not differ among treatments. Likewise, in the finishing period, there were no differences in ADG, DMI, DMI as a percentage of BW, or G:F. No differences in hot carcass weight, DP, marbling score, longissimus dorsi area, 12th-rib fat thickness, or calculated yield grade were detected among dietary treatments. Liver abscess incidence and severity were not affected by dietary treatments.
The use of a novel direct-fed microbial, B. licheniformis, in beef cattle fed in small research pens did not affect growth performance, carcass characteristics, or liver abscess prevalence or severity. Bacillus licheniformis is not a viable strategy to decrease liver abscesses in growing and finishing beef cattle.
While smoking is a well-established risk factor for surgical complications, it is unclear how frequently guideline-concordant tobacco treatments are prescribed to surgical patients. In this ...cross-sectional study including 164673 unique patients evaluated in outpatient surgery clinics at a single institution in 2020, despite a relatively high smoking prevalence (14.7%), guideline-concordant treatment rates were very low, with only 12.7% of patients receiving pharmacotherapy and 31.7% receiving any treatment. Addressing disparities in smoking cessation treatments are critical given the disproportionate impact of smoking on surgical outcomes.
Understanding microbial gene functions relies on the application of experimental genetics in cultured microorganisms. However, the vast majority of bacteria and archaea remain uncultured, precluding ...the application of traditional genetic methods to these organisms and their interactions. Here, we characterize and validate a generalizable strategy for editing the genomes of specific organisms in microbial communities. We apply environmental transformation sequencing (ET-seq), in which nontargeted transposon insertions are mapped and quantified following delivery to a microbial community, to identify genetically tractable constituents. Next, DNA-editing all-in-one RNA-guided CRISPR-Cas transposase (DART) systems for targeted DNA insertion into organisms identified as tractable by ET-seq are used to enable organism- and locus-specific genetic manipulation in a community context. Using a combination of ET-seq and DART in soil and infant gut microbiota, we conduct species- and site-specific edits in several bacteria, measure gene fitness in a nonmodel bacterium and enrich targeted species. These tools enable editing of microbial communities for understanding and control.
Sending Signals Dynamically Smock, Robert G; Gierasch, Lila M
Science (American Association for the Advancement of Science),
04/2009, Letnik:
324, Številka:
5924
Journal Article
Recenzirano
Odprti dostop
Proteins mediate transmission of signals along intercellular and intracellular pathways and between the exterior and the interior of a cell. The dynamic properties of signaling proteins are crucial ...to their functions. We discuss emerging paradigms for the role of protein dynamics in signaling. A central tenet is that proteins fluctuate among many states on evolutionarily selected energy landscapes. Upstream signals remodel this landscape, causing signaling proteins to transmit information to downstream partners. New methods provide insight into the dynamic properties of signaling proteins at the atomic scale. The next stages in the signaling hierarchy--how multiple signals are integrated and how cellular signaling pathways are organized in space and time--present exciting challenges for the future, requiring bold multidisciplinary approaches.
•Numerous studies examined youth physical activity (PA) during the COVID-19 pandemic.•Overall decreases in youth PA were seen during the first 1.5 years of the pandemic.•There were differences in PA ...by sub-populations (e.g., age, sex/gender)•There were also differences in PA by location/type (e.g., outdoor, play)•Programming and policy should focus on evolving PA promotion for youth.
The purpose of the systematic review was to identify, evaluate, and synthesize evidence from available published literature examining the impact of the coronavirus disease 2019 (COVID-19) pandemic on youth physical activity (PA). A systematic review of the literature was conducted for years 2020–2021. Published articles were searched in eight databases. Inclusion criteria included: availability of full-text, written in English language, and reported quantitative or qualitative results of original or secondary data on PA and COVID-19 related factors among youth (ages 5–17 years). A standard quality assessment tool assessed risk of bias and quality of included articles. The search retrieved 2,899 articles with 51 articles ultimately meeting inclusion criteria. The majority of articles (65 %) investigated change in PA from before to during the pandemic. Most evidence indicated an overall decrease in youth PA levels during the pandemic with differences observed among sub-populations (e.g., age, sex or gender), type, and location. Findings suggest pandemic-related closures hindered PA participation due to a high reliance on school- and sport-based PA. Programmatic strategies (e.g., activity breaks, active curriculum, free online activities/lessons) should include aligning intervention measures and geared towards evolving and ongoing PA promotion based on the latest findings.
Cohabitation is now the modal path to marriage in the United States. Drawing on data from 115 in-depth interviews with cohabitors from the working and lower middle classes, this paper explores how ...economics shape marital decision making. We find that cohabitors typically perceive financial issues as important for marriage, and we delineate several key themes. Whereas some social scientists speculate that cohabitors must think that marriage will change their lives in order to motivate marriage, our findings suggest that cohabitors believe marriage should occur once something has already changed--in this case, their financial status. Our results also imply that political and scientific discourse on financial problems as deterrents to marriage should be broadened beyond a focus on poor unmarried parents.
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