Browsing by Author "Archibeque, Shawn, committee member"
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Item Open Access An evaluation of cattle handling categories in the beef quality assurance feedyard assessment, compliance of large feedyards with these guidelines, and influence of handling practices on behavior and performance of feedlot cattle(Colorado State University. Libraries, 2015) Woiwode, Ruth, author; Grandin, Temple, advisor; Archibeque, Shawn, committee member; Engle, Terry, committee member; Kirch, Brett, committee member; Paterson, John, committee member; Rollin, Bernard, committee memberAnimal husbandry and management practices were surveyed in commercial feedlots to document compliance of select feedlots with Beef Quality Assurance (BQA) guidelines for cattle handling under the premise that this data warrants inclusion in the National Beef Quality Audit (NBQA). The BQA Feedyard Assessment for cattle handling has not yet been fully validated, and this work partially substantiates the current assessment categories. The inclusion of this handling data is essential in order to continue the track record of identifying target areas where improvement is needed, and to document growth and positive performance. Collecting and reporting of survey data is part of the verification and ongoing monitoring process that characterizes an effective HACCP plan, which was the system for management that was adopted during formation of the BQA program. It has been said that producers manage what they measure, and systematic measurement of categories for cattle handling and husbandry practices in the BQA can yield valuable information to assist producers in making management decisions. The NBQA, which has been conducted in five year increments since 1991 has accomplished just that, through the identification of targets where improvement is needed, with corresponding recommendations for improvement. The growing repository of data, collected over the course of time, reflects adjustments the industry has made in an effort to continuously improve the quality and consistency of beef production, and thus increase consumer confidence. BQA is a voluntary program that allows the use of self-assessment or third party audits to ensure compliance with the guidelines of the program. The BQA Feedyard Assessment (FA) provides guidelines for cattle handling in commercial feedlots, and is a useful tool for measuring cattle handling practices. Using these guidelines, select feedlots in 3 states (Colorado, Kansas, and Nebraska) were assessed for six current BQA categories (electric prod use, falls, stumbles, jump and run, and chute operation). These states rank 5th, 3rd, and 2nd, respectively, among all states for the number of cattle on feed each year. These three states were selected based on their ranking among the top five states for number of cattle on feed, and for the high density areas of large (1000+ head) feedyards in each state, accounting for approximately 50% of all US fed cattle each year. The feedyards included in this study were all large (1000+ head capacity) yards, with a mean capacity of 34,000 head. Across 28 sites surveyed, rate of electric prod use was 3.8% vs. the 10% current BQA critical limit (CL); only 2 sites surveyed exceeded the CL with 15% and 45% respective rates; and 12 did not use an electric prod. The rate of cattle falling when exiting the squeeze chute was 0.6% vs. BQA CL 2%, and no site surveyed exceeded the CL. The rate of cattle stumbling when exiting the squeeze chute was 5.7% vs. BQA CL 10%, with 4 sites exceeding the CL and 4 sites that had no stumbles. The rate of cattle vocalizing was 1.4% vs. BQA CL 5%; for cattle that jumped or ran when exiting the squeeze chute, 52% vs. BQA CL 25%; and mean score for cattle that were improperly captured in the squeeze chute and not readjusted was 1.2%, vs. BQA CL 0%. A second study was conducted at a commercial feedlot in Kansas. The objective of this study was to investigate if a relationship exists between handling, and behavior and ADG of feedlot cattle. Upon arrival, Hereford steers (n = 496; initial BW = 304 ± 35.6 kg) of similar genetic background were sorted into four pens to determine the effects of handling on behavior and ADG. Two handling conditions prior to processing and two conditions of release from the squeeze chute were imposed. Prior to processing, handlers were required to quietly walk all steers from their home pen to the processing area (SLOW); or handlers were permitted to bring steers to the processing area in the normal fashion (FAST). Since this condition was applied to pens, pen was considered the experimental unit for the full model. Individual steers were randomly assigned to one of two conditions of release from the squeeze chute. The first was a delay no longer than 30 seconds following the completion of procedures to allow cattle to stop struggling (DELAY); the second was release immediately following the completion of procedures (NORM). Vocalization, chute temperament, exit speed and exit behavior scores were assigned to all steers during intake processing. Paired t-tests determined that cattle exiting the chute at a walk or trot vs a run tended (P=0.08) to have higher ADG. Cattle vocalizing during restraint had lower (P=0.04) ADG than those that did not vocalize. The FAST group showed a tendency to vocalize more frequently than the SLOW group. Pearson’s correlation analysis showed a significant, positive correlation between exit speed and vocalization (P= 0.0021, r= 0.14256), and a significant, negative correlation between exit speed and ADG (P= 0.0036, r= -0.13542). Using this approach, handling was correlated with behavior and ADG.Item Open Access Environmental assessment of northern Colorado dairy systems: whole-farm predictions for past, future, and beneficial management practices(Colorado State University. Libraries, 2022) Loudenback, Andrea J., author; Dillon, Jasmine A., advisor; Archibeque, Shawn, committee member; Cramer, Catie, committee member; Mueller, Nathan, committee memberThe Northern Great Plains region is projected to experience rising average daily temperatures, greater precipitation variability, and increased overall weather variability over the next 75 years. These changes have potentially negative implications for Colorado dairy systems. The objective of this study was to (1) evaluate implications of climate change on resource use and environmental footprints of Colorado dairies through the 21st century using the Integrated Farms Systems Model (IFSM) and (2) identify and evaluate Beneficial Management Practices (BMPs) to assess the Colorado dairy industry's ability to remain sustainable and productive through 2100. The Integrated Farm System Model (IFSM) was used to estimate the carbon (CF), blue water (WF), reactive nitrogen (RnF), and energy (EF) footprints of three dairy operations: 1100-head conventional (1100C), 1100-head organic (1100OR), and 2000-head conventional (2000C). The IFSM is a whole-farm, process-based model that simulates major biophysical processes, environmental impacts, and economics of beef, dairy, and crop farms over many years of weather. Model inputs were obtained from the literature, publicly available USDA databases, and expert input. Each farm was simulated over three time periods: historic (1990-2015), mid-century (2040-2065), and late century (2075-2100). Eight general climate models (GCMs) and two representative concentration pathway scenarios (RCP 4.5 and 8.5) were used to evaluate potential climate impacts to resource use and environmental footprints of the farms. After baseline footprints were obtained, BMPs were modeled to assess the impacts on each farm's environmental footprints over each time. BMPs included 1) covered manure basin on all three farms 2) covered manure basin with flare on the 1100C farm 3) spring and fall cycle calving and milking on the 1100OR and 4) decrease in dietary crude protein from the NRC recommendation of 16% to 14% and supplementation with amino acids on the 2000C farm. The results of this study indicate that BMPs have the potential to reduce environmental footprints on dairy farms in Colorado under future climate changes. On average, manure management BMPs reduced RnF and CFs over time by 11and 5%, respectively. Reducing CP to 14% reduced ammonia emissions on the 2000C farm by up to 10% over time, however, it resulted in an increase to total CF and WF, likely from changes in upstream processes from the baseline. Spring cycle milking and calving on the 1100OR farm reduced the WF, EF, and RnF over time by 6, 3, and 5% on average, respectively. Fall cycle milking and calving increased these footprints compared to the baseline and other BMPs. Both seasonal milking BMPs increased CFs. A significant finding of the study was that WFs were predicted to decrease over time on the 1100OR and 2000C farms, both of which were producing homegrown feed. Colorado is predicted to have significant water scarcity issues in the later part of the century, and these results show that the decrease in water availability will limit the dairy industries abilities to meet its production needs. Predicted footprint values for baseline and BMP scenarios were compared to studies that evaluated regional and national dairy production using IFSM, as well as life cycle assessment (LCA) findings that averaged US dairy production from many farms. Overall, this study predicts that BMPs can be effective in reducing environmental footprints of Colorado dairy farms, which may reduce the environmental impacts of the state's dairy industry. However, farms should be wary of one size fits all solutions and need to assess their goals, productivity needs, and feasibility before implementing changes to management practices.Item Open Access Evaluation of roughage inclusion rate within a total mixed ration effects on feedlot performance, carcass characteristics, and fatty acid composition of subcutaneous adipose, intramuscular adipose, and muscle tissue of Wagyu cattle(Colorado State University. Libraries, 2015) Linton, Kathryn, author; Peel, Kraig, advisor; Archibeque, Shawn, committee member; Holt, Timothy, committee memberThe objective of this study was to investigate the effect of roughage inclusion rate of 10, 20, and 30% within a total mixed ration on feedlot performance, carcass composition and marbling distribution in Wagyu cattle (n=41). Upon arrival, cattle were acclimated to bunk style feeding. Initial body weights were collected. Animals were blocked by sex and weight to be assigned to 1 of 3 roughage inclusion rate treatments. Treatments included 1) 10% roughage inclusion on dry matter basis; 2) 20% roughage inclusion and 3) 30% roughage inclusion on dry matter basis. Diets were formulated to be isoenergentic, isonitrogenous, and isoamylolytic. Animals were weighed every 7d. For harvest animals were transported to a commercial abattoir. Hot carcass weight (HCW) was determined at time of harvest, intramuscular adipose, and subcutaneous adipose tissue was collected at harvest and snap frozen for analysis of FA composition. Longissimus muscle area (LMA) and backfat (BF) carcass measurements were determined after 21d storage at 0° C chill. A 1.25 cm cross section of longissimus dorsi at 12th and 13th rib interface was collected for Computer Vision System Ribeye Camera evaluation of marbling distribution. Limited treatment effects were observed. Feedlot performance and carcass characteristics were not significantly affected by roughage inclusion rate (P>0.05). Treatment presented a significant effect on Linoleic acid (C18:3) concentration within the longissimus muscle tissue (P=0.05). Concentration of C18:3 increased with increased roughage inclusion rate. Fatty acid profiles for LM, IMF and SQ tissues were similar across treatments. There was not treatment effect for marbling distribution collected via Computer Vision System Ribeye Camera evaluation. Overall, the data suggests that roughage inclusion rate causes very little impact on feedlot performance, carcass characteristics, fatty acid composition and marbling distribution in Wagyu cattle.Item Open Access Evaluation of the All Heifer, No Cow beef production system to improve beef production efficiency(Colorado State University. Libraries, 2019) Harrison, Meredith Ann, author; Ahola, Jason, advisor; Seidel, George, committee member; Mooney, Daniel, committee member; Archibeque, Shawn, committee memberTo view the abstract, please see the full text of the document.Item Open Access Extracting copper from dairy footbaths to prevent heavy metal bioaccumulation in agricultural land(Colorado State University. Libraries, 2018) Jalali, Sam, author; Engle, Terry, advisor; Archibeque, Shawn, committee member; Holt, Timothy, committee member; Roman-Muniz, Noa, committee memberTo view the abstract, please see the full text of the document.Item Open Access GWP* of U.S. beef and dairy systems(Colorado State University. Libraries, 2023) Molina Plaza, Erick, author; Dillon, Jasmine, advisor; Archibeque, Shawn, committee member; Denning, Scott, committee member; Sheehan, John, committee memberGlobal warming potential (GWP) is used to quantify the impact that greenhouse gases (GHG) have on the warming of the Earth's atmosphere relative to carbon dioxide (CO2). GWP* is a metric that is used to better quantify short-lived climate pollutants (SLCP) such as methane, hydrofluorocarbons, and sulfur dioxide. GWP* allows SLCP to be more consistently expressed by equating a change in the emission of the SLCP to a one-off pulse emission of CO2. Therefore, GWP* can be positive or negative. The objective of this work was to compare the GWP* and GWP100 for U.S. beef and dairy systems using livestock methane emissions data from the Food and Agriculture Organization (FAO) and the Environmental Protection Agency (EPA). Total methane emissions for this study are the sum of enteric and manure methane emissions. GWP100 was greater than GWP* for both beef and dairy systems using both datasets, with the exception GWP* for dairy using the EPA data. Dairy GWP* calculated using the EPA data was lower than GWP100 from 1990–2000, after which point on it became greater than GWP100 and continued increasing annually, because the emission factors used by the EPA increased annually, and the difference between weighted emissions from that year and the weighted emissions from 20 years prior surpassed the current emissions used in GWP100. Overall, the GWP* of EPA dairy increased by 507% from 1990–2020. The primary drivers of the differences in GWP* and GWP100 with the EPA dataset are the use of methane emission factors for manure methane, which increase yearly, and the use of a larger dairy population estimate than FAO. The EPA emission factors increase yearly based on the trend towards larger farm sizes managing more liquid manure, therefore produce more manure methane emissions. The dairy GWP* using EPA data was greater than the beef GWP* every year, despite greater total methane emissions for beef than for dairy, because the average rate of change for dairy (29.8 kt of CH4/yr) was greater than the average rate of change for beef (9.4 kt of CH4/yr). Accounting methods play a key role in the amount of methane emissions that are calculated, and thus how GWP100 and GWP* are calculated. The EPA larger population estimate and annual increase in manure methane emission factors led to greater GWP* and GWP100 values for the EPA data than for the FAO data for both beef and dairy systems. Data source is critical to the policy implications of GWP* and GWP100 for livestock systems, as evidenced by the differences in GWP* and GWP100 results between datasets.Item Open Access Invasive species management: an animal ethics perspective(Colorado State University. Libraries, 2012) Tuminello, Joseph A., author; Rollin, Bernard, advisor; McShane, Katie, committee member; Archibeque, Shawn, committee memberIn the scholarly literature on invasive species management, there exists a tendency to neglect the moral relevance of sentience when determining best possible management strategies regarding sentient members of invasive species. In addition, there is also a negative bias against invasive species, where such species are viewed as inherently "bad." Because of this negative bias, many wildlife managers, conservation biologists, and ecologists share the default view that invasive species are nuisances and must be gotten rid of, using the most cost-effective and efficient means possible. The neglect or omission of sentience within the literature often carries over into the implementation of invasive species management techniques, where sentient members of invasive species are often not treated as humanely as possible. In this thesis, I defend Bernard Rollin's animal ethic, where sentient beings are those capable of having interests, and which are also capable of self-valuation, which is necessary for possessing intrinsic value (on Rollin's view). Because such beings are capable of having interests which can be fulfilled or thwarted, they are objects of moral concern on this view. While I defend Rollin's view, any moral theory which considers sentience morally relevant at all will be compatible with the majority of my arguments regarding our treatment of sentient members of invasive species. If sentience is a morally relevant criterion, I argue that it continues to be so even when sentient beings are members of species which are considered to be "invasive." This claim is strongly supported by the large-scale vagueness and disagreement over terms such as "invasive," "native," and "exotic" within the literature. Because sentience is a morally relevant criterion when determining best possible management practices regarding invasive species, members of such species should be treated as humanely and in accordance with their respective telos as much as possible. Typically, this will entail prioritizing nonlethal and preventive methods of control over lethal methods. However, even when lethal control is deemed to be the best possible type of management strategy in a given situation, it should be implemented as humanely as possible. In addition to arguing for sentience as a morally relevant criterion when determining best possible management strategies regarding invasive species, I also argue that the negative bias against invasive species as inherently "bad" is ultimately unfounded. I support this claim by providing evidence of a variety of potential negative, positive, and neutral aspects of invasive species. Because invasive species are not inherently "bad" or "good," I argue that our attitudes toward and management of members of such species should be developed on a case-by-case basis. It is also important that the assessment of invasive species on a case-by-case basis be combined with the moral relevance of sentience. The bias against invasive species may serve to perpetuate the omission of sentience as a morally relevant criterion of invasive species management. The omission of sentience may also perpetuate the negative bias against invasive species. Understanding the moral relevance of sentience may help to diminish the negative bias against invasive species, and vice versa. After considering and responding to several objections to my arguments, I provide an overview of different sorts of lethal, nonlethal, and preventive methods of invasive species management, and discuss how each of these can be implemented in a more humane fashion, in order to present ways in which my arguments and view can be successfully applied in a variety of real-world scenarios.Item Open Access Life cycle environmental impacts of utilizing hemp seed meal as a protein source in sheep feedlot rations(Colorado State University. Libraries, 2023) Clark, Samantha Maye, author; Dillon, Jasmine, advisor; Archibeque, Shawn, committee member; Nachappa, Punya, committee member; DiVerdi, Joseph, committee memberHemp seed meal is a protein-rich byproduct of the hemp industry, obtained from the cold press extraction process used to produce hemp oil. The objective of this work was to evaluate the environmental impact of using hemp seed meal as a protein supplement in sheep production. A cradle-to-gate life cycle assessment (LCA) was conducted on three sheep production systems which differed in the feedlot phase: one fed a feedlot ration containing soybean meal as the protein source (soybean meal diet), one fed hemp seed meal in the feedlot ration (hemp diet), and one fed organic hemp seed meal in the feedlot ration (organic hemp diet). Animal performance data were collected from a nutrition trial. Hemp production, harvest, and processing data were provided by a hemp product company. Economic and physical allocation were applied to the hemp diet systems, and the ReCiPe Midpoint (H) methodology was used to calculate the global warming (i.e., carbon footprint), water consumption, land use, and fossil resource scarcity impacts on a per kg lamb live weight basis for each system. Carbon footprint ranged from 10.1 to 11.4 kg CO2eq/kg LW, water consumption ranged from 1.3 to 4.2 m3/kg LW, fossil resource scarcity ranged from 0.5 to 0.8 kg oil eq/kg LW, and land use ranged from 2.8 to 6 m2a crop eq/kg LW. Impact assessment results were not sensitive to a 10 or 20% increase in electricity demand at processing. The use of IPCC Tier 2 methods for estimating enteric methane emissions from sheep resulted in a 7.5–8.5% increase in the carbon footprint, relative to a mechanistic equation present in the Ruminant Nutrition System model. Physical allocation resulted in greater impacts of the hemp diet systems than the soybean diet systems for all categories except land use. However, economic allocation resulted in greater impacts for the soybean diet systems than the hemp diet systems for all categories evaluated. This was explained by inherent differences between the allocation method, as physical allocation attributed 80% of the environmental burden to hemp seed meal, while economic allocation attributed 0% of the environmental burden to hemp seed meal due to the current lack of an economic value for hemp seed meal. The production volume of dependent products ("dependent products", or products for which a change in demand does not affect production volume, commonly referred to as co- or byproducts) are driven by monetary value of the determining product (the product for which a change in demand affects the production volume), but relationships between co-products change overtime. Therefore, as the hemp industry continues to develop, an economic value may be placed on hemp seed meal with implications for its relative ability to reduce the environmental impacts of livestock production. As agricultural industries strive to become more environmentally efficient, they must be adaptive to changes in both monetary value and environmental impact, which are intrinsically related. This research demonstrated the importance of allocation choice in assessing the impact of feeding byproducts on the environmental impact of livestock production systems. Economic allocation better reflected the monetary driving factor for hemp production than physical allocation. As such, the inclusion of hemp seed meal in a feedlot ration reduced the environmental impact of sheep production systems.Item Open Access Low temperature effects on the transcriptome of Yersinia pestis and its transmissibility by Oropsylla montana fleas(Colorado State University. Libraries, 2016) Williams, Shanna K., author; Borlee, Brad, advisor; Bearden, Scott, advisor; Gage, Ken, committee member; Stenglein, Mark, committee member; Archibeque, Shawn, committee memberYersinia pestis, the causative agent of plague, is primarily a rodent-associated, flea-borne zoonosis. Transmission to humans is mediated most commonly by the flea vector, Oropsylla montana, and occurs predominantly in the Southwestern United States. In these studies, we hypothesized that Y. pestis-infected O. montana fleas held at temperatures as low as 6ºC could serve as reservoirs of the plague bacillus during the winter months in temperate regions with endemic plague foci. With few exceptions, previous studies showed O. montana to be an inefficient vector at transmitting Y. pestis at 22-23°C particularly when such fleas were fed on susceptible hosts more than a few days after ingesting an infectious blood meal. We examined whether holding fleas at sub-ambient temperatures (for purposes of these studies, ambient temperature is defined as 23°C) affected the transmissibility of Y. pestis by this vector. Colony-reared O. montana fleas were given an infectious blood meal containing a virulent Y. pestis strain (CO96-3188), and potentially infected fleas were maintained at different temperatures (6ºC, 10°C, 15°C, or 23ºC). Transmission efficiencies were tested by allowing groups of ~15 infectious fleas to feed on each of seven naïve CD-1 mice on days 1-4, 7, 10, 14, 17, and 21, 28, 35, and 42 post infection (p.i.). Fleas held at 6ºC, 10°C and 15°C were able to effectively transmit at every time point p.i. The percentage of transmission to naïve mice by fleas maintained at low temperatures was higher than for fleas maintained at 23ºC and indicates that O. montana fleas efficiently transmit Y. pestis at low temperatures. Moreover, bacterial loads of flea cohorts maintained at temperatures of 6ºC, 10ºC and 15ºC were statistically higher than fleas maintained at 23ºC. In addition, whole transcriptomes of Y. pestis bacteria grown at 6ºC, 10°C, 15°C and 23ºC were analyzed to assess differential gene expression at each temperature to identify genes which may contribute to an increase in virulence or survivability of the plague pathogen at the lower temperatures when compared to ambient temperature. This is the first comprehensive study to demonstrate efficient transmission of Y. pestis by O. montana fleas maintained at temperatures as low as 6ºC. Our findings further contribute to the understanding of plague ecology in temperate climates by providing support for the hypothesis that Y. pestis is able to overwinter within the flea gut and potentially cause infection during the following transmission season. The findings also might hold implications for explaining the focality of plague in tropical regions where plague occurs in cooler environments, primarily located at higher elevations.Item Open Access Management strategies to improve beef feedlot performance and assessment of nutrient composition of beef retail cuts(Colorado State University. Libraries, 2011) Schutz, Jennifer Sue, author; Engle, Terry, advisor; Belk, Keith, committee member; Archibeque, Shawn, committee member; Van Campen, Hana, committee memberTo view the abstract, please see the full text of the document.Item Open Access Methane and nitrous oxide fluxes from cattle excrement on C3 pasture and C4 native rangeland of the shortgrass steppe(Colorado State University. Libraries, 2014) Nichols, Kristopher L., author; Paustian, Keith, advisor; Del Grosso, Stephen, committee member; Derner, Justin, committee member; Follett, Ron, committee member; Archibeque, Shawn, committee memberGrazers play a major role in nutrient cycling of grassland ecosystems through the removal of biomass and the deposition of excrement in the forms of liquid, urine and solid feces. We studied the effects of cattle excrement patches on methane (CH4) and nitrous oxide (N2O) fluxes using semi-static chambers on cool-season (C3), Bozoisky-select pasture, and warm-season (C4-dominated) native rangeland on the shortgrass steppe. Trace gas measurements were conducted over a 2 year period from cattle urine (43 g N m-2) and feces (94 g N m-2) patches within replicated exclosures on each plant community. Cumulative N2O emissions for the 2 year experimental period, on a per area basis, were 55% greater from feces relative to urine patches on native rangeland (1.81 and 1.17 kg N2O-N ha-1) and 25% greater on Bozoisky-select pasture (1.66 and 1.25 kg N2O-N ha-1). While the cumulative N2O emissions were similar within treatments across plant communities, the magnitude of seasonal fluxes were different. Emissions from the excrement treatments were greater on the Bozoisky-select pasture the summer following treatment application, while emissions were greater on the native rangeland the following fall and spring. The emission factors for urine and feces did not differ for urine and feces on native rangeland (0.13 and 0.13%) and Bozoisky-select pasture (0.14 and 0.11%), but these emission factors were substantially less than the IPCC Tier 1 default factor (2%) for manure deposited on pasture, indicating that N2O emissions from these plant communities are currently overestimated. These findings suggest that the IPCC Tier 1 Default N2O emission factor of 2% for manure deposited on pasture is not representative of N2O emissions from cattle excrement on shortgrass steppe. Nitrous oxide emissions from the control plots on native rangeland and Bozoisky-select pasture were similar, 0.61 and 0.65 kg ha-1, respectively. Methane uptake was significantly less from cattle excrement compared to control plots for both plant communities. Cumulative net CH4 uptake rates were 68% greater for urine compared to feces patches on native rangeland (-2.73 and -0.88 kg CH4-C ha-1) and 86% greater on Bozoisky-select pasture (-2.16 and -0.30 kg CH4-C ha-1). Methane uptake rates were also 14% less for the control plots on Bozoisky-select pasture (-3.15 kg CH4 ha-1) compared to native rangeland (-3.60 kg CH4 ha-1). Future research should focus on CH4 and N2O fluxes from pasture 'hotspots', where nitrogen loading and soil compaction are commonly present. We tested the capacity of the biogeochemical model DAYCENT to simulate N2O and CH4 fluxes from control plots and cattle excrement amended soils of the shortgrass steppe for both plant communities. Cumulative N2O emissions from the urine treatment were overestimated using the DAYCENT model by a factor of 4 for native rangeland and by a factor of 5 for the Bozoisky-select pasture. While the measured and modeled cumulative emissions agreed reasonably well for the feces, water, and blank plots, the model did not accurately simulate the magnitude of seasonal N2O emissions from these plots, overestimating emissions during periods of high fluxes during the growing season and underestimating during periods of low fluxes such as the winter. The cause for the poor agreement between measured and modeled N2O emissions may be attributed to an overestimation of total system N, an overestimation of the proportion of nitrified-N emitted as N2O, and the possibility that a substantial amount (> 20%) of the urine-N was rapidly volatilized as NH3 due to the extremely dry conditions at the time of treatment application. Additional model validation for shortgrass steppe soils is needed using data sets that include extensive soil N data to accompany the trace gas data to determine if the model is accurately simulating nitrification rates, the proportion of nitrified-N emitted as N2O, and the proportion of N immobilized in microbial biomass. The model strongly overestimated CH4 uptake rates for the control plots by a factor of 3 for native rangeland and 2 for Bozoisky-select, while the excrement plots were overestimated by a factor of 2 for both plant communities. The model underestimated the optimum water content for maximum CH4 uptake by approximately 5%, which led to an overestimation of CH4 uptake by a factor of 2 to 4 during periods of biological limitation when soils were extremely dry. The agriculture reduction factor, which accounts for fertilization and cultivation events, reduced CH4 uptake from the urine and feces plots, but the uptake rates were still overestimated by a factor of 2 since the modeled failed to capture reduced uptake rates under low soil water content (< 0.15 volumetric water content). The overestimation of CH4 uptake may partly be resolved by increasing the optimum water content at which maximum CH4 uptake occurs, allowing the model to capture biological limitation on CH4 uptake.Item Open Access Micrometeorological studies of a beef feedlot, dairy, and grassland: measurements of ammonia, methane, and energy balance closure(Colorado State University. Libraries, 2018) Shonkwiler, Kira Brianne, author; Collett, Jeffrey L., advisor; Ham, Jay M., committee member; Kreidenweis, Sonia, committee member; Schumacher, Russ, committee member; Archibeque, Shawn, committee memberAmmonia emissions from concentrated animal feeding operations (CAFOs; most of which are beef feedlots) near the Colorado Front Range are suspected to be a large regional input of reactive nitrogen which has been found to accumulate and cause deleterious effects in nearby downwind Class I areas like Rocky Mountain National Park. Methane (CH4) is a strong greenhouse gas (GHG) emitted in large amounts from dairy anaerobic lagoons used for liquid manure management. Lagoon systems account for over half of the manure management-based CH4 emissions from agriculture in the US. There is a strong need for more emissions measurements from CAFOs like feedlots and dairies. For these data to be trusted, well-developed techniques must be utilized at emissions measurement sites and such techniques should be validated in ideal scenarios. Three micrometeorological studies were performed involving measurement of emissions using micrometeorological methods in the surface layer. The first study involved estimating summertime NH3 emissions from a 25,000-head beef feedlot in Northern Colorado. Two different NH3 sensors were used: a cavity ring down spectroscopy analyzer collected data at a single point while a long-path FTIR collected data along a 226-m long transect, both deployed along the same fenceline. Concentration data from these systems were used with two inverse dispersion models (FIDES, an inverse solution to the advection dispersion equation; and WindTrax, a backward Lagrangian stochastic model). Point sensor concentrations of NH3 were similar to line-integrated sensor concentrations suggesting some spatial uniformity in emissions. Emissions had a diurnal pattern (i.e., afternoon peak with minimum in early morning) that was driven by temperature. Emissions predicted by WindTrax were 25.2% higher than those from FIDES. Point vs. long-path measurements of NH3 had minimal effect on predicted emissions. The mean NH3 emission factor (EF) was 80 ± 39 g NH3 hd−1 d−1, with 40.0% of dietary-N emitted as NH3. The second study involved using eddy covariance and WindTrax to quantify CH4 emissions from a 3.9-ha anaerobic lagoon serving a 1400-head dairy in northern Colorado. Methane emissions followed a strong seasonal pattern correlated with temperature of the organic sludge layer on the bottom of the lagoon. Fluxes started increasing in late spring (May; ~10°C), increased rapidly in Jun (10-15°C) peaked in the summer (Jul/Aug; ~18-20°C) and remained high until mid-autumn (late Oct/early Nov; ~10°C). Fluxes then decreased and remained consistently low (up to 10 times less than peak emissions) until microbial activity ramped up again in May. The EC signal was very dependent on wind direction, with highest concentrations and fluxes associated with the direction of the lagoon. Gap-filled data showed a slight diurnal pattern to all seasons, with tenfold increases in diurnal values for summer over winter. Additionally, EFs for the lagoon varied by season with lows in the winter and highs in the summer with an annual mean of 819 ± 774 g CH4 hd-1 d-1. WindTrax overestimated EC for the lagoon (1163 ± 1049 g CH4 hd-1 d-1 versus 819 ± 774 g CH4 hd-1 d-1), but this difference may be attributable to differences in the sampling footprint and stability conditions. IPCC Tier 2-calculated EFs were extremely close to EC-based measurements and WT-based estimates. The third study involved using eddy covariance in an ideal environment (tallgrass prairie in Kansas) to test the reasons behind the "energy balance (EB) closure problem" at two landscape positions. This problem can cast uncertainty on flux measurements made by EC. One upland and one lowland EC tower each were used to measure EB components (i.e., net radiation, Rn; soil heat flux, G; total change in heat storage, deltaS; and sensible and latent heat fluxes, H and λE) during the summers of 2007 and 2008. To maximize closure, special attention was given to reduce all forms of instrumentation error and account for heat storage and photosynthesis between the soil and the reference height. Landscape position had little effect on G, H, and Rn; differences were ≤ 2% between sites. Lowland λE was 8% higher than upland λE because of greater biomass and soil moisture. On average, EB closure (i.e., Σ[λE+H] / Σ[Rn–G–ΔS]) was 0.88 and 0.94 at the upland and lowland sites, respectively. Closure was not correlated with friction velocity or the stability of the surface boundary layer. Given high confidence in Rn, G, and ΔS, turbulent fluxes depend directly on vertical velocity (w), and the fact that a systematic underestimation of w was recently found in literature, lack of closure may have resulted largely from anemometer-based underestimates of w.Item Unknown Temperament and maternal behavior of beef cattle(Colorado State University. Libraries, 2023) Rogers, Corley, author; Grandin, Temple, advisor; Engle, Terry, committee member; Archibeque, Shawn, committee member; Garry, Frank, committee memberThis thesis contains both a literature review and an observational study about temperament and maternal behavior of beef cattle. The literature review covers maternal behavior, maternal protectiveness, temperament, and stress in beef cows. The aim of the experiment was to compare the distance maternal protective behaviors were performed against measurements of temperament. The results of the study showed very little correlation between how the cow defends her calf and her behavior in the chute. The overall aim of this thesis was to was to address the paucity of data regarding how maternal protectiveness and temperament are related and if there is an inadvertent increase in the potential for predation if breeding for a docile temperament.