Location: Livestock Nutrient Management Research
2019 Annual Report
Objectives
Objective 1: Characterize and improve prediction of ammonia and greenhouse gas emissions from cattle production systems.
Subobjective 1A. Characterize methane (CH4) emissions from southern Great Plains grazing systems.
Subobjective 1B. Assess the impact of environmental conditions and management practices and their interactions on emissions of NH3 and GHG from open lot cattle production systems.
Subobjective 1C. Improve NH3 and GHG emissions measurements for feedyards and dairies.
Objective 2: Improve feed nutrient use in cattle to maintain animal productivity, reduce emissions of ammonia and greenhouse gases, and mitigate pathogens and antibiotic resistant bacteria.
Subobjective 2A. Determine effects of cattle diet on enteric CH4 production.
Subobjective 2B: Evaluate and improve models to predict enteric CH4 emissions from grazing and feedyard cattle.
Subobjective 2C. Identify and quantify sources of enteric nitrous oxide (N20) emissions from cattle in respiration calorimetry chambers.
(NEW 2019) Subobjective 2D: Develop alternative strategies that reduce methane emissions while maintaining production.
Objective 3: Manage soil and manure reactive nitrogen, phosphorus and carbon to improve soil properties, reduce nutrient loss and mitigate pathogens and antibiotic resistant bacteria.
Subobjective 3A. Evaluate the effectiveness, practicality and economics of chemical inhibitors and manure amendments to reduce N20 and NH3 emissions from beef cattle feedyards, dairies, and manure-amended soils.
Subobjective 3B. Quantify field-scale emissions of N20 from manure-amended soils.
Subobjective 3C. Establish protocols for examining AR in agroecosystems.
Subobjective 3D. Characterize forms of P in manure-amended soils.
Subobjective 3E: Evaluate soil C/N change with land use on the southern High Plains.
Approach
Beef and dairy cattle production provide vital human nutrition and important economic activity. Cattle production, like all human endeavors, also contains environmental risks. This multidisciplinary research will help us to better understand and mitigate the environmental risks from cattle production systems on the Southern Great Plains. We will quantify and improve predictions of emissions of ammonia (NH3) and greenhouse gases (GHG) from cattle production systems. The research will focus on the predominant agricultural GHG emissions of methane (CH4) and nitrous oxide (N20). Sources of these emissions include grazing animals (enteric emissions), emissions from cattle, pen and lagoon surfaces at beef feedyards and dairies, and emissions from soils following land application of manure. We will determine the effects of cattle diet on enteric GHG emissions on scales that range from single animal to whole pastures, feedyards or dairies. We will test potential mitigation methods to reduce emissions from manure surfaces and cropped fields using controlled laboratory experiments followed by pilot-scale and field-scale experiments. We will quantify the changes in soil carbon (C), nitrogen (N), and phosphorus (P) from application of manure or land use change. A collaboration of ARS laboratories will test methods to characterize antibiotic resistant (AR) bacteria and genes from manure-impacted soil. Research results will provide science-based information and technologies for livestock producers, extension specialists, and regulators to protect air quality, manage feedyard and dairy manure, enhance production efficiency, and improve sustainability of livestock production.
Progress Report
Research of the Livestock Nutrient Management Research Unit in FY19 was conducted during the third year of the project plan "Improved Practices to Conserve Air Quality, Maintain Animal Productivity, and Enhance Use of Manure and Soil Nutrients of Cattle Production Systems for the Southern Great Plains". There were sixteen Year 3 milestones; seven were fully met, six were substantially met, and three were not met.
Characterize and improve prediction of ammonia and greenhouse gas emissions from cattle production systems (Objective 1). Work on the National Institute of Food and Agriculture (NIFA)-funded Grazing Coordinated Agricultural Project (CAP), a multi-institutional effort to understand the effects of grazing cattle on greenhouse gases and the resilience of grazing systems to climate change was completed and a final manuscript submitted. Results from three intensive field campaigns during which methane emissions from grazing cattle were measured were presented at an international conference. A Unit scientist shared expertise on methane emissions with the USDA Forest Service SilvaCarbon Program in Ethiopia. Three laboratory experiments were conducted to assess the effects of manure accumulation, pH, and urine/feces deposition on the feedyard surface. Three week-long sampling campaigns were conducted at two commercial beef cattle feedyards in the Texas Panhandle. Emissions of nitrous oxide and methane were monitored before and after rainfall using automated samplers and real-time greenhouse gas analyzers. The results of the laboratory and field studies were used to construct an empirical model of nitrous oxide emissions. The frequency of manure removal was evaluated using climatological data for the 23-year period from 1996 to 2018. A laboratory experiment was conducted to compare surface-applied and incorporated manure on greenhouse gas emissions. Nitrous oxide emissions were substantially higher in the incorporated manure than in the surface-applied manure, conversely, methane emissions were lower. Laboratory studies were undertaken to measure nitrification activity and denitrification enzyme activity, microbial community structure, and nitrification gene abundances in beef feedyard manure under differing conditions. These data are being analyzed and will be published as two companion papers to shed light on source and cause of nitrous oxide emissions from beef cattle feedyards.
Improve feed nutrient use of cattle to maintain animal productivity and reduce emissions of ammonia and greenhouse gases (GHG), (Objective 2). Three laboratory experiments were conducted to evaluate the effects of wet distiller’s grains plus solubles (WDGS) and tannin-rich peanut skin (PS) diet on GHG emissions and microbial community changes. An initial study evaluated the effects of individual or equally mixed rumen liquors on in vitro ruminal gas production and GHG emissions. The effects of various levels of PS or WDGS on in vitro digestibility, GHG and other gas emissions, fermentation rate, and microbial changes in the rumen were assessed. Because mixed rumen fluid was more appropriate for in vitro gas production studies than samples taken from individual steers, mixed rumen fluid was chosen as a source of inoculum for further experiments. Tannin-rich PS and WDGS had an associative effect that suppressed methanogenesis both directly and indirectly by modifying populations of ruminal methanogens. A laboratory experiment was conducted to evaluate nitrous oxide emissions associated with nitrifying and denitrifying bacterial changes as affected by dairy cattle diets and plant secondary compounds supplementation. Methane, nitrous oxide and fecal chemical composition from samples were analyzed and statistical analysis were completed. Field experiments were initiated to evaluate the effect of different forage crops (grass and legume forages) on soil fertility, water and nitrogen fertilizer utilization, silage quality, and enteric methane emissions in beef cattle.
Manage soil and manure reactive nitrogen, phosphorus and carbon to improve soil properties, reduce nutrient loss and mitigate pathogens and antibiotic resistant bacteria (Objective 3). Research regarding characterizing the occurrence of antibiotic resistant bacteria continued in FY2019. A Unit scientist collected aseptic fecal samples from broiler, layer, swine, and cattle livestock to characterize microbial DNA, and microbial diversity analysis. Investigations to characterize the organic matter fraction of soils continued in FY2019. Unit scientists, in collaboration with researchers from ARS in New Orleans, Louisiana and University of Fairbanks, Alaska, characterized the labile fraction of organic matter in dryland soils that had been under different wheat cropping systems (continuous wheat vs. wheat-fallow) and with different tillage methods (i.e., disk plow, stubble mulch tillage, and delayed stubble mulch tillage). Archived samples collected in 1977 were compared with samples collected in 2013 from the same plots and compared with native rangeland. Results indicated that long-term cropping systems with labile carbon in water-limited, semi-arid areas may not be sufficient to remediate or recover labile soil carbon by typical conservation cropping. A Unit scientist collaborating with ARS researchers from Auburn, Alabama, examined moderately labile soil phosphorus fractions in soils high in aluminum and iron. Work continued to investigate the sequentially fractionate organic and inorganic soil phosphorus from soils amended with differing levels of poultry manure.
Accomplishments
1. Frequent manure removal reduces feedlot greenhouse gas emissions. Nitrous oxide is a greenhouse gas that has been linked to climate change. Nitrous oxide is emitted from the pen surface of open-lot beef cattle feedyards, and there are 7 million beef cattle finished annually in Southern High Plains feedyards. Scientists from USDA-ARS in Bushland, Texas, and reseaerchers from Texas A&M AgriLife Research conducted laboratory and field experiments to quantify nitrous oxide emissions and evaluate the effects of temperature, precipitation, urine deposition, and the frequency of manure removal. An empirical model based on 23 years of climatological data to assess the effect of manure removal on annual nitrous oxide emissions was developed. The model showed that most nitrous oxide emissions occurred a few days after precipitation events during the summer months. Even though annual urine deposition was equal to annual precipitation in terms of water added to the feedyard surface, nitrous oxide emissions from urine wetted feedlot surface accounted for less than 30 percent of overall emissions. Cleaning pens 2, 3, or 4 times per year reduced annual nitrous oxide emissions by 40, 56, or 63 percent, respectively, as compared to removing manure once per year. Frequent cleaning of pens would reduce nitrous oxide emissions if such emissions are regulated like ammonia emissions are.
2. Peanut skin with wet distillers grains in cattle diets reduces methane at laboratory scale. Few studies have quantified, at laboratory scale, how cattle diets affect greenhouse gas emissions associated with the rumen microbiome and rumen fermentation activities. Scientists from USDA-ARS at Bushland, Texas, and Ames, Iowa, investigated the effects of adding wet distillers grains plus solubles and tannin-rich peanut skin to rumen fluid in laboratory containers. The tannin-rich peanut skin in the presence of wet distillers’ grains plus solubles suppressed the chemical pathways that create methane directly via anti-methanogenic activity. These data will be used to fine tune dietary strategies that can reduce greenhouse gas emission for feedlot beef cattle and dairy cattle, while increasing the conversion of feed to meat.
Review Publications
Parker, D.B., Meyer, B.E., Jennings, T., Jennings, J., Dougherty, H., Cole, A.N., Casey, K. 2018. Enteric nitrous oxide emissions from beef cattle. Professional Animal Scientist. 34(6):594-607. https://doi.org/10.15232/pas.2018-01769.
Min, B., Abrahamsen, F., Gurung, N., Lee, J.H., Joo, J.W., Pacheso, W. 2019. Peanut skin in diet alters average daily gain, ruminal and blood metabolites, and carcass traits associated with Haemonchus contortus infection in meat goats. Animal Nutrition. https://doi.org/10.1016/j.aninu.2019.05.006.
Min, B., Solaiman, S. 2018. Comparative aspects of plant tannins on digestive physiology, nutrition and microbial community changes in sheep and goats: A review. Journal of Animal Physiology and Animal Nutrition. 102(5):1181-1193. https://doi.org/10.1111/jpn.12938.
