Project : USDA ARS

ARS Home » Plains Area » Bushland, Texas » Conservation and Production Research Laboratory » Livestock Nutrient Management Research » Research » Research Project #441154

Research Project: Strategies to Manage Feed Nutrients, Reduce Gas Emissions, and Promote Soil Health for Beef and Dairy Cattle Production Systems of the Southern Great Plains

Location: Livestock Nutrient Management Research

2024 Annual Report

Objectives
Objective 1: Improve use of manure as a soil amendment and develop manure processing and treatment technologies to increase production value of manure and reduce manure constituent losses to the environment. Sub-objective 1A: Determine optimal rates of manure application on soil nutrient cycling, crop productivity, and soil health on the Southern Great Plains. Sub-objective 1B: Assess long-term (36-47 y) legacy effects of high rates of land-applied beef cattle manure on soil properties on the Southern Great Plains. Sub-objective 1C: Determine long- and short-term impact of cattle manure on soil parameters attributed to soil health. Objective 2: Quantify and develop practices to reduce emissions of greenhouse gases and other gases of concern to improve nutrient use efficiency and reduce the environmental footprint of beef and dairy production systems. Sub-objective 2A: Assess the impact of environmental conditions and management practices on emissions of GHG from open-lot beef and dairy cattle production systems. Sub-objective 2B: Assess the effect of land-applied manure on emissions of N2O and CH4 from soils. Sub-objective 2C: Quantify NH3 and organic N deposition downwind of beef feedyards and open-lot dairies on the SGP. Objective 3: Assess feed additives and alternative feedstocks to reduce enteric CH4 emission and improve cattle nutrient utilization. Sub-objective 3A: In vitro fermentation experiments can identify feed additives and ingredients that can reduce CH4 emissions in beef cattle. Sub-objective 3B: Assess the effects of feed additives and ingredients on enteric CH4 production and performance of live beef cattle. Sub-objective 3C: Design, construction, and testing of respiration chambers for quantification of enteric CH4 and N2O emissions from cattle.

Approach
Beef and dairy cattle provide vital human nutrition and important economic activity to a diverse U.S. population. Nevertheless, cattle production is linked to climate change and other environmental consequences. This research project will take a multidisciplinary approach to understand and mitigate environmental risks from cattle systems common to the semi-arid Southern Great Plains (SGP). Over six million beef cattle are finished annually in SGP open-lot feedyards, and over 400,000 cows are milked, with most being in open lots containing thousands of cows. We will quantify and improve prediction of greenhouse gas (GHG) emissions and ammonia deposition from cattle systems. Research will focus on the predominant agricultural GHGs, methane and nitrous oxide. Sources of these emissions include cattle (enteric emissions), pen surfaces at concentrated animal feeding operations (CAFOs), fertilized soils, and emissions from soils near CAFO that receive ammonia deposition. Dietary effects on enteric GHG emissions (i.e., emissions from ruminant digestion) will be examined at scales ranging from laboratory studies to entire pens of cattle. We will study specific feed additives for reducing emissions, including malted barley and red seaweed. We will apply cattle manure at varying rates to different forage crops to determine best management practices for the SGP. We will quantify changes in soil health parameters, including salinity, nutrient content and soil physical factors, after manure application or land use change. The research project will provide science-based information and technologies for producers, extension specialists, and regulators to protect air quality, manage feedyard and dairy manure, and ultimately enhance efficiency and sustainability of cattle production.

Progress Report
Researchers at Bushland, Texas, completed the following research in FY24 for the project 3090-31630-006-000D “Strategies to Manage Feed Nutrients, Reduce Gas Emissions, and Promote Soil Health for Beef and Dairy Cattle Production Systems of the Southern Great Plains”. Progress on Objectives 1 and 2 was impacted by the retirement of lead scientist in January 2024 and another scientist in May 2024. Efforts to fill vacant positions are ongoing. Data collection is either completed or ongoing. Plans were made to complete delayed data analyses and publications. Objective 1: Researchers at Bushland, Texas, investigated the long- and short-term effects of manure application on soil health, environmental quality, and cattle forage production in collaboration with Dairy Agroecosystems Working Group (USDA-ARS). ARS scientists in Bushland, Texas, conducted a greenhouse study where solid dairy manure was applied to forage typically used for cattle diets. Forage biomass, nutrient content, and soil health-related properties were investigated. Laboratory and statistical analyses for the greenhouse study are complete. Based on manure application rates determined from the greenhouse study, researchers designed and conducted a two-year small-plot study intended to quantify annual application rates of solid dairy manure for optimal crop yield and improved soil properties. Laboratory analyses are complete for soil health properties, including soil phosphorus. Statistical analyses are complete for year one of the small plot study and are not complete for year two. To determine long-term effects of manure application, a large field study was initiated to investigate the premise that crops can just as readily attain the benefits of manure (such as increased carbon, nitrogen, organic matter, microbial enzymes) when applied infrequently at high rates, as crops receiving annual manure applications. ARS researchers in Bushland, Texas, established a field study with state-of-the-art precision irrigation scheduling, which is a key component of agricultural sustainability in the water-limited Texas Panhandle. In FY2024 (Year 2), the study continued with the planned protocols used in Year 1. In May 2024, dairy manure and commercial fertilizer were applied to the established alfalfa plots and to corn forage plots. Forage corn was planted in May 2024. Soil moisture content was measured by weekly neutron probe readings. These readings were used to manage irrigation rate scheduling to meet full evaporative demand of the two forage systems. Lead scientist left the agency in May 2024. Search to fill the vacant position in ongoing. In an historic legacy manure application site started by Stewart et al. (1973) and located on Conservation and Production Research Laboratory (CPRL) property, Bushland scientists characterized remaining effects of previous manure application on soil parameters relevant to dairy forage production. Soil samples from a historical site established 47 years ago were collected. Soil health laboratory analyses are completed. Plans for manuscript preparation were impacted by scientist leaving the agency in May 2024 and a retirement of collaborating scientist in January 2024. Objective 2: Two candidate commercial dairies in the Texas Panhandle were identified for the measurement and quantification of greenhouse gas (GHG) emissions and ammonia. Preparations are to deploy open-path lasers and chambers at one dairy in the fall of 2024 are on-going. Measurements of GHG emissions were taken from the small plot study using an automated chamber system connected to a real-time GHG analyzer to observe manure effects on environmental quality and GHG flux. The data collection is completed. Researchers at Bushland, Texas, designed a study to measure ammonia transport from an open-lot beef cattle feedyard as part of the USDA Ammonia Deposition from Animal Production Team (ADAPT) project. The feedlot adjacent to Bushland cropland was not available for this research. Alternative commercial feedlot (approx. 30,000-capacity) was identified in May 2024 with the help of Texas Cattle Feeders Association. Continuous air sampling for ammonia started in June 2024. Soil and plant samples at 23 sampling locations were collected in August 2024. Objective 3: Additional in vivo experiments were conducted with beef steers and investigated the effects of 1) feeding a high-anthocyanin corn cob meal to steers consuming a starter or finisher diet, 2) the effects of feeding supplemental fat to finishing steers, and 3) the influence of feeding graded levels of limestone, on growth performance, enteric methane emissions, and carcass characteristics. Currently, ARS scientists in Bushland, Texas, in collaboration with scientists from Japan are conducting an experiment to determine how a cashew nut-shell liquid product influences methane production in vitro using a finisher diet and a diet representative of a dairy ration. The incubations for the finisher diet portion have been completed and the dairy ration incubation have started. We anticipate laboratory work to be completed by the end of the fiscal year. Additionally, ARS scientists in Bushland, Texas, and Texas A&M AgriLife researchers have started a dairy experiment, where milk and methane production and dry matter intake are being assessed. Cows are being fed a control diet (approximately 0.1% dietary sulfur) or a diet containing a corn gluten feed product (approximately 0.3% dietary sulfur). We anticipate that cows fed the diets with greater sulfur content will produce less methane, due to a greater production of hydrogen sulfide providing an alternative hydrogen sink.

Accomplishments
1. Reduced animal handling still allows assessment of dietary characteristics in beef. Indigestible neutral (INDF) and acid detergent fiber (IADF) are effective markers for assessing diet dry matter digestibility (DMD), crude protein digestibility (CPD), and digestible energy (DE) of beef steers fed total mixed rations. Internal markers, such as INDF and IADF are commonly used by ruminant nutritionists to assess DMD, CPD, and DE of cattle. However, they first must be adequately measured in the diet and animal feces. Once INDF and IADF content of diets and feces is known, the next question is: how frequently should fecal samples be collected in order to estimate DMD, CPD, and DE? ARS scientist in Bushland, Texas, in collaboration with Oklahoma State University, and Texas A&M, conducted an experiment to answer this question. It was determined that as infrequently as one fecal sample collected in the morning provided adequate estimates of DMD, CPD, and DE. These studies inform researchers on appropriate methods for using internal markers to assess DMD, CPD, and DE of beef steers fed a total mixed ration. These works have also determined optimal protocols, which limit animal handling requirements, thereby advancing the 3-Rs (replacement, reduction and refinement) of Animal Use in Research.

2. Climate warming contributions of methane emissions from cattle shown to dependent on estimating institution and method used to account for warming. A team of scientists from the USDA-ARS (Bushland, Texas), Kansas State University, and Colorado State University, studied the various ways enteric methane is estimated and how that affects estimates of global warming. The team found that the large differences in the US enteric methane (CH4) emission estimates between the Food and Agriculture Organization (FAO) and US Environmental Protection Agency (EPA) reporting are driven by the accounting method used. The method used by both the FAO and EPA is the 100-year basis global warming potential (GWP100). A newer alternative method, global warming potential* (GWP*) has been developed to account for CH4. Using the GWP* method instead of GWP100 greatly reduces the implied contribution of enteric CH4 emissions from livestock to climate warming. The research points to a paradigm shift in how to decrease enteric CH4 emissions. Rather than being a significant contributor to the changing climate, GWP* indicates that a small decrease in enteric CH4 emissions can lead to a net decrease in climate warming. However, any decrease in enteric CH4 would eventually create a new steady state and enteric CH4 emissions would again start contributing to warming. Thus, reducing enteric methane emissions could be viewed as a short-term solution to reduce total anthropogenic contributions to warming.

U.S. DEPARTMENT OF AGRICULTURE

Livestock Nutrient Management Research: Bushland, TX