Funding

Funding Agency: USDA-NIFA-AFRI
Grant Number: 2020-68015-30857 
Award Total: $999,998
Start: 15 May 2020 End: 14 May 2025 

Investigating the Emergence and Ecology of Antimicrobial Resistance in High-Risk Beef Cattle

Non-Technical Summary: The emergence of antimicrobial resistance (AMR) has increased the pressure to find alternative means to eliminate or reduce the use of medically-important antimicrobials, particularly in the agricultural industry. Bovine respiratory disease complex is one of the costliest issues associated with feedlot cattle and is frequently combatted though metaphylactic administration of antimicrobials upon feedlot arrival. Therefore, research is needed to determine the emergence, ecology, and microbiome of AMR and develop science-based strategies to reduce the incidence of AMR throughout the beef production continuum.

These studies will purse the following objectives

1.  Identify a best management practice for metaphylactic antimicrobial use in high-risk cattle
2. Implement novel science-based intervention strategy to reduce the spread of AMR in the beef cattle industry
3. Develop systems based approaches to identify AMR reservoirs by evaluating the host-microbiome community dynamics
4.  Improve understanding among current and future veterinarians and nutritionists of potential food safety risks associated with carriage of AMR by beef cattle and motivate them to advise producers of best practices for antimicrobial stewardship.

Completion of this research will identify critical control points for controlling the development of AMR and provide usable science-based approaches to mitigate AMR in beef production. This information is critical for sustainability in the beef food supply and judicious use of antimicrobials in cattle production. Therefore, our first long-term goal is to characterize antimicrobial metaphylactic strategies that reduce the spread of AMR throughout the feedlot cattle production system. Our second long-term goal is to provide an alternative to tylosin phosphate to control liver abscesses in feedlot cattle. Combined, these goals will promote more judicious use antimicrobials in the beef cattle industry; thereby, reducing the spread of AMR and AMR reservoirs in bacteria important in the pathogenesis of bovine respiratory disease(BRD) in cattle and food-borne illnesses in humans. This information is critical for sustainability of the beef food supply chain and judicious use of antimicrobials in cattle production. The education and outreach activities proposed in this multidisciplinary project will deliver and evaluate outreach programs that improve the aptitude of veterinarians, nutritionists, producers and consumers to assess and adopt best management practices that mitigate potential risks from AMR. Additionally, this project will build upon an established outreach network that yields improved information transfer to consumers to increase confidence in the safety of beef products. Such information and activities are critical to improve antimicrobial stewardship and ensure a sustainable and safe food supply.

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Funding Agency: National Cattlemen's Beef Association Beef Checkoff 
Award Total: $225,000
Start: 01 October 2020      End: 31 September 2022

Evaluation of the spatial and longitudinal distribution of antimicrobial resistance genes and occurrence of potential horizontal gene transfer in high-risk cattle

Non-Technical Summary: Our plan is to conduct 2 studies with high-risk beef cattle and longitudinally collect fecal, hide, and lymph node samples to evaluate the reservoirs for antimicrobial resistance (AMR) in feedlot cattle that will enhance the understanding of ecology, emergence and transmission of AMR, specifically multi-drug resistance (MDR) Salmonella. Salmonella enterica and Escherichia coli isolates will be screened for MDR using antimicrobial sensitivity testing.  
Objectives: To investigate the association between metaphylactic treatment given to high-risk cattle at feedlot arrival and the longitudinal development of MDR Salmonella. Additionally, we will investigate the link between metaphylactic antimicrobials given to high-risk cattle at feedlot arrival and the longitudinal development of MDR E. coli. 

Funding Agency: Foundation for Food and Agriculture Research 
Grant Number: ICASATWG-0000000038 
FFAR Award Total: $200,000
Matching Funds: $200,000
Start: 01 September 2020 End: 31 August 2023 

Development of a science-based management strategy to reduce the use of antimicrobials in high-risk beef cattle 

Non-Technical Summary: The emergence of antimicrobial resistance is a continual global challenge affecting human and animal health.  Bovine respiratory disease complex is one of the costliest issues associated with feedlot cattle and is frequently combatted through metaphylactic administration of antimicrobials at feedlot arrival. Our overall objective is to influence and minimize the use of antimicrobials in feedlot production.  Our rationale is that once we develop novel science-based management strategies we will be better positioned to reduce the use of antimicrobials and the spread of antimicrobial resistant bacteria in beef production systems across the food chain.  

Our specific objectives are to:

1. Develop a science-based management strategy to individually identify and target specific high-risk cattle for metaphylactic treatment at feedlot arrival based on a non-invasive measurement of their surface temperature
2. Evaluate whether the use of targeted metaphylaxis based on a non-invasive measurement of surface temperature reduces the use of antimicrobials and the spread of antimicrobial resistant bacteria in the feedlot production system
3. Evaluate the use of targeted metaphylaxis through infrared thermography in a commercial feedlot setting in collaboration with Hy-Plains Feedyard and Veterinary Research and Consulting Services.

These studies are aligned with the ICASA working group outcomes. 

Objectives: Objective 1 is to develop a science-based management strategy to individually identify and target specific high-risk cattle for metaphylactic treatment at feedlot arrival based on a non-invasive measurement of their surface temperature.  Our working hypothesis is that body surface temperature can be used as a proxy for rectal temperature and/or blood biomarkers and a treatment threshold can be determined for use in predicting illness at feedlot arrival.  Secondarily, we hypothesize that the most ideal location for collecting body surface can be determined through correlation analyses with basal and febrile-induced rectal temperature during an endotoxin challenge.  Objective 2 is to evaluate whether the use of targeted metaphylaxis based on a non-invasive measurement of surface temperature reduces the use of antimicrobials in the feedlot production system.  Our working hypothesis is that because the majority of cattle considered high-risk for development of BRDC are receiving metaphylaxis when they arrive at the feedlot, using targeted metaphylaxis to better identify cattle that are candidates for antimicrobial treatment could reduce the administration of antimicrobials to otherwise healthy animals.  Objective 3 is to evaluate the use of targeted metaphylaxis through infrared thermography in a commercial feedlot setting in collaboration with Hy-Plains Feedyard and Veterinary Research and Consulting Services.  Our working hypothesis is that implementing a science-based method to better identify cattle that are candidates for antimicrobial treatment could reduce the administration of antimicrobials to otherwise healthy animals in a commercial feedlot setting. 

Funding Agency: Foundation for Food and Agriculture Research  
Grant Number: ICASATWG- 0000000061 
FFAR Award Total: $125,000 
Matching Funds: $125,000 
Start: 01 September 2022  End: 31 August 2024  
 
Novel Strategies to Improve the Understanding of Liver Abscess Formation in Beef Cattle 

Non-Technical Summary:  Liver abscesses are the primary reason for liver condemnation in cattle harvested in the U.S. Recently, there has been an upward trend in the prevalence of liver abscesses in beef steers. The pathogenesis of liver abscesses is alleged to be initiated by ruminal acidosis from feeding high-concentrate diets, which can lead to lesions in the rumen that predispose cattle to hepatic disease by the invasive, ruminally ubiquitous bacteria, Fusobacterium necrophorum. Tylosin phosphate is a macrolide antimicrobial continuously fed to feedlot cattle as a prophylactic antimicrobial, intended to reduce F. necrophorum, which is commonly isolated from liver abscesses and thought to be the primary causative agent. Our overall objective is to increase the understanding of the causes of liver abscesses and explore novel mitigation strategies.  
 
Objectives: Our specific objective is to: 1) develop an understanding of the gastrointestinal location, concentration, and movement of F. necrophorum and Salmonella enterica and the gastrointestinal microbiome in cattle with liver abscesses; Replacing the use of dietary antimicrobials with a novel direct-fed microbial would align with the ICASA working group goals. 

Funding Agency: National Cattlemen's Beef Association 
Award Total: $200,000
Start: 01 October 2022 End: 31 September 2024

Effects of restricted/programmed feeding on methane production, growth performance, carcass characteristics, carbon footprint, and economics in finishing beef cattle

Non-Technical Summary: The U.S. agriculture sector contributes approximately 10% of total GHG emissions, of which livestock contributes 3.8% (EPA, 2018). However, enteric emissions are responsible for 30% of the anthropogenic CH4 budget (EPA, 2018). To make any discernable impact on the CH4 mitigation in the beef industry, it is crucial to understand and implement mitigation practices that do not negatively affect current beef production levels. Practices that can decrease enteric CH4 include novel feed supplements such as seaweed and plants containing secondary metabolites such as tannins and saponins. These feed additives decrease CH4 by providing an alternative sink for ruminal H+ or through anti-methanogenic compounds such as bromide. As such, these feed additives are costly, some are scarcely available, and their use is often accompanied by a decrease in ruminal fermentation with a subsequent decrease in average daily gain and hot carcass weight. Despite the importance of CH4 emissions from beef cattle, observations in this area have been limited by the challenges associated with measuring emissions in cattle, and substantial knowledge gaps exist. Additionally, there is a need for better diet characterization and improved estimates of nutrient excretion from beef cattle. These estimates can be used to inform carbon footprint models so producers can better understand the complex relationships between inputs and outputs.

As cattle consume more feed, more CH4 is produced because of greater substrate for microbial fermentation in the rumen. Indeed, feed intake has the greatest effect on CH4 production of any measurable production characteristic. In feedlot cattle, programmed feeding is a common approach to manage feed intake, and moderate feed restriction (< 15% of ad libitum intake) can increase feed efficiency by approximately 0.6% for each 1% restriction from ad libitum intake. Maximum feed intake does not result in maximum efficiency. Cattle in the feedlot often overeat their ability to gain. Likewise, any decrease in feed inputs would decrease the overall carbon footprint during the feedlot, but there are significant knowledge gaps, and these relationships have not been adequately evaluated.

1. Evaluate the effects of restricted/programmed feeding on enteric methane (CH4) production and nitrogen excretion from finishing beef cattle

2. Determine the effects of restricted/programmed feeding on growth performance and carcass characteristics from finishing beef cattle

3. Estimate the total carbon footprint of alternative feeding programs and the amount of emissions reduction when feed intake is decreased from ad libitum

4. Conduct an economic cost-benefit analysis to evaluate the economic performance and estimate the per unit cost of decreasing CH4/CO2e emissions when using restricted/programmed feeding in finishing beef cattle