BIF 2019: Bovine Respiratory Disease (BRD) Research at US-MARC

Larry Kuehn and Tara McDaneld
U.S. Meat Animal Research Center

Bovine Respiratory Disease may be hard to diagnosis. Have to keep in mind that prey animals, like ruminants, have evolved to hide being sick.

What are the BRDC pathogens?
Bacteria

• Mannheimia Haemolytica
• Pasteurella multocida
• Mycoplasma bovis
• Others

Virus

• Parainfluencza-3
• Infectious Bovine Rhinotracheitis
• Bovine Viral Diarrhea
• Bovine Respiratory Syncytial Virus
• Bovine Coronnavirus (implications relatively recent)

Viruses typically aren't severe on their own, but they are often the gateway for bacteria infections to start.

Difficulty of BRDC treatment records as phenotypes
Disease incidence measured as 0 or 1
Subclinicals/shedders analyzed as healthy

How do we overcome these difficulties?
Large sample sizes are needed. USDA MARC is not using a subset of USMARC Germplasm Evaluation Program. MARC is also working to improve the quality of diagnoses/necropsy. They are also looking for indicator traits. They are collecting nasal samples and blood phenotypes. They are also looking at lung lesions scores at slaughter.

USDA-MARC worked with Colorado State University, they collected lung lesion scores from a packing plant in Nebraska.

Tara McDaneld is using metagenomics to look at BRDC. Metagenomics is looking at the genomics of bacterial and viral communities in environmental samples. In metagenomics, you are not looking at a single microbe, but the community of microbes. What distinguishes the microbiomes of sick and healthy cattle?

At sample collection, they collect nasal swabs, blood, fecal swabs, and other tissues. They sampled at prebreeding, preconditioning and weaning. The bacterial profiles change across these 3 time points. Also, there are different profiles of bacteria at different locations at the research center.

In different years there were different bacteria that were present in high numbers.