Antimicrobial-free Production of Beef Cattle's Affect on Gut Microbiome

The researchers plan to investigate differences in the resistome (i.e., populations of antimicrobial resistance genes) and microbiome (populations of bacteria) in feces obtained from people when they consume diets containing beef derived from cattle raised conventionally (i.e. using antimicrobial drugs(AMDs)) vs. those produced in raised without antibiotics (RWA) systems. In addition, the researchers will investigate whether specific antimicrobial resistant (AMR) genes are transmitted from food to people.

The hypothesis is that beef is not a significant source of resistant bacteria, and there is no difference in the likelihood of gut colonization with resistant bacteria in people eating beef derived from cattle raised conventionally (i.e. using AMDs) vs. those eating beef produced in RWA systems.

Inclusion criteria

• Male or female, 21-69 years old;
• BMI 22.0-34.9 kg/m2;
• Fasting serum total cholesterol <240 mg/dL, low-density lipoprotein cholesterol <160 mg/dL, triglycerides <400 mg/dL, and glucose <110 mg/dL;
• Systolic/diastolic blood pressure <140/90 mmHg;
• Body weight stable (± 4 kg in previous 3 mo);
• Medication use stable for 6 months prior and not using medications or supplements known to impact gut function;
• No use of topical, oral or parenteral antibiotic medications in previous 6 months.
• Non-smoking;
• Physical activity regimen stable for 3 months prior;
• Not drinking more than 2 alcoholic drinks per day;
• No history of gastrointestinal disorders, surgeries or cancers;
• Non-pregnant and not lactating
• No acute illness and non-diabetic;
• Willing and able to consume the prescribed diets that may include meat, dairy and gluten-containing foods and beverages.

Exclusion criteria

• Male or female, < 20 or >70 years old;
• BMI < 21.9- >35 kg/m2;
• Fasting serum total cholesterol >240 mg/dL, low-density lipoprotein cholesterol >160 mg/dL, triglycerides >400 mg/dL, and glucose >110 mg/dL;
• Systolic blood pressure >140 mmHg, diastolic blood pressure >90 mmHg;
• Body weight stable for < 3 months prior (±3 kg);
• Stable physical activity regimen < 3 months prior;
• Medication use unstable for 6 months prior and using medications or supplements known to impact gut function;
• Smoking;
• Drinking more than 2 alcoholic drinks per day;
• Diabetic;
• A history of gastrointestinal disorders, GI surgeries or GI cancers;
• Pregnant or lactating