Some Canadians have questions about antibiotic use in farmed animals. In an earlier post, we looked at the science behind the use of hormones in beef cattle. This week, in part one of a three-part series, we’re exploring another hot topic – antibiotics.

First up, an explanation of what antibiotics are, and how and why they are used.

Antibiotic or antimicrobial?

An antimicrobial is any agent that is used to treat microbial infection. An antibiotic is one type of antimicrobial, specifically made from natural microorganisms.

When looking at the safety or issues of using antibiotics in beef cattle, it makes the most sense to discuss the use of antimicrobials as a whole, rather than only antibiotics.

We spoke with Dr. Sherry Hannon, research team lead and veterinary epidemiologist at Feedlot Health Management Services Ltd. to learn more about the use of antimicrobials in feedlot animals.

Sherry explained that there are four main reasons for the use of antimicrobials in feedlots:

#1 To treat disease

“Diseases such as respiratory disease, arthritis and other lameness, abscesses, etc., are effectively treated with antimicrobials in injectable or oral form,” said Sherry.

#2 After surgery or injury

Antimicrobials are used to prevent infection in individual animals after specific events.

#3 As a preventative

Antimicrobials are sometimes used when animals have been exposed to disease, or unfavourable environmental conditions, and are at risk from an outbreak of infectious disease. They are also fed to groups of cattle at specific times to help prevent common diseases.

“Based on clinical field trials, we know that specific groups of animals may already be sick by the time they reach the feedlot after weaning, co-mingling in auction markets, and transport,” explained Sherry. “Antimicrobials help us prevent outbreaks that could spread through the herd.”

#4 To improve growth and production

The use of antimicrobials have historically been used to improve rumen function and enhance growth and production of meat, but this use is declining, and becoming increasingly regulated, due to the risk of antimicrobial resistance. We will discuss antimicrobial resistance further in part two of this series.

When antimicrobials are withheld

When an animal is sick, or at risk from disease, it would be cruel to withhold treatment.

“There are three main health implications when antimicrobials are withheld,” Sherry noted:

• Poor animal welfare – animals would become sick or die.
• Greater potential for spreading of disease among animals in a pen.
• Food safety concerns increase because animals are more likely to have infections when sent to slaughter.

Stay tuned for next week when we will discuss the causes for concern around the use of antimicrobials in beef cattle, and what’s being done to address them.

In the meantime, check out ‘Beef and hormones: what the science says’.