Producers have role in antibiotic resistance issue

Cow-calf producers must keep better records on individual animal health treatment in light of concerns about antimicrobial resistance.

Cheryl Waldner, professor of large animal science at the Western College of Veterinary Medicine in Saskatoon, said increasing oversight by Health Canada means producers should document animal treatment.

There is little information available about who uses antimicrobials, for what and when, she told the Saskatchewan Beef Industry Conference.

Previous data is more than a decade old. More recent numbers obtained through the Western Canadian Cow-Calf Surveillance Network indicate producers are thinking about what products to use, she said.

“We need to look for opportunities to minimize antimicrobial use and we need better information on how much of these products are being used and how often,” Waldner said.

Surveys aren’t reliable and computer programs have been cumbersome for producers to use, she said.

The University of Saskatchewan has developed an app called Ethica that is in testing. Once ready, it will be available free for producers to enter information on-the-go.

Waldner said the surveillance network numbers, which include feeder data from 96 prairie herds ranging from 125 head to more than 7,000, show that about 71 percent used injectable antimicrobials at least once.

Sixty-eight percent had used oral antimicrobials at least once. Of those, more than half used them as boluses to treat infection, and 31 percent provided in-feed medication.

“Only five percent of the herds were actually using medically important antimicrobials in feed, so pretty small numbers there,” Waldner said.

As well, six percent provided antimicrobials in water.

The most common antimicrobials in use were oxytetracycline, penicillin and florfenicol.

In bulls, the main reason for use was lameness, followed by eye infections and respiratory infections.

Cows were treated for lameness, reproductive infections, eye infections, mastitis and respiratory disease.

Calves prior to weaning were treated mainly for respiratory disease, diarrhea, navel ill, arthritis and disease prevention.

Treatment after weaning was for respiratory infection, eye infections, arthritis and disease prevention.

“Only six percent of the herds reported treating more than 30 percent of their cows for therapeutic reasons and only 12 percent of the herds reporting treating more than 30 percent of their calves,” Waldner said.

“That’s still a lot.”

For disease prevention, 17 percent of herds used injectables, 25 percent provided antimicrobials in feed (three percent of those were medically important) and one percent treated through water.

The producers also reported that 24 percent of them thought about the potential human impact when choosing which drugs to administer; about half thought of the potential for antimicrobial resistance.

The vast majority, 91 percent, said it would be problematic if they couldn’t have access to injectable antimicrobials.

“Only 33 percent of producers were concerned about the potential for loss of access to antimicrobials in feed and water,” Waldner added.

These were mostly younger producers with bigger herds who retained calves.

Finally, 34 percent said they had experienced antimicrobial resistance in their herds. The concerns were mainly around loss of effective treatment for lameness, calf scours and respiratory infections.

Waldner said measurements of antimicrobial resistance in three colonies of generic E. coli grown in pooled cow fecal samples from the 96 herds found one resistant isolate in 10 percent of the herds, but only 4.3 percent of all the individual isolates were resistant.

However, there were some cases of multi-drug resistance.

The most common resistance was to tetracyclines, which isn’t surprising, she said.

Waldner urged producers to be careful about using products important to human health, even though there is only potential risk.

These include third generation cephalosporins such as Excede and Excenel, fluoroquinolones such as Baytril and intramammary preparations containing polymyxin B.

“With respect to beef and the research that’s been done, there is very little evidence at all that we as an industry are contributing to this problem in human health. But resistance isn’t a human or animal health problem it’s a problem for everybody,” she said.

In China recently, a pathogen resistant to all known antibiotics has emerged, and an American woman died from pneumonia resistant to 23 antimicrobials.

Waldner said no new classes of drugs have been developed in the last 30 years and there are no promising products in development.

“The answer is not in finger pointing,” she added.

“Everybody’s got to work together. We’ve got find our piece in this complicated puzzle.

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