Building a farm with fewer antibiotics

John and Travis Grimes were born and raised in the small community of Dunbar, in North Carolina, US. From what started as a tobacco farm in the late 1800s, they are now the fourth generation of farmers on their land, caring for over 100,000 chickens.

“Everybody says it’s in your blood. I guess you can say I kinda always knew what I wanted to do,” says Travis, the younger of the two brothers, of his passion for farming.
For the first couple of years in the poultry business, the Grimes brothers readily resorted to antibiotics to prevent diseases and improve growth rates of their chicken, as did about 90% of poultry farms throughout the US at the turn of the century.

Across the poultry world, chicks used to receive antibiotics alongside their routine
vaccinations to prevent infectious pathogens from getting into the egg through the hole poked into the shell by the needle. They were also given antibiotics in their feed, throughout their entire lives, both to prevent common poultry diseases and to regulate their gut microbiome, boosting their body mass and improving growth efficiency.

But, after phasing out antibiotics, the team realised many of these processes were “crutches for good management”, says Stewart-Brown, rather than necessary tools.
Today, their farmers simply take additional mechanical steps to prevent bacteria from
entering the injection wound: they keep the eggs cleaner and mix their vaccines in
specialised, sanitised boots. With hindsight, antibiotics at the vaccination stage “was
probably the most significant overuse of antibiotics,” says Stewart-Brown.

To avoid common diseases throughout the chickens’ lives, such as coccidiosis, the farmers keep their flocks under closer scrutiny – better drinking water, tighter control of litter moisture and cleaner chicken houses – and they work to catch any early signs. “We had to kind of become coccidiosis experts and look at it in a much more holistic way,” says Stewart Brown.

In 2002, though, under the guidance of Perdue Farms – the franchise they raise chickens for – the Grimes brothers started phasing out antibiotics almost entirely. “It was a little hard first off when we first started,” says John, speaking on his initial fear and hesitation. “Apprehension and concern,” says Bruce Stewart-Brown, the chief science officer at Perdue Farms, of how some of his farmers initially reacted to halting routine antibiotic use. But a growing number of customers had been calling with concerns about antibiotic overuse nationwide. “They’re buying our chicken, so they should have a say,” says Stewart-Brown. If there was an alternative way to raise chickens, his team would find it.

To keep the chicken eating enough, Stewart-Brown’s team removed irritants from the
chicken’s feed and switched to an all-vegetable diet replete with probiotics and other non antibiotic tools that keep the chicks well-fed. Antibiotics are now only used to treat sick poultry if any disease does end up spreading throughout the flock. But because cutting back on antibiotics has required farmers to change many of their everyday poultry-raising habits, flocks are actually getting less sick than they used to, says Stewart-Brown. While about 3-5% of flocks required antibiotic treatment for disease in the early 2000s, says Stewart-Brown, the percentage of treated flocks is now less than 1%.

True judicious use of antibiotics should mean therapy only, not routine prevention or growth promotion.

Bruce Stewart-Brown, Perdue Farms

But keeping their chicks antibiotic-free has been for more than just farming best practices.

It is one step further towards fighting antibiotic resistance, a top public health threat that contributes to nearly five million deaths each year. Many of the antibiotics used for poultry in the past were the same ones used in humans for everything from acne to pneumonia, such as tetracycline and sulfonamides, or gentamicin, used for severe infections such as meningitis and blood infections.

Introducing more of these antibiotics into the world – by feeding them to chickens, releasing their byproducts into the waste system, and exposing chicken farmers to them – gave diseases more and more chances to build resistance against them.
This is a real-world issue. Antibiotic resistance has increased in two-fifths of the bacterial diseases monitored by the World Health Organization. In recent years, more than 40% of infections with E. coli and over 55% of infections with K. pneumoniae – which causes pneumonia and UTIs – showed resistance to the antibiotics used to treat them. Overall, the World Bank estimates that the epidemic of antibacterial resistance could result in $1 trillion in additional healthcare costs by 2050.

New research suggests that even ionophore antibiotics – which make up more than a third of antibiotics used in US farming, but are not used in human medicine because they are thought to be irrelevant to humans – also boost resistance in some human diseases. “Some of these assumptions we’ve made about antibiotics like ionophores probably aren’t true,” says Alex Wong, a geneticist from Carleton University in Canada.
Wong discovered that when bacteria have the sets of genes that build resistance to
ionophores, they’re also very likely to carry the sets of genes that can do the same against human-important drugs. “By accident, [ionophores] also select for these other genes thatwe care about in humans,” says Wong, who has found over 10 such links between ionophore resistant genes and resistance genes in human pathogens.
Similar research from other teams has suggested that the risk might not be as large as it seems, since the animal strain and human strains of these bacteria are slightly different – so more studies are needed to really elucidate best practices moving forward, Wong suggests. “The short version is that we need to be very careful about how we’re treating our animals,” says Wong.

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