Constant feeding of low, sub-therapeutic doses of antibiotics boosts animal growth. Apparently, without antibiotics, some part of the energy in the food is consumed by the gut microbes, not the animal. Antibiotics tame down the gut microbes, so more of the energy in the feed goes to the animal. The farmer needs less feed, and the animals grow faster.

I would guess that with antibiotics, meat production can be like 20% more efficient, maybe somewhat more.

https://en.wikipedia.org/wiki/Antibiotic_use_in_livestock#Dr...

> I would guess that with antibiotics, meat production can be like 20% more efficient, maybe somewhat more.

But at great cost. The farmer makes more short-term profit, while offloading the externality of dealing with the consequences (breeding antibiotic-resistant strains of bacteria) to the future[1] or just someone else entirely[2]. Are these costs really worth it for you to get cheap cuts of meat at the grocery store, or to ensure that the farmer makes more money (or remains profitable at all[3])?

[1] Antibiotic-resistant strains of bacteria make cattle farming impossible.

[2] Antibiotic-resistant strains of bacteria enter the general human population generating a significant health crisis.

[3] If the livestock industry can't stay afloat without these low-dose antibiotics, then maybe they should either charge more (meat becomes a luxury item), or they should just end livestock farming altogether. The production of meat isn't as essential to the functioning of society as people think. It's definitely not worth the risk of creating a health crisis just because "the meat must flow."

> (meat becomes a luxury item)

The European Union banned antibiotic growth promoters 12 years ago [1]. However, in my experience, grocery shopping for meat in the US east coast is, if anything, more expensive than meat in Europe.

[1] https://academic.oup.com/ps/article/86/11/2466/1573697

> Antibiotic-resistant strains of bacteria enter the general human population generating a significant health crisis.

From the wikipedia link above: "However, any antibiotics deemed medically important to humans by the CDC are illegal to use as growth promoters in the U.S. Only drugs that have no association with human medicine – and therefore no risk to humans – are allowed to be used for this purpose."

(I am no expert, so I don't know whats the bottom of this.)

Wait, isn't that the exact scenario that has the most danger of breeding antibiotic resistance? Constant, low doses that just suppress bacteria population but don't wipe it out.

Antibiotic resistance is becoming a huge problem recently. It sounds like farmers are slowly trading in the most effective life saving medicine we have ever discovered for a boost in margins.

Yes, its sad this train of thought is often disregarded as most of the people who I hear repeat it are anti-gmo.

Actually, the energy theory it likely incorrect. The more likely candidate for the connection between antibiotics and weight gain is the disruption they cause to the microbiome. This causes a metabolic disruption that impedes the breakdown of starches in the gut, and causes them to be converted to fat.

This is not just in cattle, by the way. It's also in humans. Antibiotic over-prescription has been linked to obesity and fatty liver disease. See, for example: https://www.nature.com/articles/pr2014157

"Erm, isn't the point that they use antibiotics en masse to prevent illness?"

Another great way to prevent illness would be to actually provide suitable conditions for the animals to live. Their current conditions are abhorrent.

I agree with the other commenters about the use of antibiotics to raise larger animals as opposed to healthier ones.

Farmers are under strong economic pressures to reduce sickness in their animals. And as mentioned be others, baseline antibiotics use is not about reducing sickness. Animal welfare is a valid and important concern, but the best place to focus is on places where the farmer's incentives are not well aligned.

But that’s not what they’re used for. Because antibiotics affect the gut flora of the animals, they tend to get fatter faster. Which is good for a farmer trying to make as much money in as little time as possible.

This is what they’re mostly used for, sadly.