Has there been any research to determine why growth improves with diminished gut bacteria?
I've seen some theories tossed around to explain the mechanism, but there is no consensus, aside from the fact that it does work.
Unfortunately, it's also led to us having human disease that no longer responds well to antibiotics that are safe to use in humans.
For instance, with Extensively Drug Resistant Tuberculosis:
> Second-line drugs are more toxic than the standard anti-TB regimen and can cause a range of serious side-effects including hepatitis, depression, hallucinations, and deafness. Patients are often hospitalized for long periods, in isolation. In addition, second-line drugs are extremely expensive compared with the cost of drugs for standard TB treatment.
https://en.wikipedia.org/wiki/Extensively_drug-resistant_tub...
Even after you fall back on lesser used antibiotics with severe side effects, the cure rate for XDR TB is below 40%.
> Antibiotics are chemotherapeutic agents used for the clinical management of infectious diseases in humans, plants and animals. However a sizeable fraction of antibiotics produced every year all over the world is used for non-therapeutic purposes. In US alone, about 24.6 million pounds of antibiotics are used in animal agriculture annually and a substantial portion of this is used as growth promoters and not for the treatment of infections...
Evidences available in the literature speak volumes on the beneficial effects obtained from antibiotics used as a feed additive. Pigs supplemented with antibiotics in their feed require 10–15% less feed to achieve a desired level of growth.
https://www.frontiersin.org/articles/10.3389/fmicb.2014.0033...