Each year, 24.6 million pounds of antimicrobials are administered to livestock for non-therapeutic purposes. Seventy percent of all antibiotics and related drugs are given to animals as feed additives. Nearly half of the antibiotics used are nearly identical to ones given to humans. There is strong evidence that the use of antibiotics in animal feed is contributing to an increase in antibiotic-resistant microbes and causing antibiotics to be less effective for humans. Due to concerns over antibiotic-resistant bacteria, the American Medical Association passed a resolution stating its opposition to the use of sub-therapeutic levels of antimicrobials in livestock.