The movement towards organic food and free-range animal products is cemented in the belief that more natural foods are healthier. The idea makes sense, as whatever the animals eat could indirectly affect your health.
Two of the most worrisome non-organic additives to livestock are hormones and antibiotics.
For example, antibiotics administered to cows can affect the kidney and liver functions of humans who eat their meat.
Farm animals who have received hormone injections may pass the hormones on to their human diners, which can alter normal hormone physiology. Testosterone production can be altered in males, which can lead to male infertility.
Though banned, some small farmers may give their dairy cows oxytocin injections to promote milk production. This hormone can be secreted into the milk, thus affecting the humans who drink it.