It's so important to know what is in our food- every piece of it. I spend a lot of time these days just digging for information to find the truth about the state of the meat industry. The more I learn about conventional meat, the happier I am that Halal Pastures exist. I get great satisfaction knowing that the chicken my family eats was raised by farmers who treated the animal with respect, allowed it to live a life free of stress and in accordance to its natural ways. I have a 15 month daughter who loves to eat, mashAllah, which makes finding quality meat that much more important!
If you want to know what the conventional meat out there is like, then read Nicolas Kristof's excellent opinion piece in the New York Times called the "Unhealthy Meat Market." You can find it here: http://www.nytimes.com/2014/03/13/opinion/kristof-the-unhealthy-meat-market.html
Kristof mentions that it is a health concern that antibiotics are used on the animals. He doesn't state how much antibiotics are used though. To give you an idea, according to the National Resource Defense Council, over 80 percent of all antibiotics used in the United States are used in food animals (and the vast majority of this use is for animals that are not sick) (http://www.nrdc.org/food/saving-antibiotics.asp). NMM doesn't use antibiotics on its animals!