Cons
The problem of disease prevention emerged first. When one animal came down with an infectious disease, all in close proximity caught it. Diseases then spread rapidly through the herd of cattle, the chicken coops, and other small enclosed places that grew meat for food. This problem was likewise solved by science; in the mid-forties, antibiotics came to the rescue. Nature and its own means of control of life, left in the background, was no longer an absolute necessity for food production.
The food industries continued racing ahead and one thing led to another. “Many animals are fed growth-promoting hormones, appetite stimulants and pesticides, fertilizers, herbicides and aflatoxins that collect in the animals' tissues and milk.” These foods when eaten by the human population are possibly compromised by the drugs with various reactions and immune system problems.
Individually each food source that is factory farmed has its own criticism and its reasons for further study: Milk comes to the cooler cases in stores already tainted with one sad fact against it: Cows are in addition to the above medications, are given a Bovine Growth Hormone that causes them to produce twice as much milk. (Just thinking of those large udders and the discomfort to the cow makes some milk drinkers shudder!) Chickens, layers and broiler, are housed in cages and are no longer able to roam and peck for exercise.
The above facts were inspired from an online site that promotes a vegetarian way of life; that way of life may work for some, but it doesn’t work for all. What are the more plausible reasons for factory farming?