Consumers are beginning to realize that taking ruminants off their natural diet of pasture and fattening them on grain or other feedstuff diminishes the nutritional value of the meat and milk. But what does a feedlot diet do to the health and well-being of the animals?
1) The first negative consequence of a feedlot diet is a condition called "acidosis." During the normal digestive process, bacteria in the rumen of cattle, bison, or sheep produce a variety of acids. When animals are kept on pasture, they produce copious amounts of saliva that neutralize the acidity. A feedlot diet is low in roughage, so the animals do not ruminate as long nor produce as much saliva. The net result is "acid indigestion."
2) Over time, acidosis can lead to a condition called "rumenitis," which is an inflammation of the wall of the rumen. The inflammation is caused by too much acid and too little roughage. Eventually, the wall of the rumen becomes ulcerated and no longer absorbs nutrients as efficiently.
3) Liver abscesses are a direct consequence of rumenitis. As the rumen wall becomes ulcerated, bacteria are able to pass through the walls and enter the bloodstream. Ultimately, the bacteria are transported to the liver where they cause abscesses. From 15 to 30 percent of feedlot cattle have liver abscesses.
4) Bloat is a fourth consequence of a feedlot diet. All ruminants produce gas as a by-product of digestion. When they are on pasture, they belch up the gas without any difficulty. When they are switched to an artificial diet of grain, the gasses can become trapped by a dense mat of foam. In serious cases of bloat, the rumen becomes so distended with gas that the animal is unable to breathe and dies from asphyxiation.
5) Feedlot polio is yet another direct consequence of switching animals from pasture to grain. When the rumen becomes too acidic, an enzyme called "thiaminase" is produced which destroys thiamin or vitamin B-1. The lack of vitamin B-1 starves the brain of energy and creates paralysis. Cattle that are suffering from feedlot polio are referred to as "brainers."
Typically, feedlot managers try to manage these grain-caused problems with a medicine chest of drugs, including ionophores (to buffer acidity) and antibiotics (to reduce liver abscesses). A more sensible and humane approach is to feed animals their natural diet of pasture, to which they are superbly adapted.