Please have a look at the video below.
http://blog.peta.org/archives/2009/12/halal.php
I myself couldnt watch all this video, its so horrible how the animals are treated in the slaughter houses.
Also, did you know that sheep have probably eaten chicken in their feed? Or that your dairy cows have probably had pork bones in their feed? Also is absolutely disgusting, blood and carcass instead of green grass in the feed of animals. Cattle, sheep, chickens, and other animals are routinely fed the ground-up bodies of pigs, chickens, and cattle, along with chicken excrement and other unsavory waste products as a supplement in their food.
The Qur'an says that animals are communities and nations unto their own and that they are more than mere resources. However, animals are treated as nothing but machines on today's "factory farms." Not only are these factory farms found in the West, they are also becoming the dominant means of meat, egg, and milk production throughout the world. More than 20 billion animals are slaughtered for food each year worldwide. These billions of animals are confined to extremely small spaces so that producers can raise as many animals as possible. Ninety percent of U.S. eggs come from chickens who are crammed together up to five to a cage the size of a record album cover, and this method of egg production is spreading throughout the globe.
Chickens have their beaks cuts off with hot irons; cattle are dehorned, castrated, and branded, and their tails are cut off without anesthetics. Dairy cows are also confined to tiny stalls and kept constantly pregnant through artificial insemination. All animals on factory farms suffer.
The overcrowding of the factory farm causes many animals to become psychotic and to mutilate themselves because of boredom or stress. To combat the diseases rampant in such overcrowded conditions, factory farmers routinely spray animals with pesticides and inject them with antibiotics. To fatten them quickly and inexpensively, animals are injected with growth hormones. Residues from these drugs and chemicals are passed on to those who consume the flesh.
These practices violate the Prophet's (SAWS) teachings to cause no pain to an animal before she or he is slaughtered. In addition, Muhammad (SAWS) forbade the cutting off of tails and other mutilations, as well as branding animals on the face (which is still practiced by some ranchers).