Kosher and Halal are simply ethical guidelines derived from religious texts, and while Islam has jewish roots, it also has its own text and therefore implications to draw from.
Like most things religious, the source text is often vague and requires interpretation. More often than not, this interpretation is skewed to some preexisting bias rather than focusing on the actual content and context.
For example, picking on a random internet source
http://www.chisty.freehosting.net/halal.html
Note while interesting, this commentary is not based on the source text, but is the writers own biased interpretation.
Interestingly, there is a rather poignant piece of paulian writing on this subject:
From the above, to a Christian, the 'halal' is utterly meaningless so can be readily eaten, but care must be taken not to be seen to 'endorse' the idoloisation.
note: neither Kosher nor Halal have or pertain to have anything to do with welfare, unnecessary suffering or humane treatment. They only exist to bring the 'believer' in line with the religious text. Whether or not the belief holder also believes in animal welfare is totally irrelevant, misleading, misguided and ultimately a strawman.