Great Commentary on Kosher Slaughter in The Jerusalem Report
Ner-David begins by talking about how repulsed she was by a cow's suffering at a kosher slaughterhouse she visited. She writes that "the way shehita is carried out today cannot be called kosher in terms of both the spirit and the letter of the law. The Shulhan Arukh (Code of Jewish Law) tells us that an animal about to be slaughtered should not see the animal being slaughtered before because fear will cause the animal to flinch and therefore be rendered a treifa because the knife will not cut smoothly. This rule (as well as other ways this cow's suffering could have been minimized) was blatantly ignored by the slaughterhouse I visited that day."
This chunk of the article is the highlight for me:
According to many halakhic authorities, shehita is meant to minimize the animal's pain ("Guide to the Perplexed," 3:26). In the past, shehita was a more humane way of slaughtering animals than was common in the surrounding cultures in which Jews lived. This is no longer true. Though stunning prior to slaughter has become the norm in non-kosher slaughter, halakhic authorities do not allow stunning. In addition, though not an absolute halakhic requirement, ultra-Orthodox rabbinic authorities and the Israeli rabbinate require that the cow be inverted during shehita, which is not the common position in non-kosher contexts.
Truth be told, if we consider complying with the requirements of tza'ar ba'alei hayim a requirement for meat to be considered "kosher," today's food industry renders all meat production non-kosher. Until recent times, animals were raised on private farms, under relatively humane conditions, and when the time for slaughter arrived, it was possible, at least, to treat the animal with dignity. This was true for kosher slaughter as well.
Today, mass production has taken over. Under these conditions, it is impossible to treat animals in a way that would comply with the laws of tza'ar ba'alei hayim. This is why all Jews concerned with Jewish values and/or Jewish law should consider vegetarianism.