For all those saying the meat industry in the UK is inhumane, I had a very interesting experience a year or so ago when I had to go and inspect intensively farmed chickens.
It's not normally part of my job, and I was fully expecting to come back horrified and probably vegetarian, but actually I was extremely impressed by what I saw. These were hens for non-free range meat for mainstream supermarkets. They were in large barns, with plenty of space, plenty of straw on the floor so they aren't standing in their own poo, natural light and fluorescent lighting. The straw is regularly topped up so that it is clean and fresh. When they are young the barns would have CDs hung from the ceiling and cardboard tubes and things that crinkled put in them so the hens had something to play with. They clearly weren't stressed or fighting.
I've kept hens myself, and when I've kept them penned in they've seemed very upset, but when I first got them and they didn't understand what the outside world was, they really didn't like it at all (the outside that is). When they don't know what they're missing, they really don't find being inside distressing.
Once the hens have grown to about 6 weeks old, they are then packed up into crates for transport. I've packed other birds, and while this is stressful at the time, they very quickly calm down once in a confined space. They were then transported to the slaughter-house which was generally about 15 minutes drive away. Some of these would then be slaughtered as halal meat, where the procedure was identical to non-halal, but within a slaughterhouse that had been appropriately inspected, with a blade that fitted requirements and with the appropriate prayers being said.
As such, overall I concluded that the quality of life for these animals was a) far better than I would ever have expected or hoped and b) that there was no difference in the humaneness between the halal slaughter and non halal in terms of animal welfare.