Okay, I know a few people have answered but I'm gonna give my take as well!
1. Why are these cattle mutilations connected with aliens? I've read something about surgical precision and sometimes even cutting between
cells, does this have something to do with it?
We don't believe that the precision and what happens with the organs and stuff can be done with our technology.
There are also usually sightings around the time (whether this is hysteria or not, no one knows)
And the cows sometimes show signs of being picked up and dropped, but no tracks around.
That and the blood going missing...
2. If these aliens now use the cattle tissue for food(As the DULCE book claims, even though the book doesn't seem to have that much
credibility) why use ranch cowns and not breed your/their own cows? A lot stealthier anyway
Hmm. That would make sense. Maybe they can't on their planet? They might not have a planet. I wouldn't like a cow in my spaceship

(Although
the Doctor does have a horse in the TARDIS)
They might not be eating the cows either, they might be testing on them. The blood is usually gone, they might only need bits.
Then there's feeding them and cleaning up after them... It might be too much hassle for these aliens to keep cows as pets when all they're gonna do
is kill them. It might upset the kids as well, seeing their pet cow killed and cut to bits.
Maybe it isn't aliens. People might notice if some weird cult gather to slaughter their own cows in odd ways.
And I'd like to say Area 51 or somewhere with a load of cows in a pen that get cut up.
3. Has there been any cattle mutilations recently or are they decreasing?
I'm not sure, you'll have to google it. Afterall, they only really hit the news when there's been a surge in them, since they do seem to happen a
canny bit.
I think there are less now than back in the day, but don't quote me on that. I might be wrong.
They definetely hit the headlines less anyway/
4. Also, I've read about black hellicopters being seen around mutilation sites, what is belived to be their purpose?
Yes, the mysterious government MIB helicopters
They're either 'part of it', checking 'it' out, or as someone said before chasing down UFOs.
Truely, I don't know. If I did, I probably wouldn't be on this site. And the mutilations probably wouldn't be a mystery!
So yeah, try googling cattle mutilations, there's loads of stuff on there, and if you need anymore helps I'm no expert but I can try my best!
[edit on 30/12/2009 by Ayana]