no stranger to long manes here and I know most braid them to keep clean and manageable, as do I most of the time...however the one time Ive tried to braid my mare's she wants to rub it...I left it loose right at the base so it wouldn't pull.  I've just been managing it by keep it clean and lots of conditioner but these last couple weeks with the heat like it is it's just matting up from her sweating (thank goodness for sweat!!) and slinging her head, I mean I'm cleaning it out multiple times a day. Any thoughts? The last thing I want to do is braid it then her rub a chunk out...it's over 2 feet long at this point 

I must be doing something wrong. Anytime I've ever braided mane, hair falls out by the handful when I take it down. I have a gelding that I'm braiding during this uncomfortable heat wave to keep him from sweating so much. When I take it down after a week to brush and rebraid, lots of hair comes out with each stroke of the brush. 

Try using electric tape 

cancan...I think that's just natural shedding like if you brushed it every day...it just seems like a lot because it's once a week instead of daily 

Hmmmm. Maybe so. It does seem like a major hair loss. I didn't realize a horse shedded it's mane. Reminds me I have to go back out and redo his mane. Do you braid tightly or loosely. Is one way better for the hair?

I've always been told leave the 1st couple crosses at the top loose then braid tight and it's worked for me. Guess I'm just going to have to try to put a bunch of bug repellent on her and braid it and see what happens. Her mane is beautiful and I want it to keep growing if it will.

I do a TON of smaller braids. Just like you mentioned, loose ish at the top and then tighten up as I got down the braid. Each braid base is MAYBE an inch wide at the top. It takes forever and a day to get it all braided but it helps them stay in better I think. 

gunnin to play...same here smaller sections pull less I think too as they stretch their necks different ways