Once you have them leading and trailering well, you can start taking them on short trails.  We have some small homemade soft panniers we put on them.  We find that as long as you don't pull their belly hair cinching them up, putting a saddle on them is absolutely no problem.  You can try tying different articles on the pack saddles to get them used to stuff flopping around or rattling.  From this point on, it just takes a LOT of time and a LOT of miles to desensitize them to everything they will meet.  When we want to stop for a short time, we tie them securely to a tree.  When we want to stop longer, we carry a hook that screws into the ground and about a 20 foot rope or chain that we attach them with. Make sure your circles don't overlap so the yaks don't get tangled.  In our are they can just graze.  We don't have to pack any extra food or water.

It is our experience that the yaks will sense anything around them long before you do.  They will stop or get nervous, and sure enough, soon something will approach you.  Usually it is the other animal that will be the most frightened.....particularly llamas.  As your yak get used to packing, the biggest problem in slowing you down will be all the people that will want to stop you and find out about them.  Yaks trek at the speed that most people walk.  We find that some yaks are "strollers" while others prefer to really step out.  Our yaks to not walk fast enough to keep up with our horses, so we do not try to pack with them behind a horse.  We always just trek with them on foot.   We always pack with a pair, and one yak will be dominate over the other.  Some yaks are very uncooperative when they have to follow yet do great when they lead.  It takes a while to get the calves paired up correctly.

When large enough, we put either a horse pack saddle on them, or there is a very good looking wooden llama pack saddle that fits them.  We use a saddle pad, their pack saddle, and the panniers we use with our horses. A full grown yak can carry up to 200#, but we usually only need to take about 50 pounds per yak.