Never give a horse a treat to bribe him to do something; only give a treat to reward a job well done. There’s a very big difference. Let’s take the example of asking the horse to load in the trailer. We’ve all seen the owner who asked their horse to get on the trailer by bribing him with a bucket of grain. That’s great, but the problem is you can only get the horse to get on the trailer if he’s hungry enough for the grain. You just hope that every time you want to take him somewhere, he’s hungry enough to want to get in. Overall, it’s just a very inconsistent way of training. Instead, reward the horse with a treat when he’s done a good job.
Think of it like giving him a gold star. You would never put a gold star on a child’s blank spelling test in hopes that it will motivate him to do well on the test. You give it to him after he’s put in the effort and has done a great job. So if one of my horses has had a great training session, I might give him a treat at the end to show him I appreciate his effort.