Less than Lethal...

Since no one else has replied. Salt is not a good idea. Not sure about peppercorns.
How about a bean bag shotgun load? Non lethal on humans so it should be fine for livestock.

Get a trailer, load them in it.
Drive them them to the BZ. Release them there. You will never be bothered by them again. There will be steaks at #1bambam's next build party at the AKShak.















Oh wait you said not harm them. Personally I might not use a fire arm.

I know we shot bowling pins together in the BZ. You won 1 of the class IIRC. I won the any gun class. I miss that rat hole. I shot 1100 rounds of .22lr there one day. It was the best place I ever plinked at.

Good times!

Airsoft BB's work like a champ.

Potato gun

If these livestock animals are considered wild and a nuisance then have at them with whatever you are legally allowed to use.

There's a lot better ways to handle escaped livestock than shooting at them IMO. Better fences come to mind, yours or the owners. Livestock is usually someones property and unless you live in a free range area its up to the owner to keep them contained. Besides, if you spook a cow, steer or horse they'll take off and run though or over anything that gets in their way and often not in the direction you expect. Just because they're on your land doesn't make them your property and any damage they get or do from being spooked by being shot at will be your legal and financial responsibility.