Dogs react differently to the shock than we do. Not to mention for it to even work, there has to be the skin contact so IME, getting it fitted just right is part of the challenge. good luck. i definitely vote for the training lead and stepping up enforced training. Enforced training meaning, you have control of the lead and only enforce the command if he doesnt follow it immediately. Whatever treats he LOVES but doesnt get often should help with positive training. He needs to get used to the calf and learn first that being calm is a must so when he's calm looking at the calf and looks away, that second he looks away reward him with the treat. But he has to look in a different direction for this to work otherwise he could associate it with looking in the direction of the calf gets him a treat.
Shasta GSD 5/5/10 CGC, ITD, TC
"Dax" Thor z vom Weberhaus BCAT CAX2 CGCA ETD HCT NCO-1 PKD-T RATI RATN RA TC TKA 3/18/2013
"Hades" Guilty vom Blutfeuer 10/26/2018
Zena GSD 6/1/03-2/16/2016
Riley GSD/BC 1/10/05-2/1/2013