This for real ?
I'm unsure this sort of idiocy is something a country should encourage. Maybe under some local affront to public decency law ? But if the sheep is slaughtered according the legal definition of slaughter that applies in the UK then there is less of an issue. However if the sheep isn't used for food afterwards but just killed and sling, then I think there ought to be something that stops it being legal.
I suspect it isn't to help his team relax (?!?!?) but put the opposing team off their game. So it could amount to cheating.