It dont work in wManager.Wow.Helpers.Bag.PickupContainerItem(0,1);

Try to add sleep time avec cast https://msdn.microsoft.com/fr-fr/library/d00bd51t(v=vs.110).aspx

wManager.Wow.Helpers.SpellManager.CastSpellByNameLUA("Feed Pet");
System.Threading.Thread.Sleep(1000);
wManager.Wow.Helpers.Bag.PickupContainerItem(0, 1);

  No effect at all with that C# code!  I think about it is errot  in wManager.Wow.Helpers.Bag.PickupContainerItem(0, 1); 
I am  sure the food that it is  correct meat in bag 0  and grid 1