I read I should switch my chickens to adult grit so I was looking on amazon (local TSC is out of all grit) and there were pretty much two options. A 5lb probiotic poultry grit for 6 bucks and a 25lb regular poultry grit for 14 bucks. Which is better? I don't think I need a 25lb bag right now but will the probiotics cause problems if they don't need them constantly? or would it be healthier for them to have the probiotics?