I give it to them in their drinker. The water I use is bottled water with no chlorine, a small pot of yoghurt to 2 litres of this water. I hold back the water for 15 minutes after feeding then give it to them, they’ll dive in and take a good drink then. You need to give yoghurt after times of stress or during a period when they look of colour and could be fighting something and after any sort of treatment.