In case you are reading this and have had mouldy nasty messes instead of lovely healthy lacto fermentation (that's what happened to me). I thought 1) i was doing it wrong, 2) it was the wrong time of year , 3) I hadn't found the right combination of ingredients or 4) it simply isn't possible for me here, now. Probably all of above were true, but I was desperate for this lacto fermentation to work.
I remembered I had an unopened bottle of EMs, otherwise known as effective microorganisms, a combination of lacto bacteria, yeasts and photosynthetic yeasts invented by a Japanese farmer. In spite of it being past its Best Before date, it smelt lovely and fresh, so it tried about 1/2 teaspoon in the chickens food, which is 1/3 pre-soaked cracked barley with some mash, 1/3 veg/ barley grass with some fruit and 1/3 left overs with enough water to cover = about 2 gallons. In 48 hours it was bubbling like it was on the stove when I stirred it and it smelt lovely. It was quite warm where I kept it but it was the same place I experienced all my failures. My 12 1 month old chicks LOVE it and their coop and run don't smell at all.