The fungi / yeast doing the fermentation may use / consume some of nutrients the formulated food (Layena in your case) is designed to supply the chickens with. If enough consumed, then chicken consuming the nutrient deficient feed will in time begin to slow in growth / productivity or develop health problems. Generally speaking the person formulating diets provide a little overage (excess) of the nutrients known to be essential but when the feed is somehow degraded (fermentation, age, excess heat) that overage may not apply.
As a general rule when using a quality layer feed cut with intact grains, I do not have the layer feed make up any less than 2/3's of the total intake, otherwise the diet can be nutrient deficient especially in respect to protein. It is usually more than 3/4's. Only exceptions to that are during cold winter months and when natural foraging makes up a significant proportion of intake.
You birds low water intake is also a a function of fermentation process where the feed is hydrated. The hen is recieving a significant proportion of her water need through that and thus has less need for water which limits the amount of medication ingested.
