ACV is very good for hens, I give mine first week in each month, so I remember.
below is what is in it, the cloudy sort from large pet shops. used for dogs horses etc.
Apple Cider Vinegar
Apple cider vinegar (acv) is known as a general pick me up for chickens. It is often used to reduce stress during moulting and also when adding new stock to the flock. It also helps to maintain the health of their feathers.
Apple Cider Vinegar provides enzymes and important minerals, such as potassium, calcium, magnesium, sulphur, chlorine, phosphorous, iron, silicon and other trace elements. The vitamins contained in Apple Cider Vinegar are bioflavonoid (vitamin P), beta-carotene (precursor to vitamin A), vitamin C, E, B1, B2 and B6. Tannins from the crushed cell walls of fresh apples as well as malic acid and pectin and other powerful nutrients. ~ostlerscidermill.co.uk
It is given at the rate of 2% i.e. 20mls per 1 litre of water in a plastic drinker (as it will corrode the galvanised types).
In the case of chicks only give it at the rate of 1% ~ 10mls per litre of water ~ don't forget the pebbles or marbles to prevent the chicks drowing themselves in the water!
The best sort to buy is the cloudy type usually found in equestrian supply places not the more refined type that you get in supermarkets
