there are a lot of different products on the market - I have used Check from Stock Nutrition for donkeys years, (it smells a bit of strawberrys) and being a concentrate lasts ages, but to be honest when I ran out a few weeks ago I used some Zoflora, and the garden smelled lovely. Not that I have a problem as I get up whatever they do straight away, and always keep a watering can with some disinfectant in it for their wees.
http://www.doghealth.co.uk/hygiene.htm#Check.
Found out the weekend that my friend uses Zoflora to clean out her goat house.