Its a grey area at the moment, probably due to it being very much a marginal business.
The description below is how a trade association over here understands the difference.
There are two basic systems for enclosed deer, although many farms fall somewhere between the two.
1. Park – Deer are raised in a park type setting, where they are able to roam freely with minimal input.
They may be provided with some supplemental feed, calves are unlikely to be weaned, nor antlers removed, stock is not housed and
management is generally with a rifle. When contact with the deer is minimal, they may be classified as being wild and not farmed and
as a consequence the slaughter and carcass handling procedures are those applicable to wild deer.
Other parks consider their deer farmed and follow the requirements for farmed deer at slaughter; these may be organic whereas
wild deer cannot be.
2. Farm – Deer may be farmed following the conventional agricultural practices, including organic, grazing is rotated, some or all stock
may be housed in the winter (not all year round). Nutritional and mineral supplements are provided when necessary to maintain the
deer’s health, injuries and health problems receive prompt veterinary attention. Calves are usually weaned, antlers, certainly of the
young stock, are removed on safety grounds.
It may very well be that building handling facilities would tip me over into being a farm, which would be a mistake. At the moment the only method of 'handling' is with a rifle. As soon as its a 'farm' the animals would need to be transported for slaughter.
The problem therefore is to have sufficient facilities to aid management without having to endure the nightmare of regulations that cover modern livestock farming.
Grant