An interesting feature of Woodhenge is the shortest distance between the egg-shaped rings as Alexander Thom described them in Megalithic Sites in Britain. This distance corresponds remarkably well with the typical length of a cow, about 2 m 63.
If you count the rings of Woodhenge from the outside to the inside and start with roman numeral I, there are 18 posts in rings IV and V. These are the only rings with exactly 18 posts. The spaces between 2 adjacent pairs of these posts (each pair consisting of a post of ring IV and a nearby post of ring V), could have been used for cattle.
The spaces between rings II and III have 32, respectively 16 posts. The distance between rings II and III is twice the distance between other adjacent rings, so about 5 m 27. One could divide the space between rings II and III by taking 3 adjacent posts in ring II and 2 (occasionally 3), adjacent, nearby posts in ring III. Each space could suffice for a group of pigs. One half of the side with 3 posts in ring II could contain an opening to let the pigs in or out.
One or more of these spaces may also have been used for sows and calves.
One or more of these spaces may also have been part of a corridor to facilitate movements of livestock from and to the main entrance/exit.
The description of the underlying geometry of Woodhenge by Alexander Thom seems rather convincing except for the arcs that join the arcs of the larger and smaller circles of the egg-shaped rings. The posts on these arcs seem to be placed less accurately. This can be due to tree trunks which were not really straight, but why are inaccuracies in the position of postholes more pronounced there and less so on the other parts of the rings? Maybe the builders of Woodhenge simply did not know very well to make such an egg-shaped ring of posts in all its details. Maybe precision for a barn was not considered as important as for a house to live in or for a purely religious building.