The Duke wrote:
In SO4...you have a thing known as 'The Breeding Barn' which takes horses away from your stable and into the sheds.
You can have upto 100 horses racing in your stable at any one time, and I think it's 60+ in your breeding barn on top of this, and believe me you'll never reach these limits anyway.
I fully recommend having played SO2 that you upgrade to SO4, it's just so much better allround. Believe me, you won't regret it.
I have 100 horses at the start of every season Duke, I then have to prune 25-30 away during the season to make room for my home bred 2 year old crop. Breeding barn at the moment has about 25 but this is obviously rising season on season, so, unfortunately, the limits can be reached.