Advertise, advertise, advertise.
Per horse or per barn, once a link is in you can add the associated barn into the text.
Pop links into the Classifieds (Search, Classifieds)
Pop links into the Forums e.g. Stallion Ads, Broodmare Ads, and Straw Embryo ads.
As many as appropriate.
But, your animals should have a sellable feature, colours and or ratings. Could be all disciplines or single discipline.
It helps if they are on any leaderboard.
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Once you have advertised for a couple of months then your profile will rise and hopefully a few watchers.
However I find that even without watchers the adverts work.
P.S. Check the similar animals for going prices. This is best done at the begining of the month before the good guys/girls have sold out. Then you can then get the price right balancing profit and sellability.