Animals dissapearing

I just added a few months ago the Horse Ranch expansion and, I don't understand why, but in Chestnut Ridge my chicks, cocks, sheeps and goats keep dissapearing. I buy another ones and they just keep dissapearing! Not all of them at the same time, but suddenly I have -2 goats, or there is no **bleep** in the coop anymore. This happens everytime I travel somewhere and return home.