Ace and tirediron have already covered the "hey, good luck with THAT" aspect of this plan. All I'd say is, don't quit your day job!
Learning to take outstanding photos that are worth selling is HARD. But it turns out, that's actually the EASY part. Actually making money from selling them, that's far tougher!
Anyway, with that caveat out of the way:
You don't say WHO you plan to sell these photos to, or how you plan to go about that.
Are you selling to the general public through craft shows, and such? Are you trying to get your photos into some local stores or art galleries? Do you plan to try to sell them (particularly the horse photos) AT specific events?
To me, a Portfolio is NOT a collection of photos for sale. Your portfolio is your photographic resumé. It's the physical collection of your BEST work; it's what you show people like art gallery curators, gift shop owners, etc. to convince them that your "body of work" is worth their time to market.
If you're selling directly to the public, you wouldn't be showing them a portfolio. You'd just have whatever photos you want to sell already printed, plus a price list for ordering other sizes, etc.
Do you know how much you need to charge to even begin to make a profit? Do you know what your actual cost of doing business would be?