first time quickbooks user, we have a hobby equine farm with a few animals, how do i set up sales and purchase for the horses and cattle

You should have QBO Plus or Advanced to utilize the Location feature.

https:// quickbooks.grsm.io/US

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You can designate each horse/cattle as a "business" to manage them separately. Please note, discounted rates do not apply when upgrading your QBO plan from a lower plan.

https:// quickbooks.intuit.com/learn-support/en-us/help-article/track-location/set-use-location-tracking/L2raFkEBC_US_en_US?uid=lakak4oo

Welcome to the Community, @judlamg!

I'd love to assist you today so you can track your sales transactions in QuickBooks Online. 

In QBO, you can track what's on hand, get alerts when it's time to restock and see insights on what you buy and sell. Non-inventory goods and services can also be entered so you can simply include them in your sales forms. 

If in your case you want to track how much you sell, purchase, and track its quantities, we need to add inventory items. To get started, we need to turn on inventory tracking first. 

Note: Inventory features are available for QuickBooks Online Plus and Advanced. If you don’t have Plus or Advanced, upgrade your QuickBooks plan to start tracking your inventory.

Once turned on, we're now ready to add inventory items. Let me show you how:

1. Go to Sales and select Products and Services.
2. Select New and choose Inventory. 
3. Add a Name, SKU, or Category for what you're tracking. Learn more about item categories. 
4. Add your item's Initial quantity on hand. Then enter when you started tracking quantity in the As of date field. Note: Since you're new to QuickBooks, the initial quantity on hand depends on what date you plan to start tracking your business. For example, if you’ll start tracking from the beginning of your fiscal year, enter your products’ quantities at that time. But if you’re simply adding a new product from a vendor, enter “0” as its initial quantity. Then, after saving, track how many of these products you receive from vendors. This ensures you don’t double its initial quantity.
5. You can also add a Reorder point. You can use this if you're items are from your vendors and QuickBooks will notify you when it's time to reorder. 
6. Select the Inventory asset account dropdown and select Inventory Asset. 
7. Fill in your item's Description, Sales price/rate, and Income Account. Tip: You can use an income account QuickBooks already set up for you. But if you need a new account, scroll to the top of the drop-down list and select + Add new. Or learn more on chart of accounts first.
8. Select the Sales tax category drop-down and specify how the item should be taxed. If you don’t see this drop-down, set up sales tax in QuickBooks.
9. Fill in the Purchasing information, Cost, and Preferred vendor. 
10. From the Expense account drop-down, select Cost of Goods Sold. QuickBooks uses this account to track the cost of items you sell.
11. Select Save and close.

I've added some screenshots that you can refer to:

Once set up, you're all good to track them when they sell. You can either Create an invoice if you'll get paid later or Create a sales receipt if your customer paid on the spot.  QuickBooks then decreases what's on hand by the amount on the invoice or sales receipt. 

I've also added some articles that you may find helpful in managing your sales transactions in QuickBooks Online:

• Record invoice payments in QuickBooks Online.
• Use reports to see your sales and inventory status. 

Should you need anything else in managing your sales transactions in QuickBooks Online, I'm just a reply away. Have a great day!