You'll need an additional account to record your commissions or any additional fees. This expense / income account will sit within your accounting software. 

Recording it via Figured

When you add a purchase / sale into Figured, you'll add in your livestock information as you would normally, and then add a non-stock line.

In that section, you'll then select your newly created account and then add in any financial values - enter these values as a negative number if you had to pay money, or as a positive number if it was an additional income.

That'll then flow through to your preferred accounting software!

Recording it via preferred accounting software

You can also do it the same in your accounting software - raise an invoice for your livestock, then add an additional line using your new account. Then you can reconcile your livestock information as normal.