A customer of mine in Ghana has asked me to help him find a bulk supplier of food for his kennels business. Searching online gets sellers of large bags, but where would I get it in ton bags?

I doubt you can get it in ton bags.

What would be the market? You could probably get pallets with multiple 15k-20g bags on them maybe.

Something like this:

http://www.petsupplyuk.com/2-x-Pallets-of-Rufus-Complete-Dry-Dog-Food-120-x-15kg-sacks,name,21226,item_id,ad_details

or these people (dunno if international):

To buy dog food in bulk an order would usually start at about 30 bags, which is roughly 1/2 tonne (33 bags at 15kg). We deliver these bags on a pallet, wrapped to protect the dog food and transported via haulage companies. The length of time for delivery, from the date of order, would normally be three working days.

https://www.cobbydog.com/Trade-and-Bulk/Bulk-Orders.aspx

I’d suggest you want to talk to the (dry) dog food producer, sound obvious but.. there one local factory that makes everyone’s branded dog food. The factory will sell there own unbranded food to bulk purchasers. How you locate the producer is a different story (can’t help you)

These people make the stuff.
http://www.bearts.co.uk/feed.php

I don’t suppose you’re any where near Crufts today? I’m guessing there will be someone there who could help?

Why would they want it in ton bags as opposed to 15-25kg sacks on pallets?

Appart from the handling issues there is also the risk of it spoiling or vermin, at least with sacks it’s immediately obvious if water or pests are an issue.

Even horse yards just use sacks.