TLDR: Instead of spending your exports on livestock to process at a loss and resell the meat for produce, just buy the the produce with your exports in the 1st place.

If a Trader comes to you with nothing you need, there is nothing wrong with telling him to pack up & move along. The sooner you end your business with a trader the sooner the next one will be along.

In the end, (surplus) Meat, Firewood, simple Coats, and (non-wheat) Ale are great (renewable) exports. Seeds & Livestock are poor imports for any town that already has that particular species.

According to banishedinfo.com: Slaughtering a cow gets you 6 leather & 200 beef, slaughtering a sheep gets you 200 Mutton, and slaughtering a chicken (animal) gets you 6 chicken (food). Making the purchase of Cattle & Chickens for slaughter a "bad trade" & Sheep an investment of labor for no value gained.

• Cattle @ 800 -> 200 Beef @ 3 + 6 Leather @ 10 = 660 or a loss of 140.
• Sheep @ 600 -> 200 Mutton @ 3 = 600 or breaking even if you don't count the time invested for the herdsman to slaughter, laborers to store & traders to return to the post.
• Chickens @ 400 -> 6 chicken @ 3 = 18 or a loss of 382.

Eggs & Wool are byproducts of keeping a number of your chickens & sheep alive.

Why are we doing this?

A) If you want to process imports for profit:

• Logs -> Firewood
• Fruit -> Ale
• Leather or Wool -> Coats

Warm Coats are great for keeping your people working but worth less in trade. Make Hide/Wool Coats for trade.

Tools can be made from imports at a small profit, but as Iron & Coal are not renewable, there may be more value in stockpiling Steel Tools.

B) If you want a source of protein for your people:

If you want to import your protein, buy nuts or fish.

There are 4 sources of home grown protein in the game:

• Fishing Dock: The Fishing Dock is labor intensive, but has a very small footprint and utilizes otherwise hard to use real-estate.
• Hunting Cabin: The Hunting Cabin is likewise labor intensive and requires a large land reservation, but in an early town may be your only source of clothing materials.
• Orchard (growing nuts): Orchards, like Crop Fields, are land and labor efficient, but require a few years before they become productive and are subject to the vagaries of weather.
• Pasture: Pastures are likewise land and labor efficient, can provide raw materials for your Tailor, but have a considerable startup time. Chickens have a great growth rate, reducing startup time, but produce the least protein and nothing for the Tailor. Cattle in a pasture can be a replacement for your Hunting Lodge. Sheep are king! They supply the most protein for your pasture and wool equal to 3 times the leather produced by the same sized cattle pasture. Prepare to export Wool Coats!