Swapping two kids for half a pig

Last week we sold two of our goat kids, the two nannies. They aren't going far, just across the hedge into the next allotment where Steve and Vicky, the new allotment holders, have decided to start keeping goats. And the price to be paid (at the end of this year)?: half a pig. Steve and Vicky are also planning to keep pigs so this was an ideal opportunity for a great swap.