Sword of the North
A Human character may carry up to 10 times their Strength characteristic without being considered over-encumbered and suffering a -1 penalty to their movement score. For every 50 lbs more the character carries, they suffer another -1 penalty to their movement score.
A dray animal, such as a horse, pony, yak or donkey can carry significantly more than a normal human being. A horse can carry 20 times their characteristic, a pony 10 times, a yak 30 times and a donkey 15 times their strength characteristic.
It is advisable to bring multiple dray animals if you’re expecting a large haul or transporting heavy goods. Usually one animal to carry goods you cannot carry and another animal to carry the feed for the animals.