Q:

What is the feed/day limit for various pack animals?

Wikipedia lists these common pack animals

Camel
Yak
Reindeer
Goats
Water buffaloes 
Llama
Equines including horses, donkeys, and mules
Dogs (packing and sledding should have different values)

Each animal has a weight it can carry normally described as a percent of its body weight, and food requirement that can also be described as a percent of its body weight. An animal who is carrying only its own food reaches a limit, where it can only trekk so many days. 
Several years ago I found a list that showed these values, and described it better then I have here.  But my google skills are failing me on this.  

A:

For horses I've seen various numbers but 125 to 250 seems to be the range.  This depends on the breed, the difficulty of the terrain, and the length of the trip.  Horses need a lot of time to graze.  You can carry hay (required in many parks) or you can carry grain to supplement grazing.  Advocates for the lower number point out that the load is always on the same parts all day, unlike a person who shifts about.
For dogs carrying, about 1/3 of their body weight.  Dogfood is calorically denser, but dogs don't graze.  You won't find that number in the trail guides, but I did see it in the accounts of a man who used sled dogs in winter, and used them as pack dogs when there wasn't enough snow to slide.
For dog sledding, much again depends on the terrain and the snow conditions.  During the klondike where most of the travel was on the Yukon River (flat) pulling 600 pounds with a team of 6 large dogs was common.  Under really good traveling conditions, a team could haul two sleds.  You'd unhook at a portage and make two trips over the portage.  Must have been interesting bringing a team back without a sled.
At one point in my life I trained dogs for freight races.  We could put 7 milk crates of frozen wet sand (about 900 lbs) and still go at a pace that the musher couldn't run fast enough to keep up -- at least for a few miles on broken trail.
Dogs don't like unbroken trail.  (Exception: if they are very familiar with the route, they will do an unbroken trail.  And there are exceptional lead dogs...) Usual routine is to either have at least 2 of the party break trail on snowshoes, or to break trail the day before, move up to the end of the trail and repeat.  Sleds don't slide well at very cold temps, even the modern HDPE sleds.  New snow is stickier than old snow.  Temperatures just below freezing can put you in situations where the compression of the runners melts a film which is incredibly slippery -- and flash freezes back to ice, glueing you the the trail if you stop.  Water bodies often have water on top of the ice, forming a layer of slush under the snow.  This works about as well as hitting a tar patch on a hot summer day.  And the dogs don't like getting their feet wet.  One musher told me a story of hitting 8 inches of overflow, and as soon as the sled stopped the entire team came back and perched on the sled to get there feet out of the water.
Llamas are ~80 pounds carrying capacity.
You can load a travois ('A' frame triangle with narrow end on animals front shoulders) with about 2-3 times what you can carry if you have suitable terrain.  (Fairly open, reasonably level or rolling) 
While goats I guess could be used for packing, they are little.  I think it would be very aggravating to pack them up in the morning. 
Humans:  The usual number given is 1/3 of body weight.  In practice having run expeditions I would put it at 1/2 of lean body mass.  This gives you about the same number for skinny fit people, but prevents overloading those with a BMI of 30.  This is also why 14 year old boys can carry proportionally more weight than their scoutmaster.

