The one-way range of an animal that carries its own feed is its load divided by twice its daily ration: 60 kg of grain at 5 kg a day lasts 12 days, a one-way range of 6 days or 150-210 km, but if the 7-8 kg of hay is carried too, the same load lasts only 4.6-5 days and the range falls to about 2.3-2.5 days, or 58-88 km. A cart with 600-1,200 kg of capacity spends only 20-43% of it on feed for a 10-day one-way trip, so wheels extend range far more than packs do. Grazing for 2-3 hours a day cuts the carried feed by half.
Part of Logistics & Load Planning
How far an animal can travel on feed it carries itself, and what carrying, grazing and caching do to that range.
A Pack Animal’s Range Is Set By How Much Of Its Load It Eats
The parent article states the problem: a working horse or mule eats about 5 kg of grain and 7-8 kg of hay a day, so the animals eat their own payload. A horse carrying 60 kg of grain eats it in 12 days, which limits a one-way range to about 6 days because the other half is needed for the return, and that is roughly 150-200 km with no resupply. The solutions the parent lists are to forage along the route (grazing 2-3 hours a day cuts carried feed by half), to pre-position feed caches, to replace half the grain with grazing time, and to use oxen, which need no grain.
The parent’s 150-200 km counts grain only. Hay is the larger part of the ration, and the arithmetic below shows what happens when it is counted too.
What You Need
- The daily ration of each animal: 5 kg grain, 7-8 kg hay (parent).
- The load capacity of the animal or vehicle. See Carts and Wagons for 600-1,200 kg per two-horse cart.
- The daily distance. See Timing & Daily Schedule.
- Knowledge of grazing along the route.
Method: Compute The Range
Step 1: Set the ration R Kilograms of feed that must be carried per day.
Step 2: Set the capacity C Kilograms the animal or vehicle can carry.
Step 3: Compute the round-trip supply Days of feed = C / R. A round trip of N days each way consumes 2N days of feed, twice the one-way supply.
Step 4: Solve With no resupply, N = C / (2R) days one way, and the cargo left is C − 2NR.
Step 5: Adjust Subtract grazing, add caches, or switch to a cart.
Worked Example: Packs, Carts And Grazing
The parent’s case, grain only. C = 60 kg, R = 5 kg per day. Supply = 60 / 5 = 12 days. N = 60 / (2 × 5) = 6 days. At 25-35 km a day (horse cart, good road, from Timing & Daily Schedule) that is 6 × 25 = 150 km to 6 × 35 = 210 km, matching the parent’s 150-200.
With hay carried too. R = 5 + 7 = 12 kg to 5 + 8 = 13 kg a day. Supply = 60 / 12 = 5.0 days to 60 / 13 = 4.6 days. N = 2.5 days to 2.3 days. Range = 2.3 × 25 = 58 km to 2.5 × 35 = 88 km. The same animal can travel less than half as far, because the hay is carried as well as the grain. The parent’s 6 days holds only if the hay is grazed or cached along the route.
With grazing. If grazing cuts the whole carried ration in half, R = 6.0 to 6.5 kg: N = 60 / 12 = 5.0 days to 60 / 13 = 4.6 days. Grain only at half ration: R = 2.5, N = 12 days.
Carts. C = 600 to 1,200 kg, R = 12 to 13 kg, no resupply: supply 600 / 13 = 46 days to 1,200 / 12 = 100 days; N = 23 to 50 days one way. For a 10-day one-way trip: feed = 2 × 10 × 12 = 240 kg to 2 × 10 × 13 = 260 kg. As a share of capacity: 240 / 1,200 = 20% up to 260 / 600 = 43%. For a 5-day trip each way: 120 to 130 kg, 10% to 22%. A pack animal with 60 kg of capacity could not carry 240 kg of feed at all: 240 / 60 = 4 times its capacity.
Result: wheels multiply range because a cart’s capacity is ten or twenty times a pack animal’s, while the ration is the same.
Common Mistakes
- Counting grain only — the hay doubles the weight.
- Ignoring the return leg — the animal must eat on the way back, too.
- Assuming grass is always there — grazing depends on season and route; see Seasonal Route Selection.
- Carrying cargo and feed in the same capacity without a budget — the cargo left is C − 2NR.
- Oxen as a cure-all — they need no grain but travel at 3-4 km/h, so the trip takes longer.
Safety
A hungry animal on a long leg
An animal that runs out of feed mid-route weakens and may collapse, with no way to bring help. Carry a reserve of at least a day’s feed beyond the plan, and turn back when half the carried feed is gone unless a cache lies ahead.
What’s Next
- Learn next: Water Sources & Planning — the other constraint
- Combine with: Route Optimization — routes through good grazing