Chicken tractors and pastured poultry

What Polyface does

Joel Salatin's Polyface Farm in Virginia runs laying hens in an "Eggmobile" behind the cattle. It's a 12 × 20 ft henhouse on mobile-home axles.

• Salatin's stated purpose: hens "scratch through the cow dung, spread it into the soil, and peck out fly larvae — like a biological pasture sanitizer".

• Timing: a Polyface apprentice describes the hens following the cows by about 3 days, when fly larvae are "perfectly plump for the pecking". SARE relays Wisconsin farmers running hens 2–3 days behind cattle. Polyface's own pages give no number of days.

• Flock size: Salatin reported 400 hens per Eggmobile in 2007. A 2015 account describes a two-section unit with 400 per section.

• Other layers: some hens live in a quarter-acre of electric netting ("Feathernet"), 1,000 hens to a pen, moved every 3 days, with the cows "mowing ahead".

• Broilers: raised in 10 × 12 × 2 ft floorless pens of about 75 birds, moved daily.

What the evidence shows

Why do it anyway? Eggs and meat from the same land. Cattle keep grass short and fresh for the birds. Manure from both species gets spread across the farm instead of piling up. And daily moves keep both species on clean ground.

Fly control comes from other tools (see the Pasture rotation lesson).

How to run hens behind cattle

This is a practical sequence built from the verified practices above. The hen lag is practitioner guidance.

1. 1

   Cattle graze a paddock for 1–3 days, down to about 3–4 in.

2. 2

   Cattle move on. About 2–3 days later, bring the hen house and netting into the paddock they left.

3. 3

   Hens forage there for a few days. Polyface moves its netted layers every 3 days. ATTRA says to move layer houses at least weekly (at most every 2 weeks) to avoid nutrient buildup.

4. 4

   The paddock rests for the full regrowth period before cattle return (see the Pasture rotation lesson).

Setup tips:

• Housing: range houses with feed and nests inside need about 2 sq ft per hen. Give 6–8 in of roost per bird, about 3 ft off the ground.

• Netting: electric poultry netting keeps out skunks, opossums and raccoons. Coyotes, bobcats and dogs can jump it.

• Shade: hawks and owls aren't stopped by netting. A canvas tarp over a 3-ft frame gives shade and cover.

• Guardian dog: a trained one helps, but may not be trustworthy until about 3 years old.

• Placement: keep pens away from wooded edges, and stack protections.

• Water: in hot weather, refresh it 2–3 times a day, and move units in the cool morning or evening.

Broiler tractors

Timeline for Cornish Cross (Penn State/UMaine):

• Weeks 1–2: brooder.

• Week 3: tractor with a heat lamp.

• Week 4: onto pasture. Move the tractor every 2–3 days.

• Weeks 5–6: move daily.

• Weeks 7–8: move twice a day.

• When to move: whenever about half the grass is used.

• Harvest: at 6–8 weeks. Older Cornish Cross risk sudden death, lameness and heart problems.

• Totals per bird: about 15 lb of feed and 3.6 gallons of water.

• Slow-growing breeds: about 2–3 weeks longer and handle heat better.

Planting after the birds pass: in SARE-funded Louisiana work, vegetables grew best when planted 14 days after the birds moved across. Raw-manure waiting periods before harvesting vegetables (120 days for crops that touch the soil, 90 days for others) are covered in the Manure management lesson.

Heat and cold

Heat:

Cold:

• Breeds: pick small-comb breeds (pea comb) to avoid frostbite.

• Housing: snow and ice end foraging, so many keepers move hens to a deep-bedded house for winter. Polyface houses hens in hoop houses for about 100 winter days.

• Heat lamps can start fires.

Keep the houses moving

• What fixed houses do: they concentrate manure. In an Italian study, soil phosphorus and nitrate were highest within about 16 ft (5 m) of the hen house.

• Germs build up too. Manure dropped on pasture isn't composted, so Salmonella and Campylobacter can build up if pens stay put.

• The fix for both is moving the houses.

The trade-off:

• What APHIS advises: separate species, and keep poultry covered and away from wild birds.

• What the Polyface model does: hens range openly across cattle pasture.

• What the evidence says: in the 2024 Michigan H5N1 outbreak, virus moved from dairy herds to poultry, including one backyard flock, mostly through shared people, vehicles and equipment.

  • Virus was high in milk. Manure "does not appear to be a meaningful viral source."
  • Chickens were present on 40% of the affected dairies.

If you keep dairy animals and poultry:

• Raw milk: keep raw and waste milk away from birds and other animals.

• Gear: use separate boots and tools for each species.

• Outbreaks nearby: watch for HPAI detections in your area and follow state orders. During outbreaks, house birds under cover.

Germs on pasture: pastured poultry can carry Salmonella and Campylobacter, and studies disagree on whether they carry more than barn-raised birds. Moving pens keeps manure from building up.

Current prices haven't been researched; the prices above are dated.