- Apr 17, 2016
- 113
- 137
- 186
Are you doing this for meat birds or layers?
The 75/tractor model Salatin has is specifically for Cornish X meat birds, from 3 weeks to about 8 weeks of age, with daily moves. He's doing it on a stretch of pasture that's been mob-grazed by his cows so much that the soil fertility is incredible, and if memory serves correctly he says in Pastured Poultry Profits that he doesn't run chickens across the same patch of land more than twice in a season (his pastured poultry operation is seasonal, so realistically that means no more than twice in a year), because the soil couldn't handle the nitrogen load and his cows still need to eat that grass.
If you don't have enough space to run 75 Cornish X in a tractor for 35ish days, you might consider decreasing your tractor size and maintaining the same density... so, maybe 25 birds in a 40 sqft tractor.
But as soon as you change one of those variables, your calculations change. If you're raising a more active meat bird like a Ranger, you'll need more space in the tractor. If you're raising heritage roosters for meat, you'll need even more space. But by decreasing the stocking density, you're also decreasing the chemical burden on the soil, so you could feasibly run the tractor over the same patch of land multiple times. If you've got crummy soil, you may need to move twice daily. If it's hilly, certain spots may not work as well in the rain. On and on the calculations go.
On the other hand, if you're raising Egg layers, you've got a mess of other variables to consider:
Nesting Boxes. These should be present at a rate of about 1 for every 3-4 laying hens. At a standard 12 inches wide, you could fit 12 nesting boxes along the longest wall of a Salatin tractor, so you're already maxed out at 48 layers.
Layer Breed. A production layer like the white leghorn has supposedly been bred to minimize the ranging/foraging instinct and be fine in a cage where it's got about 48 square inches to call its own. I don't buy that, but if you want to stock your tractor at confinement housing levels, I guess you could run the full 48 birds out there.
By contrast, most heritage breeds are foragers by instinct, and most folks who raise them believe the freedom to range in spaces larger than factory cages improve the quality of the eggs. Even when our birds are contained, they're contained in runs that provide several square feet of space per bird, rather than several birds per square foot of space. Also, heritage breeds vary in how docile they are, and giving space reduces the likelihood of serious fighting... something which won't be plausible in a tractor no matter how often it's moved.
Fowl Size: Bantams need less space than Large Fowl. I could imagine fitting 48 bantams in a 120 sqft tractor... but then, I've never had bantams, so I have no idea how my imagination squares with reality.
The last thing I'll say about the egg layer side of the equation is that most raisers of pastured meat birds in tractors have a different method for their layers. Joel Salatin has his "Eggmobile," where the ladies are given a large amount of space to roam and the Eggmobile is just the feeder, roost, and nesting area. Most of the YouTube personalities who raise pastured meat birds have a similar setup (check out Justin Rhodes' ChickShaw for a homestead-level equivalent). Tractors are great for a lot of things, and they can work for egg layers, but only with modification and forethought.
