Animals in the System

An animal on a subsistence farm is not an input and not a product. It is a working member of the loop that eats what the farm cannot eat and leaves behind what the farm needs. The case for keeping stock is strong. It is also true that most beginners lose money, feed and time on the wrong animal at the wrong scale.

What an animal does for a farm

It converts what you cannot eat into what you can: grass, browse, kitchen scraps, cull vegetables, acorns. It produces manure, the fastest and most complete fertility package on the farm. It does work, since the pig turns ground, the goat clears brush and the chicken spreads manure. And it closes nutrient loops, because a gut can do what a plant cannot.

A chicken or a duck swallows grit and small stones, and the gizzard runs as an acidic mill, low enough in pH to break down limestone and phosphate rock into minerals a crop can take up. Those pass out in the manure onto the bed. On a farm with no outside inputs, that is new bioavailable phosphorus and calcium made from rock already on the property. Comfrey lifts minerals, but only moves what is in the vault.

The manure rules that matter

Manure is a store of nitrogen, and nitrogen leaves. Volatilization strips ammonia off a heap left open to sun and rain. Varro shaded the pit with leaves and branches and sprinkled water on it, "for the sun draws out from the manure those elements which the land requires." Columella built two pits, one holding fresh dung for a year and one for the rotted dung being hauled out, both packed with clay so the moisture could not drain. The modern version is the same practice: a covered heap and a carbon layer of straw or woodchip to catch what the nitrogen would otherwise lose.

The honest feed arithmetic

On a closed boundary the plant-only farm and the animal farm are different systems, and the difference can be counted.

A closed-loop modeling study, medium confidence with its assumptions stated, ran a two-acre holding feeding a family of five. The harvest takes roughly 45 pounds of nitrogen, 15.5 of phosphorus, 22 of calcium and 38 of potassium out of the topsoil each year, and the household's own waste leaves the field. The plant-only version pays with legumes and deep roots. Legumes fix about 56 pounds of nitrogen a year on half an acre, but cold surface decomposition loses 35 to 45 percent of it to the air, so under 31 pounds reaches the food rows against 45 required. All four heavy elements end in deficit. Route the legume biomass through a flock instead, where the fast avian gut and a high-carbon deep-litter bedding hold the volatile nitrogen, and the same four lines turn to surplus.

The human side closes the same way. B12 is made by neither a plant nor the human body, and the liver stores only a few thousand micrograms, which runs dry in five to fifteen years on a plant-only farm behind a closed boundary. Three or four eggs a week covers it. Treat the figures as a model rather than a measurement: the direction is robust and the precision is not.

Where animals help, and where they are a liability

Poultry first, because they ask the least and give the most: eggs through the winter, manure, pest and weed control, on a waste stream that would otherwise be a problem. The homestead flock is a working flock, moved around, let into beds after harvest and kept out of the growing crop. The pig turns ground and converts surplus. The goat takes the rough corner nothing else will work and turns brambles into milk.

A cow is not the first animal of a building farm. On a small holding it asks for more than it gives in hay, water, fencing and time, and the family stretched thin for labour is the family that cannot afford it. A flock in the garden will eat seedlings and scratch out seed. Stock on wet ground compacts it worse than a tractor. And winter feeding is the test of the whole thing: if you have not grown and stored what the animal will eat in February, you are buying it, and the loop is open.