I agree that 18 months is the better time to refresh for reliable egg laying to food ratio. However, hens have good uses beyond egg laying too. It all depends how you're set up. At the moment, you're carting a lot of inputs in by hand, to your property because of road access. All to feed the soil. But older hens can produce manure for you on site, and double as pest and weed controllers, if you build some more portable chicken tractors.

Not saying you have to, just putting it out there as an idea. Instead of hauling inputs with ATV's through water, you could be using your ATV to move chicken tractors around site to where you need them. I've heard from farmers who do this, actually getting better laying ratios from their older hens, because they're getting access to their natural diets - more protein in other words.

You can also use older hens to manage compost for you, and get better laying ratios out of them, because of the bugs with high protein content they get from the compost. I figure if you're going to buy a hen, you could do well to make them multi-purpose, once their egg counts start to drop. Otherwise, you're investing your energy into gaining more inputs externally. You have to kill the older hens, raise new ones AND haul inputs in on ATV which causes more wear and tear on your vehicle, than if you built infrastructure with recycled materials, to manage manure inputs on your land. Your older chickens could be finishing off your composted goat manure piles, for example, to get all those weed seeds out. Or at least, a lot of them.

I'm feeding 6 layers at the moment and 2 are older hens, I'm not getting eggs from. But they are adding to the manure in the coop, which I use on the garden. They also help eat through the weeds I toss in the coop from the garden. I have to keep reminding myself as we run short on eggs, they're more than egg producers on our land. They're also land management inputs I don't have to cart in from elsewhere. We're planning to build more infrastructure, to put our hens to work directly on the land. That way, we can increase our numbers and not worry about not having enough food to go round.

When you return the manure from any free range livestock to your own land, you are returning nutrients subtracted from that land MINUS the nutrients retained in their bodies AND the nitrogen outgassed from their urine (or chicken droppings). That still results in a NET deterioration of the land, contrary to the popular myth.

When you return the manure from the droppings of your animals fed from outside sources, you are ADDING nutrients from someone else's soil to yours, resulting in a net gain in fertility.

Lots of interesting comments here!

Chris --- We really value the meat of old hens. It tends to be much more nutritious than that of young broilers. So I don't think it's a waste at all to kill birds once their laying declines. After all, you can get the same scratching/fertilizing effects from productive hens for the same amount of feed. And, Doc is right, you don't actually add nutrients to the soil unless you're bringing in purchased feed. For pure fertility purposes, actually, ruminants are a far more effective animal to add to your farm.

Deb --- We've used different hatcheries. Last year, we used Cackle, and they sent us great chicks. The trouble was that they lost our order the first time around, which I think is due to their system having to be manually overhauled at the first of each new year and me wanting to order chicks ASAP to ensure I get a batch exactly when I want them. So I changed my loyalties back to Murray McMurray, who are more expensive but also more dependable. Hopefully in 2017 we'll be back to hatching our own chicks, which we haven't in the past few years because I've been experimenting with different breeds.

Everyone abides by the values in their personal set-up, and I can respect that. Your older hens are serving your requirements and not going to waste. Also, you're doing a good job managing your food supply the way you do.

If I may, docs calculations (Hi doc, no offence meant) are academic and somewhat simplified to the inputs nature calculates with. Land + animals does not equal a subtraction in nutrients through digestion.

The complex calculation which nature value adds upon, involves external inputs too, but nature brings them in. We don't calculate the thousands of grasshoppers and the broods of chicks being raised by birds, who are attracted to the grasshoppers and other insects. For that matter, we don't calculate the numbers of insects and invisible to the eye, soil microbes it takes to enable the biological process of composting to take place, either.

Simplified academic calculations, which attempt to alter nature's value adding process, by omission, does not make it a myth. It's an omission. Your composting toilet is a small scale example of what I'm talking about with chicken manure. The fact you composted your own manure on site, attracted files which built a huge network of organisms to break your manure down. You ate a lot of the food you produced on your land, with some external inputs. But nature still brought the flies, whether you ate external inputs or not. Countless other animals ate from the files life cycle and added something to your land in return too.

The fact we don't calculate all those tiny and seemingly insignificant inputs, doesn't mean, they aren't added to the final tally. The more composting stations you can build on your land (whether that be through ruminants, fowl, fungi or humans - whatever works best for you) nature adds her own surplus which we cannot possibly calculate.

This is not to say, your system is wrong. Rather, the simplified calculation of a single animal taking something from digesting food, is. It only accounts for that one kind of animal, not the complex biological organism, that it takes part in.

Chris, we only count the inputs that we have to pay for (in money or time) and the outputs that are of value to us. Of course nature is doing all the work and none of us would be alive if the energy from the sun wasn't pouring upon our planet for free.

And yes you are right, it is very complicated to attempt to calculate all these nutrient cycles and energy flows. But it is useful to try to figure out how these things are connected and make estimations to the best of our abilities. I don't think it should be dismissed as "academic". I think it can be insightful even if we just have to make gross estimates. To use your example: How many flies might come to our land and how they might lay eggs in manure and whether the manure is better for the garden if it has been colonized by maggots or if it was deep in a compost pile. We can try different things to check our ideas. That's called science.

In Anna's case, I think a young chicken would be using nearly the same inputs as an old one, but providing an additional output, eggs. What is the optimal age you are suggesting for culling laying hens? Yes a chicken tractor is a useful system and many people love them, but you are sill left with the question of when to cull the flock are you not?

Hi Martin, I started my original comment by agreeing with Anna that 18 months is a good age to replace hens, for feed to egg ratio. So I have not dismissed inputs as academic when it comes to keeping hens for egg production. My comment about keeping older hens, was to expand on their remaining potential for the land, if it suits the individuals set-up.

To answer your question about when to cull older hens in tractors, it depends on the variables. Like when the capacity of the land to carry them, is exceeded. Or the climatic factors, reduce natural feed available. Even if the equipment used to move tractors were rendered useless for longer than a few days, numbers would have to be culled. Or simply when you do a change over to new layers, and you've reached the maximum number of older hens to tractors available. This last one, is what makes all our decisions.

The reality of having to be culled as hens, doesn't change. It just depends how you want to implement them in your overall design and process for the land.