The cornish cross goes from hatch to slaughter weight in 6 to 8 weeks. From a farmers point of view that's a very quick crop. Because the grow-out time is so short, the labor costs are less, as well.
Here's the breakdown for 100 cornish cross:
equipment for 100 chicks:
4 30 gallon rubbermaid tubs and metal shelving (to keep the chicks in the tubs)
4 heat lamps,
$52. 4 heat bulbs,
$32 4 feeders,
4 1 gallon waterers, $35
This equipment lasts for at least 2 years, and during the year will be used to raise 6 batches of chicks. Notice -- more batches of chicks per year. So I'll assign 1/12th the cost of the equipment to this particular batch, or $16.10. If you were to raise fewer batches you'd be assigning a higher fraction.
Labor I calculate the labor as if I were paying someone minimum wage + all of the associated overhead taxes (medicare, social security, unemployment insurance, bookeeping, which adds about 40% to the base wage). I can't imagine getting someone to work for me for less than an hour a day, so figure labor at $7/day, or $50 a week. Over the course of the 8 weeks to brood out this batch, that's $400. More labor for cornish cross because they require more bin cleaning because of the large food intake.
Mortality Figure 15% mortality. That's pessimistic, but pessimists are only pleasantly surprised. Consumables :
Purchase price of chicks + shipping: $1.57/each
300lbs chick starter, 2100bs lbs of chick grower, $330. Yes, they will eat more than a ton of food.
(calculated as 100 chickens * 6lbs per chicken * 4lbs of feed per pound of chicken produced)
Wood chips/sawdust, $70 - we use free chips from tree service companies, but if we had to buy sawdust or chips, that's what it would cost in bulk.
Total cost to produce 85 chicks: $957, or $11.25 a chicken.
That's cost -- with any business you need to make a profit for when you lose a batch of chickens to a weasel, or your shelter blows away, or any of a number of other bad things.
So if you retail these chickens at $4/lb dressed, and they dress out at 4.5lbs, this gives you a gross sale amount of $18.00. Out of the $6.75 gross profit you'll subtract whatever you need to for processing costs. I figure that one person at minimum wage will clean 5 chickens an hour, and that adds up to a processing cost of $3 per bird, giving you a net profit of $3/bird. So a batch of 85 birds will net you $240 every other month. I've ignored marketing costs and the cost of whatever processing equipment you'll need.
I think that $4/lb is a little low. $4.50 a pound would give you a net of $5.25, which seems more reasonable. The problem is that many folks out there are selling birds for less than that. Usually these folks last a year or two, but there's always enough of them that you'll have lower-than-your-cost every year. $5/lb gives you a little more cushion. Maybe you give your minimum wage guy a $1/hour pay raise.
Buff orpington and cornish cross at 10 days of age
You'll find a similar breakdown of the costs of raising heritage birds here.