marque green
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marque green

Freeport, Maine, US

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Learn about the low carbon protein concept

It may sound antithetical, how could a small batch(extra production/ processing energy) and heirloom breeds( lower feed conversion ratio and longer grow time), how could this chicken have a lower carbon cost than your conventionally raised cornish cross, with an industrialized feed conversion ratio, produced in batches of 10's of thousands and bred to dress less weight of organs, at the detriment of the health of the animal?

Long question I know, 

short answer, its not,

long answer, its a different product.

Here at marque green producing the best food at the lowest possible carbon cost is very important, at our current scale we recognize a lot of inefficiencies, ones we hope to iron out as we grow, 

back to comparing one of our chickens to a conventional fed barn raised cornish cross. 

looking for a 4.5lb carcass on a male bird(the dress out weight varies from roosters to hens).


lets start with fcr( feed conversion ratio). This is the ratio feed:live weight

conventional chicken has an fcr hovering below 2:1, two pounds of feed to one pound of live animal

our delawares fcr(in a barn) is about 3.5:1

The birds use more energy when raised on pasture, more walking, scratching, and thermo-regulating and because our birds are raised on pasture and moved into an unheated greenhouse space in the winter, we will use cornish 2:1 and delaware 5:1 as our fcr's

Dress out percentage:

This is the yield of meat from a live animal. Typically ignoring the use-ability of  organs and feet. 

delawares dress out at ~64%, of their live weight, 64% is considered useable

cornish cross dress out to 68%

some numbers

so we are looking for a 4.5 lb carcass with the delaware appearing on the left and the cornish cross on the right, 

4.5lb/.64                4.5lb/.68

7.03lb live weight                     6.62lb live weight

lets factor in our fcr. we will multiply the fcr by our desired live weight

5*7.03lb.                      2*6.62lb

so our feed requirements are 

35lb                          13.24lb

the delawares requiring  3x more feed to reach the same carcass weight 


To get a cornish cross to the 6.62lb live weight that we want, takes about 44 days

to get the delaware to a 7lb live weight takes about 18 weeks, almost 3x as much time.

What the numbers mean

To produce an heirloom chicken on pasture of the same carcass size as a cornish cross, raised in a barn: takes 3x more feed and labor and housing time. 

Body structure

the muscle proportions on heirloom birds is dramatically different than that of  a cornish cross, the most pronounced difference being the breast. The cornish cross has been bred to develop a large breast muscle, to the point that when birds are raised past 6 weeks, the animals spend a majority of their time hunched over, unable to stand up. Heriloom birds have a more proportional leg to breast ratio, meaning they can walk, run, and even fly for their whole lives. 

The organs have been bred out of the cornish cross. weird to hear I know but the market for chicken organs isnt large enough to justify breeding for quality and size of the organs. This means that organ failure is likely to occur in cornish cross past 8 weeks. Their body to organ ratio is to high that their hearts cant keep up with their movements. 

quality of meat

All of that extra feed, time, and movement means that the heirloom birds have an incredible mild flavor, a complex texture, and a nutritive value unrealized for any cornish cross, even the ones raised on pasture. 

When the animal uses its muscles,  they develop textures that when prepared wrong(hot and fast cooking) can be tough, but when cooked low and slow can be fall off the bone tender. As the  muscles strengthen they incorporate nutrients and flavor, raising the nutritive values, in the form of higher quality proteins, vitamins and minerals.

Lets get back to the question

How is this obviously more energy intensive chicken a low carbon option? And to the long answer, because now we know why its a different product. 

Lets zoom out and look at protein carbon cost, Kg of carbon equivalents per 100 grams of protein. 

Greenhouse gas emissions per 100g of protein. (Credit: Poore, J., & Nemecek, T. (2018). Additional calculations by Our World in Data. Additional data by Hannah Ritchie)
Greenhouse gas emissions per 100g of protein. (Credit: Poore, J., & Nemecek, T. (2018). Additional calculations by Our World in Data. Additional data by Hannah Ritchie)

We are less concerned with the exact numbers here and more with the ratios. We can assume that small batch production is slightly more carbon intensive than factory production but again we are thinking more about ratios here. 

The major carbon input in chicken is feed production, and we know that our heirloom birds eat about 3x the feed. 

conventional chicken 5.7kg

heriloom chicken 18kg

goat 20kg

beef 50kg

Premium quality- low carbon

The goal of this project is to make an alternative premium protein to beef and other high carbon cost proteins