The global poultry industry

Chicken before the green revolution

From humble origins in the jungles of Asia, chickens have come a long way. Both eggs and chicken meat are ingredients found in the recipe books of almost every culture, with over 90 million tons of chicken meat and over 70 million tons of eggs produced globally each year.

Chickens are thought to have spread to ancient civilisations via trade routes from the Indian subcontinent, eastwards to China and westwards to the Indus Valley, the Fertile Crescent, the Mediterranean and beyond. Archeological evidence has shown consumption of chicken (and presumably eggs) in these regions to have been ongoing for at least three millennia, with the earliest samples in China even dating to 5,400 BC. However, although domesticated chickens have been around for a long time, the ubiquity of their meat and eggs in our food is something relatively new.

Prior to the green revolution of the mid-twentieth century, chickens fulfilled far less of the diet of the average human as they do today. Despite being valued for their eggs, and providing the basis of a tasty occasional meal, meat and egg production was a local and casual enterprise. So what has changed between now and then?


Since the 1950’s, the world’s population has tripled. In addition, the nutritional demands of its populace has changed. Not only are there now significantly more people, these people are increasingly demanded a more protein-rich diet. As with the rest of the agricultural sector, the conventional provider of protein, the livestock sector, saw huge growth in this time. To fuel such growth, the way in which all food was produced changed dramatically, but arguably the starkest transformation seen is that of poultry.

Traditionally chickens would have been kept in coups overnight for shelter from predators and the elements, but would be free to roam yards in the daytime. In fact, for healthy chickens, such roaming was necessary in order to get enough vitamin D. Supplementation of food with vitamin D meant chickens could be kept inside permanently. This allowed tighter regulation of feeding schedules, temperatures and other parameters. Introduction of other supplements to food improved growth and antibiotics prevented the spread of disease associated with the ever increasing stocking densities such barns provided. Breeding also contributed massively to increased outputs. Selection for hens with better egg production and chickens with faster growth rates led to two distinct varieties of chickens, layers and broilers (respectively).

But as intensity of production increased, the darker consequences of the tools used to improve outputs began to surface. Ever increasing stocking densities led to a range of problems for broilers and to caged egg production for layers. Misuse of antibiotics led to livestock becoming reservoirs for antibiotic-resistant bacteria. Broilers became bred to grow so fast that their bodies could not support the resultant muscle mass (so called “plofkip”) and layers became so optimised for egg production that the males were unable to put on enough weight to have any economic value in meat production.

In recent years, much has been done to start solving the problems described above. Caged hens are no longer legal in the EU, the movement for antibiotic cessation is gaining traction, and pressure on breeders to stop “plofkip” has been successful. However, despite their obvious benefits, these solutions are low-hanging fruit. The more complex problems to solve are still present. Each year billions of male layer chicks are killed on the day of hatching. Our gender screening technology will soon make this something for the history books, and we are working on a range of other projects with goals to do the same for other issues.

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