As you’ve probably heard, there’s an egg shortage. It was caused by the worst bird flu outbreak in U.S. history, which has killed nearly 50 million chickens and turkeys since December.

Fewer chickens has meant fewer, more expensive eggs, forcing restaurants, bakeries and consumers to cut back on pricey poultry. While the disease is under control for now, egg prices will stay inflated for more than a year as farmers struggle to rebuild their flocks (See Want a Bird-Flu Free World? Breed Resistant Birds).

Aside from its effect on the food industry, the so-called “poultry apocalypse” has raised an important question: Is U.S. chicken farming fundamentally unsustainable? How many chickens can we keep cramming into factory farms to meet