With avian flu devastating a significant portion of the nation’s egg-laying hens, major food companies and restaurant chains are bracing for shortages and scouting the country to find alternative supply sources.

Roughly 87 percent of the birds stricken with the disease are laying hens, according to the Department of Agriculture, and many of the eggs they lay are turned into ingredients used by food businesses in things like scrambled egg patties and baked goods.

And on Thursday, Hampton Creek, a small business that makes plant-based egg substitutes, shipped tens of thousands of pounds of its Just Mix powdered egg substitute to General Mills, which uses egg products in things like its Betty Crocker Angel Food Cake Mix and a variety of refrigerated cookie doughs.

“Eight companies called today to see if we could do anything for them,” Josh Tetrick, chief executive at Hampton Creek, said last week in an interview at the company’s office in San Francisco. “Everyone is worried about a shortage of eggs.”