The Obama administration’s effort to improve food safety and curb the spread of salmonella will add a number of new regulations for egg producers. Nearly all egg producers with more than 3,000 laying hens—which account for the vast majority of eggs consumed by Americans—will be required to buy chicks from suppliers who monitor for salmonella bacteria. In addition, producers will be required to test their poultry houses regularly, step up pest control and take measures to guard against bioterrorism threats. They will also have to refrigerate eggs at 45 degrees Fahrenheit no later than 36 hours after the eggs are laid. The Food and Drug Administration estimates that the additional safety measures will cost the egg industry about $81 million a year but provide $1.4 billion in public health benefits, driven in large part by a projected 60 percent drop in the number of illnesses caused by contaminated eggs.