May 21, 2007

Egg spots correlate with stress levels in birds

The number of spots on chicken egg shells can indicate stress levels in chickens, a study in Spain suggested.

The team, Santiago Merino and colleagues at the University of Alcala, Spain, discovered that the eggshell pigment protoporphyrin could indicate the stress levels in chickens.

As stress levels increases, the pigment chemical increases as well, thus giving the egg shell a more spotty look, the researchers said.

The team studied 112 blue tit egg clutches in central Spain and discovered that eggs with more spots represented a mother that weighed less and had higher levels of a stress-related protein.