It's enough to make a Chicken Run

Pungent egg boosting pyrazine. Click on picture to get molecule in ChemSketch format.

Bigger eggs and better memory are two of the effects on chickens of a whiff of 2-methoxy-3-isobutylpyrazine, a compound found in human and coyote urine and commonly used as a flavour enhancer with the odour of green bell peppers.

The discovery was made by Miriam Rothschild working with Anat Barnea of the Israeli Open University. The team discovered that pieces of cotton wool dabbed with pyrazine and left next to chicken cages led to a five to ten percent increase in the egg mass of Leghorn chickens. Rothschild does not yet know the underlying mechanism but it could be that the scent of the pyrazine delays the surge of luteinising hormone that releases an egg so presumably the egg takes on board more yolk and albumen before being expelled.

Rothschild presented the findings at the New Frontiers in Science meeting this summer staged by the UK's Royal Society.

	The shape of things to come?

Odours are known to affect reproduction in many animals, such as rats and in humans pheromones of which are not consciously aware can influence a woman's menstrual cycle. This is the first time that an odour effect has been observed in birds, however.

The team also found that birds exposed to pyrazine were more likely to remember which of their drinking vessels had been laced with the very bitter-tasting compound quinine. Rothschild suggests that the odour may have an "attention grabbing effect" on the chickens which boosts their memory of the bad taste. She adds that several poisonous insects exude pyrazine too perhaps as a warning signal.