Like mammals, bird embryos are capable of chemosensory learning but the ontogeny of their feeding preferences has not been examined, according to a paper published recently in Chemical Senses. Aline Bertin and colleagues at INRA in Nouzilly tested whether the timing of stimulation in chicken embryos modulates the impact of in-ovo olfactory stimulation on later food preferences.

They exposed chicken embryos to an olfactory stimulus for a four-day period in the middle or towards the end of the incubation period. The chicks were tested for their preference between feeds, with and without the olfactory stimulus in three-minute choice tests and on a 24-hour time-scale.

Regardless of the type of feed (familiar or novel) or the duration of the test, the control chicks not exposed to the olfactory stimulus consistently showed significant preferences for non-odorised foods.

Chicks that were exposed in-ovo to the olfactory stimulus, on the other hand, did not show a preference for odorised or non-odorised foods. Only those chicks that were exposed to the olfactory stimulus toward the end of the incubation period differed from the controls and incorporated a higher proportion of odorised food into their diets on a 24-hour period.

According to the researchers, their results indicate that olfactory stimulation at the end of embryonic development has a stronger impact on later feeding preferences. They added that their findings contribute to the growing pool of recent data appreciating the impact of olfactory signals on behaviour regulation in avian species.

Reference

Bertin A., L. Calandreau, C. Arnould and F. Lévy. 2012. The developmental stage of chicken embryos modulates the impact of in ovo olfactory stimulation on food preferences. Chem. Senses, 37(3):253-261. doi: 10.1093/chemse/bjr101

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