Seasonal reproduction of Pekin ducks
Deep brain photoreceptors mediate photosensitivity and maintain testicular function in Pekin ducks.
Pekin ducks were domesticated from the wild mallard but the Pekin duck has maintained many of the growth and reproductive characteristics of its wild predecessor. A prominent physiological characteristic is seasonal reproduction and their photosensitivity to increasing day length which triggers rapid gonadal growth.
In mammals, photoreceptivity involves the activity of rods and cones within the retina of the eye. In contrast, there is compelling evidence in birds that photoresponsiveness is partly mediated by non-retinal photosensitive neurons that have been referred to as deep brain photoreceptors.
In collaboration with Hope College in Holland, Roslin researchers have discovered that multiple different, but related, deep brain photoreceptors are required to fully maintain testicular function in Pekin drakes. Moreover, they found that maintenance of gonadal function is dependent upon the particular wavelength of light and this has associated implications for breeding duck husbandry.
R. Haas et al (2017) Expression of deep brain photoreceptors in the Pekin drake: a possible role in the maintenance of testicular function. Poult Sci pex037. DOI: https://doi.org/10.3382/ps/pex037