Differential allocation of carotenoids and testosterone into egg yolks affects the immune performance of Japanese quail chicks.

PELUC, S. I.; REED, W. L.

Boston, MA

Congreso; Annual Meeting of the Society for Integrative and Comparative Biology.; 2009

In birds, females can influence variation in offspring performance by differentially transferring resources such as nutrients and hormones to eggs. In this study we assigned 48 female Japanese quail (Coturnix coturnix japonica) to one of the following treatments: a carotenoid supplemented diet, an injection of GnRH, a carotenoid supplemented diet combined with GnRH challenges, and control, over a period of seven weeks. On a weekly basis we measured carotenoid and testosterone levels in yolks for each female, and incubated and hatched eggs from these females. After two weeks of growth, we examined the ability of the chicks? plasma to fight off bacteria, and we measured the dimensions of the bursa of Fabricius on all chicks. Testosterone levels were higher in eggs from the GnRH challenged females relative to eggs from carotenoid supplemented or control females and testosterone levels were even higher in eggs from females receiving carotenoid supplemented diets and GnRH challenges. Chicks from females receiving carotenoid supplemented diets only had considerably enhanced immune responses. Those chicks had larger bursa than chicks from other treatments and female chicks had significantly larger bursa than males. Moreover, bacteria killing ability of their plasma was higher than in chicks from other treatments. We provide evidence that female allocation of carotenoids in eggs can influence immune performance of chicks, and discuss the extent to which increased levels of testosterone in the yolk may compromise chick immune function.