HUGGINS, KA*; NAVARA, KJ; HILL, GE; MENDONCA, MT; Auburn University: Long Term Performance Detriment In Songbirds With Extensive Carotenoid-Based Plumage Coloration: Are Carotenoids Toxic?

Although there is extensive literature addressing the beneficial effects of carotenoids as antioxidants and immune enhancers, there are also studies that indicate that high doses of carotenoids may actually have a toxic effect. Songbirds with extensive, carotenoid-based plumage tend to maintain high levels of circulating carotenoids in plasma, which could represent a potential tradeoff between maintaining brightness at the expense of carotenoid-related toxicities. To test this hypothesis, we maintained American goldfinch males on either a high (n=40) or a low (n=40) dose of lutein/zeaxanthan treatment for 60 days during the time of molt. We took blood samples from animals before, during, and after supplementation, and analyzed the samples for baseline corticosterone as a measure of physiological stress, glutathione as a measure of oxidative stress, and creatine kinase as a measure of muscle degradation. Additionally, we tested muscle function in a subset of the population using a vertical jump test, a novel technique that tests the performance capability of the pectoral muscles in birds. We found that creatine kinase levels were significantly higher in animals receiving a high dose of dietary carotenoids, indicating the presence of muscular degradation in these birds. The birds supplemented with the high dose of carotenoids also significantly reached lower elevation in the jump trials (p=0.0009) indicating that there was a direct effect between increased carotenoid intake, increased creatine kinase levels and outward physical ability. Further results will be discussed.