Meeting Abstract

P1.83A  Wednesday, Jan. 4  Interactions between yolk testosterone levels and post-hatch food availability in male chickens: Early indicators of sexual maturation GARREHY, C.A.*; BENOWITZ-FREDERICKS, Z.M.; SWEENEY, K.; Bucknell University; Bucknell University; Bucknell University cag025@bucknell.edu

C. Garrehy K. Sweeney Z.M. Benowitz-Fredericks Bucknell University Both maternal androgen deposition and post-hatch environmental conditions have the potential to alter avian fitness. However, the phenotypic changes induced by the interactions between both maternal androgens and the post-hatch environment have yet to be investigated. We hypothesized that domestic chickens (Gallus gallus) with high yolk androgen exposure in a favorable post-hatch environment may experience greater fitness benefits than chickens with low-yolk androgen levels, but might suffer greater fitness costs in a challenging post-hatch environment. In particular, rates of sexual maturation might be accelerated by high yolk androgens under favorable conditions; this would be reflected in circulating androgen levels and increased expression of androgen-dependent secondary sexual characteristics. We investigated this interaction by manipulating yolk testosterone levels and post-hatch food availability. Unincubated chicken eggs were injected with 5 ng of testosterone dissolved in 50 μL of sesame oil (“T”) or 50 μL of sesame oil (“C”). On day 7 post-hatch, 30 T males and 20 C males were evenly distributed into diet cohorts of either 70% qualitative food restriction or food ad libitum. Diet lasted 14 days, then comb size was measured, and the reflectance spectrum of the comb was determined with a spectrophotometer. We found evidence for an interaction between diet and yolk treatment in regards to its influence on male comb coloration—specifically red chroma. We conclude that maternal effects and post-hatch environment may interact to generate a complex array of fitness consequences.