Found this article. http://journals.plos.org/plosgenetics/article?id=10.1371/journal.pgen.1002914 Makes sense because good egg laying leghorns have big floppy combs. So if you want to increase the egg production in your flock- choose and breed the hens and roosters with the largest combs. This strategy will go against the grain of the standard of perfection but all of you that are breeding for egg production this is a good thing. The article is heavy read- just skip all the blah blah and look for the causative statements. fecundity is abundant egg production here is part of the paper I will check back and see if anyone posts a question or comment. The comb of the chicken is used to base mating decisions on by both males and females in wild-derived populations , . In males it is an indicator of social rank, with females actively soliciting matings from males with larger combs , , as well as also correlating with bone mass . In females it is indicative of greater reproductive potential, through an increase in egg production , . In turn, egg production is highly dependent on bone morphology in the chicken, with one of the principal limitations to egg production being calcium deposition. Calcium is stripped from the hard outer cortical bone and transferred into the soft, inner medullary and trabecular bone and from there mobilised to the egg shell . Similarly, calcium is also mobilised away from the ends of the bones (the metaphyses) and into the central part (the diaphysis) during egg-laying periods, where it is then more easily mobilised into medullary bone (see Figure 1). The genetic architectures for comb mass, egg production and bone allocation (important for egg production) have all been shown to overlap in the chicken . Therefore fine-scale quantitative trait loci (QTL) mapping and expression quantitative trait locus (eQTL) mapping of these separate traits (comb mass, bone allocation and egg production) should allow the assessment of the importance of pleiotropy in both domestication and a sexual ornament. The bi-sexual expression of the comb in both males and females makes the comb somewhat unusual as a sexual ornament, with male-only effects of ornaments more often considered , and also makes the genetic analysis of this ornament in particular of greater relevance.