Autosomal Barring
Here is a tidbit that I copied and borrowed from this website
http://www.nsppa.ca/documents/poultry_genetics2.pdf
(this is a nice site as it puts the basics in layman terms)
"Genetics of patterns
New research has indicated that several major patterns in chickens are not due to independent genes as
previous believed. The single lace, double lace, autosomal barring (horizontal penciling) and spangling
are now thought to be due to interactions with the Pg gene (pattern gene). For a review of the original
literature, see W.C. Carefoot in Crawford’s volume. Single lace pattern can be obtained with the genes:
Ml (melanotic), Pg (pattern gene) and Co (Columbian) on either eb, ey or eWh background genes.
Double lace pattern is obtained from the single lace pattern by removing the Co gene. Spangling is
obtained with Db (dark brown), Ml (melanotic), Pg (pattern gene) on either the E or eb background.
Penciling is obtained with the Pg gene on the eb or e+ background. Autosomal barring (sometimes called
horizontal penciling) is obtained with the Db and Pg genes. The table below, originally constructed by
Brian Reeder, is intended to serve as a guide to the patterns seen in chicken plumage. A similar table is
found in Poultry Breeding and Genetics, R.D. Crawford, ed., Table 5.3, page 127."
(P.S., to my knowledge, Pg is a gene that is not suppose to be in the Marans genetics)
This is a chick that showed autosomal barring.