If you put an Iowa Blue cockbird over any barred hen, you'll get sex-linked chicks. The males will have a white dot on their heads. Now, all of our breed history states that one can breed an Iowa Blue cockbird over RIR or New Hamp, as well as White Rocks and Light Sussex. However, none of the current breeders have attempted this. The last person to have made a claim of creating sex-links from Iowa Blue cockbirds was W.C. Fenton of Fenton Hatchery in Strawberry Point, Ia. He sold his hatchery in 1972 and thus the sex-link creation came to an end. Currently we have no pictures of his sex-links.
The White Rocks (or even White Wyandottes) in my estimation will not breed sex links consistantly unless you know what is hidden under the recessive white that the Rocks are carrying. Iowa Blues also carry the Silver gene so what you're having to rely on is the Pattern gene (Pg) in the Iowa Blue to generate the sex-link. However, depending on what the Rock is carrying under the white, the pattern gene will either sex-link easily or will be impossible to sex-link. Again, results depending on what the Rock hens are carrying. And each hen could be carrying something different.
Using the red hens to create a sex-link would be much easier and reliable than using the White Rock. The chicks should segregate out with the males a golden color and the females a cleaner white color. Because of the Columbian gene in the RIR and NH, the offspring will grow out with some random and wierd black marking on the body, particulary the head, tail, and primaries. Keep in mind, the RIR carries mahogany and therefore could mess up your sex-link results if there aren't enough modifiers to keep them in check..........
Your best and safest bet to use the Iowa Blue for sex-link chicks is 1) any of the barred hens and 2) the New Hamps. Hope that helps out. One of our long term goals for the breed is to do some experiental breeding with the Iowa Blue and sex-link creation.
Oh, one more very important thing. If your cockbird is Birchen colored, you will not be able to produce the sex-links. You must use a Silver Iowa Blue male to produce the desired result. Historically, the Iowa Blue was the color of what has been coined by the breeders as the "Silver" variety. The "Birchen" coloration came about in the early 2000's (roughtly 2004), is currently an "non-standard" color within the Iowa Blue club, and is unusable genetically in the creation of sex-links. You could have success using a Birchen male over a barred female. However, the exaggerated black melanization found in the Birchen Iowa Blues could severely mess up any plans for using barred hens in a sex-link program.
Good Luck and keep us posted on your results. If you could take pictures and post them, they would be of great value to other Iowa Blue breeders.
