Okay, so one day you breed two blacks together...or, two rabbits you would SWEAR up and down are both black...completely solid colored rabbits, no markings of any kind, just black.
A month later, you go out to your barn and find a nestbox full of...CHESTNUTS? Wait...that isn't supposed to be possible...two selfs producing an agouti color???
Unfortunately, this is starting to happen more and more as the Red Fox
gets developed and the non-extension gene gets around. What you are
seeing is not actually the impossible...but the possible. These animals
that throw the agoutis are known as super steels and only come out
where a recessive flushes the steel gene. If this happens to you, then at least one of the parents of the litter is not a true self at all, but a steel agouti masquerading as a self. Sneaky, huh? This is generally considered to be quite an undesirable happening, and I strongly recommend that you introduce the tort gene into your herd and work on flushing it out over time. The recessives which occur in this breed can be fun and even exciting for some people, but when they link up with the agouti gene and start modifying it, the number of varieties you can get will increase to what seems an exponential number. Keeping track of them all can be difficult, and you can really turn your herd into the biggest genetic nightmare on earth if you do not stop and address this issue. Also, apart from super steels, agouti will prevail in the creation of more and more nonshowable rabbits, which can be discouraging if you are trying to come up with something to enter.
Colors that can NOT carry agouti are Sable, Tort, and SIamese Sable. You can use all these colors to flush out the agouti gene; the reason I recommend sticking with tort is that it is not only much more widely accepted, it also is a non-extension and will help you to flush out steel as well.
The genetic code of a super steel is probably going to involve two steel genes (Es), but it may include only one with modifiers. The presence of only one agouti gene (A) is necessary to produce a super steel, however two may be present. I will go into more detail about the steel gene in the E Locus (Extension) page.