The Complexities of Test Breeding Ayam Cemani

Fans of the Ayam Cemani may find that test breeding is often recommended, but rarely well explained. Proper test breeding requires a tremendous amount of time, education, space, patience, and an eye for detail. The process cannot be simplified in a short article, or thoroughly demonstrated in a single graphic. It is not simply a matter of breeding an Ayam Cemani to any non-fibromelanistic chicken. 

Almost all recommendations for test breeding concentrate solely on test breeding to determine whether a subject is heterozygous or homozygous for fibromelanism (Fm/Fm). While fibromelanism a hallmark of the breed, it is not the only defining feature of the Ayam Cemani. Homozygous Fm is not difficult itself to achieve. Anyone can breed two Fibro Easter Eggers to one another and achieve homozygous Fm. This does not mean the bird will be an Ayam Cemani, and it certainly does not mean a bird will possess fully black plumage. The fibromelanism gene has absolutely no bearing on feather color or the amount of color leakage a bird may show in the plumage. Fm only controls the pigment in the skin, soft tissues, and bones of a specimen. As breeders and buyers, we must acknowledge the need of other melanizing genes - both for skin and feather - as essential qualities. To date, these other ESSENTIAL genes for the Ayam Cemani, have gone largely undiscussed. It is a disservice to the breed to focus solely for fibro expression while neglecting conformation and other color impacting genes.

The genotype for an Ayam Cemani is 

E^R/E^R (or E/E), S/S, Fm/Fm, Ml/Ml, id+/id+, cha/cha, along with other un-named melanizers. 

So homozygous fibromelanism (Fm/Fm) is only a fraction of the equation.

No matter what breed we are working with, we should not lose sight of the fact that conformation (type) should always come before color. Our focus in breeding quality Ayam Cemani should lie in the conformation just as much as color. In making our breeding decisions, it would be a travesty to correct the color first and then find the need to bring in unknown color genetics to correct the type on your tried and true black flock.

A young Ayam Cemani cockerel suspected to be homozygous for fibromelanism.

Let’s say that we already have an Ayam Cemani with a properly conformed topline, a tail with the proper angle, and a straight, upright comb, at minimum. And now we want to test breed, because we are told that is what we should do. 

At one time, the most commonly suggested breed to use for test breeding was the White Leghorn. The outcome of a cross of Ayam Cemani to White Leghorn is very different depending on the sex of the parents. 

Leghorn cockbirds generally carry two copies of TWO dominant genes that have a negative impact on fibro expression. Those genes are the Inhibitor of Dermal Melanin (Id) and the barring (B) gene. Both of these genes reside on the Z sex chromosome. Male birds have two Z chromosomes and will pass one of them to every offspring. Female birds have one Z chromosome and one Y chromosome. 

If you use a Leghorn male over an Ayam Cemani female, he is going to pass a Z chromosome to his offspring EVERY SINGLE TIME. This means that all of his sons and daughters will inherit one copy of Id and one copy of B. All of his offspring - even if they get a copy of Fm and other melanizers from the Cemani hen - will have the fibro expression negatively impacted. At the point of hatch, it will appear that the chicks did not inherit Fm at all, thus unfairly suggesting that the hen is not homozygous for Fm. The chicks usually grow out to have red combs with black splotches and white or yellow legs with black splotches. All chicks should have white plumage due to the dominant white gene of the Leghorn. Some spots of black plumage should be expected, and that black plumage will likely show barring.

So what happens if we try the reverse - Ayam Cemani male over White Leghorn female? Hens only carry one Z chromosome with the dominant Id and B genes. When a Leghorn hen is mated, she passes one of her sex chromosomes to her offspring. If she passes her Y chromosome, the offspring will be female and will not possess Id or B. If she passes her Z chromosome, the offspring will be male and her male offspring will inherit one copy of Id and one copy of B, which means that their dermal melanin will be inhibited x2. Only her daughters will have dark skin, legs, beak, and comb because they did not inherit the Z chromosome that the inhibitors reside on. This cross is known as a sex-linked cross because males and females inherit different physical characteristics. This cross technically could be used to test Fm homozygosity, but the analysis would only depend on whether 100% of the females or 50% of the females exhibit Fibromelanism. All chicks should have white plumage due to the dominant white gene. Some spots of black plumage should be expected.

In summary, test breeding to a White Leghorn only works if you cross an Ayam Cemani cock over a White Leghorn hen, and only the female offspring may be used to determine whether your cock is homozygous (Fm/Fm) or heterozygous (Fm/fm+) for Fibromelanism. This process still does not address the numerous other genes that are integral to our breed. There are other breeds that can yield better results and provide clues to whether or not your Ayam Cemani possesses certain necessary genetics in addition to fibromelanism. Knowing the genotype of the breed and variety you are using for test breeding is important for predicting outcomes with reasonable certainty.

Test breeding is not a simple process, nor should it be undertaken without a thorough understanding of the expected outcomes. If you believe test breeding is necessary, the Ayam Cemani Breeders Association recommends doing so under the guidance of an experienced mentor.