Tag Archives | Abaco Barbs

The Banjo Quotient

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My friend Carra McClelland recently referred to the issue facing the Abaco Barbs as the “Banjo Quotient”. Although the cultural reference might be lost on some of our foreign readers, for most Americans – especially those who, like me, grew up in the Appalachian region – it is a humorous way to refer to alarming levels of inbreeding.

Right now, even if all the remaining horses on Abaco are still living and can reproduce, the numbers represent high levels of inbreeding for the long term. There are three mares, of which two are mother and daughter. The relationship of all three mares to the stallions are not known, but they are presumed to be related. What’s more, the original herd of 35 was said to have been rebuilt from just three horses. That is what is known in genetics as a bottleneck. Bottlenecks reduce genetic diversity, which is essential to the health and fertility in animals. Abaco Barbs have apparently had at least one (extreme) bottleneck, and now are facing a second.

Unfortunately in horses, the obsession with the concept of “blood purity” can doom rare breeding groups like the Abacos. There is the perfectly understandable desire to preserve them. Unfortunately modern notions about what makes something a breed can narrow the options, as is often seen in purebred dog populations. This is particularly frustrating with horses, however, because there is often a disconnect between this relatively recent idea, and how horses have historically been managed.  In many ways it has more in common with the history of dog breeding than with that of horses – with a notable exception.

Arabians have been maintained as a breed much the same way dog breeds have been. There are known male and female founders, and their descendants are maintained in a closed registry. What Arabians also have in common with dogs is a fairly widespread acceptance of close inbreeding. The horse pictured at the top is Ibn Rabdan, a dark chestnut Arabian born in Egypt in 1917. He is relevant to the subject of Banjo Quotients in that he is the sire line for the Babson Egyptians. The only sire line. That’s because there are six horses that make up the “straight Babson Egyptian” bloodline: one stallion (*Fadl) and five mares (*Bint Bint Durra, *Bint Bint Sabbah, *Bint Serra I, *Bint Saada and *Maaroufa). The stallion, *Fadl, was by Ibn Rabdan. So were two of the mares. One of the mares, *Maaroufa, was a full sister to *Fadl. So while straight Babson Eyptian horses (like this one and this one) trace in all male lines to *Fadl (and therefor Ibn Rabdan), the horses are more closely related than that. Ironically, crossing the descendants of the same six already-related horses for close to 80 years is called preservationist breeding in that community.

Those involved in genetics would call it insanity. But this approach, which is hardly unique to those breeding straight Babsons, has come to color what many horsemen see as normal and acceptable.

And yet with modern genetic tools, we have options for preservation that were not available just a short time ago. In the past, outcrossing to broaden the genetic base for a breed relied on hearsay. That is how we got early Appaloosa breeders recommending that Arabians be used when available (in the 1930s, these were still relatively rare). It was thought that breeding back to Arabians would bring the horses back to the Barbs where the “spotting gene” was believed to have originated. I am sure images like this early 19th century Currier & Ives print of a circus “Barb” did a lot to encourage that idea.

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Relationships can be determined by genetic analysis now. It is still a very new science, and often the results raise as many questions as they answer, but it does provide an avenue for objective evaluation of potential outcrossing groups. It might be too late for the Abaco Barbs, and some horsemen might still reject the idea of outcrossing at all, but for those willing to consider it the information might help preserve unique groups without creating family trees that don’t branch.

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Fate of the Abaco Barbs

799px-Hopetown-lighthouse

Hurricane Irene, which hit the Abaco Islands a few days ago, had many people wondering about the fate of the critically endangered Abaco Barbs. The good news is that the three mares that are kept on the preserve are apparently fine. To my knowledge nothing is known about the fate of the stallions, but that has been true for a long time. There are at most two, and they are not kept on the preserve with the mares. The last sighting was of the 22 year-old stallion Hadar, made in February of this year. The second stallion, the splash overo Capella (made famous by Breyer), has only been sighted twice in the last five years. A flyover of the island in 2010 did not turn him up.

Even without a hurricane, though, the future of this breeding group appears grim. No foals have been born since 1998, and the three remaining mares are believed to be infertile, possibly due to exposure to pesticides. But even if they were fertile, and the two stallions still alive and fertile, their small numbers would create dangerous levels of inbreeding. (Two of the mares are mother and daughter, so there are not even three distinct female lines now.)

From a color perspective, the splash overo pattern is still there by the slimmest of margins. If Capella, a homozygous splash, is still alive, then the prospect of preserving the pattern are much better. If not, probably the only source is the heterozygous splash mare Nunki. She looks very typical of splash carriers in breeds without sabino. The other two mares, Acamar and her daughter Alnitak, are plain bays. Acamar does have a star, and some splash carriers are pretty cryptic, but it would be slim hope were she the only one. Acamar and Alnitak do have frosty roaning in their coats, but it is not as pronounced as that on a dark-headed roan.

So the steps that must be taken now is to find one of the five horses still alive and still able to breed. If that can be done, out-crossing is going to have to take place. If experts are consulted, a preservation program can be created that would utilize animals from genetically similar backgrounds. That kind of research will be the subject of a future post, because it is a wonderful tool not only for preserving livestock diversity, but also for shedding light on the true relationships between the different breeds. The Barbs on Abaco may well be a cautionary tale – rather than a success story – about preserving genetically distinct populations, but there are many endangered groups where the outlook is more optimistic and there is still time to take action.

(Pictured is the lighthouse at Hope Town in the Abaco Islands of the Bahamas.)

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