A recent article published by UC Davis entitled "How a Genetic Mutation From 1 Bull Caused the Loss of Half a Million Calves Worldwide" illustrates the necessity of thorough genetic testing before allowing a stock bird to establish its influence throughout a family of Performing Roller pigeons or other types of Domestic Animals.
The article tells the story of how one bull, Pawnee Farm Arlinda Chief, was single-handedly responsible for the introduction of a lethal gene into the genepool of Holstein dairy cattle that up to current day has resulted in the loss of a half million Holstein calves as a result of spontaneous abortion.
Chief, who was born in 1962, through the miracle of modern breeding practices, sired 16,000 daughters, who in turn gave rise to over 500,000 grand daughters and more than two million great grand daughters. Several of his sons, including Walk Away Chief Mark, who was sired in 1978, also became dominant sires in the Holstein breed in North America. Mark was even more prolific than his sire, fathering over 60,000 daughters. According to UC Davis, Pawnee Farm Arlinda Chief is single-handedly responsible for 14% of the genome in the current Holstein population of North America which is estimated at being about 9.2 million cows.
Recent genetic sequencing in Holstein cattle turned up a group of mutant genes simply identified as "APAF1" which is a recessive lethal gene that was not only associated with lower fertility rates, but also spontaneous mid-term abortions in cattle. Over the last 35 years, this lethal gene has cost the dairy industry an estimated $420 million just in veterinary costs as a result of complications. The source of this devastating lethal mutation was found to be none other than this single legendary sire: Pawnee Farm Arlinda Chief, who was also noted to have otherwise dramatically improved the production capabilities of Holstein dairy cattle.
While we Performing Roller breeders lack the sort of breeding technology that cattle breeders do and there is no genuine likelihood for a single stock bird to produce offspring by the thousands, it is still relatively easy to spread the genetic influence of a single bird throughout an entire family of pigeons. This is, in fact, an inevitable when the culmination of every Roller breeder's desire is to create his own family of first class rolling pigeons. This can only be done by starting with a small select group of pigeons and utilizing linebreeding/inbreeding techniques in an effort. Regardless of their aerial quality, great care must be taken in selecting the pigeons that are used in building up a family of pigeons, in that even the best pigeons may possess unwanted recessive genes. If a breeder does not pay close attention and neglects to work to expose these latent and unwanted characteristics, it is relatively easy to spread them through their family in such a way that inside of a half dozen or dozen generations, they become such a plague as to destroy our breeding efforts completely. These types of latent genes may range from common aerial faults such as poor stability, lack of homing instinct, infrequency, poor kitting ability, improper wing action, etc. on up to more severe and far more damaging genes that have negative impacts on reproduction, physical or physiological issues or even sub-lethal or lethal genes.
Some examples of known recessive genes in pigeons that if accidentily perpetuated in a line of Performing Rollers would have a destroying affect include such genes as those for Ataxia, Clumsy, Wobbly, Silky, Porcupine or Scraggly plumage and others. As one example, Ataxia, which is a recessive gene known to exist in Birmingham Rollers and some related breeds, results in physiological behavior that is almost remindful of the symptoms of Paramyoxovirus (PMV-1) in that an underdevelopment of the neural areas of the brain results in a lack of complete coordination of physical movement. Such birds exhibit an abnormal gait, exhibit peculiar flight and for all intents and purposes, exhibit other behaviors that could be simply described as a sort of "mental retardation". In the early 1990's, the late Gary Blain, who could best be described as a "serious backyard pigeon geneticist", had among his many various genetic color projects, several pairs of Roller X West of England Tumbler crosses that routinely produced Ataxiac offspring. For several years he kept several birds afflicted with Ataxia at his loft for observation purposes. One of these was a Recessive Red cock with short grouse legs that exhibited not only a strange gate that resulted in the bird rocking side by side and even backward whenever he walked, but also strange neck tremors and irregular modes of flight. I saw this bird on a number of occasions and one of my major observations was that the bird had very peculiar pupils. Not only were they irregularly placed, being set very far forward and rather down toward the join of the mandibles of his beak, they also had a very peculiar shape, being almost diamond-like opposed to round. Like many rolldowns, the pupils of this bird also seemed very slow to react to the shining of a bright light in his eye. While none of his siblings or cousins exhibited the strange pupils and seemed far less afflicted than this bird by the neurological characteristics of this genetic disease, they were, none-the-less, also afflicted in varying degrees. The double grandfather of these Ataxiac birds was a Roller cock that was so possessed by the roll that he could barely get off the ground and had come from a fairly notable breeder in Southern California, while the double grandmother was a West of England from a prominent show breeder in California. It was never clear which grandparent had actually contributed the gene to these birds, but the results of inbreeding their offspring was so devastating that within a few generations, Mr. Blain decided to destroy every last one of them (including both grandparents) because he knew that the gene, being a recessive, would be just about impossible to breed out of them and always yield a large percentage of birds that were afflicted with the disease. While Ataxia, as well as Scraggly and other types of genes responsible for what could best be described as "damaged plumage" would pose obvious genetic problems in a family to even the most casual observer, there are other genes out there that are just as devastating, even if their effects are less obvious to the average breeder. For example, in the 1940's, the late Dr. Willard . Hollander and Wendell M.Levi put up a paper on the Polydactyly gene which was discovered among a family of Silver Utility Kings at the Palmetto Pigeon Plant. This simple recessive gene resulted in an extra back toe and also sometimes other characteristics. While a feature like this might go mostly unlooked and even be reasonably tolerated in a Utility breed or a Sporting breed, much the same as webbed-feet which are common in Birmingham Rollers, the writers also found that the gene was a sub-lethal, in that every bird that was afflicted (some 25 of them) did not live to maturity. In later years, Dr. Hollander, who I corresponded with quite regularly and who was responsible for teaching me much about pigeon genetics, discovered another gene, this one, sex-linked, that he-called "web lethal" that appeared in Racing Homers in the loft a breeder named Dennis Peterson. While some of the afflicted birds died at young ages, quite a number were "dead-in-shell". Later on, the well known pigeon geneticist, Robert Mangile, finally actually managed to produce a cock bird that was homozygous for the gene that actually lived to maturity. Another odd mutation called "Erratic" was documented by Mangile in 1983 that resulted in birds that when alarmed showed odd head movements that sometimes resulted in the bird holding its head upside down over its back, birds that walked in circles, seemed incapable of flight and also would not eat feed off the ground. Most of them had to be handfed, while weaning the squeakers was next to impossible to such an extent that by 2014, the birds that Mangile was studying ceased to exist due to all the difficulties involved in their survival. In 1987, Mangile also reported on a gene he called "Foggy" about which he reported "they appear to have a frozen owl-like gaze in your direction with their bill slightly elevated. Unlike normal birds which seem comfortable viewing you with one eye, foggy birds tend to look at you over their bill, with both eyes, not unlike a real owl. This aspect may shed light on the malady. Their skull appears wider between the eves, thus producing a flattened "knob-like" head with wide-set eyes (see photos). In a few instances the widened skull was noted in newly hatched squabs. Fledglings appear to be vision-impaired and less mobile than loft mates; and restricted to the floor".
This list of known "nasty genes" could go on and on, but the point is, they are hiding out there. Without adequate genetic testing, some of these genes could be easily spread throughout an entire family of birds, some of them completely un-noticed by the average breeder apart from perhaps an observation that "something doesn't seem right".
On the otherside of the coin, there are also many genetic factors in rollers that are responsible for what could best be described as "faults" and "quirks". As a whole, we do not know much about these genes because they've never been adequately studied, and as a result, they have often given rise to some pretty wild, if not controversial, theories about breeding rollers such as the idea that continually breeding dark birds together results in infrequency and later and later development, that "the pearl eye puts more fly into them", that "some colors, like white selfs and yellows, can't roll due to some genetic inferiority" and so on, that have no real basis in sound genetic science. In reality, these sort of unwanted "quirks" that start to appear in most families are really the result of genes that were already present, yet lying latent in the birds that made up the foundation of the family. Those genes may be mere aerial, behavioral or physical faults, or they may be physiological.
In decades past, much ado was made out of so-called "Inbreeding depression", which was the theory that continued inbreeding and linebreeding, regardless of how it was carried out, would always lead to issues of infertility, genetic diseases and ultimately, the ability of a bloodline to continue to reproduce and survive. While this can in fact, take place, the general population, including many animal breeders, chalked it up to a sort of mysticism that took place because this type of inbreeding is viewed as un-natural and the result of our "playing God with nature". In reality, Inbreeding depression takes place because of the presence of what are called "recessive deleterious alleles". That is to say, they are caused by genes which are only rarely expressed in a large population, but become frequently visible in a small population due to the level of inbreeding which creates a lower genetic variation as each generation passes. When we breed Rollers or other types of domestic animals with some sort of standard of excellence in mind, lowering the genetic variation among our breeding stock is the name of the game, assuming that the characteristics we are perpetuating come as close to "the standard" as possible, for the simple fact that the end result is a (hopefully) higher and higher percentage of birds produced each generation that come near that standard. The only way to lower the genetic variation in your loft, and thereby produce more birds which come close to the standard, is by inbreeding and linebreeding as close as possible, always keeping in mind that the genes we are cultivating in higher percentages each generation include not only the positive ones, but also the negative ones too. As stated earlier, those genes we "don't want", may not be physically apparent to the naked eye of the breeder for a few generations and often, when they do become visible, it may be too late to stop them.
With these facts in mind, the birds we select to build our base from must be thoroughly tested to the best of our ability before we begin to allow their genes to heavily influence our breeding program.
By far, the fastest way to adequately test a stock bird that we are considering using as a foundation bird, is to breed it to at least two different mates, breed as many offspring from the two matings as possible and to then inbreed the offspring for a few generations. For the best results, we would take our potential foundation cock, breed him to two different hens and breed at least 10 youngsters from each mating. In an ideal world, those two hens would be his own daughters. We would then take all those youngsters and breed them together, making up full sibling matings from each breeding, as well as some half sibling matings consisting of a youngster from each mating paired together. From these, we would breed as many youngsters as we could, keeping very good records on them. At this point, we should begin to have a good idea what sort of recessive genes the potential foundation cock is carrying. For an even more thorough test, we would take some youngsters from these matings and also breed some of those together, which would be composed of not only some more full sibling matings, but also some linebred first cousin matings. In the meantime, you can also breed the cock to the best of his linebred grand daughters and great grand daughters.
In the above manner, we can quickly lower the genetic variation of the resulting offspring, limiting it to mostly the genetic influence of the potential foundation cock which allows us to determine fairly good insight into his genetic makeup, both his strengths and his weaknesses.
As one can imagine, since it is necessary to fly Rollers to adequately test them, the above process can take much time and effort. In spite of this, it is the only way to adequately test a potential foundation bird if a breeder wants to insure that he has made the right choice for his foundation.
And if the foundation cock was indeed the "right choice", you will find yourself way ahead of the rest, because once you've done this sort of test, you will probably find that this breeding exercise has resulted in a good many pigeons that have the qualities you desired from the cock.
~ Jack Chambers
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