ANNEX G Related Background Reading “Waiting on Providence " never did nor ever will be attended with satisfactory results – William Scarth Dixon The sentiment in the statement above was made by a man who is revered in the history of the Cleveland Bay Horse Society, William Scarth Dixon. He was a founder member of the Cleveland Bay Horse Society in 1884 being its first secretary and what he said was perhaps prophetic for the present times. Not waiting on providence is at the core of the Grading Register proposal. Contents 1. Dr Phillip Sponenberg DVM, Ph.D. - The CBHS has been asked not to publish this article in a PDF document format. It may be seen on the RBST website via the following link: http://www.rbst.org.uk/files/Graspingthe%20Nettle%20- %20Should%20we%20or%20Shouldn't%20we%20Part%201.pdf 2. Dr Ian Gill - The CBHS has been asked not to publish this via a PDF document format. It may be seen on the RBST website via the following link: http://www.rbst.org.uk/files/Grasping%20the%20Nettle%20- %20Should%20we%20or%20Shouldn't%20we%20Part2.pdf 3. Akhal-teke horses 4. Friesian horses 5. CBHS Stud Book selections SELECTED PAGES FROM THE WEBSITE OF THE Akhal-teke http://www.akhalteke.info/inbreeding-depression-1-51-en.html InbreedingDepression Inbreeding depression is reduced fitness in a given population as a result of the breeding of related individuals. Breeding between closely related individuals, called inbreeding, results in more recessive deleterious traits manifesting themselves The more closely related the breeding pair is, the more homozygous deleterious genes the offspring may have, resulting in very unfit individuals. Another mechanism responsible is over dominance of heterozygous alleles leading to a reduction in the fitness of a population with many homozygous genotypes, even if they are not deleterious. Currently it is not known which of the two mechanisms is more important. In general, populations with more genetic variation do not suffer from inbreeding depression. Inbreeding depression is often the result of a population bottleneck Natural selection cannot effectively remove all deleterious recessive genes from a population for several reasons first, deleterious genes arise constantly through mutation within a population second, in a population where inbreeding occurs frequently, most offspring will have some deleterious traits, so few will be more fit for survival than the others. It should be noted, though, that different deleterious traits are extremely unlikely to equally affect reproduction. An especially disadvantageous recessive trait expressed in a homozygous recessive individual is likely to eliminate itself, naturally limiting the expression of its phenotype.third, recessive deleterious alleles will be "masked" by heterozygosity, and so heterozygotes will not be selected against.Introducing new genes from a different population can reverse inbreeding depression. Different populations have different deleterious traits, and therefore will not result in homozygosity in most loci in the offspring. This is known as outbreeding enhancement, practiced by conservation managers and zoo captive breeders to prevent homozygosity. However, intermixing two different populations may give rise to unfit polygenic traits in outbreeding depression.Inbreeding depression is expressed in a variety of results, some of them are:significant reduction of lifespansdecreased fertility and fecundityfluctuating asymmetries and morphological variation disease susceptibility decrease in size At least one population of horses bred with a closed studbook is known, which has been and still is going through a severe inbreeding depression, including several lethal and semi-lethal recessives having surfaced, as well as grave problems to general health and fertility. In fact, all of the above mentioned results are being experienced by this breed. This is the Friesian horse, with a current breeding population of some 8,000 to 10,000 individuals, a general COI of 17%, one major bottleneck around 1900 (3 registered sires left) and breeding practice which includes color-breeding, show breeding, popular sires and severe culling towards visual and performance traits. These days there are roughly 100 foals per year suffering from dwarfism and from hydrocephalus (often enough killing the birthing mares as well) in the Netherlands alone, with a significant higher amount of mares suffering from a variety of fertility- related issues, such as e.g. retention of the placenta, low rates of mares taking or lower semen quality. Additionally the breed is susceptible to a higher and severer incidence of colics and quite some skin and allergy-related issues.The Friesian breed management is at long last reacting to these problems, though the measures have been found out to be not efficient enough. Inbreeding is discouraged, with COI data being rendered to the breeders upon registration of the foals, a moderate opening of the studbook towards horses formerly rejected as breeding animals has taken place with Appendix sections I and II and data about horses spreading dwarfism is given to the breeders. It is noteworthy that inspite of the lethality of several of these defects and inspite of the quite severe culling in evidence among this breed (far surpassing that of e.g. the Akhal Teke), there is no noteworthy amount of purging evident. Another population with closely maintained statistical records, the English Thoroughbred, has also been found to be adversely influenced by COI exceeding 10%. Recent research has found that different species and different breeds within one species do not react in the same manner to inbreeding. Factors in this regard are the genetic health status of the breed founders, the amount of diversity being cut off within a set time, abrupt changes in selection and culling methods, change of breeding criteria or likelihood to evolve mutations. A further factor is how steadily and how fast inbreeding coefficients are rising within a breed. If the genetic load encompasses more medium-import deleterious recessives instead of lethal ones, then there is no or only a very low purging effect to be found, a lack which also furthers inbreeding depression. As to the Akhal Teke, the close observer already is able to discern the telltale signs, such as a continueing reduction of lifespans, an ever rising amount of barren mares, aborted, deadborn or weakborn foals, poor semen quality in older sires, lately also in younger studs, as well as of course the rising amount of lethal recessives cropping up among the breed. Due to the habit of mostly linebreeding, instead of close inbreeding, the general COI of the breed is better than that of e.g. the Friesian. However, the AVK is much worse and lessening each generation by several points. There are currently no horses with an AVK above 55% and a growing fastly amount of horses with one under 35%, this after barely 10 to 12 registered generations! This constitutes a loss of diversity not expressed by simple COI data, but one which nevertheless has the same effects and it is a quite enormous loss. The Turkoman horses were breeds of enormous diversity, having existed up to the 1900 bottleneck in huge numbers (herds of 100,000 horses among one tribe only were not unheard of), a huge amount of landrace strains and free interbreeding within these breeds and strains. Whole chunks of this vast genepool were destroyed at the same time, even the surviving 650-700 horses which entered the first studbook were not used completely, large portions of that small group did not make it into the modern genepool at all. It needs to be remembered that during this crucial survival phase the breed was culled on size and on race results, even though there should have been no culling at all. The overall COI is rising currently in a curve rather than in a linear manner, aided by the opinion of many breeders, that linebreeding is no inbreeding, and little to no awareness of these problems among western breeders. Already there are quite a few horses having COIs of 10+%. Omertà - or the Conspiracy of Silence. The expression "conspiracy of silence" relates to a condition or matter which is known to exist, but by tacit communal unspoken consensus is not talked about or acknowledged. Conditions considered shameful or disadvantageous by society or a certain group of people result in avoidance of recognition of some problem in order to officially bury or hide it and thus prevent accusations, investigations or liability. A conspiracy of silence in some field has effects at many levels: those who are directly suffering, or causing others to suffer, perpetuate their cycle of harm and suffering, those who have suffered have their suffering extended by being having their condition ignored or minimized, and are not considered seriously or redressed appropriately, lessons that might be learned for the future are not learned, conditions are exacerbated or even this way allowed to become entrenched in the first place. Conspiracy of silence is a well-known and much executed behaviour among many if not most modern breeders. Unlike breeders of former times, who had to present animals well able to perform and had no problem with destroying those individuals which were showing faults or defects, especially as their livelihood usually depended on their good name in this respect, many if not most modern breeders are more or less hobbyists or - if themselves professionals - selling mainly to hobbyists. Unless they are selling directly to the meat market that is. These hobby breeders usually feel that the name of their breeding is riding on the health state of their animals, or indeed often considerable amounts of money invested are riding on the trust customers and fellow breeders place in them or they do not wish to start over rsp. are unable to buy new breeding stock. In view of the fact that since roughly 100 to 150 years ago studbooks of most pet breeds are closed as a rule and in view of the advent of pure showbreeding also among many if not most pet animal species, decisive and relentless culling has become more necessary than ever.