{"id":18094,"date":"2020-05-08T15:50:16","date_gmt":"2020-05-08T15:50:16","guid":{"rendered":"http:\/\/labgenvet.ca\/?page_id=18094"},"modified":"2026-01-15T21:38:55","modified_gmt":"2026-01-15T21:38:55","slug":"horse-genetics-4-0-evolution-breeds-breeding-strategies-and-inbreeding","status":"publish","type":"page","link":"https:\/\/labgenvet.ca\/en\/horse-genetics-4-0-evolution-breeds-breeding-strategies-and-inbreeding\/","title":{"rendered":"Horse Genetics 4.0: Evolution, Breeds, Breeding Strategies and Inbreeding"},"content":{"rendered":"

[vc_row][vc_column][vc_column_text]<\/p>\n

Horse Genetics 4.0: Evolution, Breeds, Breeding Strategies and Inbreeding<\/h1>\n

 <\/p>\n

The Evolution of the Horse<\/h3>\n

The horse (Equus ferus caballus<\/strong><\/em>) is a mammalian herbivore with post-gastric fermentation. It has uniparous reproduction. The horse is an ungulate meaning that it has hooves. The horse genome is comprised 2.4 billion base pairs organized into 32 pairs of nuclear chromosomes, in addition to a single cytoplasmic mitochondrial chromosome.<\/p>\n

\"\"<\/a>The evolution of the horse is particular amongst the domestic animals.\u00a0 The archaeological record shows that the first ancestor of the horse was a small three-toed herbivore that lived in the forests of the Americas about 50 million years ago.\u00a0 This animal is given the poetical name of Eohippus, or \u201cdawn horse\u201d.\u00a0 Eohippus was an ungulate animal, meaning that it walked on the tips of its hooved toes.\u00a0 Eohippus would give rise to the order Perissodactyles (perisso-, odd numbered; dactyls, toes), the ungulate species that walk on an odd number (one or three) toes per limb.\u00a0 These species include the modern-day tapirs, five species of rhinoceros, and seven species of equids (horses and related animals).<\/p>\n

The first early equids appeared five million years ago in North America, from where they migrated to also inhabit Europe and Asia.\u00a0 These proto-horses were originally omnivores but were to become true herbivores as they adapted from living in forests to living on the prairies.\u00a0 Their size increased and now they walked (ran) on just one toe per limb.\u00a0 Their teeth and digestive system adapted to function on the rough forage provided by the prairies.\u00a0 They were prey animals, with good vision, a well-developed flight reflex, the ability to run quickly and a social structure organized to help them survive.\u00a0 These early equids gave rise to the zebras, donkeys and the domestic horse.<\/p>\n

\"\"<\/a><\/p>\n

[\/vc_column_text][\/vc_column][\/vc_row][vc_row][vc_column][vc_column_text]<\/p>\n

The Domestication of the Horse<\/h3>\n

\"\"<\/a>About 10,000 years ago, at the end of the last ice age, these early horse species died out in the Americas but were able to survive in Eurasia.\u00a0 And it was in Eurasia that the horse was domesticated by humans, forever changing the fate of both species. Current knowledge places the domestication of the horse in the Eurasian steppes, equivalent to modern-day eastern Ukraine, around 4,200 years ago, among a group of Copper Age hunter-gatherers known as the Yamnaya (or Pit) culture. Horses were selected first and foremost for their gentle behavior, then for their strong backs, and finally for their attractive colors.\u00a0 Horse culture gave the Yamnaya tribes both practical and strategic advantages, and the domesticated horse quickly spread east and west. Interestingly, genetic analysis suggests that this spread occurred by mating a limited number of immigrant stallions with numerous local mares.\u00a0 It is also interesting to note that the Yamnaya culture gave us not only the horse, but also, at the same time, our family of Indo-European languages, transmitted on horseback and now spoken by more than 40% of the world’s population.\u00a0 \u00a0\u00a0\u00a0Horses were useful to humans because they served as a means of transportation, as draft animals, they provided a tactical advantage in warfare, and, if necessary, they were a a source of protein.\u00a0 Yes, the domestication of horses changed human culture: we are what we are today thanks to horses.<\/p>\n

It is interesting to note that a second horse species also survived the last ice age, the wild horse of Mongolia (Equus ferus przewalskii<\/em>).\u00a0 This animal has an additional chromosome pair compared to the domestic horse.\u00a0 The wild horse of Mongolia disappeared from nature in the 1960s but has been kept alive as a species in zoos.\u00a0 Efforts to re-establish this wi\"\"<\/a>ld horse back into its natural habitat were initiated during the 1990s with some success.\u00a0 Currently there are about 300 truly wild horses living in the wild out of a total world population of 1,500 individuals.\u00a0 All other horses on earth, estimated at 58 million (in 2008), are genetically the domestic horse.\u00a0 It must be stated that the wild ancestor of the domestic horse no longer exists.\u00a0 It can be argued that the domestication process was a remarkably successful survival tactic for the horse.<\/p>\n

The Developement of Horse Breeds<\/h3>\n

\"\"<\/a>The special relation between man and horse, i.e. the domestication of the horse, relied on the particular function and utility that the horse provided to man.\u00a0 This has resulted in 300 or so traditional and regional breeds of horse, ranging from large, heavy work horses, agile mid-sized saddle horses to small ponies. Indeed, the horse is second only to the dog for the range in body size seen within a domestic species.<\/p>\n

[\/vc_column_text][\/vc_column][\/vc_row][vc_row][vc_column][vc_column_text]<\/p>\n

In more recent times, purebred horse breeds, with pedigree registries and studbooks, were developed to control the form, function and reproduction of a particular horse breed.\u00a0 The first such registry was the General Stud Book, established in 1791 to govern the Thoroughbred breed.\u00a0 Horse breeds have been developed via two general strategies: either through the mixing of the genetics of many founder animals from diverse genetic sources over long time periods, or the exclusive use of the genetics of very few founder animals.\u00a0 Breed registries can be closed, where both parents must belong to the registry in order for their offspring to be registered; this is the situation for the Thoroughbred horse breed and is what is commonly seen for purebred dog breeds.\u00a0 Alternatively, horse registries can be more relaxed (only partially closed), to allow genetic contributions from other breeds; this is the case for the Quarter Horse and the Appaloosa breeds.\u00a0 Both breeding strategies have consequences for the conformation as well as the genetics of the animals produced which will be relevant to a discussion of inbreeding (see section on inbreeding<\/a>).<\/p>\n

Horses in the Americas<\/h3>\n

\"\"<\/a>The story of the horse in the Americas needs a final chapter.\u00a0 As of 1492 and the beginning of European colonization, the domestic horse began to be re-introduced into the Americas.\u00a0 When these domestic horses escaped and bred in the wild, feral populations of horses were established.\u00a0 The genetic source of these wild \u201cmustang\u201d horses of the Americas remained the domesticated horse of Eurasia. \u00a0Over time, the regionally modified genetics of mustang horses were to contribute to the formation of a number of modern American breeds of horses.<\/p>\n

[\/vc_column_text][\/vc_column][\/vc_row][vc_row el_class=”bloc_info”][vc_column][vc_column_text]<\/p>\n

Breeding Strategies<\/h3>\n

Several breeding strategies are available to the horse breeder.\u00a0 In general these strategies are various combinations on two somewhat opposing themes: \u201cbreeding for type\u201d, where obtaining uniform physical characteristics in offspring is paramount, and breeding by pedigree, where close genealogical relationships are avoided at the expense of uniformity.<\/p>\n

Inbreeding<\/strong> \u2013 involves breeding of animals that are members of the same close family, with common ancestors on both paternal and maternal sides of the pedigree.\u00a0 This is the strictest form of \u201cbreeding for type\u201d as it will fix the desired phenotypes in the offspring.\u00a0 However, at the same time genetic variation of the offspring will be reduced and the coefficient of inbreeding<\/a>\u00a0 will be increased compared to the parents.\u00a0 Another name for inbreeding is an incestuous breeding.<\/p>\n

Line breeding<\/strong>\u00a0\u2013 involves breeding of animals that are members of the same breed and show similar traits (breeding for type) but come from different lines (pedigrees).\u00a0 Thus, there is no (or very little) recent common ancestry.\u00a0 This is a compromise between breeding for type while still maintaining an equilibrated genetic base within the offspring.\u00a0 The coefficient of Inbreeding of the offspring will be maintained at about the same level as the parents. \u00a0Not all horse breeds have the sufficient numbers of animals to support line breeding.<\/p>\n

Outbreeding<\/strong>\u00a0\u2013 involves the breeding of animals of the same or similar breeds, from completely different lines where traits are not necessarily similar.\u00a0 There are no ancestors in common.\u00a0 The desired physical traits are not necessarily maintained in the offspring.\u00a0 The genetic variation of the offspring is increased compared to that of the parents, thus reducing its coefficient of Inbreeding.<\/p>\n

Crossbreeding<\/strong>\u00a0\u2013 involves the breeding of animals of two different breeds; there are no ancestors in common.\u00a0 Neither the type of the paternal parent nor the type of the maternal parent is maintained in the offspring.\u00a0 The genetic variation of the offspring is increased compared to that of the parents, and its coefficient of inbreeding is reduced.<\/p>\n

[\/vc_column_text][\/vc_column][\/vc_row][vc_row][vc_column][vc_column_text]<\/p>\n

Pedigrees<\/h3>\n

\"\"<\/a>Pedigrees are the official record of the parentage and thus the ancestry of an animal.\u00a0 They are an integral part of the official record keeping required by a breed club to register new animals.\u00a0 Pedigrees are also a valuable resource for the genetics of an animal, whereby the genetic contribution of a particular ancestor can be estimated and the genetic relatedness of two individuals can be determined.\u00a0 As we will see, the pedigree is also used for determining inbreeding estimates for animals.<\/p>\n

Pedigrees are organized like the branches of a tree.\u00a0 In the standard format, the paternal contribution is presented above and the maternal contribution is presented below for the animal (offspring) in question.\u00a0 With each generation, the genetic contribution of a particular ancestor is divided by two.\u00a0 Thus, an animal (offspring) has 2 parents each of whom contributed 50% to the genetic constitution of their offspring and 4 grandparents each of whom contributed 25% to the genetic constitution of the offspring, and so on.\"\"<\/a><\/p>\n

Inbreeding<\/h3>\n

When two animals that share common ancestors are bred together, a condition of inbreeding exists in the offspring.\u00a0 This inbreeding has two consequences for the phenotype of the offspring:<\/p>\n

    \n
  1. Increased uniformity of \u201ctype\u201d<\/strong>(i.e. phenotype) within the offspring, with increased \u201cprepotency\u201d, i.e. the ability of parents to transmit or fix a phenotype in the next generation. This uniformity of type is desirable to breeders.<\/li>\n
  2. Inbreeding depression<\/strong>, which includes a reduction of vitality, reduced weight, reduced fertility, reduced rate of growth; increase rates of congenital anomalies, increased mortality, increased rates of recessive genetic diseases; a shortened life span.\u00a0 Inbreeding depressionis cumulative: with increased inbreeding and over time there is an increase in inbreeding depression.<\/li>\n<\/ol>\n

    \"\"<\/a>At the level of the genome, inbreeding has the effect of increasing the percentage of homozygous genetic alleles (N\/N<\/strong>, M\/M<\/strong>) and reducing the percentage of heterozygous genetic alleles (M\/N<\/strong>, carriers).\u00a0 Mutations that are recessive will accumulate in the homozygous state (M\/M<\/strong>), thus increasing the frequency of recessive genetic disease, which contributes to the deleterious effects of inbreeding depression. See\u00a0Horse Genetics 3.0 Simple Genetic Diseases<\/u>.<\/p>\n

    Stated simply, Mother Nature does not like uniformity, neither in phenotypes nor in genotypes.\u00a0 She much prefers variations, diversity and differences, for these are the motors of evolution.<\/p>\n

    A limited number of foundation animals, closed pedigree books for a purebred breed and the tendency to use only a fraction of animals within a breed as parents for the next generation (popular sire effect) all contribute to the reality that purebred horse breeds often represent a more or less inbred population of animals.<\/p>\n

    The Coefficient of Relation (a)\u00a0and the\u00a0Coefficient of Inbreeding\u00a0(COI)<\/h3>\n

    In 1921-22, Sewall Wright, an American mathematician and geneticist, defined two mathematical values based on a given genetic pedigree: the\u00a0Coefficient of Relation (a)<\/strong>\u00a0and the\u00a0Coefficient of Inbreeding<\/strong>\u00a0(COI<\/strong>, inbreeding coefficient or sometimes simply \u201cF<\/strong>\u201d).\u00a0 These two values are useful for the art and science of domestic animal breeding.\u00a0 Neither of these values represent specific DNA or genes of an animal.\u00a0 They are abstract values, calculated on the assumption that all of our genes follow simple mendelian genetics with dominant and recessive alleles (versions).\u00a0 This assumption is of course simplistic.\u00a0 In spite of this, the Coefficient of Relation and the Coefficient of Inbreeding have proven to be useful measures with practical applications for animal and plant breeders.\u00a0 They allow an estimation of the genetic relationship between two animals and also an estimation of the genetic variation (or lack thereof) found within the genome of a particular animal.\u00a0 With these measures, breeders can estimate the risks of having undesirable health effects (inbreeding depression) in future offspring and generations due to a lack of genetic variation caused by too much inbreeding.<\/p>\n

    \n

    The Coefficient of Relation (a)<\/strong>\u00a0is an estimation of the quantity of DNA that is in common between two animals within a pedigree.\u00a0 The simplest formula representing the coefficient of relation is as follows:<\/p>\n

    \"\"<\/a><\/p>\n

    Where:<\/p>\n

    a\u00a0= the Coefficient of Relation between two animals.<\/p>\n

    \u00bd = the genetic contribution of a parent towards its offspring.<\/p>\n

    n\u00a0<\/em>= the number of pathways (number of generations) that separate two animals within a pedigree.\u00a0 Stated differently,\u00a0n<\/em>\u00a0is the number of meiosis (cell division of sex cells) separating two animals. In other words, the number of times productive sex occurred between the ancestors (or descendants) of the two animals in question.<\/p>\n

    \u2211 = the sum of the calculations for all possible pathways linking the two individuals.<\/p><\/blockquote>\n

    This equation is derived from the fact that we (and our horses) are diploid, and that we have received half of our DNA from our mother and the other half from our father.\u00a0 The DNA of our parents was divided in two (1\/2) within their germ cells, and then added together (1\/2 + 1\/2) during fertilization to generate the full double (diploid) genetic complement (100% or 1.0) needed to form us and make us function.\u00a0 If two animals are not genetically linked then their Coefficient of Relation is 0.\u00a0\u00a0 On the other hand, if two animals are linked within a pedigree, their Coefficient of Relation will be higher than 0 and can be calculated.<\/p>\n

    <\/a>The Coefficient of Inbreeding\u00a0<\/strong>(COI<\/strong>, inbreeding coefficient, \u201cF<\/strong>\u201d) is an estimation of the loss of genetic variation for an individual animal, due to the fact of having a common ancestor on both the paternal side and the maternal side of its pedigree.\u00a0 The Coefficient of Inbreeding can be derived from the Coefficient of Relation by the following simple formula:<\/p>\n

    COI \u00a0= \u00a0(1\/2)\u00a0a \u00a0<\/em>= \u00a0(1\/2)\u00a0<\/strong>n+1<\/sup><\/em><\/strong><\/p>\n

    A more comprehensive presentation of the Coefficient of Inbreeding formula is as follows:<\/p>\n

    \"\"<\/a><\/p>\n

    Where:<\/p>\n

    F\u00a0= the Coefficient of Inbreeding (COI) for the individual in question.<\/p>\n

    \u00bd = the genetic contribution of a parent towards its offspring.<\/p>\n

    n\u00a0<\/em>= the number of pathways (number of generations) between a common ancestor and the individual in question.<\/p>\n

    +1 = an additional factor of (1\/2) is added to represent the anticipated loss of genetic diversity due to common ancestors on both maternal and paternal sides of the pedigree.<\/p>\n

    \u2211 = the sum of the calculations for each individual ancestor in common.<\/p>\n

    If the common ancestor has itself common ancestors, then the common ancestor will itself have a positive inbreeding coefficient value.\u00a0 The inbreeding coefficient for the animal in question is now multiplied by the following correction factor:<\/p>\n

    (1 + Fa)<\/strong><\/p>\n

    Where:<\/p>\n

    Fa = the Coefficient of Inbreeding for the ancestor in common.<\/p><\/blockquote>\n

    For intrepid souls, mathematical masochists, mad dogs and Englishmen, these formulas can get even more complex:<\/p>\n

    http:\/\/www.genetic-genealogy.co.uk\/Toc115570144.html<\/a><\/p>\n

    http:\/\/www.genetic-genealogy.co.uk\/Toc115570148.html<\/a>.<\/p>\n

    Examples of Coefficients of Relation and Coefficient of Inbreeding<\/h3>\n

    Here are some examples of Coefficients of Relation (once again, the average amount of shared DNA) between two parents without common ancestors, as well as the Coefficient of Inbreeding (measurement of loss of genetic diversity) for their hypothetical offspring:<\/p>\n\n\n\n\n\n\n\n\n\n\n\n
    Relationship<\/strong><\/td>\nCoefficient of Relation (a)<\/strong><\/td>\nCoefficient of Inbreeding (COI)<\/strong>
    \nof offspring<\/strong><\/td>\n<\/tr>\n
    Parent \u2013 child<\/td>\n50%<\/td>\n25%<\/td>\n<\/tr>\n
    Brother \u2013 sister<\/td>\n50%<\/td>\n25%<\/td>\n<\/tr>\n
    Grandparent \u2013 grandchild<\/td>\n25%<\/td>\n12.5%<\/td>\n<\/tr>\n
    Uncle\/aunt \u2013 nephew\/niece<\/td>\n25%<\/td>\n12.5%<\/td>\n<\/tr>\n
    Half brother \u2013 half sister<\/td>\n25%<\/td>\n12.5%<\/td>\n<\/tr>\n
    Cousins<\/td>\n12.5%<\/td>\n6.25%<\/td>\n<\/tr>\n
    Half-cousins<\/td>\n6.25%<\/td>\n3.125%<\/td>\n<\/tr>\n
    Second cousins<\/td>\n3.13%<\/td>\n1.063%<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

    For example, a child shares 50% of its genes with its parent, and the Coefficient of Relation (a) between the parent and child is 50%.\u00a0 The child has a Coefficient of Inbreeding of 0.\u00a0 However, the offspring resulting from an incestuous relationship between a parent and their child, or between a brother and sister, will have a Coefficient of Inbreeding of 25%.\u00a0 This means that, on average, there will be a 25% loss of genetic variation (loss of M\/N) and an equivalent 25% gain in genetic uniformity (gain in N\/N, M\/M) at the level of the offspring\u2019s DNA.\u00a0 In terms of human laws, marriages between cousins are generally permitted even if children resulting from such marriages will have a Coefficient of Inbreeding of 6.25%.<\/p>\n

    Inbreeding and the Loss of Genetic Diversity<\/h3>\n

    Once again, for a Coefficient of Inbreeding of 10%, this would mean that for genetic sites that are heterozygous (M\/N, carriers) in a common ancestor, there is a 10% chance that these sites will become homozygote (N\/N or M\/M) in the descendant.\u00a0 In other words, there is on average a 10% net loss of genetic diversity (or gain in genetic uniformity if you will) in the offspring due to matings involving inbreeding.\u00a0 A particular genetic site that has been converted from heterozygous (diversity) to homozygous (uniformity) in an offspring due to inbreeding is said to be\u00a0identical by descent<\/strong>\u00a0due to the common ancestor.<\/p>\n

    Pedigrees and the Coefficient of Inbreeding<\/h3>\n

    \"\"<\/a>How many generations of a pedigree should be considered when calculating the Coefficient of Inbreeding?\u00a0 The more generations that are available, the more reliable the calculation.\u00a0 Using a small number of generations tends to give coefficient values that are artificially low compared to values obtained when more generations are included.\u00a0 In practical terms, use all the pedigree information that is available.\u00a0 This could be as few as three generation or as many as all the generations in the pedigree going back to the founding animals for the breed.<\/p>\n

    Thanks to the power of the internet, many horse pedigrees are available on web sites dedicated to this purpose.\u00a0 Here are several examples:<\/p>\n

    http:\/\/www.allbreedpedigree.com<\/a><\/p>\n

    https:\/\/www.aqha.com<\/a><\/p>\n

    For a given animal, the known pedigree is presented, common ancestors are noted, and often inbreeding coefficients can be calculated for the known generations.\u00a0 A useful function for breeders is the ability to calculate and compare inbreeding coefficients for possible future breedings (\u201cvirtual<\/strong>\u00a0breeding<\/strong>\u201d function).<\/p>\n

    Using Inbreeding Coefficients for Breeding Decisions<\/h3>\n

    \"\"<\/a>Inbreeding coefficients, used correctly, are a powerful tool for breeders when it is the time to choose the parents of the future generation of horses. \u00a0In a general fashion, the inbreeding coefficient is an indication of the global state of genomic health of an animal.\u00a0 The genome is the sum total of all the genes that are necessary for the creation as well as the function of an animal.\u00a0 More specifically (as mentioned above), the inbreeding coefficient represents a numerical percentage, based on the analysis of a pedigree, that estimates the loss of genetic variation in an individual caused by the fact of having common ancestors on both the paternal and the maternal sides of the pedigree.\u00a0 \u00a0Having common ancestors on the two sides of the pedigree will result in a percentage of genetic sites that were heterozygous (M\/N) in the common ancestor to become homozygote (either N\/N or M\/M) in the descendant.\u00a0 This condition is known as being\u00a0identical by descent<\/strong>\u00a0due to the fact of having a common ancestor.<\/p>\n

    From the genetic perspective, a loss of genetic variability is undesirable as it can result in the condition of\u00a0inbreeding depression<\/strong>.\u00a0 Inbreeding depression has been well documented for many animal and plant species.\u00a0 Also well documented is the effect of outbreeding or crossbreeding, which will increase the genetic variation in the genome of an animal and result in\u00a0hybrid vigor<\/strong>\u00a0(heterosis).\u00a0 Hybrid vigor is the genomic flip side of inbreeding depression.<\/p>\n

    \"\"<\/a>It is important to keep in mind that the inbreeding coefficient does not represent the genetic variation that will be found at a specific genetic site or gene, but rather is a global estimation of genetic variation for the genome of an animal.\u00a0 If there are no common ancestors between the paternal side and the maternal side of a pedigree, the offspring will have no loss of genetic variation compared to a standard population.\u00a0 The offspring will then have an inbreeding coefficient of 0.\u00a0 If there are common ancestors on both the paternal and the maternal side of the pedigree, there is now the potential of loss of genetic variation (genetic identity by descent), and the potential for inbreeding depression.\u00a0 The Coefficient of Inbreeding is now a positive number greater than 0, often expressed as a percent.\u00a0 It is estimated that for every 1% increase in the inbreeding coefficient there is a 1% reduction in whatever trait is being measured.\u00a0 In practical terms the inbreeding coefficient is most useful for estimating the effects of recent inbreeding.<\/p>\n

    It is not surprising that Mother Nature likes genetic variation as this is the long-term key to the survival and evolution of a species.\u00a0 Unfortunately for our domestic animals, breed standards favor phenotypic uniformity (breeding for type<\/strong>), and in order to achieve this uniformity, a certain level of inbreeding and reduced genetic variation is involved.<\/p>\n

    Interpretation of Inbreeding Coefficients<\/h3>\n

    \"\"<\/a>An elevated inbreeding coefficient for an animal indicates that the undesirable effects of inbreeding (i.e. inbreeding depression) will start to be evident.\u00a0 On the other hand, an elevated inbreeding coefficient will increase the chances that desirable traits associated with the breed in question will be fixed.\u00a0 Thus, the inbreeding coefficient can be viewed as a compromise.\u00a0 The deleterious effects associated with inbreeding start to be seen when the coefficient of inbreeding is higher than 5%, which is just below the value obtained for the offspring of a mating between two cousins (=6.25%).
    \nIt is advised to maintain a coefficient of inbreeding that is below 10% which should allow a number of desired traits to be fixed without allowing the undesirable effects of inbreeding to become too pronounced.\u00a0 Incestuous crosses resulting in offspring with coefficients of inbreeding above 12.5% should not be performed; these include parent-offspring, brother-sister, grandparent-grandchild, half-brother-half-sister matings.\u00a0\u00a0 In practice it is recommended to choose crosses that will result in offspring that have reduced coefficients of inbreeding compared to the average of the breed in question.\u00a0 If a number of breeding possibilities are available that will reduce the average inbreeding coefficient in the offspring compared to the breed average, then ideally the breeding that will result in the lowest inbreeding coefficient while still maintaining the desired traits for the breed<\/em> is recommended.<\/p>\n

    [\/vc_column_text][\/vc_column][\/vc_row][vc_row el_class=”bloc_info”][vc_column][vc_column_text]
    \nIn general:<\/strong><\/p>\n

      \n
    1. Select a breeding pair that will reduce the coefficient of inbreeding in the offspring compared to the average of the breed.<\/strong><\/li>\n
    2. If possible, do not use an animal for breeding if it has common ancestors within its pedigree, at least not within the 3 to 4 most recent generations.<\/strong><\/li>\n
    3. Avoid incestuous breedings, with coefficients of inbreeding of 12.5% or greater.<\/strong><\/li>\n
    4. Try to keep inbreeding coefficients lower than 10%.<\/strong><\/li>\n
    5. Ideally, keep inbreeding coefficients lower than 5%.<\/strong><\/li>\n
    6. Think about sacrificing a bit of \u201ctype\u201d in an individual animal in order to increase the genomic health of your breed.<\/strong><\/li>\n<\/ol>\n

      [\/vc_column_text][\/vc_column][\/vc_row][vc_row][vc_column][vc_column_text]
      \nLink to       Inbreeding Calculator<\/a> provided by Labgenvet.<\/p>\n

      Link to Labgenvet’s page on Horse Genetics 4.1: Inbreeding Calculator, Detailed Instructions and Interpretation<\/a><\/p>\n

      \u00a9 2020 Dr. David W. Silversides[\/vc_column_text][\/vc_column][\/vc_row]<\/p>\n<\/div>","protected":false},"excerpt":{"rendered":"

      [vc_row][vc_column][vc_column_text] Horse Genetics 4.0: Evolution, Breeds, Breeding Strategies and Inbreeding   The Evolution of the Horse The horse (Equus ferus caballus) is a mammalian herbivore with post-gastric fermentation. It has uniparous reproduction. The horse is an ungulate meaning that it has hooves. The horse genome is comprised 2.4 billion base pairs organized into 32 pairs…<\/p>\n","protected":false},"author":1,"featured_media":0,"parent":0,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"_acf_changed":false,"footnotes":""},"class_list":["post-18094","page","type-page","status-publish","hentry","description-off"],"acf":[],"aioseo_notices":[],"_links":{"self":[{"href":"https:\/\/labgenvet.ca\/en\/wp-json\/wp\/v2\/pages\/18094","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/labgenvet.ca\/en\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/labgenvet.ca\/en\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/labgenvet.ca\/en\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/labgenvet.ca\/en\/wp-json\/wp\/v2\/comments?post=18094"}],"version-history":[{"count":76,"href":"https:\/\/labgenvet.ca\/en\/wp-json\/wp\/v2\/pages\/18094\/revisions"}],"predecessor-version":[{"id":24238,"href":"https:\/\/labgenvet.ca\/en\/wp-json\/wp\/v2\/pages\/18094\/revisions\/24238"}],"wp:attachment":[{"href":"https:\/\/labgenvet.ca\/en\/wp-json\/wp\/v2\/media?parent=18094"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}