linebreeding and inbreeding

Alan Porter says " One constant in the pedigrees of top horses is the occurrence of linebreeding to superior ancestors and their near relatives."

Studies done by Clive Harper and Donald Lesh found that outstanding performers had a significantly higher percentage of inbreeding and linebreeding than lesser performed horses and to the breed in general - both to more instances of duplicated ancestors and sex balanced line breeding.  

LInebreeding has been the cornerstone of man made selective breeding and a central tool for reducing genetic variance in the foal - and fixing, retaining and amplifying top tier genetic traits in the  breeding of all  animals. 

It attempts to concentrate the genes of specific  superior ancestors to increase the likelihood of breeding a foal with the same superior characteristics and abilities

LInebreeding is where both parents have a duplicated ancestor in common  and the ancestor must be present on both sides of the pedigree.

 If the parents have related horses in common it maximises the chance that their valuable sport traits will appear in the foal by reinforcing the same DNA several times

It narrows the pedigree to a few closely related lines of descent - it is not about repeating just any name in the pedigree - it has to be a specific target that is a well established and reliable progenitor of sport talent, and be sound and sane  - and contribute toward your breeding goals in terms of ahtleticism, performance and conformation

 It is designed to focus the blood of specific ancestors with less risk than inbreeding 

Linebreeding is commonly done in the engine room of a pedigree   3 - 6th generation. 

Duplications may commonly appear as 4 x 4,  3 x 5,  4 x 5 ,  3 x 6, 

  6 x 5,   6 x 6.

With hybrid breeds like warmbloods we can include further generations if there are multiples of an ancestor with some duplications in the engine room. 

 This would mean duplications at 4  x 8 x 7 are still effective 

Linebreeding can overcome the dilution of important  ancestors that are fading  in later generations -

Genetic affinities and older proven nicks  need to be reinforced closer in so the same gene groupings and  genetic codes  can be created which  enables superior ancestors to transmit ability

Inbreeding is simply closer in - with the duplications of an ancestor appearing within the first three generations. It has been the number one tool for all breeders, especially in the early establishment of a breed  - it  is done to bring  about breed improvement - to get the best possible result from a mating and to upgrade foals.  It more rapidly  consolidates traits  and can help in establishing a certain  recognisable type as  well as  other desirable characteristics. 

It has the effect of  making  more pairs of genes homozygous and therefore more likely to be passed on. It is   very important to be incredibly selective of the individuals you are duplicating

On pedigrees it will appear as 1 x 2,  2 x 1,  1 x 3,  2 x 2,  2 x 3,  3 x 3,  2 x 4,  3 x 4.

Inbreeding can take different forms - it is not necessarily about breeding full and half siblings together which is a common misunderstanding. It can just be a simple sex balance of a bloodline within 3 generations

Landadel (Pedigree above) is 2 x 3 to Ladykiller via a son and daughter. He is an inbred stallion and this has helped him enormously in passing on his sport characteristics. 

Pik Konig is 1 x 4 to Pik As son and daughter. 

Franklin is  a very inbred sire. He is 3 x 2 to Ferro sex balanced

3 x 3 to two Flemmingh daughters - filly factor.

5 x 5 x 4 to Farn daughters - filly factor.

It is far more powerful to inbreed to sons and daughters of mares within 3 generations, particularly if it involves the falling tail dam line - the second, third or fourth dam.  

Sky diamond - GP horse is an example of this. He is 2 x 1 to son and daughter of the mare Loretta - the son being Sandro hit, the daughter being Loreana.

Capitol I is 3 x 2 to son and daughter of the mare Vase

United Touch is  1 x 1 to son and daughter of mare Cantate Touch

Inbreeding is certainly not for every mating - nor  every breeder.  It can create incredible sport horses and breeding stock whose influence lasts for generations.  It is a risk  -  It  can have potential downsides -  it should only be attempted by breeders who truly understand the issues and who have the superior animals to use for this.  

The simple fact is that most breeders   probably do not have  the mares for very close inbreeding to reinforce their own female  tail line - as in Sky Diamonds pedigree. 

The type of mare to breed back into  and reinforce her own falling dam line , are mares from top  families with alot of close relatives that have produced licensed sons, top sport horses and top broodmares . These are matings that create  a    sibling type  relationship in a part of the pedigree stemming from the mares own female line

Inbreedings which reinforce the tail female line of a mare are the most powerful matings of all - they will take advantage of any superior mtDNA and sex linked genes - but this requires  mares where it is possible to achieve this

Even though some breeders in Australia (and other countries) have imported mares from Europe, very few have mares from these super producing dam lines.  Imported mares are chosen largely on sire / dam sire and type, or because they are mare show winners -  rather than being purchased specifically for the attributes of their dam line. 

If a breeder is fortunate enough to have mares from this type of damline, then yes, inbreeding in this manner can be a good idea - if the parents are also outstanding Individuals. 

 It can certainly create the superstar performers  such as Kostolany , Quaterhit , United Touch, Sky Diamond,   Hilltop bugatti,  - and can certainly create super broodmares and stallions. 

It is about weighing risks - any method of selecting breeding -  linebreeding, inbreeding and outcrossing -  all carry the risk of undesirable recessive genes being expressed in roughly the same ratios. 

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For some breeders yes, the inbreeding  risk is worth it in the quest to breed the superior horse. It is important that some breeders  are willing to take risks in the name of breeding better horses and it is the best way to  create prepotent breeding stock.

It should only be attempted by breeders who understand how to put these type of matings together -  with careful thought and planning and keeping the next generations in mind. 

Inbreeding to get a super filly  or a stallion for breeding  -  should  be done to build up potency in a bloodline to get to the point where it needs an outcross mating . 

If a breeder has been following a program of linebreeding and inbreeding in some mares - it  will reach a point where only an outcross mating will bring the necessary improvement - and this is where the magic happens.

The art and science of breeding is knowing when to perform the outcross

Not all inbred matings require breeding to reinforce the female tail  line -  you can inbreed to any horse  just within the pedigree itself.

If your mare has Sandro Hit on the 2nd generation and you breed her to a stallion with Diamond Hit as grandsire,  then you will have a 2 x 2 inbreeding to the mare Loretta who is the dam of these brothers - see the dame of Hot Hit GP horse as an example.

Reinforcing siblings anywhere in a pedigree is a very powerful thing to do to increase the success of a mating

The  3 x 3  and 3 x 2  pedigree position can be excellent for sons and daughters of a particular superior sire - sex balanced line breeding -  or for daughters of a sire 

Examples are Franklin,  Boston, Chambertin,  Proud James,  Calido,  Graf,  Lordanos,  Falkland

similarly    3 x 2 - it is a powerful position for breeding stock to transmit superior characteristics also

Paul Shockemohle's mare Gesina is a great example of an inbred mare who can produce top horses to a variety of stallions including For Romance I and II.

She is 3 x 3 to Donnerhall and  3 x 2 to three quarter siblings Sandro Song and Gapo[by

Linebreeding is considered the safer bet in general for the average breeding wanting to upgrade the quality of their foals  -  it will still keep a higher percentage of genes from a particular ancestor to reinforce their superior traits - while maintaining more genetic diversity than inbreeding - it will  still produce foals that are more predictable in type and aptitude and still has the effect of making more pairs of genes homozygous. 

Full Siblings and closely related horses

Full siblings and three-quarter related horses have a far greater effect in pedigrees than any other type of ancestors.

Clive Harper said on siblings " Full siblings and three-quarter relatives in a pedigree bring performance class and set up the pedigree for success in sport and excellence in the breeding shed. Full and 3/4 siblings seem to be able to gather the strength from the past and bring it forward for utilisation in the current generation. They appear to give a higher probability of success to the mating."

The effect of close ancestors having more influence in a pedigree makes sense in that genes have a tendency to travel in tightly grouped clusters - therefore closely related horses with common ancestors have a higher chance of their genes travelling forward together - they are much more likely to pass on specific sets of genes and traits to foals.

This is caused by "linkage disequilibrium" - where genes close together on a chromosome tend to be inherited together 

Gene programming is inherited from the parents and also from dominant ancestors whose gene groupings travel down and remain together

Ken Mclean " Scientific research confirms the ability for certain gene groups to remain intact and able to be transmitted unchanged from generation to generation"

Linebreeding and inbreeding are ways of concentrating these clusters. They are more likely to have identical DNA segments and pass on a consistent more predictable set of genes .

 The foal is more likely to inherit the specific large chromosome blocks from these ancestors. 

This is why two parents who may be brilliant performers - but have nothing  in common in their bloodlines or are both loose genetic outcrosses - are far less likely to pass on their own great characteristics or produce successful progeny.

Popular Stallion Syndrome

Alot of the industry is suffering from popular stallion syndrome leading to an inbreeding depression of absolute saturation in Donnerhall and Sandro hit - and their sons and daughters

The Donnerhall / Pik Bube cross is also reaching saturation in many horses because it is being repeated in pedigrees via sons and daughters of this cross.

The same saturation is happening in other studbooks

If you have a pedigree with Don Schufro twice, Diamond Hit, Sunny Boy and Davignon then you have 5 siblings in the one pedigree and probably don't even know it - because you may only see one of these within 3 generations

An example could be - if you have a mare by Diamond Hit / Riverside / Sirocco / Sunny Boy - then you already have 4 crosses of the Donnerhall / PIk Bube cross.

If you then bring in a stallion like Sezuans Donnerhall - you will be at 3 x 3 bringing in 2 crosses of Don Schufro - who incidentally is a three-quarter brother to the same cross in the above stallions, all close up.

The resulting foal would have these three-quarter brothers 6 times within 6 generations - how many breeders would proceed with this mating if they were aware of this factor?

This is one advantage of studying pedigrees - you can actually see what patterns you may be setting into your foals

Horses that are inbred to these popular stallion lines will definitely need an outcross mating to avoid inbreeding depression. 

Read about Outcrossing next.