Selection of Breeding Individuals

Breeders are  generally not particularly concerned about producing horses that are better adapted to survive in the wild - they are more   concerned with moulding the horse to have superior athletic performance and a certain phenotype to suit the desired job.

At the same time, it is extremely important for the benefit of the breed as a whole - not to lose sight of the objective to produce horses that are sound and free of genetic disorders.   

Geneticists stress that breeders must prioritise the health and betterment  of the breed as a whole  - rather than focusing  on the    individual  - to create spectacular and extravagent  performance animals. 

The excessive focus on popular sires is also a problem - it creates what is known as genetic bottlenecks - which leads to decreasing genetic diversity and the move toward certain phenotypical traits.

Mother nature does continue to take care of these issues with genetic variation, and recessive genes, as well as recombination and the inherent random nature of inheritance - but breeders still must be mindful of what they are selecting for  - because applying selection pressure over time on one or two features can end up changing certain conformation features  of the horse which may not be desirable for durability.

Soundness is even more important in sport horses for dressage, jumping and eventing, as these horses are not retired at 3, 4 or 5 from sport as racehorses  and often quarter horses are. 

Warmbloods and sport horses for GP dressage and jumping will take 10 and more years to reach the top tier of competition - and it is hoped they will compete well into their late teens and remain sound.   

As breeders we are trying to select horses for better athletic sport performance - but we must be just as mindful in selecting for soundness, longevity and temperament and to eliminate undesirable genes from the population

Temple Grandin did extensive research in livestock genetics and said "Breeding should prioritise functional long-term health over maximum single trait production.  Horses can suffer negative effects with over selection for both physical and behavioural traits.  White patches in paint horses, conformation and showjumping ability in warmbloods, conformation and speed in racehorses, cow cutting ability in quarter horses - are examples of single traits that when selected to the extreme can cause problems in other traits."

She advises against breeding for extremes and spectacular features and that breeders should find the optimal balance for soundness and health. Effectively this may mean not breeding to freakish young movers each year - it requires selection on a whole different level  and consideration as to what genes are being brought into the mix

What is the effect of continually selecting horses for freakish movement qualities and away from strong fundamentals?  With horses the results take years to be properly evaluated  -  it is  not like puppies or pigs where there are several offspring  to evaluate with short gestation time frames and much quicker growth rates

Temple Grandin says traits are linked in unexpected ways and that selecting for a particular trait can bring into play another trait that is not desirable  

"Overselection for one trait may have adverse or unexpected effects on other traits" (Lerner 1954)

It was observed that selecting for rapid growth and high lean meat yield in cattle happened to coincide with difficult to handle and excitable animals.

"Behaviour is a heritable trait that directly affects performance and safety"

In horses there are already certain bloodlines that are well known for being overly sensitive and highly anxious  - which also happen to bring forth superior sport talent with excellent movement.   We do not want to inadvertently bring in more difficult temperament issues as a result of heavily selecting for something like spectacular trots - or some other extreme feature.

What are the other possible consequences of selecting for trots where the knee comes up under the horse's chin? What conformation factors enable a horse to perform this? 

Could we end up changing the length of leg, the  shape of bone and joint angles,  or  selecting an unexpected trait for fragile shaped bones , or very lax pasterns and tendons, or problems possibly leading to neurological, muscular or spinal issues?

Long and lax pasterns may give impressive movement in a 3 yo but that same horse may be unsound at 5 years

We seem to be moving away from the fundamental basics of very strong correctly built horses in the quest for specularity and extreme movement. 

With top performance being the goal , breeders are sometimes being seen to overlook faults in the stallions  -  such as poor leg conformation and  stallions who have had  OCD and bone chips removed.   Stallions that are retired early from sport because of   'supposed ' injury  or from unsoundness,  are often selected as mates for mares.  Fertility is not particularly high on the list either - breeders will still breed to a stallion who has inferior semen quality because they feel they must use that  stallion -  all   in the hope of the foal inheriting the  superior sport talent. 

All these factors are moving away from what is best for the health of the breed as a whole, and can come at the expense of general soundness and athletic longevity

"Over selecting for spectacular traits or extreme factors such as conformation and movement can lead to negative side effects, increased lameness, reproductive failure and heart issues" Temple Grandin

It can also lead to horses that require regular veterinary management to remain sound, rather than being strong healthy creatures with correct fundamentals - and it results in higher rates of early retirement. 

In other livestock - animals with undesirable  traits would quickly be removed from the breeding herds

Breeding for sport performance  requires a series of complex genes all working together to create the ultimate  athlete - we do  need the genes for top performance which may unwittingly bring in unwanted dominant and recessive genes 

Breeders need to find a balance between the current trends of bigger and higher movement, with ethical and acceptable choices  for the health of the breed  - which also  strengthen their breeding programs long term