Highland Pony Society SPARKS

1.      INTRODUCTION
The Highland Pony Society (‘the Society’) is adopting SPARKS to raise awareness and address inbreeding in the Highland Pony population. This is needed because inbreeding leads to loss of genetic diversity in the population. In turn, this threatens the health of individual horses and the health and sustainability of the breed as a whole, because it has the following consequences:

·       Increased infertility

·       Increased foal mortality (deaths)

·       Increased likelihood of harmful genes accumulating in the breed

·       Increases risk of inherited diseases and deformities

·       Reduced overall fitness of the breed and resistance to diseases

A powerful way of doing this is by managing ‘Mean Kinship’ through selection of mare/stallion pairings.

2.      WHAT IS SPARKS?
SPARKS is an advisory scheme that helps manage Mean Kinship and inbreeding. It is a computer programme that calculates Mean Kinships for every living pure-bred Highland Pony on the Highland Pony Grassroots Database, measuring how related any one pony is to all others. SPARKS also calculates the potential inbreeding of foals resulting from specific mare/stallion pairings.  Based on this analysis, SPARKS produces Kinship Tables for mares.

3.      HOW ARE KINSHIP TABLES USED?
The Kinship Tables give the ‘Co-ancestry Coefficient of Progeny’ for each stallion/mare pairing. This is the level of inbreeding that the resulting foal would have. The lower this coefficient, the less inbred the foal would be.

Using SPARKS is voluntary and intended to help mare owners to select a stallion. The Tables do not relate to the physical attributes of any mares, stallions or potential foals. Breeders should continue to use their own best judgement on this. The Tables are an additional tool to add genetic health to dam/sire pairing decisions.

To help interpretation of the Kinship Tables, the potential matings between mares and stallions are ranked into four Tiers. Tier 1 represents the genetic pairings that are encouraged while Tier 4 matings are those that should be avoided because of potential impact on the genetic health of the whole population.

It should be noted that the “tiering” is an assessment of the merit of pairing of two animals and is not an endorsement or criticism of the genetic makeup or quality of either of the individuals.

The Tiers are “traffic light” colour coded as follows:

TIER 1: The mare and stallion are from the same or an adjacent Kinship Band AND the mating would produce a foal of lower co-ancestry coefficient than the Mean Kinship of the Mare. These matings are said to be ‘SPARKS compliant’ and are coloured green in the Kinship Tables. THESE MATINGS ARE ENCOURAGED

TIER 2: The mare and stallion are from the same or an adjacent Kinship Band BUT the mating would result in a foal of higher co-ancestry coefficient than the Mean Kinship of the mare but still less than 0.1. These matings represent ‘The Best of the Rest’ and are coloured yellow in the Kinship Tables. THESE MATINGS ARE THE PREFERRED ALTERNATIVE IF A SPARKS COMPLIANT OR ‘GREEN’ MATING DOES NOT EXIST OR IS NOT DESIRABLE.

TIER 3: The mare and stallion are from widely differing Kinship Bands and Kinship Coefficients less than 0.1. These matings bring together genes in a way that puts less common genes at greater risk of loss. They are coloured orange in the Kinship Tables and ARE DISCOURAGED.

TIER 4: These matings, coloured red in the Kinship Tables, are highly inbred (resultant foal with a coefficient of 0.1 or above) and increase the probability of deleterious genes / harmful traits being expressed in future generations as well as accelerating the loss of genetic diversity. THESE MATINGS SHOULD BE AVOIDED.

Please note:

·       The traffic light colours are shown on the names of the stallions, but do not represent the level of inbreeding of the stallions themselves. They represent the level of inbreeding that the foal would have if the stallion was mated with the named mare.

4.      IMPORTANT NOTES ON USING THE KINSHIP TABLES
Kinship Tables are valid for one year only because the Highland Pony population, and therefore the kinship relationships within it, changes each year. Tables are therefore only valid for the year in which they are produced.

New tables are produced each year.

5.      CORRECTIONS AND ANOMALIES
The information in the Kinship Tables is only as good as the information in the Society’s Database (Grassroots), so the more up to date we can get Grassroots, the better the SPARKS data will be. Therefore, if you see a pony registered to you, in the Kinship Tables, that has died or identify a stallion who has been gelded, please follow the guidelines on the Society website regarding notification of Death of a Pony and Transfer to Gelding. Likewise, if you see information that is not or might not be correct about any pony, please let the office know.

6.      CONTACT DETAILS AND HELP
Mrs S Keron, Secretary

Garbh Allt House

Maidenplain Place

Aberuthven

Perthshire PH3 1 EL

Tel: 01764 664000

www.highlandponysociety.com

NB The data provided in this set of sheets is highly filtered from the SPARKS database and should not be taken as a true representation of the current HIGHLAND Pony population. As such it is not suitable for research purposes.

 

Q&A

See responses to questions raised after the seminar:

1. Where a Sire or Dam have common parentage how far back in the pedigree would you need to go before it would no longer be considered inbreeding? Or is it always inbreeding no matter how far back?And how will this affect Line breeding? Many breeders follow particular lines.

Where does line breeding stop and when does it become inbreeding – probably at about second cousin level i.e. 0.0625 We have set the SPARKS red line at 0.10 or 10% for the Highland Pony – i.e. quite a lot higher than 6.25%. Line breeding was what fixed the breed type, but eventually it can have negative effects by the accumulation of homozygosity and an increasing probability of deleterious traits manifesting themselves which outweigh the phenotypic benefits of continued linebreeding/inbreeding. Deleterious alleles can be purged under random mating but that is atypical of breeding practice in the highland pony.

2. Is there anything for stallion owners to look at see what there stallion are good with without searching all mares etc

The tables can be produced this way but are not available and would be very large documents and unwieldy to work with - this functionality maybe available via Grassroots when the SPARKS module is launched.

3. There are some matings that show as red but when I look at the pedigree there are not common ancestors in the recent pedigree. What else comes into the "red" calculation and how far back in a pedigree will result in a red?

The algorithm sums all repeats on both sides of a pedigree right back to the start of the electronic data – that could easily be 12 or more generations back - and maybe not visible in the 4 generations available in a Grassroots view of a pedigree.

4. What if my pony is "Red"

If foals are red that is not a problem – just more important that if they go on to breed themselves to try to avoid future red matings – i.e. break the chain. There will be green matings for animals that themselves were red matings. Foals that are the product of a red mating are not inferior or any less valuable than those of a green mating - remember - this is no reflection on the quality of the pony itself or the result of "irresponsible breeding"- this is an assessment of the ponies genetic make up in the context of the overall breed.