Inbreeding & kinship

DIVERSITY TAKES US FURTHER

Welcome to the Inbreeding & Kinship page

Maintaining sufficient genetic diversity is an issue within breeding that is important to the studbook and its breeders. Because without diversity, no progress! We do this by keeping inbreeding and relatedness in the population low. What exactly does this mean and why is this important? This page addresses this matter and summarizes information about inbreeding and kinship. However, this page is still under development and will be added to in the near future.

The 2020 breeding plan already included a recommendation to conduct more research on inbreeding and kinship within the NWR section. The research was conducted in 2024 in consultation with the NWR/WPBR Breeding Technical Committee and is in its completion phase. Through various means, breeders have been kept informed of developments regarding this research and the theoretical basis behind inbreeding and kinship, for example presentations and articles in the Welsh Magazine. Meanwhile, the FTC will continue to work on measures to promote diversity.

As breeders, there is also a shared responsibility to bring the kinship down where possible and promote even use of stallions.

Inbreeding rate

In My Welsh, the Inbreeding Percentage is displayed for all ponies. Also, fictitious matings between animals can be tested to calculate the inbreeding percentage of the possible offspring. This result can be included in the choice of stallion for the mare.

What does this percentage mean?

The inbreeding percentage, often referred to as the inbreeding coefficient (F) is a measure of the degree of inbreeding in a population or individual. It is used in genetics to indicate the probability that an individual has inherited two identical copies of a gene from a common ancestor. In other words, how likely is it that an animal is homozygous for a gene by inheriting identical alleles.

The higher the inbreeding percentage, the greater the chance of inherited defects in the offspring. Importantly, inbreeding is not hereditary, so if two highly inbred animals are crossed, the offspring can still be low inbred. As long as the parents are not directly related. A rough rule of thumb is that an inbreeding percentage for an offspring should preferably remain below 5%.

Where is this in My Welsh?

When opening the details of an NWR pony, the animal's inbred% is listed.

The percentage of a potential offspring can be calculated under the heading “Selfservice actions” to > Inbreeding calculation. Here the mare can be searched and then a potential stallion. Then the inbreeding percentage of the future foal is displayed.

Kinship percentage

In addition to the inbreeding percentage, the kinship percentage is also an important trait for breeding. Recently, this percentage is also displayed in My Welsh for the Section NWR.

The kinship percentage indicates how much an animal is similar to the rest of the population, or in other words, how unique the pony is. If the percentage is low, then the bloodline is not common. The higher the kinship percentage, the more animals there will be with similar bloodlines. When the inbreeding rate in a population is high, using the animals with a low kinship percentage can help increase diversity.

Change with time

The inbreeding percentage is basically a given. However, the kinship percentage changes over time. This is because the population changes and therefore how much the animal resembles the population. If a stallion with low kinship is breeding a lot, his kinship will go up when the foals arrive. This is because there are then more animals with him and his ancestors in the lineage. In contrast, older animals will often slowly go down in terms of kinship as the population changes. Therefore, this percentage is recalculated every year and re-scaled into which kinship class it falls.

Where can I find the kinship percentage in My Welsh?

In My Welsh, the kinship percentage can be found when opening the details of a pony. For now, this can only be seen for animals in the NWR section. The percentage will show in which class it falls. The catalogs for inspections will also show this percentage for NWR animals.

The percentage of a potential offspring can be calculated under the heading “Selfservice actions” to > Inbreeding calculation. Here the mare can be searched and then a potential stallion. Then both the inbreeding percentage and the kinship percentage of the future foal are shown. The class is not visible here. This can be looked up in the table above.

What exactly does this mean?

It is important to note that these percentages say nothing about the quality of the animal. The conformation, movement, character, etc. are independent of this. These percentages give additional information about the animal or a potential offspring and it is wise to take this into account in breeding choices.

For example: make a top 5 of stallions that would suit the mare. Find out what the inbreeding and relationship percentage is. A high inbreeding percentage increases the risk of a foal with hereditary defects such as visible defects like hydrocephalus, but these can also be less visible defects such as less growth, less resistance, poorer fertility, etc.

The higher the kinship percentage, the less unique the foal will be. With this, the foal from one stallion may give a more interesting foal for breeding than from another stallion. How much this should be included in the consideration also depends on the later purpose of the pony. Especially if it will be used in breeding, kinship and inbreeding are important characteristics. This is how we keep the breed healthy in the long run.

If you want to delve further, read below

-Articles Welsh Magazine first, second

- Spring meeting presentation

–Electronic Breeding Textbook - Wageningen University & Research