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Inbreeding, AVK, and kinship

Before breeding, you want to know how animals are related to each other. But what is the difference between inbreeding coefficient, relatedness and AVK? What is inbreeding and the meaning of inbred? And what is the meaning of related and kinship?

What is AVK?

AVK is a German term. It stands for AhnenVerlust-Koeffizient, or ancestry loss. Here we look at how many ancestors appear twice in a family tree of five generations. If every ancestor is unique, then the AVK is 100%. But has there been linebreeding in the past, then the value is lower. If all five generations are complete, there are 62 animals in the pedigree. If 2 animals are duplicated in the pedigree, there are 62-2 = 60 unique animals left. The calculation is 60 divided by 62, times 100 percent. The AVK is then 96.77%.

If the AVK is less than 100% there is always inbreeding in an animal's pedigree, but you cannot tell whether this is inbreeding from the animal itself or from one or more of its ancestors. Therefore, the AVK of an animal is not directly related to its inbreeding coefficient.

What is kinship?

Kinship indicates the extent to which two animals are genetically similar. When two parent animals have children, they each pass 50% of their genes to the young animal. Thus, the animal is 50% related to its father and 50% related to its mother. The genes are passed on generation to generation. The relationship coefficient is calculated by ZooEasy based on the pedigree. The percentages below apply if the parents are not related to each other. If they are, the percentages are higher:

  • Identical twins: 100%
  • Full siblings: 50%
  • Animal and older: 50%
  • Half-brothers and half-sisters: 25%
  • Animal and grandparent: 25%
  • Uncle or aunt and cousin: 25%
  • "Double" cousin or niece: 25%
  • "Single" cousin: 12.5%
  • Animal and great-grandparent: 12.5%
  • No family relationship: 0%

In a double cousin, the fathers are full brothers and the mothers are full sisters. In the case of a single cousin, two of the four parents are full brothers or sisters.

What is inbreeding?

Inbreeding occurs when two related animals (see kinship) are bred to each other. In other words, if the father and mother are related, the offspring is inbred. Mammals and birds have two strands of DNA, so each gene comes in pairs. Human DNA consists of about 40,000 gene pairs. Of each gene pair, one gene comes from the father and the other from the mother. The inbreeding coefficient is the probability that both parents pass on the exact same gene to their offspring. So the inbreeding coefficient calculates how likely it is that the animal actually passes on two exactly the same genes from both parents. That is the meaning of inbreeding.

Meaning inbreeding coefficient

  • 0 = no inbreeding
  • 0.25 = arises, for example, when a full brother and sister are bred to each other
  • 1 = complete inbreeding: every gene pair is equal

Source: Dr. P. Bijma, Chair Group of Breeding and Genetics, Wageningen University & Research