Inbreeding and ALC

Inbreeding

At any form of breeding with related animals there is inbreeding. The degree of inbreeding is indicated by the coefficient of inbreeding. Just like humans, every animal has two copies of each gene, the animal received one copy from its father and the other one came from its mother. Or, in other words, half of the genes originate from the father and the other half from the mother. At inbreeding the risk of two identical genes increases. For example, if a brother and sister are crossed, there is a 25% chance that the animals transfer a similar gene to their offspring.

The coefficient of inbreeding indicates the percentage of the chance that the genes in both sets (the gene package of the father and the gene package of the mother) will be identical through descent. The coefficient of inbreeding is generally calculated over five generations using Wright's equation:

Fx=sum((1/2(n1+n2+1))X(1+FA))

Fx=the coefficient of inbreeding of animal x
n1=number of generations of parent 1 from x up to common parent
n2= number of generations of parent 2 from x up to common parent
FA=coefficient of inbreeding common parent

In case there are several common ancestors, the coefficients of inbreeding should be added together.

ALC ancestral loss coefficient

Apart from the coefficient of inbreeding, the ancestral loss coefficient, also known as ALC, is important in breeding. At determining the coefficient of inbreeding possible loss of genes in earlier generations is not taken into account. With the coefficient of inbreeding one just looks at common ancestors of the parents, so ancestors that are present both on father's as well as on mother's side. Ancestors that occur several times on just one side, are not included in the coefficient of inbreeding. Because of that one cannot give a complete picture of the genetic quality of a dog by just using the coefficient of inbreeding. The ALC indicates the predicted loss of genes and in that way inbreeding in earlier generations can be proved.

The ALC, called ancestor - , or ancestral loss coefficient, was developed by professor Schlegel of the University of Vienna. The Dutch abbreviation AVK derives from the German word 'Ahnenverlustkoeffizient'. In Dutch the expression 'ouderschapsverlieswaarde' or 'AVK-coëfficiënt' is used.

The ALC is calculated by dividing the number of unique ancestors by the total number of possible ancestors. Because of this, ancestors that occur several times on just one side of the pedigree, are also included in the calculation. Just like the coefficient of inbreeding, the ALC is generally calculated over five generations. A pedigree of five generations can include a maximum of 62 different ancestors (namely 2 parents, 4 grandparents, 8 great-grandparents, etcetera). In most cases the number of unique ancestors is less than 62, because animals of a particular line are used several times.

A calculation example:
In a pedigree of 5 generations there are 62 parent animals. Suppose that 2 dogs occur in the pedigree both on the side of the dog as well as on the side of the bitch. In that case there are 60 unique parent animals in the pedigree. 60 divided by 62, times 100% is 96.8%. We then say that the ALC is 96.8%. This percentage indicates that 3.2% of the gene variation (heterozygote) has got lost.

The closer the coefficient of inbreeding is to 0%, the better it is. The Nieuwlandsehof aims not to breed with a combination of parent animals if the coefficient of inbreeding exceeds 3.5 %. For the ALC applies: the higher the value, the healthier the pedigree. With regard to this the Nieuwlandsehof will not allow the value to drop below 85%.