Recently we calculated the probabilities of several mating scenarios producing a homozygous recessive, assuming the test animal (invariably a male) is a carrier. As most recessive alleles are not wanted, the sooner a carrier can be identified, the sooner it can be culled from a breeding programme.
But knowing the odds aren’t quite enough — odds are an indicator and not a guarantee of outcome. By sheer luck a carrier may produce a homozygous recessive after just one mating. Or it could take three, or ten, or more, matings — it’s all down to the random assortment of alleles and which sperm fertilises which egg.
As well as knowing the odds, breeders also need to know how many matings are required to be confident that a tested animal isn’t a carrier. We need to know the level of confidence.
more »