Estimation of Frequency for Recessive Genes Based on Known Ancestral Genotypes

Abstract Methods for estimating gene frequencies with known genotypes of "original parents" are presented. The "original parent" concept defines an independent set of ancestors from which all genes in an animal would have originated. A minimum estimate further was adjusted with an expected gene frequency among unknown ancestral genotypes. Expected gene frequencies depend on a probability some ancestral carriers are unknown and undetected. Example results are presented for recessive genes effecting abnormal phenotypes, Rectal-Vaginal Constriction and Limber Leg in the Jersey breed. Monitoring the occurrence of undesirable phenotypes caused by a recessive gene can facilitate development of breeding policies useful to breed improvement. Continuous and reliable reporting of abnormal progeny from identified parents is essential.