Quantifying genetic contributions to a dairy cattle population using pedigree analysis

Abstract

A variety of techniques were employed in the analysis of the change in genetic diversity of the UK Holstein–Friesian population over the last 30 years using the Holstein Friesian Society database (which has a base year of 1960). The parameters estimated were average inbreeding coefficient, average degree of relationship between cows, and two measures of genetic diversity, founder equivalent and founder ancestor number. The cow population was seen to change in founder origin from 96% British Friesian in 1967 to 24% British Friesian and 76% North American Holstein in 1997. The change in origin was seen to affect the rate of increase in inbreeding and to a lesser extent relationship, however the measures of genetic diversity were largely unaffected by the Holstein importation. In 1997 average relationship between cows had reached 1.34%, average inbreeding coefficient was 0.4% and the founder equivalent and founder ancestor number had converged at 93. The average inbreeding coefficient was seen to fall from 0.74% in 1982 to 0.38% in 1992 and to remain fairly constant up to 1997. The maternal structure of the cow population born in 1997 was also analysed. It was found that 93% of the cows were in maternal families of only one to four cows and only 0.5% of cows were in maternal families with more than 100 members, where a maternal family is a group of cows related only by maternal lineage.