Inbreeding in Danish Dairy Cattle Breeds

Abstract

The purpose of this study was to monitor current and predict future rates of inbreeding in the Danish dairy breeds. Calves born from 1999 until 2003 and registered as Danish Holstein (1,883,983), Danish Jersey (336,966), or Danish Red (261,047) were reference populations. Average complete generation equivalent was approximately 7. For calves born in 2003, average inbreeding was 3.9, 3.4, and 1.4% for Holstein, Jersey, and Danish Red, respectively. In recent years, effective population sizes were 49, 53, and 47, respectively. Based on coancestry statistics, future effective population sizes will be 43, 42, and 51, respectively. The effective number of founders, effective number of ancestors, and effective number of founder genomes were calculated. These measures of genetic diversity were all low for Holstein and Jersey and somewhat larger for Danish Red. The most important ancestors of Danish Holstein were Elevation (13.8%), Chief (10.9%), and Bell (8.5%). The most important ancestor of Danish Red was Momentum (9.4%), a Red Holstein-Friesian. The most important ancestor for Danish Jersey was FYN Lemvig (12.1%) with a large number of progeny in the reference population. The results of this study indicate the necessity for active management of the rate of inbreeding in the future.

Genetic diversity of Guernsey population using pedigree data and gene-dropping simulations

“…The PCI of the GCN in this study was comparable to the values reported for Danish dairy cattle breeds, 94% on average (Sørensen et al, 2005). The GSA and GUS showed relatively lower completeness.…”

“…Similarly, an effective size of 47 in Canadian Jersey breed, in recent years (2003 to 2007) was reported (Stachowicz et al, 2011). Moreover, the effective population sizes of three Danish dairy breeds were within or below the range of 50 to 100 (Sørensen et al, 2005), which was mentioned to be the recommended size for livestock breeds. Small effective population size and an increasing inbreeding coefficient will lead to lower genetic diversity in the future.…”

“…In this study, the rate of inbreeding per year between 2002 and 2007 ranged from 0.16% in GSA to 0.19% in GCN population. Similarly, an increase in inbreeding per year of 0.18% to 0.22% in Danish dairy breeds (Sørensen et al, 2005) and of 0.23% and 0.15% in the Tunisian and Luxembourg Holstein populations were reported (Hammami et al, 2007), respectively. Moreover, comparable annual rates of inbreeding in US and UK Holsteins (0.20% and 0.17%, respectively) were reported (Wiggans, 1995;Kearney et al, 2004).…”

“…The parameters derived from the probabilities of gene origin precisely describe genetic diversity of populations after a small number of generations, although inbreeding coefficient and effective population size are important in monitoring diversity over longer periods of time (Boichard et al, 1997;Honda et al, 2004). Pedigree information has been commonly used in monitoring and evaluating the genetic diversity of various breeds based on effective population size and probabilities of gene origin (Lacy, 1989;Sørensen et al, 2005).…”

Evaluation of genetic variation in the international Brown Swiss population

“…The start of national genetic evaluations in many European countries dates back to the 1980s, which witnessed a rising rate of exchange of the genetic material. The effective population size of the Brown Swiss population from 1995 onwards was above the recommended effective population size, that is, between 50 and 100 animals (Food and Agriculture Organization of the United Nations, 1998; Bijma, 2003;Sorensen et al, 2005). It should be noted, however, that the recommended number was based on the assumption that natural selection cancels out inbreeding depression (Sorensen et al, 2005).…”