Genomic selection has aided Nordic Jersey to decrease risks of inbreeding

Saija Riitta Tenhunen*, Jørn Rind Thomasen, Lars Peter Sørensen, Peer Berg, Morten Kargo

*Corresponding author for this work

Research output: Contribution to conferenceConference abstract for conferenceResearchpeer-review

Abstract

Recently, many dairy cattle populations across the world have demonstrated a rapid increase in inbreeding which may
lead to inbreeding depression. The main reasons for this have been reported to be the changes in breeding practices
due to genomic selection (GS). This research aimed to identify and study past events which have influenced the rate
of inbreeding (ΔF) and coancestry (ΔC) in the Nordic Jersey (NJ) population. Retrospective analysis was performed
of 99,083 NJ animals with pedigree information and 41,896 SNP imputed genotypes. Animals were divided into two
groups: before (2009-2014) and after (2015-2021) GS implementation in the NJ population. Pedigree (PED) was
used to calculate yearly ΔF and ΔC and runs of homozygosity (ROH) was used to calculate genomic ΔF where shared
segments (SEG) between pairs were used to calculate genomic ΔC. Effective population size (Ne) was calculated
from ΔF and ΔC was used to calculate future effective population size (FNe) for each animal group. The yearly
average generation interval (L) decreased from 4.7 to 3.2 after GS. PED ΔF was at the same level before and after GS,
but there was a distinct increase in ROH ΔF from 0.0035 to 0.0052. PED ΔC had decreased from 0.0031 to 0.0017
between the periods and no changes in SEG ΔC were seen. Ne PED increased from 32 to 55 and Ne ROH was 30
in both periods. FNe PED increased significantly after GS implementation from 34 to 91, and FNe SEG saw a more
moderate increase from 41 to 57. Increases in Ne ROH and FNe SEG were mainly caused by a decrease in L between
the periods. From the yearly estimates we could identify a period before GS when ΔC increased rapidly in the NJ. In
this period, heavy use of related sires was observed. This may explain the increased ΔC in the population which may
have caused the higher ΔF after GS. Ne is currently on the increase in the NJ population and FNe indicates that this
trend will continue in the coming years. In conclusion, GS seems to have been instrumental in decreasing the risk for
inbreeding depression now and in the future.
Original languageEnglish
Publication date2023
Number of pages1
Publication statusPublished - 2023
Event
74th Annual Meeting of European Federation of Animal Science
- Lyon, France
Duration: 26 Aug 20231 Sept 2023
Conference number: 74

Conference

Conference
74th Annual Meeting of European Federation of Animal Science
Number74
Country/TerritoryFrance
CityLyon
Period26/08/202301/09/2023

Keywords

  • inbreeding
  • coancestry
  • dairy cattle
  • jersey

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