Efficient use of genomic information for sustainable genetic improvement in small cattle populations

Jana Obšteter, Janez Jenko, John Hickey, Gregor Gorjanc

Research output: Contribution to journalArticlepeer-review


In this study, we compared genetic gain, genetic variation, and the efficiency of converting variation into gain under different genomic selection scenarios
with truncation or optimum contribution selection in a small dairy population by simulation. Breeding programs have to maximize genetic gain but also ensure
sustainability by maintaining genetic variation. Numerous studies have shown that genomic selection increases genetic gain. Although genomic selection
is a well-established method, small populations still struggle with choosing the most sustainable strategy to adopt this type of selection. We developed a simulator of a dairy population and simulated a model after the Slovenian Brown Swiss population with ~10,500 cows. We compared different truncation selection scenarios by varying (1) the method of sire selection and their use on cows or bull-dams, and (2) selection intensity and the number of years a sire is in use. Furthermore, we compared different optimum contribution selection
scenarios with optimization of sire selection and their usage. We compared scenarios in terms of genetic gain, selection accuracy, generation interval, genetic and genic variance, rate of coancestry, effective population
size, and conversion efficiency. The results showed that early use of genomically tested sires increased genetic gain compared with progeny testing, as expected from changes in selection accuracy and generation interval. A faster turnover of sires from year to year and higher intensity increased the genetic gain even further but increased the loss of genetic variation per year. Although
maximizing intensity gave the lowest conversionefficiency, faster turnover of sires gave an intermediate conversion efficiency. The largest conversion efficiency was achieved with the simultaneous use of genomically
and progeny-tested sires that were used over several years. Compared with truncation selection, optimizing sire selection and their usage increased the conversion efficiency by achieving either comparable genetic gain for a smaller loss of genetic variation or higher genetic gain for a comparable loss of genetic variation. Our results will help breeding organizations implement sustainable
genomic selection.
Original languageEnglish
JournalJournal of Dairy Science
Early online date30 Aug 2019
Publication statusE-pub ahead of print - 30 Aug 2019


  • Small population
  • Sustainability
  • Genomic Selection
  • Optimum Contribution Selection,


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