Breeding for a global dairy market using genomic selection

From the simulation of a closed nucleus breeding program for dairy cattle it was concluded that the introduction of genomic selection and the use of young animals as parents increased the rate of genetic gain by a factor 2.4 when genetic markers explained 50% of the genetic variance. In this situation, all bulls in the top 100 EBV list were young bulls. While genomic selection reduced the rate of inbreeding, the actual rate of inbreeding per year was increased by a factor 1.6 because of the use of young animals as parents. When a reference population was available in environment A but not in environment B, selection based on the average EBV in environment A and B was the most effective strategy when the genetic correlation between A and B was ¿0.90. When the genetic correlation between A and B was ¿0.75 the rate of genetic gain was lower across all strategies. Splitting the population gave the highest rate of genetic gain but also the highest rate of inbreeding.