Symposium review: Exploiting homozygosity in the era of genomics-Selection, inbreeding, and mating programs

摘要

The advent of genomic selection paved the way foran unprecedented acceleration in genetic progress. Theincreased ability to select superior individuals has beencoupled with a drastic reduction in the generationinterval for most dairy populations, representing bothan opportunity and a challenge. Homozygosity is nowrapidly accumulating in dairy populations. Currently,inbreeding depression is managed mostly by culling atthe farm level and by controlling the overall accumulationof homozygosity at the population level. A betterunderstanding of how homozygosity and recessive loadare related will guarantee continued genetic improvementwhile curtailing the accumulation of harmful recessivesand maintaining enough genetic variability toensure the possibility of selection in the face of changingenvironmental conditions. In this review, we presenta snapshot of the current dairy selection structure asit relates to response to selection and accumulationof homozygosity, briefly outline the main approachescurrently used to manage inbreeding and overall variability,and present some approaches that can be usedin the short term to control accumulation of harmfulrecessives while maintaining sustained selection pressure.