Symposium review: Genomic selection for reducing environmental impact and adapting to climate change

摘要

The world has been warming as greenhouse gases accumulate.Worldwide from 1880 to 2012, the averagesurface temperature has increased by about 0.85°C andby 0.12°C per decade since 1951. The world’s cattlepopulation is a contributor to atmospheric methane,a potent greenhouse gas, in addition to suffering fromhigh temperatures combined with humidity. This makesresearch into reducing the global footprint of dairy cowsof importance on a long-term horizon, while improvingtolerance to heat could alleviate the effects of risingtemperatures. In December 2017, genomic estimatedbreeding values for heat tolerance in dairy cattle werereleased for the first time in Australia. Currently, heattolerance is not included in the Balanced PerformanceIndex (Australia’s national selection index), and thecorrelation between heat tolerance breeding values andBalanced Performance Index is −0.20, so over time,heat tolerance has worsened due to lack of selectionpressure. However, in contrast, sizable reductions ingreenhouse gas emissions have been achieved as a favorableresponse to selecting for increased productivity,longevity, and efficiency, with opportunities for evengreater gains through selecting for cow emissions directly.Internationally considerable research effort hasbeen made to develop breeding values focused on reducingmethane emissions using individual cow phenotypes.This requires (1) definition of breeding objectivesand selection criteria and (2) assembling a sufficientlylarge data set for genomic prediction. Selecting for heattolerance and reduced emissions directly may improveresilience to changing environments while reducing environmentalimpact.