These results suggest that measurement of at least one adult expression would improve the
accuracy of selection for lifetime wool production and value. A companion paper in these
proceedings (Swan and Brown 2013) used the genetic parameters presented here and estimated the
trait and economic gains that can be achieved for various combinations of measurements across
ages and as well as incorporating genomic selection. These results confirm that recording at least
one adult assessment produced significantly greater trait and economic gain for both traits.
Furthermore genomic selection also increased the progress in both fleece weight and fibre
diameter.
Additional analysis of the breeding values of sires from these analyses shows that despite the
Proc. Assoc. Advmt. Anim. Breed. Genet. 20:110-103 112very high correlation between traits some sires have breeding values that either increase or
decrease over time. Thus breeders with concerns about changes in fleece value across age should
be encouraged to record annual fleece value traits. The genetic evaluation for Sheep Genetics will
be modified to include annual expressions of adult fleece traits.
These were preliminary analyses, so they ignored maternal effects (genetic and environmental),
genetic group effects and the effects of previous and current physiological state which are known
to affect wool production (Hinch et al. 1996; Huisman and Brown 2009). It is likely that
accounting for these effects would further improve the correlations between traits recorded across
different ages.
There is also a general lack of recording of liveweight at adult ages in the MERINOSELECT
database. With the increasing focus on mature weight of sheep due to maintenance costs, welfare
and occupation health and safety concerns this appears to be an opportunity for breeders to record
this trait and increase the focus on this trait in the breeding program.
It is significant to note that this industry data set was/is large enough, and contains sufficient
recording of fixed effects, to support very accurate genetic parameter estimation.
CONCLUSIONS
These preliminary estimates from industry data are consistent with those in the literature and
reconfirm that assessments made on young animals are good genetic predictors of adult
performance. However, genetic correlations do support the need for breeders to collect at least one
adult assessment. The adult expressions were all very highly correlated and can be treated as the
same trait genetically and support the model currently employed by Sheep Genetics. Additional
data and analyses are required to investigate other lifetime traits such as live weight, fertility and
wool quality traits.
ACKNOWLEDGMENTS
This research is funded by Meat and Livestock Australia and Australian Wool Innovation, and
Sheep Genetics is made possible through the support of the Australian sheep industry. The authors
acknowledge the contributions of the Sheep CRC Information Nucleus, the Australia Merino Sire
Evaluation Association and industry-funded research flocks.
These results suggest that measurement of at least one adult expression would improve theaccuracy of selection for lifetime wool production and value. A companion paper in theseproceedings (Swan and Brown 2013) used the genetic parameters presented here and estimated thetrait and economic gains that can be achieved for various combinations of measurements acrossages and as well as incorporating genomic selection. These results confirm that recording at leastone adult assessment produced significantly greater trait and economic gain for both traits.Furthermore genomic selection also increased the progress in both fleece weight and fibrediameter.Additional analysis of the breeding values of sires from these analyses shows that despite theProc. Assoc. Advmt. Anim. Breed. Genet. 20:110-103 112very high correlation between traits some sires have breeding values that either increase ordecrease over time. Thus breeders with concerns about changes in fleece value across age shouldbe encouraged to record annual fleece value traits. The genetic evaluation for Sheep Genetics willbe modified to include annual expressions of adult fleece traits.These were preliminary analyses, so they ignored maternal effects (genetic and environmental),genetic group effects and the effects of previous and current physiological state which are knownto affect wool production (Hinch et al. 1996; Huisman and Brown 2009). It is likely thataccounting for these effects would further improve the correlations between traits recorded acrossdifferent ages.There is also a general lack of recording of liveweight at adult ages in the MERINOSELECTdatabase. With the increasing focus on mature weight of sheep due to maintenance costs, welfareand occupation health and safety concerns this appears to be an opportunity for breeders to recordthis trait and increase the focus on this trait in the breeding program.It is significant to note that this industry data set was/is large enough, and contains sufficientrecording of fixed effects, to support very accurate genetic parameter estimation.CONCLUSIONSThese preliminary estimates from industry data are consistent with those in the literature andreconfirm that assessments made on young animals are good genetic predictors of adultperformance. However, genetic correlations do support the need for breeders to collect at least oneadult assessment. The adult expressions were all very highly correlated and can be treated as thesame trait genetically and support the model currently employed by Sheep Genetics. Additionaldata and analyses are required to investigate other lifetime traits such as live weight, fertility andwool quality traits.ACKNOWLEDGMENTSThis research is funded by Meat and Livestock Australia and Australian Wool Innovation, andSheep Genetics is made possible through the support of the Australian sheep industry. The authorsacknowledge the contributions of the Sheep CRC Information Nucleus, the Australia Merino Sire
Evaluation Association and industry-funded research flocks.
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