Breeding Worth provides farmers with an economic measure of genetic merit (profit per five tonne of dry matter) and is calculated for all dairy cattle. During a National Breeding Objective Review in 2012, BCS (particularly late lactation BCS) was identified as an important trait with economic value to farmers.
NZ Animal Evaluation Ltd (NZAEL), a wholly-owned subsidiary of DairyNZ, estimates the economic value of BCS to be $106 per BCS score. It was also determined that rates of genetic gain in BW would be enhanced by the inclusion of the BCS breeding trait. This view is supported by national and international review.
NZAEL manager Dr Jeremy Bryant says the economic value of BCS comes from two components.
“The first and main component is the increased value of a cow with good conditionmilking well into late lactation, rather than drying her off early because she is too thin.
“The second component is the reduced cost of a cow maintaining condition, as compared to a cow that loses condition in the spring, and as a result requires more feed through autumn or winter when it is more expensive.”
Dr Bryant says that both of these components are based on the value of increased body condition score in late lactation rather than early in lactation.
“With this in mind, it important that the breeding value for this trait represents genetic differences between animals in late lactation.
“Our studies showed there were minimal differences between breeds in late lactation BCS, especially between Friesians and Jerseys, and farmers often make decisions to dry off cows based on both BCS and breed. Because of this, the BCS breeding value will be breed neutral, so it is more aligned to a late lactation equivalent,” says Jeremy.
A ‘breed neutral’ adjustment will be applied to the breeding value and will come into effect in June 2015 and BCS will be included in the BW calculation from February 2016.
For further information visit www.dairynz.co.nz/bcs-bw.