Breed­ing value cal­cu­la­tion changes afoot

Matamata Chronicle - - Rural Delivery -

Mata­mata dairy farm­ers need to be aware that liveweight breed­ing val­ues for dairy cat­tle change this month af­ter data analy­ses was car­ried out by NZ An­i­mal Eval­u­a­tion Limited (NZAEL), a wholly owned sub­sidiary of DairyNZ.

Changes to th­ese breed­ing val­ues and the flow-on ef­fects for the over­all mea­sure of cow and sire ge­netic merit, Breed­ing Worth ( BW), was im­ple­mented on Fe­bru­ary 16.

Th­ese im­prove­ments are fo­cused around the con­ver­sion of liveweight in­for­ma­tion into a ma­ture weight equiv­a­lent.

‘‘His­tor­i­cally this con­ver­sion has been done within the liveweight an­i­mal eval­u­a­tion model, but over time the in­for­ma­tion that we re­ceive has be­come heav­ily weighted to­wards data for two- year- olds, which skews the cal­cu­la­tion,’’ NZAEL Manager Dr Jeremy Bryant said.

The new method con­verts all weights to a ma­ture equiv­a­lent be­fore the data en­ters the liveweight an­i­mal eval­u­a­tion model.

‘‘The aim of the NZAEL re­search was to im­prove the ac­cu­racy of ge­netic pre­dic­tion for liveweight, which then leads to a more ac­cu­rate BW for dairy farm­ers,’’ he said.

The re­search has been un­der­taken over the past year and has been re­viewed by the Stand­ing Ad­vi­sory Com­mit­tee of NZAEL, which in­cludes lead­ing ge­neti­cists from New Zealand, and ap­proved by the NZAEL Board.

The ef­fect of this im­prove­ment to liveweight breed­ing val­ues will be seen across all an­i­mals but par­tic­u­larly when com­par­ing breeds. The liveweight breed­ing val­ues for jer­sey and cross­bred an­i­mals gen­er­ally de­crease, and those for hol­stein friesians in­crease.

The rou­tine up­dates of eco­nomic val­ues in BW also came into ary 16.

‘‘ NZAEL up­dates eco­nomic val­ues ev­ery year, in or­der to keep aligned with mar­ket sig­nals.’’

This year, mod­er­ate changes are seen in the value as­signed to fat and pro­tein yield.

Th­ese come from a com­bi­na­tion of a fall­ing milk price, as well as slight changes to the cal­cu­la­tion of milk vol­ume penal­ties and flow-on ef­fects for fat and pro­tein yield.

The com­bined ef­fect of the liveweight changes and eco­nomic value up­date mean that, on av­er­age, the BW of herds will re­duce.

‘‘ Farm­ers with pre­dom­i­nantly jer­sey dairy cat­tle will see a slight in­crease in herd BW and farm­ers with pre­dom­i­nantly hol­stein friesian dairy cat­tle should no­tice a de­crease in herd BW. Cross­bred herds will be in­ter­me­di­ate be­tween the two breeds,’’ Bryant said.

ef­fect on Fe­bru-

Photo: FAIR­FAX NZ

CHANGES: Liveweight breed­ing val­ues for dairy cat­tle change this month.

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