Page 76 - Hereford Magazine 2021

trait influences profitability, and the economic value of NZ Herefords selection indexes
improving each trait.
The three selection indexes calculated for NZ Herefords
3. The BreedObject software then assesses what emphasis animals are:
needs to be applied to each EBV trait to achieve the • Hereford Prime Index
maximum profitability in the production system and • Beef Heifer Index
market end point that that index was designed for. • Dairy Beef Index

4. The importance placed on each EBV results in the index Each selection index describes a different production/
value that is calculated for each animal. market scenario and relates to a typical commercial herd
using Hereford bulls. Producers are advised to use the
Recent developments in the BreedObject software selection index that most closely aligns to their production
system. Each selection index is focused on efficient beef
Like Breedplan, research into improving the BreedObject production, including maternal traits where appropriate.
methodology is ongoing and recently a new version of the In addition, each selection index targets the following
BreedObject software has been made available by AGBU. New specifications.
developments in this version of the software include:
Hereford Prime Index
• Improved modelling of young animal growth. This includes: Estimates the genetic differences between animals in net
• Separate modelling for each sex rather than assuming profitability per cow joined for a typical self-replacing
there is a fixed difference between them. commercial herd where Hereford bulls are joined to either
• Revised modelling of feed requirements for young Hereford or other British breed females and targeting the
animals and how this changes with body composition/ production of grass-finished steers for the Hereford Prime
stages of growth. programme. Selected heifers are retained for breeding and
so maternal traits are of importance. Steers target 550kg live
• Improved modelling of cow weight and condition score weight (300kg carcass weight and 7mm P8 fat) at 20 months
throughout the year. This includes: of age, and heifers 475kg (260kg carcass weight and 8mm fat
• More advanced modelling of cow weight, and depth) at 22 months of age.
subsequently feed requirements, at times of year when
feed is in short supply and/or expensive. Typically Beef Heifer Index
in New Zealand this is during the winter when grass Estimates the genetic differences between animals in net
growth slows or stops and cow feed requirements are profitability per heifer joined for a typical self-replacing
increasing due to cold and pregnancy. commercial herd where Hereford bulls are joined to either
• Inclusion of cow condition score and production Hereford or other British breed heifers. Selected heifers
penalties for cows outside of optimum condition (e.g. are retained for breeding and so maternal traits are of
too lean or too fat, affecting milking ability and/or importance. Steers target 510kg live weight (280kg HSCW and
fertility). 7mm P8 fat depth) and heifers 450kg (250kg HSCW and 8mm
• Revised methodology for valuing cows when culled. P8 fat depth) at 20 months of age.
This allows for variation in sale weight and value
between cows culled for various reasons (e.g. cast for Dairy Beef Index
age, reproductive failure, poor condition, etc.). Estimates the genetic differences between animals in
net profitability per dairy female joined with all progeny
• Enhanced modelling of carcass market specifications destined for slaughter. Steers and heifer progeny target
and values. 550kg live weight (300kg carcass weight and 6mm fat depth)
• This includes the ability to handle non-linear price at 24 months of age, and at 475kg live weight (260kg carcass
structures like beef schedules that penalise both too weight and 7mm fat depth) at 22 months, respectively.
lean and too fat carcasses, and/or those that penalise
under and overweight carcases. All selection indexes are reported as an EBV, in units of
net profit per cow mated ($) for a given production/market
These developments have changed how EBVs are valued in scenario. They reflect both the short-term profit generated by
selection indexes. In particular, the enhanced modelling of cow a sire through the sale of his progeny, and the longer-term
weight increases the impact that total cow feed costs (i.e. length profit generated by his daughters in a self-replacing cow herd
of feeding + feed price + feed quality) have on the profitability (where applicable).
of the represented production systems. This means that the All selection index values have been derived using
new software can construct indexes that can be tailored to the BreedObject technology. More detailed information regarding
different production environments that are found across New each selection index can be accessed through the NZ
Zealand where variation in cow feed costs exist. Herefords website.

If you have any further queries regarding the New Zealand
Hereford selection indexes, please contact the NZ Herefords
general manager or a member of the technical committee.

74 HEREFORD MAGAZINE Year 2021