Page 10 - Beechwood, Richon & Woodburn Catalogue eBook.pdf

Rib and rump - Rib Fat and Rump Fat EBVs (mm) estimate the genetic differences in the fat depth at
the 12/13th rib and P8 sites respectively, adjusted to a standard 300kg carcase. More positive EBVs
indicate more subcutaneous fat on the carcase.
RBY% – Retail Beef Yield Percent EBV (%) represents total (boned out) meat yield as a percentage of a
300kg dressed carcase. A more positive EBV indicates higher percentage yield for the 300kg carcase size.
IMF % – Intra-muscular Fat Percent EBV (%) is an estimate of the genetic difference in the percentage
th
of intra-muscular fat at the 12/13 rib site in a 300kg carcase. Depending on target markets, larger
more positive values are generally more favourable.

Accuracy
ACC (%) - is based on the amount of performance information available on the animal and its close
relatives- particularly the number of progeny analysed. Accuracy is also based on the heritability of the
trait and the genetic correlations with other recorded traits. Hence accuracy indicates the “confidence
level” of the EBV. The higher the accuracy value the lower the likelihood of change in the animal’s EBV
as more information is analysed for that animal or it’s relatives.

Understanding Hereford Selection Indexes

Index values are reported as EBVs, in units of relative earning capacity ($) for a given market.
They reflect both the short-term profit generated by a sire through the sale of his progeny, and the
longer-term profit generated by his daughters in a self-replacing cow herd. A selection index combines
the EBVs with economic information (costs and returns) for specific market and production systems to
rank animals based on relative profit values. Note that different types of animals can give similar profit
values, so consideration should be given to both the index and the component EBVs when selecting
animals for a particular production system. More information is available on selecting animals using a
selection index.
The Index values are derived using BreedObject technology. More information is available from the
BreedObject web site.
Hereford Prime Index ($) - Estimates the genetic differences between animals in net profitability per
mixed age cow joined for a typical self-replacing commercial herd where Hereford bulls are joined to
either Hereford or other British breed females and targeting the production of grass finished steers for
the Hereford Prime program. Selected heifers are retained for breeding and so maternal traits are of
importance. Steers target 550 kg live weight (300 kg carcase weight & 7 mm P8 fat) at 20 months of
age, and heifers 475 kg (260 kg carcase weight & 8 mm fat depth), at 22 months of age.
Beef Heifer Index ($) - Estimates the genetic differences between animals in net profitability per yearling
heifer joined for a typical self-replacing commercial herd where Hereford bulls are joined to either Hereford
or other British breed heifers. Selected heifers are retained for breeding and so maternal traits are of
importance. Steers target 510 kg live weight (280 kg HSCW and 7 mm P8 fat depth) and heifers 450
kg ( 250 kg HSCW and 8 mm P8 fat depth) at 20 months of age.
Dairy Beef Index ($) - Estimates the genetic differences between animals in net profitability per mixed
age dairy cow joined with all progeny destined for slaughter. Steers and heifer progeny target 550 kg
live weight (300 kg carcase weight and 6 mm fat depth) at 24 months of age and at 475 kg live weight
(260 kg carcase weight and 7 mm fat depth) at 22 months, respectively.
Note that $Index values for individual animals are sensitive to the assumptions used in the BreedObject
analysis to calculate the selection index. More information is available on the weightings used in the
Hereford Selection Indices.

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