Page 9 - Monymusk Herefords Catalogue eBook.pdf

CARCASE WEIGHT EBV (KG) is based on abattoir carcase records SELECTION INDEXES
and is an indicator of the genetic differences in carcase weight at the
standard age of 650 days. New Zealand Herefords currently report three different selection
indexes. These are the Hereford Prime Index, Beef Heifer Index and
EYE MUSCLE AREA EBV (SQ CM) is calculated from the Dairy Beef Index. These Indices relate to typical commercial herds
measurements from live animal ultrasound scans and from abattoir in New Zealand targeting these specifications.
carcase data, adjusted to a standard 300 kg carcase. This EBV
estimates genetic differences in eye muscle area at the 12/13th rib Index values are reported as EBVs, in units of relative earning
site of a 300 kg dressed carcase. More positive EBVs indicate better capacity ($) for a given market. They reflect both the short-term
muscling on animals. Sires with relatively higher EMA EBVs are profit generated by a sire through the sale of his progeny, and the
expected to produce better-muscled and higher percentage yielding longer-term profit generated by his daughters in a self-replacing
progeny at the same carcase weight than will sires with lower EMA cow herd. A selection index combines the EBVs with economic
EBVs. information (costs and returns) for specific market and production
RIB FAT AND RUMP FAT EBVS (MM) are calculated from systems to rank animals based on relative profit values. Note
that different types of animals can give similar profit values, so
measurements of subcutaneous fat depth at the 12/13-rib site and the consideration should be given to both the index and the component
P8 rump site (from live animal ultrasound scans and from abattoir EBVs when selecting animals for a particular production system.
carcases) and are adjusted to a standard 300 kg carcase. These More information is available on selecting animals using a selection
EBVs are indicators of the genetic differences in fat distribution on index.
a standard 300 kg carcase. Sires with low, or negative, fat EBVs are
expected to produce leaner progeny at any particular carcase weight The Index values are derived using BreedObject technology.
than will sires with higher EBVs.
HEREFORD PRIME INDEX - Estimates the genetic differences
RETAIL BEEF YIELD EBV (%) indicates genetic differences between animals in net profitability per mixed age cow joined for a
between animals for retail yield percentage in a standard 300 kg typical self-replacing commercial herd where Hereford bulls are joined
carcase. Sires with larger EBVs are expected to produce progeny with to either Hereford or other British breed females and targeting the
higher yielding carcases. production of grass finished steers for the Hereford Prime program.
Selected heifers are retained for breeding and so maternal traits are
INTRAMUSCULAR FAT EBV (%) is an estimate of the genetic of importance. Steers target 550 kg live weight (300 kg carcase weight
difference in the percentage of intramuscular fat at the 12/13th rib & 7 mm P8 fat) at 20 months of age, and heifers 475 kg (260 kg
site in a 300 kg carcase. Depending on market targets, larger more carcase weight & 8 mm fat depth), at 22 months of age.
positive values are generally more favourable.
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