Page 5 - Lochburn Shorthorn Catalogue eBook.pdf

FOREWORD

400 days of age. This EBV is an estimate of an animal’s genetic merit for scrotal size. There is
also a small negative correlation with age of puberty in female progeny and therefore selection
for increased scrotal size will result in reduced age at calving of female progeny.
Days to Calving EBV (days) indicates the fertility of the daughters of the sire. It is the time
interval between the day when the female is first exposed to a bull in a paddock mating to the
day when she subsequently calves. A negative EBV for days to calving indicates a shorter
interval from bull-in date to calving and therefore higher fertility.
Carcase Weight EBV (kg) is based on abattoir carcase records and is an indicator of the
genetic differences in carcase weight at the standard age of 650 days.
Eye Muscle Area EBV (sq cm) is calculated from measurements from live animal ultrasound
scans and from abattoir carcase data, adjusted to a standard 300 kg carcase. This EBV
estimates genetic differences in eye muscle area at the 12/13th rib site of a 300 kg dressed
carcase. More positive EBVs indicate better muscling on animals. Sires with relatively higher
EMA EBVs are expected to produce better-muscled and higher percentage yielding progeny at
the same carcase weight than will sires with lower EMA EBVs.
Rib Fat and Rump Fat EBVs (mm) are calculated from measurements of subcutaneous fat
depth at the 12/13-rib site and the P8 rump site (from live animal ultrasound scans and from
abattoir carcases) and are adjusted to a standard 300 kg carcase. These EBVs are indicators
of the genetic differences in fat distribution on a standard 300 kg carcase. Sires with low, or
negative, fat EBVs are expected to produce leaner progeny at any particular carcase weight
than will sires with higher EBVs.
Retail Beef Yield EBV (%) indicates genetic differences between animals for retail yield
percentage in a standard 300 kg carcase. Sires with larger EBVs are expected to produce
progeny with higher yielding carcases.
Intramuscular Fat EBV (%) is an estimate of the genetic difference in the percentage of
intramuscular fat at the 12/13th rib site in a 300 kg carcase. Depending on market targets,
larger more positive values are generally more favourable.
COMPARING EBVs:

The EBVs for Beef Shorthorns can not be compared with EBVs for animals of another breed.
They should be compared with the current average EBVs for Australasian Beef Shorthorn
shown below.
2021 SHORTHORN BREEDPLAN AVERAGES
FOR 2019 BORN CALVES

DIR DTRS GL Birth 200 Wt 400 Wt 600 Wt McW Milk
+1.6 +1.3 -1.7 +2.9 +27 +38 +51 +44 +6
SS DtC CWT EMA Rib Rump RBY% IMF%
+1.5 -1.6 +34 +4.3 -0.2 -0.1 +0.9 +0.6

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