Page 11 - Wairere 2021 Catalogue ebook

Scrotal Size EBV (cm) is calculated from the market targets, larger more positive values are generally
circumference of the scrotum taken between 300 and 700 more favourable.
days of age and adjusted to 400 days of age. This EBV
is an estimate of an animal's genetic merit for scrotal size. Docility EBV (%) is an estimate of the genetic differences
There is also a small negative correlation with age of between animals in temperament. Docility EBVs are
puberty in female progeny and therefore selection for expressed as differences in the percentage of progeny
increased scrotal size will result in reduced age at calving that will be scored with acceptable temperament (ie.
of female progeny. either “docile” or “restless”).

Days to Calving EBV (days) indicates the fertility of the Selection Indices There are currently two different
daughters of the sire. It is the time interval between the selection indexes calculated for New Zealand Angus
day when the female is first exposed to a bull in a paddock animals. These are Self-Replacing and AngusPure.
mating to the day when she subsequently calves. A Each selection index describes a different
negative EBV for days to calving indicates a shorter production/market scenario and relates to a typical
interval from bull-in date to calving and therefore higher commercial herd in New Zealand that is targeting the
fertility. following specifications.

Carcase Weight EBV (kg) is based on abattoir carcase Index values are reported as EBVs, in units of relative
records and is an indicator of the genetic differences in earning capacity ($’s) for a given market. They reflect
carcase weight at the standard age of 750 days. both the short-term profit generated by a sire through the
sale of his progeny, and the longer-term profit generated
Eye Muscle Area EBV (sq cm) is calculated from by his daughters in a self-replacing cow herd. More
measurements from live animal ultrasound scans and information is available on selecting animals using a
from abattoir carcase data, adjusted to a standard 400 kg selection index.
carcase. This EBV estimates genetic differences in eye
muscle area at the 12/13th rib site of a 400 kg dressed The Index values are derived using BreedObject
carcase. More positive EBVs indicate better muscling on technology. More information is available from the
animals. Sires with relatively higher EMA EBVs are BreedObject web site.
expected to produce better-muscled and higher
percentage yielding progeny at the same carcase weight Self-Replacing Index ($) - Estimates genetic differences
than will sires with lower EMA EBVs. between animals in net profitability per cow joined for a
self-replacing commercial herd, targeting the production
Rib Fat and Rump Fat EBVs (mm) are calculated from of grass finished steers. Steers are assumed marketed
measurements of subcutaneous fat depth at the 12/13-rib at 525 kg live weight (280 kg carcase weight and 10 mm
site and the P8 rump site (from live animal ultrasound fat depth) at 16 months of age.
scans and from abattoir carcases) and are adjusted to a
standard 400 kg carcase. These EBVs are indicators of AngusPure Index ($) – Estimates genetic differences
the genetic differences in fat distribution on a standard between animals in net profitability per cow joined for a
400 kg carcase. Sires with low, or negative, fat EBVs are self-replacing commercial Angus herd, targeting the
expected to produce leaner progeny at any particular production of grass finished steers for the AngusPure
carcase weight than will sires with higher EBVs. programme. Steers are assumed marketed at 525 kg live
weight (280 kg carcase weight and 10 mm fat depth) at
Retail Beef Yield EBV (%) indicates genetic differences 18 months of age with a significant premium paid for
between animals for retail yield percentage in a standard marbling.
400 kg carcase. Sires with larger EBVs are expected to
produce progeny with higher yielding carcases. Note that $Index values for individual animals are
sensitive to the assumptions used in the BreedObject
Intramuscular Fat EBV (%) is an estimate of the genetic analysis to calculate the selection index. More
difference in the percentage of intramuscular fat at the information is available on the weightings used in the
12/13th rib site in a 400 kg carcase. Depending on New Zealand Angus Selection Indices.