Page 6 - Fossil Creek 2021 ebook

BULL BUYERS

At Fossil Creek Angus we devote a lot of time to recording of weights at calving, weaning and yearling as well
as mature cow weights. We also use ultrasound scanning for fat cover, Rib Eye Area and Marbling in the Angus
herd. We do this to ensure that we provide you with the maximum accuracy possible for EBVs for 17 traits. It
pays to make sure that your bull breeder has that commitment.

NZ ANGUS TACE Birth Weight EBV (kg) is based on the measured birth weight of
progeny, adjusted for dam age. The lower the value, the lighter the
Understanding the EBVs, Selection Indexes and Accuracy calf at birth and the lower the likelihood of a difficult birth. This is
particularly important when selecting sires for use over heifers.
EBVs 200-Day Growth EBV (kg) is calculated from the weight of progeny
An animal’s breeding value is its genetic merit, half of which will be taken between 80 and 300 days of age. Values are adjusted to 200
passed on to its progeny. While we will never know the exact breeding days and for age of dam. This EBV is the best single estimate of an
value, for performance traits it is possible to make good estimates. animal’s genetic merit for growth to early ages.
These estimates are called Estimated Breeding Values (EBVs).
In the calculation of EBVs, the performance of individual animals 400-Day Weight EBV (kg) is calculated from the weight of progeny
within a contemporary group is directly compared to the average of taken between 301 and 500 days of age, adjusted to 400 days and
other animals in that group. A contemporary group consists of animals for age of dam. This EBV is the best single estimate of an animal’s
of the same sex and age class within a herd, run under the same genetic merit for yearling weight.
management conditions and treated equally. Indirect comparisons 600-Day Weight EBV (kg) is calculated from the weight of progeny
are made between animals reared in different contemporary groups, taken between 501 and 900 days of age, adjusted to 600 days and
through the use of pedigree links between the groups. for age of dam. This EBV is the best single estimate of an animal’s
EBVs are expressed in the units of measurement for each particular genetic merit for growth beyond yearling age.
trait. They are shown as + ive or - ive differences between an individual Mature Cow Weight EBV (kg) is based on the cow weight when the
animal’s genetics difference and the genetic base to which the animal calf is weighed for weaning, adjusted to 5 years of age. This EBV
is compared. For example, a bull with an EBV of +50 kg for 600-Day is an estimate of the genetic difference in cow weight at 5 years of
Weight is estimated to have genetic merit 50 kg above the breed age and is an indicator of growth at later ages and potential feed
base of 0 kg. Since the breed base is set to an historical benchmark, maintenance requirements of the females in the breeding herd. Steer
the average EBVs of animals in each year drop has changed over time breeders wishing to grow animals out to a larger weight may also use
as a result of genetic progress within the breed. the Mature Cow Weight EBV.
The absolute value of any EBV is not critical, but rather the differences Milk EBV (kg) is an estimate of an animal’s milking ability. For
in EBVs between animals. Particular animals should be viewed as sires, this EBV indicates the effect of the daughter’s milking ability,
being “above or below breed average” for a particular trait. inherited from the sire, on the 200-day weights of her calves. For
Whilst EBVs provide the best basis for the comparison of the genetic dams, it indicates her milking ability.
merit of animals reared in different environments and management
conditions, they can only be used to compare animals analysed within Scrotal Size EBV (cm) is calculated from the circumference of the
the same analysis. Consequently, NZ ANGUS BREEDPLAN EBVs scrotum taken between 300 and 700 days of age and adjusted to
cannot be validly compared with EBVs for any other breed. 400 days of age. This EBV is an estimate of an animal’s genetic merit
Although EBVs provide an estimate of an animal’s genetic merit for for scrotal size. There is also a small negative correlation with age
a range of production traits, they do not provide information for all of puberty in female progeny and therefore selection for increased
of the traits that must be considered during selection of functional scrotal size will result in reduced age at calving of female progeny.
animals. In all situations, EBVs should be used in conjunction with Days to Calving EBV (days) indicates the fertility of the daughters
visual assessment for other traits of importance (such as structural of the sire. It is the time interval between the day when the female
soundness, temperament, fertility etc). A recommended practice is is first exposed to a bull in a paddock mating to the day when she
to firstly select breeding stock based on EBVs and to then select subsequently calves. A negative EBV for days to calving indicates
from this group to ensure that the final selections are otherwise a shorter interval from bull-in date to calving and therefore higher
acceptable. fertility.
EBVs are published for a range of traits covering fertility, calving Carcase Weight EBV (kg) is based on abattoir carcase records and
ease, milking ability, growth, carcase merit and feed efficiency. When is an indicator of the genetic differences in carcase weight at the
using EBVs to assist in selection decisions it is important to achieve a standard age of 750 days.
balance between the different groups of traits and to place emphasis
on those traits that are important to the particular herd, markets Eye Muscle Area EBV (sq cm) is calculated from measurements from
live animal ultrasound scans and from abattoir carcase data, adjusted
and environment. One of the advantages of having a comprehensive
range of EBVs is that it is possible to avoid extremes in particular to a standard 400 kg carcase. This EBV estimates genetic differences
in eye muscle area at the 12/13th rib site of a 400 kg dressed carcase.
traits and select for animals with balanced overall performance.
Calving Ease EBVs (%) are based on calving difficulty scores, birth More positive EBVs indicate better muscling on animals. Sires with
relatively higher EMA EBVs are expected to produce better-muscled
weights and gestation length information. More positive EBVs are
favourable and indicate easier calving. and higher percentage yielding progeny at the same carcase weight
than will sires with lower EMA EBVs.
CE % Direct = Direct Calving Ease - The EBV for direct calving ease
indicates the influence of the sire on calving ease in purebred females Rib Fat and Rump Fat EBVs (mm) are calculated from measurements
calving at two years of age. 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
CE % Daughters = Daughters’ Calving Ease - The EBV for daughters’ are adjusted to a standard 400 kg carcase. These EBVs are indicators
calving ease indicates how easily that sire’s daughters will calve at of the genetic differences in fat distribution on a standard 400 kg
two years of age. carcase. Sires with low, or negative, fat EBVs are expected to produce
Gestation Length EBV (days) is an estimate of the time from leaner progeny at any particular carcase weight than will sires with
conception to the birth of the calf and is based on AI and hand higher EBVs.
mating records. Lower (negative) GL EBVs indicate shorter gestation Retail Beef Yield EBV (%) indicates genetic differences between
length and therefore easier calving and increased growth after birth.
6 Fossil Creek Bull Sale 2021