Page 6 - Woodbank-Matariki ebook

EBVs EXPLAINED

An animal’s breeding value is its genetic merit, half of
which will be passed on to its progeny. While we will never
know the exact breeding value, for performance traits it is
possible to make good estimates. These estimates are called
Estimated Breeding Values (EBVs).

In the calculation of EBVs, the performance of individual
animals within a contemporary group is directly compared to
the average of other animals in that group. A contemporary
group consists of animals of the same sex and age class
within a herd, run under the same management conditions
and treated equally. Indirect comparisons are made between
animals reared in different contemporary groups, through
the use of pedigree links between the groups.
EBVs are expressed in the units of measurement for each
particular trait. They are shown as + ive or - ive differences
between an individual animal’s genetics difference and
the genetic base to which the animal is compared. For
example, a bull with an EBV of +50 kg for 600-Day Weight
is estimated to have genetic merit 50 kg above the breed
base of 0 kg. Since the breed base is set to an historical
benchmark, the average EBVs of animals in each year drop
has changed over time as a result of genetic progress within
the breed.
The absolute value of any EBV is not critical, but rather the
differences in EBVs between animals. Particular animals
should be viewed as being “above or below breed average”
for a particular trait.
Whilst EBVs provide the best basis for the comparison
of the genetic merit of animals reared in different
environments and management conditions, they can only be
used to compare animals analysed within the same analysis.
Consequently, TACE EBVs cannot be validly compared with
EBVs for any other breed.

Although EBVs provide an estimate of an animal’s genetic
merit for a range of production traits, they do not provide
information for all of the traits that must be considered
during selection of functional animals. In all situations,
EBVs should be used in conjunction with visual assessment
for other traits of importance (such as structural soundness,
temperament, fertility etc). A recommended practice is
to firstly select breeding stock based on EBVs and to then
select from this group to ensure that the final selections are
otherwise acceptable.

4 Woodbank Angus & Matariki Herefords Bull Sale 2021