Page 11 - Turiroa Angus Sale 2021 ebook

TRANSTASMAN ANGUS CATTLE EVALUATION EBVS

EBVS “above or below breed average” for a particular trait.
An animal’s breeding value is its genetic merit, half of which will be passed Whilst EBVs provide the best basis for the comparison of the genetic merit
on to its progeny. While we will never know the exact breeding value, for of animals reared in different environments and management conditions,
performance traits it is possible to make good estimates. These estimates they can only be used to compare animals analysed within the same
are called Estimated Breeding Values (EBVs). analysis. Consequently, TACE EBVs cannot be validly compared with EBVs
In the calculation of EBVs, the performance of individual animals within a for any other breed.
contemporary group is directly compared to the average of other animals Although EBVs provide an estimate of an animal’s genetic merit for a range
in that group. A contemporary group consists of animals of the same sex of production traits, they do not provide information for all of the traits that
and age class within a herd, run under the same management conditions must be considered during selection of functional animals. In all situations,
and treated equally. Indirect comparisons are made between animals EBVs should be used in conjunction with visual assessment for other traits
reared in different contemporary groups, through the use of pedigree links of importance (such as structural soundness, temperament, fertility etc).
between the groups. A recommended practice is to firstly select breeding stock based on EBVs
EBVs are expressed in the units of measurement for each particular trait. and to then select from this group to ensure that the final selections are
They are shown as + ive or - ive differences between an individual animal’s otherwise acceptable.
genetics difference and the genetic base to which the animal is compared. EBVs are published for a range of traits covering fertility, calving ease,
For example, a bull with an EBV of +50 kg for 600-Day Weight is estimated milking ability, growth, carcase merit and feed efficiency. When using EBVs
to have genetic merit 50 kg above the breed base of 0 kg. Since the breed to assist in selection decisions it is important to achieve a balance between
base is set to an historical benchmark, the average EBVs of animals in each the different groups of traits and to place emphasis on those traits that are
year drop has changed over time as a result of genetic progress within the important to the particular herd, markets and environment. One of the
breed. advantages of having a comprehensive range of EBVs is that it is possible
The absolute value of any EBV is not critical, but rather the differences to avoid extremes in particular traits and select for animals with balanced
in EBVs between animals. Particular animals should be viewed as being overall performance.