Page 12 - Tarangower Angus Catalogue ebook
P. 12


       EBVS                                                   Whilst EBVs provide the best basis for the comparison of the genetic
       An animal’s breeding value is its genetic merit, half of which will be   merit of animals reared in different environments and management
       passed on to its progeny.  While we will never know the exact breeding   conditions, they can only be used to compare animals analysed within
       value, for performance traits it is possible to make good estimates.     the same analysis.  Consequently, TACE EBVs cannot be validly
       These estimates are called Estimated Breeding Values (EBVs).  compared with EBVs for any other breed.
       In the calculation of EBVs, the performance of individual animals within   Although EBVs provide an estimate of an animal’s genetic merit for
       a contemporary group is directly compared to the average of other   a range of production traits, they do not provide information for all
       animals in that group.  A contemporary group consists of animals   of the traits that must be considered during selection of functional
       of the same sex and age class within a herd, run under the same   animals.  In all situations, EBVs should be used in conjunction with
       management conditions and treated equally.  Indirect comparisons   visual assessment for other traits of importance (such as structural
       are made between animals reared in different contemporary groups,   soundness, temperament, fertility etc).  A recommended practice is to
       through the use of pedigree links between the groups.  firstly select breeding stock based on EBVs and to then select from
                                                              this group to ensure that the final selections are otherwise acceptable.
       EBVs are expressed in the units of measurement for each particular
       trait.  They are shown as + ive or - ive differences between an individual   EBVs are published for a range of traits covering fertility, calving
       animal’s genetics difference and the genetic base to which the animal   ease, milking ability, growth, carcase merit and feed efficiency.  When
       is compared.  For example, a bull with an EBV of +50 kg for 600-Day   using EBVs to assist in selection decisions it is important to achieve a
       Weight is estimated to have genetic merit 50 kg above the breed base   balance between the different groups of traits and to place emphasis
       of 0 kg.  Since the breed base is set to an historical benchmark, the   on those traits that are important to the particular herd, markets and
       average EBVs of animals in each year drop has changed over time as   environment.  One of the advantages of having a comprehensive
       a result of genetic progress within the breed.         range of EBVs is that it is possible to avoid extremes in particular traits
                                                              and select for animals with balanced overall performance.
       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.
   7   8   9   10   11   12   13   14   15   16   17