Page 5 - Ranui Angus Sale Catalogue eBook
P. 5


      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
      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
      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.
      EBVs are published for a range of traits covering fertility, calving
      ease, milking ability, growth, carcase merit and feed efficiency.  When
      using EBVs to assist in selection decisions it is important to achieve a
      balance between the different groups of traits and to place emphasis
      on those traits that are important to the particular herd, markets and
      environment.  One of the advantages of having a comprehensive
      range of EBVs is that it is possible to avoid extremes in particular
      traits and select for animals with balanced overall performance.
      Calving Ease EBVs (%) are based on calving difficulty scores, birth
      weights and gestation length information.  More positive EBVs are
      favourable and indicate easier calving.
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