Page 5 - Blenheim 2021 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 (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.
      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.

                        BLENHEIM BULL SALE
   1   2   3   4   5   6   7   8   9   10