Page 6 - Waiterenui 2020
P. 6


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

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