Page 16 - Totaranui Angus Catalogue ebook
P. 16

ESTIMATED BREEDING VALUES



       EBVS EXPLAINED






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

       Calving Ease                                           400-Day Weight
       Calving Ease EBVs (%) are based on calving difficulty scores, birth   400-Day Weight EBV (kg) is calculated from the weight of progeny
       weights and gestation length information. More positive EBVs are   taken between 301 and 500 days of age, adjusted to 400 days and
       favourable and indicate easier calving.                for age of dam. This EBV is the best single estimate of an animal’s
                                                              genetic merit for yearling weight.
       CE % Direct = Direct Calving Ease
       CE % Direct = Direct Calving Ease - The EBV for direct calving   600-Day Weight
       ease indicates the influence of the sire on calving ease in purebred   600-Day Weight EBV (kg) is calculated from the weight of progeny
       females calving at two years of age.                   taken between 501 and 900 days of age, adjusted to 600 days and
                                                              for age of dam. This EBV is the best single estimate of an animal’s
       CE % Daughters = Daughters’ Calving Ease               genetic merit for growth beyond yearling age.
       CE % Daughters = Daughters’ Calving Ease - The EBV for
       daughters’ calving ease indicates how easily that sire’s daughters   Mature Cow Weight
       will calve at two years of age.                        Mature Cow Weight EBV (kg) is based on the cow weight when the
                                                              calf is weighed for weaning, adjusted to 5 years of age. This EBV is
       Gestation Length                                       an estimate of the genetic difference in cow weight at 5 years of
       Gestation Length EBV (days) is an estimate of the time from   age and is an indicator of growth at later ages and potential feed
       conception to the birth of the calf and is based on AI and hand   maintenance requirements of the females in the breeding herd.
       mating records. Lower (negative) GL EBVs indicate shorter gestation   Steer breeders wishing to grow animals out to a larger weight may
       length and therefore easier calving and increased growth after birth.   also use the Mature Cow Weight EBV.
       Birth Weight                                           Milk
       Birth Weight EBV (kg) is based on the measured birth weight of   Milk EBV (kg) is an estimate of an animal’s milking ability. For
       progeny, adjusted for dam age. The lower the value, the lighter the   sires, this EBV indicates the effect of the daughter’s milking ability,
       calf at birth and the lower the likelihood of a difficult birth. This is   inherited from the sire, on the 200-day weights of her calves. For
       particularly important when selecting sires for use over heifers.   dams, it indicates her milking ability.
       200-Day Growth                                         Scrotal Size
       200-Day Growth EBV (kg) is calculated from the weight of progeny   Scrotal Size EBV (cm) is calculated from the circumference of the
       taken between 80 and 300 days of age. Values are adjusted to 200   scrotum taken between 300 and 700 days of age and adjusted to
       days and for age of dam. This EBV is the best single estimate of an   400 days of age. This EBV is an estimate of an animal’s genetic merit
       animal’s genetic merit for growth to early ages.       for scrotal size. There is also a small negative correlation with age

        14                                                                                    TOTARANUI 2YR OLD BULL SALE
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