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UNDERSTANDING TRANSTASMAN ANGUS CATTLE EVALAUTION EBV

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

72 Earnscleugh 36th Annual Sale