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