Page 8 - Ariki ebook

to 600 days and for age of dam. This EBV is the best single
estimate of an animal’s genetic merit for growth beyond
yearling 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 an estimate of the genetic difference in cow
weight at 5 years of age and is an indicator of growth at later
ages and potential feed maintenance requirements of the
females in the breeding herd. Steer breeders wishing to grow
animals out to a larger weight may also use the Mature Cow
Weight EBV.
Milk EBV (kg) is an estimate of an animal’s milking ability. For
sires, this EBV indicates the effect of the daughter’s milking
ability, inherited from the sire, on the 200-day weights of her
calves. For dams, it indicates her milking ability.
Scrotal Size EBV (cm) is calculated from the circumference
of the scrotum taken between 300 and 700 days of age and
adjusted to 400 days of age. This EBV is an estimate of an
animal’s genetic merit for scrotal size. There is also a small
negative correlation with age of puberty in female progeny
and therefore selection for increased scrotal size will result in
reduced age at calving of female progeny.
Days to Calving EBV (days) indicates the fertility of the
daughters of the sire. It is the time interval between the day
when the female is first exposed to a bull in a paddock mating
to the day when she subsequently calves. A negative EBV for
days to calving indicates a shorter interval from bull-in date to
calving and therefore higher fertility.
Carcase Weight EBV (kg) is based on abattoir carcase records
and is an indicator of the genetic differences in carcase weight
at the standard age of 750 days.
Eye Muscle Area EBV (sq cm) is calculated from
measurements from live animal ultrasound scans and from
abattoir carcase data, adjusted to a standard 400 kg carcase.
This EBV estimates genetic differences in eye muscle area at
the 12/13th rib site of a 400 kg dressed carcase. More positive
EBVs indicate better muscling on animals. Sires with relatively
higher EMA EBVs are expected to produce better-muscled and
higher percentage yielding progeny at the same carcase weight
than will sires with lower EMA EBVs.

Rib Fat and Rump Fat EBVs (mm) are calculated from
measurements of subcutaneous fat depth at the 12/13-rib site
and the P8 rump site (from live animal ultrasound scans and

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