Page 56 - Woodbank Matariki 2021 Catalogue ebook

UNDERSTANDING HEREFORD EBVS

CALVING EASE EBVS (%) are based on calving difficulty scores, birth weights and gestation
length information. More positive EBVs are favourable and indicate easier calving.
CE % DIRECT = Direct Calving Ease - The EBV for direct calving ease indicates the
influence of the sire on calving ease in purebred females calving at two years of age.
CE % DAUGHTERS = Daughters’ Calving Ease - The EBV for daughters’ calving ease
indicates how easily that sire’s daughters will calve at two years of age.
GESTATION LENGTH EBV (DAYS) is an estimate of the time from conception to the birth
of the calf and is based on AI and hand mating records. Lower (negative) GL EBVs indicate
shorter gestation length and therefore easier calving and increased growth after birth.
BIRTH WEIGHT EBV (KG) is based on the measured birth weight of progeny, adjusted for
dam age. The lower the value the lighter the calf at birth and the lower the likelihood of a
difficult birth. This is particularly important when selecting sires for use over heifers.
200-DAY GROWTH EBV (KG) is calculated from the weight of progeny taken between 80
and 300 days of age. Values are adjusted to 200 days and for age of dam. This EBV is the best
single estimate of an animal’s genetic merit for growth to early ages.
400-DAY WEIGHT EBV (KG) is calculated from the weight of progeny taken between 301
and 500 days of age, adjusted to 400 days and for age of dam. This EBV is the best single
estimate of an animal’s genetic merit for yearling weight.
600-DAY WEIGHT EBV (KG) is calculated from the weight of progeny 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 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 650 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 300 kg carcase. This
EBV estimates genetic differences in eye muscle area at the 12/13th rib site of a 300 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 from
abattoir carcases) and are adjusted to a standard 300 kg carcase. These EBVs are indicators
of the genetic differences in fat distribution on a standard 300 kg carcase. Sires with low, or
negative, fat EBVs are expected to produce leaner progeny at any particular carcase weight than
will sires with higher EBVs.
RETAIL BEEF YIELD EBV (%) indicates genetic differences between animals for retail yield

54 Woodbank Angus & Matariki Herefords Bull Sale 2021